Venkata Narasimham Nori- Unsteady Flow in a Mixed-Compression Inlet at Mach 3.5
Transcript of Venkata Narasimham Nori- Unsteady Flow in a Mixed-Compression Inlet at Mach 3.5
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UNSTEADY FLOW IN A MIXED-COMPRESSION INLETAT MACH 3.5
By
VENKATA NARASIMHAM NORI
A THESIS PRESENTED TO THE GRADUATE SCHOOLOF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE
UNIVERSITY OF FLORIDA
2003
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Copyright 2003
by
Venkata Narasimham Nori
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To the One and only One.
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ACKNOWLEDGMENTS
I would like to sincerely thank Dr. Corin Segal for providing me this opportunity
and guiding me carefully on this path. Without his advice and incredible patience, this
work would not have been possible. I would like to thank Dr. David Mikolaitis and Dr.
Bruce Carroll for their advice and valuable suggestions to improve the quality of work.
This work was supported both by the Office of Naval Research with Dr. Gabriel
Roy as the technical monitor, and NASA Glenn Research Center under the supervision of
Rene Fernandez.
I would like to thank Jonas for helping me so much in virtually all stages of this
work. It was a great pleasure learning from him that with patience, perseverance and
enthusiastic attitude any problem is surmountable. His wit and sense of humor restored
tranquility amidst a raging storm and maintained poise in the lab.
Then there is Nelson who was adept in solving practical problems of any kind.
Without him, the sting support would have bent and the model would have had hundreds
of test flights in the wind tunnel! He modified Nike’s punch line to “Don’t think! Just Do
It” which made us rapidly converge to a working experimental setup. I am happy to have
worked with such a cheerful and pragmatic guy.
Abhilash demonstrating the “shocking truth” whenever he ran a test, Danny
fiddling with his Scram “jet set” facility and Jayanth figuring out ways to detect “leaks”
using mass spectrometer also contributed in maintaining the tempo of the group.
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I thank Sudarshan for sharing his experiences and also suggesting ways to
troubleshoot some problems. I sincerely thank Ron Brown for his timely suggestions and
neat fixes in times of calamities, the climax being a clever temporary solution for the
Wind Tunnel. He was always eager to help and always enquired about the progress of the
project. I thank Ken Reed for his brilliant machinist skills and professionalism without
which the models would not be so good.
My heartfelt thanks go to Srikanth (SV) who has taken the pains to wake me up
every day, early in the morning making a long distance call. With encouraging words and
thoughts of strength, he recharged my batteries.
I am grateful to my roommates Gopal, Saurav and Archit who were very
understanding and supportive. Laudable are their efforts to adjust and accommodate a
guy like me. Thanks to their enthusiasm, I had sumptuous food at the end of the day.
They always offered a lending hand whenever I was troubled and confused.
I thank Priya kutti and Jose for their encouragement and their concern about the
progress of the project.
A million thanks go to Charan, Anand, Sasidhar, Sai Shankar, Naveen, Chakri,
Sriram, Sai Krishna, Anurag, Rax, Hari, Ryan, Quentin, Weizhong, Amith, Sujith, Balaji,
Bolt, Ahmed, Sampath and many more. Last but not least, cheers go to the people of
gatorland who by their friendly smiles kept me in “high spirits,” making my stay in
Gainesville a very enjoyable and memorable experience.
Really speaking, these words are still insufficient to convey my heartfelt wishes to
all the people mentioned above.
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TABLE OF CONTENTS
page
ACKNOWLEDGMENTS ................................................................................................. iv
LIST OF TABLES........................................................................................................... viii
LIST OF FIGURES ........................................................................................................... ix
LIST OF OBJECTS ........................................................................................................... xi
ABSTRACT...................................................................................................................... xii
CHAPTERS
1 INTRODUCTION ...........................................................................................................1
1.1 Review of Relevant Literature on Inlet Flow Oscillations ....................................... 21.2 Motivation for Current Study.................................................................................... 8
1.2.1 A New Engine Concept-Pulse Detonation Engine.......................................... 8
1.2.2 Intent and Scope of Work ............................................................................. 11
2 EXPERIMENTAL SETUP............................................................................................12
2.1 Introduction............................................................................................................. 12
2.2 Basic Inlet Geometry .............................................................................................. 12
2.3 Backpressure Excitation Mechanism...................................................................... 172.4 Description of the Wind Tunnel ............................................................................. 22
2.5 Instrumentation ....................................................................................................... 24
2.6 Schlieren Setup ....................................................................................................... 26
2.7 Oil Flow Visualization............................................................................................ 26
3 RESULTS ......................................................................................................................28
3.1 Introduction............................................................................................................. 283.2 Flow Field Inside the Inlet ...................................................................................... 28
3.2.1 The Supersonic Inlet ..................................................................................... 28
3.2.2 The Supercritical Inlet................................................................................... 293.3 Preliminary Calibration........................................................................................... 30
3.4 Static and Stagnation Pressure Measurements........................................................ 31
3.4.1 Effects of Injection Configuration ................................................................ 323.4.2 Effects of Mass Injection .............................................................................. 41
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3.4.3 Frequency Effects.......................................................................................... 50
3.4.4 Exit Stagnation Pressure ............................................................................... 513.5 Implications of Design and Size ............................................................................. 54
4 SUMMARY...................................................................................................................55
APPENDIX
A DATA ACQUISITION PROGRAM............................................................................57
B MATLAB PROGRAM FOR DATA REDUCTION ....................................................93
C INLET DRAWINGS...................................................................................................114
D SCHLIEREN MOVIES ..............................................................................................120
LIST OF REFERENCES.................................................................................................130
BIOGRAPHICAL SKETCH ...........................................................................................132
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LIST OF TABLES
Table page
2-1. Coordinates of points that make the ramp profile ......................................................13
2.2 Location of wall static pressure taps............................................................................16
C-1. Coordinates of points relative to the leading edge of the ramp that make the ramp
profile...................................................................................................................116
D-1. List of schlieren movies...........................................................................................121
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LIST OF FIGURES
Figure page
1-1. PDE cycle schematic showing the events typical of operation of a single detonationtube.........................................................................................................................10
2-1. Views of the inlet showing the main components and the provision for backpressureexcitation................................................................................................................12
2-2. Shock structure as calculated from simple oblique shock relations ...........................14
2-3. Inlet schematic showing the location of static pressure taps and bleed plenums.......14
2-4. Oil flow test on the ramp. ...........................................................................................15
2-5. Top view of the ramp showing the bleed holes and the static tap locations...............16
2-6. CAD drawings ............................................................................................................17
2-7. Frontal and rear view of the exit injection block........................................................18
2-8. Illustration of the exit injection block with the port designations and the injection
configurations below..............................................................................................19
2-9. Layout of the key components of the air injection mechanism..................................21
2-10. Schematic of the pulse generator circuit...................................................................23
2-11. Schematic of tunnel valve control.26
.........................................................................25
2-12. Schematic of the schlieren system.26
........................................................................27
3-1. Comparison of mean static pressures in the inlet for the blocked and the unblockedconfiguration..........................................................................................................29
3-2. Schlieren images.........................................................................................................30
3-3. Comparison between the ramp and the cowl mean normalized static pressures........31
3-4. Views of the exit injection block with the stagnation pressure rake embedded in itwith the probe designations. ..................................................................................32
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3-5. Plots for comparing the excited and the unexcited inlet, for Minj=20% and
Frequency = 5 Hz case...........................................................................................35
3-6. Schlieren images for the 5 Hz and 20% mass injection36
3-7. Comparing the effects of injection configuration on the inlet flowfield. ...................38
3-8. Comparing the effects of mass injection for two different injection mass flows-20%
and 40% of capture. ...............................................................................................43
3-9. Schlieren images for comparing the 20% and 40% mass injection cases. .................46
3-10. Static pressure –time trace for the AS-2 coupling, 20% mass injection and 5 Hz
case.........................................................................................................................47
3-11. Static pressure –time trace for the AS-2 coupling, 40% mass injection and 5 Hz
case.........................................................................................................................49
3-12. Comparing the effects of two different excitation frequencies-5 Hz & 10 Hz.........52
A-1. Flowchart showing the data acquisition and experimental automation.26
.................58
C-1. The cowl...................................................................................................................114
C-2. The inlet ramp. .........................................................................................................115
C-3. The sideplates...........................................................................................................117
C-4. The sting...................................................................................................................117
C-5. The exit injection block. ..........................................................................................118
C-6. The inlet assembly. ..................................................................................................119
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LIST OF OBJECTS
Object page
D-1.S-2 Coupling, Minj=20.7%, F=10 Hz. .....................................................................122
D-2. AS-2 Coupling, Minj=20.7%, F=10 Hz. .................................................................122
D-3. 90 Phase Coupling, Minj=20%, F=10Hz.................................................................123
D-4. AS-2 Coupling, Minj=18.5%, F=5 Hz. ...................................................................123
D-5. S-2 Coupling, Minj=18.5%, F=5 Hz. ......................................................................124
D-6. S-1 Coupling, Minj=19.5%, F=5 Hz. ......................................................................124
D-7. AS-3 Coupling, Minj=19.5%, F=5 Hz. ...................................................................125
D-8. 90 Phase Coupling, Minj=23%, F=5 Hz..................................................................125
D-9. S-1 Coupling, Minj=39%, F=5 Hz. .........................................................................126
D-10. AS-3 Coupling, Minj=39%, F=5 Hz. ....................................................................126
D-11. S-2 Coupling, Minj=39%, F=5 Hz. .......................................................................127
D-12. AS-2 Coupling, Minj=39%, F=5 Hz. ....................................................................127
D-13. 90 Phase Coupling, Minj=39%, F=5 Hz................................................................128
D-14. Zoomed view of terminal shock for the S-2 Coupling, Minj=23%, F=5 Hz case.128
D-15. Zoomed view at capture for the 90 Phase Coupling, Minj=47%, F=5 Hz case. ...129
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Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Science
UNSTEADY FLOW IN A MIXED-COMPRESSION INLETAT MACH 3.5
By
Venkata Narasimham Nori
May 2003
Chair: Corin Segal
Major Department: Mechanical and Aerospace Engineering
A study of flow field in a two dimensional, mixed compression, supersonic inlet
under periodically varying external excitation of the backpressure was conducted at a
freestream Mach number of 3.5. The aim of the study was to simulate the effects of
combustion tube detonations due to a pulse detonation engine on the inlet. Four air
disturbance ports located at the corners of the exit cross-section simulated the pressure
perturbations. The frequency, coupling of the disturbance ports and the airflow rates
through the ports were varied. A terminal normal shock in the diffuser was observed in
the unexcited inlet whose oscillations during the backpressure excitation caused the
associated pressure oscillations. The mean levels of static pressure downstream of the
throat increased in all the test conditions due to mass injection. The schlieren and oil flow
visualization images confirmed the existence of a large separation bubble on the second
wedge of the ramp, which caused a complex shock and wave system. Large injection
mass flows result in inlet flow oscillations measured throughout the entire inlet, yet did
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not cause inlet unstart. Except for the 90 Phase coupling, there was no effect of injection
mass flows on the mean levels of static pressure but higher pressure oscillations were
observed for the larger injection mass flows. Pressure data and schlieren images showed
that the lower frequencies of excitation result in greater pressure oscillations. The 90
Phase coupling produced the highest mean levels of static pressure but generated the
lowest levels of pressure oscillations when compared to other injection configurations.
The mean stagnation pressure recovery at the exit was about 0.32 and the static pressure
rise in the inlet was about 15.
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CHAPTER 1INTRODUCTION
The function of the inlet is to provide appropriate mass flow and velocity to the
engine with high total pressure recovery, flow uniformity and flow stability, all of which
are important to the overall engine efficiency. The leading edge shock system, the
terminal shock boundary layer interaction, the decelerating subsonic flow and the
associated rapidly growing boundary layers combine to form typical inlet flows. Stability
of flow is one of the major considerations in designing supersonic inlets. The interaction
between the inlet and the engine flowfield may cause instability for the entire system.
Analysis of supersonic inlet flows are complicated by the presence of mixed subsonic and
supersonic flows, shock boundary layer interactions that may or may not cause
separation. The disturbances/transients in the inlet or the engine can be decomposed in to
three components: entropy generation, vorticity and acoustic modes. The response
generated may contain all the three disturbance types. However, the entropy and vorticity
disturbances are always convected downstream and only the acoustic response has an
upstream moving part. It is this response that actually affects the inlet flow.1
The pressure
oscillations generated by unsteady combustion may induce shock wave oscillations in the
inlet duct. These oscillations can grow, causing large distortions in the shock structure
leading to dramatic degradation of the engine performance. This work examines the
effect of pressure oscillations arising from the combustion tube detonations due to a pulse
detonation engine on the flowfield, in a two dimensional, mixed compression, supersonic
inlet.
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1.1 Review of Relevant Literature on Inlet Flow Oscillations
Over the past few decades, theoretical and experimental research on both self
excited and externally excited flow oscillations in air intakes have been conducted to
identify the flow patterns and parameters that induce instabilities that decrease engine
performance. Most of the research on the inlet-engine interactions focused on instabilities
arising from the combustion chambers of Ramjet engines and confined to transonic
diffuser flows. This chapter reviews the study on pressure oscillations in air intakes by a
selected few researchers, followed by the motivation for this study.
Mullagiri et al.2, 3
have experimentally investigated the effects of a PDE on the air
induction system on two-dimensional and axisymmetric inlets at freestream Mach
numbers of 2.5 and 2.1. The pressure perturbations at the diffuser exit have been
simulated by mechanically varying the exit area resulting in a sinusoidal excitation of the
backpressure, both spatially and temporally. The excitation was varied from 15 to 50 Hz
and the amplitude was varied by increasing the blockage at the exit plane. It was
observed that the pressure oscillations were confined to the downstream of the throat in
both the cases. Also, a decrease in the amplitude of the pressure perturbations with
increase of excitation frequency was observed. Moreover, increase in the amplitude of
excitation caused an increase in the mean pressure field in the diffuser.
Chen et al., Bogar et al., and Sajben et al.4–8
conducted a series of experimental
investigations into inlet diffuser flows with pressure oscillations, to better understand the
unsteady flow behavior in a Ramjet engine. Various unsteady flow phenomena, such as
shock induced separated flows and shock/acoustic wave interactions under self excited
and forced oscillations were treated in detail. From the experiments of supercritical
transonic diffuser flows displaying self-excited fluctuations, it was found that the bulk of
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the fluctuation energy was contained in the frequency range of shock oscillations, which
were below 300 Hz. The diffuser was run at a supercritical condition at Mach numbers
ranging form 1.1 to 1.5. Depending on the Mach number, two different flow patterns
were identified. At lower Mach numbers, a flow separation was caused by adverse
pressure gradients (weak shock case) whereas at higher Mach numbers shock induced
separation was observed (strong shock case). For the weak shock case the peak
oscillation frequency decreased with shock strength whereas for the strong shock case
peak frequencies, pressure and shock oscillation amplitude both increased with shock
strength. For the weak shock case the characteristic frequencies observed follow the
acoustic predictions and frequencies upto third harmonic were observed but for the strong
shock case the single characteristic frequency observed does not follow acoustic
predictions.
Forced oscillation experiments on the same model were conducted to investigate
the role of oscillations induced in inlets of Ramjets by combustor instabilities. The
pressure oscillations were simulated asymmetrically by mechanical modulation of the
diffuser cross sectional area near the channel exhaust. A triangular prism shaped rotor
was rotated to simulate excitation frequencies in the range of 15-330 Hz. The pressure
perturbation amplitudes arising from the combustor can reach upto 20% of the local mean
pressure causing the expulsion of the shock train resulting in an inlet unstart. However,
this mechanism resulted in rms intensities, which varied between 0.5- 2% of the local
static pressures. Shock displacement and pressure amplitudes decreased with increasing
frequency at all Mach numbers, although the effect was more pronounced in weaker
shock systems. In weak shock systems, the pressure and velocity perturbations behaved
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as one dimensional acoustic waves, while the interaction of the perturbation with the
shock structure and the boundary layer is more complex compared at higher Mach
numbers. A very interesting observation was the lack of resonance conditions in the inlet,
even when the natural and excitation frequencies were equal. It was conjectured that the
method of excitation led to oscillation modes different from those existing in natural
conditions. To the existing two dimensional transonic channel, a ramp/cowl configuration
was incorporated to simulate inlet flows. Supercritical oscillations are dominated by
shock boundary layer interaction’s (SBLI) and displayed broadband spectral character,
while oscillations involving sub and non critical states, produced significant periodic
spectral contributions in dual mode and a rigorously periodic intense oscillation in the
triple mode (when the shock position range overlaps all 3 ranges of criticality, viz.
subcritical, critical and supercritical). With mechanically generated downstream
perturbations, in super critical operations the pressure varied linearly with the fluctuations
at the exit station even for large exit station amplitudes (8% of exit mean static pressure).
However, in subcritical condition, the excitation interacted nonlinearly with the naturally
present, highly periodic oscillations by either modifying the natural frequency, if the
excitation was near a natural harmonic, or by having the excitation modulate the naturally
occurring oscillation.
However, Laser Doppler Velocimeter studies by Bogar 9
on self excited
oscillations to ascertain the differences in natural and forced oscillations in the
supercritical transonic diffuser showed similar flow patterns in both excited and
unexcited inlets. It was suggested that the gross motion is a vertical oscillation of the core
flow, causing an oscillation in the boundary layer thickness. It was also inferred that the
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separation bubble appears to be a more effective medium for propagating shock
generated disturbances downstream than the high-speed core flow.
Hongprapas et al.10
investigated the phenomenon of supersonic inlet buzz on a
generic axisymmetric, external compression inlet at a Mach number of 2.4. The model
had the provision to control the exit area in order to vary the inlet operating condition.
Varying the exit area produced steady operation for larger exit area and inlet buzz for
smaller exit area. Dailey’s type of buzz11
was observed. During buzz supersonic inlets
exhibit considerable oscillation of the shock system in front of the inlet and
corresponding large pressure fluctuations downstream. It was stated that the separated
flow inside the inlet had a substantial influence on the onset of instability.
Wie et al.12
studied a small-scale rectangular inlet at Mach 3. cowl length and
cowl height parameters were studied for their effect on the inlet starting characteristics.
Inlet unstarts were classified as “hard” or “soft.” Hard unstarts appear to occur when the
flow at the inlet throat chokes while soft unstarts occur as large-scale separation develop
within the inlet. For shorter cowls and higher cowl heights, hard unstarts are prevalent
whereas the softer unstarts occur for the longer cowl lengths and lower cowl heights. In
our present model “soft” unstarts were observed due to separation at the compression
corner at the second wedge.
Fernandez and Nenni13
performed tests on a two dimensional, mixed compression
inlet from which the present inlet of study was designed. The main flow entering the inlet
had substantial amount of boundary layer and had to be bleeded out. In the supercritical
case the cowl shock was almost perfectly cancelled by the throat shoulder with only weak
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oblique shocks occurring in the downstream flow. The wind tunnel Mach number was 3.5
and the total pressure recovery was 0.37.
Theoretical studies were carried out, focussing mostly in transonic regimes and
Ramjet inlet/combustor interactions. These analyses mostly assumed simple geometries,
inviscid flows and small amplitude oscillations, while the solution methods involved
acoustic, asymptotic methods, and (or) linear stability analysis. Some of them were
numerical studies solving the Navier-Stokes equations for transonic/supersonic flows in
order to study the experimental results of Sajben et al.4-8
Nevertheless, results predicted
the experimental results quite accurately.
Culick and Rogers14
analyzed the stability of normal shocks in the diverging
section of inlets for Ramjet engines. The inviscid flow analysis showed that the shock
waves always attenuated the pressure fluctuations while the shock wave may act to drive
the oscillation over a broad range of low frequencies and high Mach numbers in the
viscous analysis. It was determined that stability of the normal shocks in diverging
channels could be unfavorably influenced by the separation region created downstream of
the shock. According to these results, the physical origin of the instabilities arises from a
reduction in pressure recovery due to the separated region downstream of the shock.
Hsieh et al.15-17
studied the flow field within an unsteady two-dimensional inlet.
The unsteady cases calculated were performed with exit plane pressure variations on the
order of 14% of the mean static pressure. The resulting flow field contained notable
features such as curved terminal shocks that disappeared and reformed, more than one
normal shock coexisting in the inlet at once (shock trains) and separation region
bifurcation, formation and disappearance. Unfortunately, experimental data was not
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available to check the accuracy of the calculation. So, in order to check their assumptions
and calculations they performed numerical simulations of self excited oscillations in a
two dimensional transonic diffuser flow (experiments of the Sajben group5-9
). They
agreed well with the experimental results though qualitatively; i.e. the computation
accurately predicts the length of the separation pocket but underpredicts its thickness.
Similarly on the downstream side of the separation pocket, the experiment indicates a
fully developed channel flow, whereas the calculation features an inviscid core region.
They also investigated the unsteady flow of a two-dimensional Ramjet diffuser by
introducing unsteadiness in the form of a sinusoidal exit plane pressure disturbance with
amplitude 20% of the mean exit pressure. Both acoustic theory and small perturbation
models predict that the sinusoidal pressures at the exit plane will generate sinusoidal
velocity of the same frequency, but with altered phase angle and amplitude. But here a
sinusoidal large amplitude pressure fluctuation generates non-sinusoidal variation in exit
plane velocity and recovery pressure. However the accuracy of the calculations remains
to be determined, as the experimental data was not available for comparison.
Biedron and Adamson18
have analyzed unsteady flow through a two dimensional
supersonic diffuser with a normal shock wave using asymptotic methods. It was shown
that the low frequency back pressure fluctuation or the large amplitude fluctuations were
equally capable of causing an inlet unstart, which was detrimental to the diffuser
performance. These results also implied that separated flow can play an important role in
phenomena like self sustained shock wave oscillations.
Hsieh and Yang19
investigated the unsteady flow structures in a supersonic
Ramjet engine by treating both the internal flowfield in an axisymmetric mixed
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compression inlet (at a Mach number of 2.1) and a coaxial dump combustor. The
calculations revealed a low frequency pressure oscillation at 135 Hz with a peak to peak
approximately at 20% of the average pressure in the combustor. The terminal shock in
the inlet diffuser oscillates at the same frequency, but out of phase with the pressure
fluctuations in the combustor, suggesting a strong coupling between inlet and combustor.
Large vortical motions, coupled with acoustic motions, were observed in the combustion
chamber, which in turn modified the inlet flow structures.
Pegg et al.20
analyzed a mixed compression inlet design concept for a PDE for the
Mach 3 condition. They simulated the operation of multi duct PDE rotary valves by an
array of four sonic nozzles (valves) in which the flow areas were rapidly varied in various
opening/closing combinations. They indicate that a terminal shock train can be stabilized
in the isolator and that the pressure perturbations and the expansion waves caused by
simulated PDE valve area changes do not disturb the terminal shock system, thereby not
effecting the inlet’s operability or performance. Computed internal inlet stagnation
pressure recovery was roughly 70%.
1.2 Motivation for Current Study
1.2.1 A New Engine Concept-Pulse Detonation Engine
The present study deals with the flowfield in a supersonic inlet of a pulse
detonation engine (PDE). PDEs are currently attracting considerable research and
development attention because they promise performance improvements over existing air
breathing propulsive devices. The drivers for all this work are the promises of high
efficiencies, lighter weight and less complexity than existing gas turbine engines21, 22
. The
ideal thermodynamic cycle efficiency is higher than that of a Brayton cycle, and the rapid
detonation processes in the PDE produce larger combustion chamber pressures thus
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generating more thrust than the Gas Turbine engines.23, 24
The fact that the PDE has far
less moving parts than a typical Gas Turbine engine facilitates ease of maintenance and
service. If one compares a PDE system to a Ramjet system, which has a similar level of
lightweight and simplicity, the PDE has the added benefit of being able to generate static
thrust. The potential for vector thrust with no mechanical throttling motion or nozzle
adjustments is yet another advantage. In addition, PDEs can be fabricated at low cost
from off the shelf materials using standard manufacturing methods.
PDE development is still in early stages of development with many key issues to
resolve. Some of the issues concerning the development of the PDEs are: the integration
of the supersonic air induction system with the unsteady flow PDE cycle; arrangement of
the PDEs for a stable system; short, stable and repeatable ignition cycles; and good
sealing at high temperatures and pressures.
One of the primary characteristics of the PDE is the unsteady nature of the
combustion process. A representative PDE cycle of an individual pulse detonation tube
comprises of the following three phases: 22, 25
1. Filling Phase
2. Detonation Phase
3. Blowdown Phase
In the filling phase of the cycle, the fuel is injected into the duct and the right amount of
the incoming air is scooped from the flow, before the upstream valve is closed. In the
detonation phase of the cycle, the fuel air mixture is ignited initiating a detonation at the
closed end that propagates downstream. The products of combustion are pumped out of
the duct’s exhaust system in the subsequent blowdown phase. Positive axial thrust is
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produced in phases 2 and 3.
Rarefaction waves
Detonation Initiation
Patm
V = 0 Patm
RarefactionsPatmPatm
Exhaust
PCJPCJ
Patm
P1
Rarefactions
Fuel-air mixture
PoM = 0
PatmPo VdetPo
P3
1a 1b 1c
2b 2c 3a 3b
V = 0 V = 0
V = 0
Figure 1-1. PDE cycle schematic showing the events typical of operation of a single
detonation tube.
The focus of this study was the PDE inlet. The PDE inlet is subjected to the
upstream travelling pressure and expansion waves generated by the operation of the PDE
valves. In order to reduce the effect of intermittent combustion on the air induction
system, it is necessary for the PDE module to be made up of a group, or cluster of pulse
detonation ducts that operate out of phase such that the airflow rate in the PDE module’s
common inlet duct is relatively constant. However, such configuration can cause severe
effects on the backpressure and affect the operation of the inlet including the potential of
hammershock and unstaring of the inlet. The pressure oscillations arising in the diffuser
because of the operation of the PDE valves are spatially non-uniform and periodic in
nature. A single inlet acting as a plenum for multiple detonation tubes reduces the effect
of backpressure on the inlet flow field allowing for flow transfer from the blocked
channels to the open ones. The calculations based on CFD techniques22
indicate that
during the transient flow at the inlet exit, produced by the valving system of a stack of
detonation tubes, the time available for the transfer of air between adjacent tubes is O (10
µs), which is significantly shorter than the time required to from the hammershock (O (10
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ms)), thus supporting the plenum inlet concept. These backpressure fluctuations at the
exit of the inlet, although not causing inlet unstart, can lead to flow separation in the
diffuser, resulting in stagnation pressure losses and affecting the operation of the
detonation tubes present in the wake of the separated region.
1.2.2 Intent and Scope of Work
Most of the researches on inlet-engine interactions dealt with studies on
oscillations from the combustion chamber, wherein the oscillations were assumed to be
uniform across the cross-section of the inlet. However, the inlet of a PDE experiences
non-uniform oscillations both temporally and spatially. The present study deals with the
experimental simulation of the effects, due to the operation of an array of adjacent PDEs
on the flowfield of a supersonic inlet.
Chapter 2 describes the modeling of the backpressure excitation mechanism, the
experimental set up and instrumentation. Experimental results are reported in chapter 3
followed by the summary of the results obtained in chapter 4.
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CHAPTER 2EXPERIMENTAL SETUP
2.1 Introduction
This chapter describes the supersonic inlet model, simulating the opening and
closing of the PDE detonation valves, experimental facility, instrumentation and the data
acquisition system used.
2.2 Basic Inlet Geometry
The present inlet is a modified version of the two dimensional, supersonic, mixed
compression inlet investigated by Fernandez and Nenni13
. The leading edge of the ramp
was modified as the inlet was designed to operate at a Mach number of 3.5. Figure 2-1
shows the inlet model with the 4 disturbance ports at the exit. The two-dimensional
compression system consisted of two 50
wedges on the ramp, and the cowl. The cowl is
inclined at a constant, -40
relative to the horizontal.
Plexiglass sideplates Cowl static taps
Air injection tubesExit stagnation rake
Cowl
Ramp
Static Taps onramp
Bleed Tubes
Exit injection block
Figure 2-1. Views of the inlet showing the main components and the provision for backpressure excitation.
12
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The throat height, H is 0.2442.” The coordinates of the points, with respect to the
leading edge of the ramp that make the ramp profile are given in Table 2-1. The
contraction ratio (defined as the ratio of the areas at the throat that at the capture) is 0.6,
which is well within the self start limits at Mach 3.5, described in reference 12. The
diffuser section that follows the throat is 10.27 H long and the model is L=21.73 H long.
Table 2-1. Coordinates of points that make the ramp profile
Point X(in) Y(in) Point X(in) Y(in)
1 0 0 12 3 0.348
2 0.5 0.05 13 3.25 0.325
3 1 0.125 14 3.5 0.295
4 1.25 0.168 15 3.75 0.26
5 1.5 0.212 16 4 0.223
6 1.75 0.254 17 4.25 0.186
7 1.865 0.276 18 4.5 0.151
8 2 0.294 19 4.75 0.121
9 2.25 0.325 20 5 0.1
10 2.5 0.353 21 5.25 0.087
11 2.75 0.359
The sidewalls are made of Plexiglas to allow for full optical access. The position
of the leading edge of the cowl is such that the area of the captured stream tube is 98% of
the area of the stream tube at subsonic Mach number of 0.38. This allows a 2% spillage
of the air mass flow at the entrance. Figure 2-2 illustrates the mixed-compression inlet
with shocks occurring both outside and inside of the inlet as calculated from the oblique
shock relations. The dashed vertical line in the figure represents the geometric throat
location. However, because of viscous effects, a separation region was observed between
tap locations 1 and 3 due to which there is increased spillage at the inlet entrance. To
mitigate this problem of flow separation, bleed plenums were incorporated accordingly.
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Figure 2-2. Shock structure as calculated from simple oblique shock relations
Figure 2-3. Inlet schematic showing the location of static pressure taps and bleed plenums
The locations of the wall static pressure taps and the bleed plenums are shown in
Figure 2-3. The bleed plenums act as low-pressure chambers and aid in the removal of
the separated boundary layer, upstream of the throat. A separation region spanning from
the location of tap 1 to tap 3 was observed. Figure 2-4 shows a picture from an oil flow
test where the flow separation region could be identified. As a consequence, the shock
angles at both the wedges increased, leading to increased spillage at the inlet entrance.
Moreover, the efficiency of the inlet would go down due to the accompanied stagnation
pressure losses. The bleed locations are at X/L=0.276 and X/L=0.427, where X/L is the
non-dimensional axial coordinate measured from the leading edge of the inlet. Three
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rows of 0.01” diameter holes (20 holes per row) were drilled on the ramp surface as
shown in Figure 2-5. The air from these holes was then emptied into a bleed plenum,
which was connected to the vacuum line outside the wind tunnel through a set of Tygon
tubes. The total area of the bleed holes is 0.00945-in2. An estimated amount of 6% of the
inlet capture is bleeded out
Flow Separation
region
Figure 2-4. Oil flow test on the ramp.
The geometric throat of the inlet is located between the taps 5 and 6. The
distances of the static pressure ports from the leading edge of the inlet normalized with
the length of the inlet are given in Table 2.2. Static pressure measurements were also
taken on the cowl at 4 locations corresponding to the last 4 taps on the ramp to compare
and check if there was any discrepancy in the pressure distribution, aft of the terminal
shock in the separated region. The static taps on the ramp lie along a common axis, which
is at a distance of 0.4125” from the inlet centerline. This had to be done so that the inlet
could be well supported by the sting passing through the inlet centerline.
The inlet exit is also a crucial factor as the exit pressure (backpressure) dictates
the flow characteristics in the inlet. The backpressure can be manipulated by blocking the
flow exit accordingly. For this purpose an exit injection block was used, which also had
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provision for air injection. Initially an injection block with 4 circular holes whose total
area was 20% more than the calculated area that required to choke the flow at the exit
Figure 2-5. Top view of the ramp showing the bleed holes and the static tap locations.
Table 2.2 Location of wall static pressure taps.
Tap X / L Tap X / L
1 0.226 7 0.66
2 0.321 8 0.735
3 0.396 9 0.811
4 0.471 10 0.886
5 0.547 11 0.9626 0.584
was used. Incidentally, this area requirement made the diameter of the circular holes very
close to the height of the exit section. It was observed that this arrangement increased the
backpressure to such an extent that it unstarted the inlet, which is undesirable for the
engine operation. So, a two-dimensional injection block was made with the same exit
area requirement as that of the injection block with 4 circular holes. This block has a
converging section, which brings down the area from that of the inlet exit to the required
injection block exit area. Even this arrangement caused an inlet unstart, because of which
the injection block exit area was increased by 25%. This enabled the inlet to start and a
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terminal shock was observed at X/L~0.73. AutoCAD drawings for both the injection
blocks are shown in Figure 2-6.
(a)
(b)
Figure 2-6. CAD drawings. (a) the injection block with 4 circular holes and (b) the two-dimensional injection block.
2.3 Backpressure Excitation Mechanism
The purpose of this study was to simulate the effect of pressure oscillations
arising from the opening and closing of the PDE valves. When there are a stack of PDEs,
each operating at different phases but drawing air from the same inlet, the pressure
perturbations at the exit vary both in space and time. In previous studies, these
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oscillations at the exit were simulated by mechanically varying the exit area2, 3, 5-9
. In the
present study fluidic injection was used to simulate these perturbations. The present inlet
(derived from an existing NASA inlet13
) was designed such that the flow was supersonic
throughout with an oblique shock train terminating well beyond the geometric throat. The
airstream entering the detonation chambers has to be low subsonic for efficient operation
of the PDE. An injection block was mounted at the exit of the inlet as a means of
blocking the flow, thereby increasing the backpressure, which, in turn produces a normal
shock downstream of the throat, and decelerates the flow to subsonic speeds. Moreover,
the injection block also housed the air disturbance ports, which were located at the 4
corners of the exit cross section of the inlet. Air is injected along the diagonals of the
rectangular exit cross section Figure 2-7 shows the injection block as viewed from the
front and as viewed from the back.
Figure 2-7. Frontal and rear view of the exit injection block.
The intent is to parametrically vary the operation of these disturbance ports to
observe as to how the inlet reacts to periodically varying pulsed disturbances. Air
injection through the inlet exit corers was done in the configurations shown in Figure 2-8.
The words injection configuration and coupling are used interchangeably. Note that (1,2)
means that port 1 and 2 inject air in phase. The operating frequency of any port was the
same and was either 5 Hz or 10 Hz depending on the test conditions.
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1 2
3 4
Figure 2-8. Illustration of the exit injection block with the port designations and the
injection configurations below.
1. Antisymmetric-1 (AS-1) coupling. Ports (1,2) inject air.
2. Antisymmetric-3 (AS-3) coupling. Ports (3,4) inject air.
3. Symmetric-1 (S-1) coupling. Ports (1,3) inject air.
4. Antisymmetric-2 (AS-2) coupling. Ports (1,2) and (3,4) inject air, 1800 out of phase.
5. Symmetric-2 (S-2) coupling. Ports (1,3) and (2,4) inject air, 1800
out of phase.
6. 900
phase offset (90 Phase) coupling. Each port injects air at 900
out of phase with the
neighboring ports.
Figure 2-9 depicts the layout of the air injection mechanism. Air was supplied
from an Industrial grade Nitrogen cylinder (2500 psi). The airstream is then split into 4
paths along which it is filtered using inline filters, and then recombined back into a single
stream using the manifold as shown in the figure. This filtered air is then led through a
TESCOM regulator. The outlet of the regulator is connected to a manifold. A set of 4
solenoid valves is connected to this manifold with the help of 4 Rubber hoses. These set
of solenoids are used to inject air into the inlet through the disturbance ports. We also
find another set of 4 solenoids, which are connected to a vacuum line (2” ID Galvanized
Iron pipe). The air in the vacuum line is removed using a vacuum pump (capacity of ~0.7
SCFM) and pressures as low as 0.5 psi can be obtained in the vacuum line. Each of the
disturbance ports in the back body is connected via a Teflon tube, to an injection solenoid
and a vacuum solenoid. Pressure transducers were installed along the injection solenoid
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line to measure the pressure upstream and downstream of the injection solenoid. From
these measured pressures and the known Cv of the injection solenoid the amount of mass
injected per solenoid can be estimated. The plan was to use the vacuum solenoids to
“start” the inlet (which might be difficult with the exit blockage) and then initiating the
pulsed disturbances at the exit, with the injection solenoids. The amplitude of the
oscillations is directly related to the flow rate of the injected air. Changing the regulator
setting varies the flow rate. Frequency and coupling of the injection solenoids were
varied using a pulse generator circuit that is described in the next section.
The pulse generator circuit can be considered as the heart of the backpressure
excitation system. The circuit diagram is shown in Figure 2-10. This circuit modifies the
signal from a Leader LFG-1300S Function Generator and then converts this modified
signal into the opening and closing of the solenoid valves. The Leader LFG-1300S
Function Generator is adjusted to produce a square wave with a 50% duty cycle. The
NTE 7493A (4-bit counter), the NTE 7404 (NOT gate) and the NTE 7408 (AND gate)
TTL chips change the frequency of the square wave and produce 4 output signals with
900
phase offset state. These outputs are connected to a set of 4 OAC-5 P&B solid state
relays which energize the injection solenoid valves accordingly. The analog signal from
the computer determines the operation of either the vacuum solenoids or the injection
solenoids. Relay 1 and Relay 2 (both general-purpose relays) are activated by 2.7 volt and
8.3 volt signal respectively. Relay 1, when activated, connects the square wave signal
from the Function Generator into the TTL circuit. Relay 2 supplies the AC power to both
sets of injection and vacuum solenoids. Both Relay 1 and Relay 2 should be activated in
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TESCOM Regulator
Pin=3000psi, Pout=150psi S
4 x Injectionsolenoids
Backbody connectedto the Inlet
Pressure Manifolds
3/8” OD, 1/4” ID Teflon tubes.
Operating pressure=250 psi.
4 x Vacuum Solenoids
ASCO; Cv=3
2” G.I Pipe
To Vacuum tank
Figure 2-9. Layout of the key components of the air injection mechanism
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sets of injection and vacuum solenoids. Both Relay 1 and Relay 2 should be activated in
order to open and close the injection solenoid valves accordingly. The vacuum solenoid
valves open when Relay 2 is deactivated. The transistor circuits were made to amplify the
current of the analog signal so as to activate the relays. Thus, changing the frequency
setting on the Function Generator and by clubbing the signal outputs from the TTL
circuit, the desired changes in frequency and the coupling of the injection solenoids could
be produced. Two frequencies of excitation were attempted: 5 Hz and 10 Hz. The
response of the solenoids deviates from the input square wave for frequencies higher than
20 Hz.
2.4 Description of the Wind Tunnel
The tests were carried out in the Mach 4 wind tunnel at the Department of MAE
at the University of Florida. The test section Mach number can be varied from 1.5 to 4.
The wind tunnel has a sliding lower wall made of aluminum block and mounted on a
worm gear. The position of the lower wall can be changed, affecting the throat area of the
wind tunnel throat, for different test section Mach numbers. The test section Mach
number is calibrated with a block position counter. In our case, the counter setting of 390
produces the desired test section Mach number of 3.5. The minimum stagnation pressure
required to attain this Mach number of 3.5 is 120 psi.
Two large external tanks act as reservoirs of high-pressure air for the blow down
tests. A 750 hp Quincy compressor supplies air to the reservoirs. The compressor can
compress the air to a maximum pressure of 225 psig. All the tests were run at Mach 3.5
and the available run time was about 25s.
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R
R
Vcc=12 V
120 V AC line120 V AC line
120 V AC line
4 x Vacuum Solenoids
120 V AC Neutral
4 x Injection Solenoids
120 V AC Neutral
LFG-1300SSquare wave, dutyc cle 50% F Hz
Vcc=12 V
Relay 1
2.7 V Analog Signal
NTE 7493
4 bit counter TTL Circuit
NTE 7404 NOT Gate
NTE 7408
AND Gate
Figure 2-10. Schematic of the pulse generator circuit.
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The stagnation pressure is controlled by a pneumatically operated spring-loaded
butterfly valve. A valve positioner supplies the required actuating pressure to the valve
mechanism. The valve positioner has PID logic to determine the amount of actuating
pressure that must be supplied to the valve mechanism depending on the input pressure
supplied to the postioner. The input pressure to the valve postioned is in turn supplied by
a TESCOM ER3000 electronic regulator, which also is based on PID logic. The output of
the electronic regulator can be controlled by computer commands via a serial port. A
nitrogen cylinder supplies the actuating fluid to both the ER3000 electronic regulator and
the valve positioner. The computer issues a set-point to the ER3000in the range between
400 (no output) and 3700 (maximum output). Based on this input, the ER3000 regulates
its output pressure, which acts as a set-point pressure for the valve positioner. The valve
positioner then tries to match its output pressure to the set-point pressure. This output
from the valve positioner acts on the dome-based regulator that drives the butterfly valve
mechanism. Figure 2-11 shows the schematic of the tunnel valve control.
The test section is 6” x 6” in cross section and 18” in length, with a near constant
cross-section. Optical access is provided with two 0.5” thick glass windows on the
sidewalls of the test section. The model is mounted on a C-shaped sting and the angle of
attack can be varied from –10o
to +10o
with an accuracy of 0.1o.
2.5 Instrumentation
The wall pressures were measured by using a Pressure SystemsTM
PSI 9010
Scanner and OmegaTM
PX-303 transducers. The PSI 9010 has 16 pressure ports with a
range of 0-10 psia (ports 1-4), 0-45psia(ports 5-9), 0-100psia(ports 10,11) and 0-250 psia
(ports 12-16). The PSI 9010 communicates with the serial port and the number of
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Figure 2-11. Schematic of tunnel valve control.26
samples that are averaged before reading out the data can be set in the hardware. The
maximum scan rate reading all channels is 10 Hz and this can be increased by decreasing
the number of channels that are read. Scanner ports 5-15 were used for data acquisition
and the scan rate increased to 25 Hz, thereby capturing the pressure oscillations up to
12Hz. A National Instruments AT-MIO-16-E2 data acquisition card was used on a
Pentium II – 266 MHz computer. The card can read 16 differential inputs at a maximum
rate of 500 kHz at a maximum cumulative scan rate of 500 kHz. Two analog output
channels on the AT-MIO-16-E2 board were used to activate the Relays in the Pulse
Generator circuit. The tunnel control and data acquisition was done by a program written
in LabVIEW. The software with the relevant programs in LabVIEW are explained in
detail in Appendix A. A Matlab program was used to compile the data and for further
data reduction to produce the plots. The MATLAB program is included in Appendix B.
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2.6 Schlieren Setup
To visualize the flowfield in the inlet, a schlieren system was set up. The
schematic of the schlieren is shown in Figure 2-12. A Mercury short arc lamp was used
as the light source and this lamp is different from the other short arc lamps, as it should
be mounted with the anode at the base, for better arc stability and longer life. The
schlieren images were recorded by a SONY camcorder. The limitation of the schlieren
system is that it produces an image, which is an integrated effect of the deflections
undergone by the light beam travelling through the flow. So, this technique is a powerful
tool in visualizing two-dimensional flows, from which we can make quantitative
estimates, for e.g., the oblique shock angles, the position of the normal shock etc.
2.7 Oil Flow Visualization
This technique serves for visualizing the flow pattern close to the surface of a
solid body exposed to airflow. The observed pattern can indicate the positions of
transition from laminar to turbulent flow in the wall boundary layer, and the positions of
the flow separation and reattachment. The surface of the ramp was coated with an oil-
based paint (white pigment) to determine the regions of separation if any.
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Hg arc lamp
Converging lens
6” collimating mirror
Figure 2-12. Schematic of the schlieren system.26
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CHAPTER 3RESULTS
3.1 Introduction
The purpose of this study was to simulate the effects of combustion tube
detonations due to a pulse detonation engine on the inlet, at a free stream Mach number
of 3.5. The backpressure fluctuations were produced by injecting air from the corners at
the exit cross section, into the inlet . The following effects were the focus of this study:
• Mass flow injected into the inlet.
• Injection configurations, which corresponds to the inlet response to periodic, variable
spatial blockage.
• Frequency of air injection. Two frequencies, 5 Hz and 10 Hz, were attempted.
Wall static pressures were measured at eleven different streamwise locations along the
inlet. Stagnation pressure measurements were taken at the exit of the inlet with a
stagnation pressure rake having three probes. The probes were stacked one over the other
and spaced equidistantly. Static pressures were measured aft of the terminal shock both
on the cowl and the ramp simultaneously in selected experiments. Schlieren images were
taken during tests.
3.2 Flow Field Inside the Inlet
3.2.1 The Supersonic Inlet
The present inlet was derived from a scaled down version of an existing NASA
inlet13
, which was designed for hypersonic Mach number of 6. The flow was fully
supersonic inside the inlet, as can be seen from the values of static pressures in Figure 3-
1.
28
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3.2.2 The Supercritical Inlet
The PDE inlet has to decelerate the flow to low subsonic before feeding it to the
detonation tubes. Therefore, the inlet has been modified to operate supercritically with
subsonic exit flow, as required by PDE. Thus, a normal shock appeared in the diffuser. A
typical wall pressure distribution is included in Figure 3-1 for comparison with the
supersonic inlet. In both cases, boundary layer suction was actively done from the ramp
(see Figure C-2 in Appendix C) at locations X/L=0.276 and X/L=0.427, where X/L is the
non-dimensional axial coordinate measured from the leading edge of the inlet. Figure 3-
2a, shows the shock patterns set up both outside and inside of the inlet and Figure 3-2b
shows the zoomed-in picture of the normal shock in the diffuser for the non-injection
case. Figure 3-2b clearly indicates that the shock is partly normal and terminates as a
lambda shock on both the cowl and ramp walls. Therefore, the pressure rise across the
shock is about 50% of the value calculated for a normal shock that occupies the entire
cross section. The terminal shock in the inlet occurs at the location X/L ~ 0.73.
X / L
p
/ P o 1
0 0.2 0.4 0.6 0.8 10
0.05
0.1
0.15
0.2
0.25 Supersonic Inlet
Current, Supercritical Inlet
Figure 3-1. Comparison of mean static pressures in the inlet for the blocked and the
unblocked configuration.
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(a) (b)
Cowl
Ramp
Figure 3-2. Schlieren images. (a) The entire flowfield within the inlet without injection.(b) Zoomed in view of the terminal shock structure. The shock occurs at
X/L~0.73.
From the Figure 3-1 it can be inferred that the static pressure rise in the inlet,
defined as the ratio of the exit static pressure to the freestream static pressure, is about 15.
The inlet was operated at a backpressure ratio (ratio of mean backpressure to the
freestream stagnation pressure) of 0.2.
3.3 Preliminary Calibration
Static pressure measurements were taken on both the cowl and the ramp surfaces
at the locations immediately after the normal shock to check if there were any
discrepancies in the static pressure profile downstream of the normal shock, due to the
shock induced separation region. Figure 3-3a and b compares the mean normalized static
pressures measured on the ramp and the cowl for both the non-injection and the injection
case. In the injection case, 90 phase coupling injecting 39% of the inlet capture and
operating at a frequency of 5 Hz was used.
It can be seen that the static pressure measurements on the cowl and the ramp
agree, but with variation at X/L=0.89. In general, the static pressures measured on the
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cowl are little bit lower than those measured on the ramp, in the non-injection case. This
may be due to the difference in shock strength along the shock, which can be imagined
(a) X / L
p
/ P o 1
0 0.2 0.4 0.6 0.8 10.05
0.1
0.15
0.2
0.25 Ramp
Cowl
(b) X / L
p
/ P o 1
0 0.2 0.4 0.6 0.8 10.05
0.1
0.15
0.2
0.25 Ramp
Cowl
Figure 3-3. Comparison between the ramp and the cowl mean normalized static pressures. (a) Non-injection case and (b) Injection case.
from the different degree of flow separation from the cowl and the ramp side as shown in
Figure 3-2b. In the Injection case, the shock moves upstream and thus becomes relatively
weak and therefore there is a better agreement between the cowl and the ramp static
pressure profiles in Figure 3-3b. All the static pressure measurements shown in the
following data were recorded from the ramp.
3.4 Static and Stagnation Pressure Measurements
Experiments were carried out with the following conditions:
• Six different injection configurations (as discussed in Chapter-2).
• Two different injection mass flows- 20%, 40% of inlet capture.
• Two different frequencies -5 Hz, 10 Hz.
The mass is given as a percentage of the capture mass flow. In each experiment the
injection began when the wind tunnel stagnation pressure reached a steady value of 120
psia. At this tunnel stagnation pressure the inlet capture mass flow is 0.2kgs-1
.
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A stagnation pressure rake located at the exit section of the inlet measured
stagnation pressure. The rake had three probes stacked one over the other, which
measured stagnation pressure at Y* = 0.145,0.5 and 0.855 at the exit section. Y* is the
non-dimensional distance of the probe location from the ramp i.e.,
*0.3378
yY =
Where y is the distance of the probe from the ramp and the distance from the cowl to the
ramp is 0.3378”.
Figure 3-4 shows the exit injection block with the stagnation rake embedded in it.
The rake designations are also shown. The results obtained from the stagnation pressure
measurements are presented in section 3.4.4.
Cowl side probe
Ramp side probe Core probe
Figure 3-4. Views of the exit injection block with the stagnation pressure rake embedded
in it with the probe designations.
3.4.1 Effects of Injection Configuration
For a given injection mass flow and backpressure excitation frequency, the effect
of injection configuration on the inlet characteristics could be inferred. The 20% mass
injection and 5 Hz backpressure excitation frequency case is considered for comparing
the pressures in the unexcited inlet with those measured in the inlet during the injection
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phase and for comparing the injection configurations as well. The assignment of exit
injection block ports, injection configurations and their abbreviations are discussed in
Chapter 2. S-2 coupling and 90 Phase coupling are considered for comparing the
unexcited inlet with that of the excited inlet and the plots shown in Figure 3-5. In cases of
Figure 3-5a and b, the first and the third plots, graph the normalized mean wall static
pressure and the fluctuation of static pressure with X/L. The fluctuation of static pressure
( ) is defined as the difference between the maximum ( P ′ Peak P ) and minimum ( )
pressures attained, to the average pressure ( ) during injection i.e.,
valley P
avg P
( ) peak valley
avg
P P P
P
−′ =
In the plots of the center column, the ordinate Y* is plotted with the normalized mean
stagnation pressure. Both the mean static pressure and the mean exit stagnation pressure
were normalized with the freestream stagnation pressure. Figure 3-7 gives the plots,
which compare the selected injection configurations.
From Figure 3-5 it can be observed that the mean levels of static pressures
downstream of the throat in the excited inlet are higher than the corresponding ones of
the unexcited inlet. The same trend is observed with the pressure oscillations produced in
the inlet. The stagnation pressure at the exit also changed because of the terminal shock
oscillations. The exit stagnation pressures follow the typical trend in that the pressure
values are lower near both the cowl and ramp walls and increasing from the walls to the
center section. It is also observed that the ramp side stagnation pressure is always lower
than the cowl side measured stagnation pressure because of the greater degree of
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separation on the ramp side. All these phenomena can be attributed to the large-scale
terminal shock oscillations generated in the excited inlet.
Figure 3-6 compares the schlieren images for the unexcited and the excited inlets
for the S-2 and the 90 Phase injection configurations. The flow direction is from the left
side to the right. The sidewalls of the inlet, made of 0.25” Plexiglas, have beveled leading
edges to facilitate smooth airflow past them and prevent bow shocks from forming at the
entry of the inlet. These beveled regions being opaque to light appear as dark bands along
the left edge of the images. The thin tubes seen in the images are the 1/16” OD SS tubes
used for static pressure measurements while the thicker tubes are the 1/8” ID SS tubes
used for boundary layer suction. Images were taken by a SONY camcorder, which had a
frame rate of approximately 30 Hz. So, on an average 6 images were acquired during a
period of the injection cycle with excitation frequency of 5 Hz. Schlieren movies are
presented in Appendix-D to further supplement the information provided here. There was
a relative terminal shock displacement in the excited inlet when compared to the
unexcited inlet, which can be clearly seen in both the cases considered. The weakening of
the terminal shock, as it moves upstream in the excited inlet, can be observed. It can be
inferred that the shock induced separation region moves with the oscillating terminal
shock.
For understanding the effect of injection configuration on the static pressure and
stagnation pressure at the exit, Figure 3-7 is considered. From Figure 3-7a it can be
observed that the AS-2 and the S-2 injection configurations produced almost identical
levels of static pressure, stagnation pressure at the exit and their associated oscillations,
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S-2 Coupling
(a)
X / L
p
/ P o 1
0 0.2 0.4 0.6 0.8 10
0.05
0.1
0.15
0.2
0.25 Without Injection
With Injection (5 Hz - 18.5%)
Po / Po1
Y
*
0 0.1 0.2 0.3 0.4 0.50
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1 Without InjectionWith Injection (5Hz - 18.5%)
X / L
( P p
- P v ) / P a v
0 0.2 0.4 0.6 0
0.2
0.4
0.6
0.8
1 During Injection
90 Phase Coupling
(b)
X / L
p
/ P o 1
0 0.2 0.4 0.6 0.8 10
0.05
0.1
0.15
0.2
0.25 Without InjectionF=5 Hz, Minj= 23%
Po / Po1
Y
*
0 0.1 0.2 0.3 0.4 0.50
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1 Without Injection
F=5Hz, Minj= 23%
X / L
( P
p
- P v ) / P a v
0 0.2 0.4 0.6 0
0.2
0.4
0.6
0.8
1 During Injection
Figure 3-5. Plots for comparing the excited and the unexcited inlet, for Minj=20% and Frequency = 5 Hz
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(a)
Unexcited Inlet Excited Inlet
(b)
Unexcited Inlet Excited Inlet
Figure 3-6. Schlieren images for the 5 Hz and 20% mass injection. (a) 90 Phase coupling
(b) S-2 coupling.
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during injection. The same is true with the AS-1, AS-3 and the S-1 injection
configurations as can be deduced from Figure 3-7b and c. The AS-2 and the S-2
configurations generated larger mean static pressures and their associated oscillations and
larger mean exit stagnation pressures, when compared to the AS-1, AS-3 or the S-1
configurations, as can be inferred form Figure 3-7d. But the differences in the fluctuation
Vs X/L plot for the S-2 coupling and S-1 coupling, as shown in Figure 3-7d can be
attributed to the differences in the mean pressure levels attained in the respective
injection configuration. The AS-2 and the S-2 configurations produced shock oscillations
whose effects propagated farther upstream than those of the AS-1, AS-3 or the S-1
couplings, as can be deduced from Figure 3-7d. The differences may be due to the fact
that in the AS-2 and the S-2 coupling configurations, air is injected from all the ports in
the exit injection block, which may have caused larger degree of shock displacement, and
thus all the observed effects. From Figure 3-7e, it can be inferred that among all the
injection configurations, the 90 Phase configuration produced the largest levels of mean
static pressure in the inlet. It was interesting to observe that the 90 Phase coupling
produced the lowest levels of shock oscillations and, therefore pressure oscillations. For
example, considering Figure 3-7f, the rms intensities reached to a maximum of 7%of the
local mean static pressure in the case of 90 Phase coupling while a maximum of 25% was
attained in the case of Symmetric and the Antisymmetric couplings.
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S-2 & AS-2 Configurations
(a)
X / L
p
/ P o 1
0 0.2 0.4 0.6 0.8 10
0.05
0.1
0.15
0.2
0.25 S-2AS-2
Po / Po1
Y
*
0 0.1 0.2 0.3 0.4 0.50
0.2
0.4
0.6
0.8
1 S-2AS-2
X / L
( P p
- P v ) / P a v
0 0.2 0.4 0.60
0.2
0.4
0.6
0.8
1S-2AS-2
AS-1 & S-1 Configurations(b)
X / L
p / P o 1
0 0.2 0.4 0.6 0.8 10
0.05
0.1
0.15
0.2
0.25 AS-1
S-1
Po / Po1
Y
*
0 0.1 0.2 0.3 0.4 0.50
0.2
0.4
0.6
0.8
1 AS-1
S-1
X / L
( P p
- P v ) / P a v
0 0.2 0.4 0.60
0.2
0.4
0.6
0.8
1 AS-1
S-1
Figure 3-7. Comparing the effects of injection configuration on the inlet flowfield.
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AS-1 & AS-3 Configurations
(c)
X / L
p
/ P o 1
0 0.2 0.4 0.6 0.8 10
0.05
0.1
0.15
0.2
0.25 AS-1AS-3
Po / Po1
Y
*
0 0.1 0.2 0.3 0.4 0.50
0.2
0.4
0.6
0.8
1 AS-1AS-3
X / L
( P p
- P v ) / P a v
0 0.2 0.4 0.60
0.2
0.4
0.6
0.8
1AS-1AS-3
S-2 & S-1 Configurations(d)
X / L
p / P o 1
0 0.2 0.4 0.6 0.8 10
0.05
0.1
0.15
0.2
0.25 S-2
S-1
Po / Po1
Y
*
0 0.1 0.2 0.3 0.4 0.50
0.2
0.4
0.6
0.8
1 S-2
S-1
X / L
( P p
- P v ) / P a v
0 0.2 0.4 0.60
0.2
0.4
0.6
0.8
1 S-2
S-1
Figure 3-7 (contd.). Comparing the effects of injection configuration on the inlet flowfield.
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90 Phase and AS-2 Configurations
(e)
X / L
p
/ P o 1
0 0.2 0.4 0.6 0.8 10
0.05
0.1
0.15
0.2
0.25 90 PhaseAS-2
Po / Po1
Y
*
0 0.1 0.2 0.3 0.4 0.50
0.2
0.4
0.6
0.8
1 90 PhaseAS-2
X / L
( P p
- P v ) / P a v
0 0.2 0.4 0.60
0.2
0.4
0.6
0.8
190 PhaseAS-2
90 Phase and S-1 Configurations(f)
X / L
p
/ P o 1
0 0.2 0.4 0.6 0.8 10
0.05
0.1
0.15
0.2
0.25 90 Phase
S-1
Po / Po1
Y
*
0 0.1 0.2 0.3 0.4 0.50
0.2
0.4
0.6
0.8
1 90 Phase
S-1
X / L
( P p
- P v ) / P a v
0 0.2 0.4 0.60
0.2
0.4
0.6
0.8
1 90 Phas
S-1
Figure 3-7 (contd.). Comparing the effects of injection configuration on the inlet flowfield.
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41
3.4.2 Effects of Mass Injection
In the present work, the effects of injecting different quantities of mass into the
inlet were investigated as well. For a given injection configuration and backpressure
excitation frequency, the effects due to variation in injected mass flows, on the inlet
characteristics could be inferred. In the present study the injection mass flows of 20% and
40% are compared. The plots for all the 6 Injection configurations at a backpressure
excitation frequency of 5 Hz are shown in Figure 3-8. In figure 3-8a, for the 90 Phase
coupling increased quantities of mass injection leads to an increase in the mean levels of
static pressure downstream of the throat. Its interesting to note that the oscillations
produced in the 40% case are either equal or less than those produced in the 20% case.
Interestingly for the other injection configurations, as in figure 3-8b-f, the mean levels of
the static pressure are almost identical for both the injection flow cases. Nevertheless, for
the 40% case, large pressure oscillations are generated and the effect is clearly felt in the
static taps upstream of the throat, for all the Antisymmetric and Symmetric
configurations. Thus, in general, the 20% injection case produced pressure oscillations,
which were confined to the downstream of the throat, whereas the 40% injection case
produced oscillations, which effected the static pressure all the way up to the capture.
This can be clearly visualized by comparing the fluctuation Vs X/L plots for both the
cases. In the 40% case a small drop in pressure could be observed in the first three static
taps during injection. This was due to the increased spillage in the 40% injection case and
the accompanied weakening of the leading edge wave system, which can be clearly
observed in the schlieren images, as discussed below.
Figure 3-9 compares the schlieren images for the 20% and the 40% injection case,
with the aid of S-2 and 90 Phase injection configurations respectively. The flow direction
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is from the left side to the right. From the schlieren images, the increased spillage and the
weakening of the capture wave system, in the 40% case can be clearly seen. Schlieren
movies are presented in Appendix-D to further supplement the information provided
here. In the schlieren movies of Appendix-D, one can clearly see the increased spillage,
during injection for the 40% case, in all the injection configurations. In almost all cases,
except the 90 Phase coupling, the terminal normal shock is periodically expelled from the
inlet, during the injection cycle.
The effect of mass injection on the exit stagnation pressure is not significant. In
all the injection configurations a slight drop in the exit stagnation pressure in the ramp
side probe and the core probe can be observed in the higher mass injection case when
compared to the lower mass injection case, in Figure 3-8. For the 40% case, though the
increased spillage weakened the shocks and the expansion waves in the inlet, the large
mass of relatively low momentum fluid into the inlet has a negative effect on the exit
stagnation pressure. But the compensating effect is provided by the upstream moving
normal shock and thus the exit stagnation pressure is the net resultant of these effects. For
the 20% case, as there was negligible or no spillage, only the effect of the upstream
moving normal shock is dominant and thus the level of the mean stagnation pressures at
the exit relatively increased during injection in all the injection configurations. This was
due to the weakening of the shock as it moves upstream in the diffuser section, as it
encounters a lower relative Mach number.
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90 Phase Coupling
(a)
X / L
p
/ P o 1
0 0.2 0.4 0.6 0.8 10
0.05
0.1
0.15
0.2
0.25 F=5 Hz, Minj=39%F=5 Hz, Minj=23%
Po / Po1
Y
*
0 0.1 0.2 0.3 0.4 0.50
0.2
0.4
0.6
0.8
1 F=5 Hz, Minj=39%F=5 Hz, Minj=23%
X / L
( P p
- P v ) / P a v
0 0.2 0.4 0.60
0.2
0.4
0.6
0.8
1F=5 Hz, MF=5 Hz, M
AS-2 Coupling(b)
X / L
p
/ P o 1
0 0.2 0.4 0.6 0.8 10
0.05
0.1
0.15
0.2
0.25 F=5 Hz, Minj=39%
F=5 Hz, Minj=18.5%
Po / Po1
Y
*
0 0.1 0.2 0.3 0.4 0.50
0.2
0.4
0.6
0.8
1 F=5 Hz, Minj=39%
F=5 Hz, Minj=18.5%
X / L
( P p
- P v ) / P a v
0 0.2 0.4 0.60
0.2
0.4
0.6
0.8
1 F=5 Hz, M
F=5 Hz, M
Figure 3-8. Comparing the effects of mass injection for two different injection mass flows-20% and 40%
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S-2 Coupling
(c)
X / L
p
/ P o 1
0 0.2 0.4 0.6 0.8 10
0.05
0.1
0.15
0.2
0.25 F=5 Hz, Minj=39%F=5 Hz, Minj=18.5%
Po / Po1
Y
*
0 0.1 0.2 0.3 0.4 0.50
0.2
0.4
0.6
0.8
1 F=5 Hz, Minj=39%F=5 Hz, Minj=18.5%
X / L
( P p
- P v ) / P a v
0 0.2 0.4 0.60
0.2
0.4
0.6
0.8
1F=5 Hz, MF=5 Hz, M
S-1 Coupling(d)
X / L
p
/ P o 1
0 0.2 0.4 0.6 0.8 10
0.05
0.1
0.15
0.2
0.25 F=5 Hz, Minj=39%
F=5 Hz, Minj=19.5%
Po / Po1
Y
*
0 0.1 0.2 0.3 0.4 0.50
0.2
0.4
0.6
0.8
1 F=5 Hz, Minj=39%
F=5 Hz, Minj=19.5%
X / L
( P p
- P v ) / P a v
0 0.2 0.4 0.60
0.2
0.4
0.6
0.8
1F=5 Hz, Minj=39
F=5 Hz, Minj=19
Figure-3.8 (contd.). Comparing the effects of mass injection for two different injection mass flows-20%
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AS-1 Coupling
(e)
X / L
p
/ P o 1
0 0.2 0.4 0.6 0.8 10
0.05
0.1
0.15
0.2
0.25 F=5 Hz, Minj=39%F=5 Hz, Minj=19.5%
Po / Po1
Y
*
0 0.1 0.2 0.3 0.4 0.50
0.2
0.4
0.6
0.8
1 F=5 Hz, Minj=39%F=5 Hz, Minj=19.5%
X / L
( P p
- P v ) / P a v
0 0.2 0.4 0.60
0.2
0.4
0.6
0.8
1F=5 Hz, MF=5 Hz, M
AS-3 Coupling(f)
X / L
p
/ P o 1
0 0.2 0.4 0.6 0.8 10
0.05
0.1
0.15
0.2
0.25 F=5 Hz, Minj=39%
F=5 Hz, Minj=19.5%
Po / Po1
Y
*
0 0.1 0.2 0.3 0.4 0.50
0.2
0.4
0.6
0.8
1 F=5 Hz, Minj=39%
F=5 Hz, Minj=19.5%
X / L
( P p
- P v ) / P a v
0 0.2 0.4 0.60
0.2
0.4
0.6
0.8
1 F=5 Hz, M
F=5 Hz, M
Figure-3.8 (contd.). Comparing the effects of mass injection for two different injection mass flows-20%
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S-2 Coupling
(a)
40% Mass injection 20% Mass injection
90 Phase Coupling
(b)
40% Mass injection 20% Mass injection
Figure 3-9. Schlieren images for comparing the 20% and 40% mass injection cases.
Figure 3-10 and Figure 3-11 show the staggered plots of the time trace of the
static pressures, normalized by the freestream stagnation pressure, at all the static tap
locations along the inlet for both the non-injection case and the injection case. In Figure
3-10, AS-2 coupling, injecting 20%, operating at 5 Hz is considered while in Figure 3-11,
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AS-2 coupling, injecting 40%, operating at 5 Hz is considered. Figure 3-10 indicates that
the upstream static ports 1-4 are virtually uneffected by 20% mass injection. From the
plots of Figure 3-11, it can be seen that the upstream static taps 1-4 are effected for the
40% mass injection case. It can be observed that the induced oscillations have a
fundamental frequency that matched the excitation frequency.
Figure 3-10. Static pressure –time trace for the AS-2 coupling, 20% mass injection and 5
Hz case.
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Figure 3-10 (contd.). Static pressure –time trace for the AS-2 coupling, 20% mass
injection and 5 Hz case.
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Figure 3-11. Static pressure –time trace for the AS-2 coupling, 40% mass injection and 5
Hz case.
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Figure 3-11 (contd.). Static pressure –time trace for the AS-2 coupling, 40% mass
injection and 5 Hz case.
3.4.3 Frequency Effects
Tests were conducted with the same injection mass flow i.e., 20% of the inlet
capture, but with different excitation frequency for three representative injection
configurations namely the 90 Phase coupling, AS-2 and the S-2 coupling. So, for a given
injection configuration and the same given injection mass flow, effect of excitation
frequency on the stability of the inlet could be understood.
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Figure 3-12a, b and c compare the effects produced by the excitation frequencies
5 Hz and 10 Hz on the inlet flowfield. The change in excitation frequency has a direct
effect on the magnitude of the static pressure oscillations as can be seen in Figure 3-12.
In all the injection configurations considered here the 5 Hz excitation case produced
larger pressure oscillations than the 10 Hz case as can be seen in the fluctuation Vs X/L
plots of Figure 3-12. The change in frequency did not have any significant effect on the
mean pressure levels on the AS-2 and S-2 configurations considered but the higher
injection mass flow in the 5 Hz case produced slightly higher mean pressure levels for the
90 Phase coupling.
The mean exit stagnation pressure in the 10 Hz case was higher when compared
to those in the 5 Hz case, for all the injection configurations, as shown in Figure 3-12. It
can be observed that the ramp side stagnation pressure measurement is the same in all
cases. The movies in Appendix-D show that the terminal shock displacement on the ramp
is the same for both 10 Hz and 5 Hz cases but the curvature of the shock increases on the
cowl side for the 10 Hz case thereby increasing the pressure recovery on the cowl side
and the core stagnation probes.
3.4.4 Exit Stagnation Pressure
The injected configuration, the amount of mass injection and the backpressure
excitation frequency, as discussed in the previous sections, effected the exit stagnation
pressures. But the mean stagnation pressures in the excited inlet was not appreciably
different from the unexcited inlet. Mean total recovery of 0.3 and 0.32 were produced in
the unexcited and the excited inlet respectively. The mean total recovery is defined as the
mean of the normalized exit stagnation pressures measured with the rake. This low
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90 Phase Coupling
(a)
X / L
p
/ P o 1
0 0.2 0.4 0.6 0.8 10
0.05
0.1
0.15
0.2
0.25 F=10 Hz, Minj=20%F=5 Hz, Minj=23%
Po / Po1
Y
*
0 0.1 0.2 0.3 0.4 0.50
0.2
0.4
0.6
0.8
1 F=10 Hz, Minj=20%F=5 Hz, Minj=23%
X / L
( P p
- P v ) / P a v
0 0.2 0.4 0.60
0.2
0.4
0.6
0.8
1F=10Hz, MF=5 Hz, M
AS-2 Coupling(b)
X / L
p
/ P o 1
0 0.2 0.4 0.6 0.8 10
0.05
0.1
0.15
0.2
0.25 F=10 Hz, Minj=20.7%
F=5 Hz, Minj=18.5%
Po / Po1
Y
*
0 0.1 0.2 0.3 0.4 0.50
0.2
0.4
0.6
0.8
1 F=10 Hz, Minj=20.7%
F=5 Hz, Minj=18.5%
X / L
( P p
- P v ) / P a v
0 0.2 0.4 0.60
0.2
0.4
0.6
0.8
1 F=10Hz, M
F=5 Hz, M
Figure 3-12. Comparing the effects of two different excitation frequencies-5 Hz & 10 Hz.
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S-2 Coupling
(c)
X / L
p
/ P o 1
0 0.2 0.4 0.6 0.8 10
0.05
0.1
0.15
0.2
0.25 F=10 Hz, Minj=20.7%F=5 Hz, Minj=18.5%
Po / Po1
Y
*
0 0.1 0.2 0.3 0.4 0.50
0.2
0.4
0.6
0.8
1 F=10 Hz, Minj=20.7%F=5 Hz, Minj=18.5%
X / L
( P p
- P v ) / P a v
0 0.2 0.4 0.60
0.2
0.4
0.6
0.8
1F=10Hz, MF=5 Hz, M
Figure-3.12.(contd.) Comparing the effects of two different excitation frequencies-5 Hz & 10 Hz.
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pressure recovery is a result of both the shock system losses and existence of large
separation zones in the inlet. A separation bubble on the second wedge, near the inlet
capture and the separation regions aft of the terminal shock are the primary separation
zones, which could be identified. Experiments on a similar inlet by Fernandez et al.13
produced a total pressure recovery of 0.37. The inlet used in their experiments has
variable geometry with adjustable ramp and cowl. Moreover the inlet was larger than the
inlet of the present study and thus has relatively lower losses.
3.5 Implications of Design and Size
The vehicle’s flight envelope largely dictates the design of the inlet. The size of
the inlet is dependent on the size of the vehicle and its mission. The size of the current
inlet would be comparable to that in a typical missile and hence the performance. The
size of the inlet would have been larger in the case of an aircraft. It would be expected
that in a larger size inlet, separation zone at the leading edge would be less severe leading
to an improved performance when compared to the current one. Furthermore, for
extended mission, bleed control may be employed reducing the adverse separation
effects.
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CHAPTER 4SUMMARY
The present study evaluated the effects of mass injection in a supercritical inlet for PDE
at Mach number of 3.5. The air injection simulated the operation of several PDE tubes
placed at the inlet exit. Effects of amount of mass injected, the excitation frequency and
the injection configurations have been evaluated. The results indicated the following.
• A terminal normal shock in the diffuser induced separation on both the cowl and the
ramp. The shock is partly normal and terminates as a lambda shock on both the cowland the ramp walls. As a result the pressure rise is half of the theoretical estimate.
• A separation bubble was noted on the second wedge, which disrupts the flow and
caused a complex shock and expansion wave system.
• There was good agreement between the ramp and the cowl static pressure
measurements aft of the terminal shock.
• In general, terminal shock oscillations were observed due to air injection and the
mean levels of static pressure downstream of the throat increased during injection.
• Large amplitude pressure oscillations were observed and rms intensities as high as
25% of the local mean static pressure were attained in the Symmetric and theAntisymmetric injection configurations.
• Even when a substantial amount of the inlet capture mass was injected, i.e., 40% of
capture, the inlet remained started, though with increased spillage.
• For a given injection mass flow and excitation frequency, the 90 phase coupling
produced the lowest levels of pressure oscillations but interestingly produced thelargest levels of mean static pressure downstream of the throat, in the inlet when
compared to the Antisymmetric and the Symmetric injection configurations.
• For a given injection mass flow and excitation frequency, the Symmetric-2 and theAntisymmetric-2 injection configurations produce similar mean levels of static
pressure through out the inlet during injection. The same is true with theAntisymmetric-1, Antisymmetric-3 and the Symmetric-1 couplings, but the meanlevels of static pressure produced in these cases is slightly less than those produced by
the Antisymmetric-2 and the Symmetyric-2 couplings.
• For a given injection mass flow and excitation frequency, the Antisymmetric-2 and
the Symmetric-2 produced shock oscillations whose effects propagate farther
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upstream than those of the Antisymmetric-1, Antisymmetric-3 and the Symmetric-1
couplings.
• For a given excitation frequency, the 20% injection case resulted in pressureoscillations, which were confined to the downstream of the throat, whereas the 40%
injection case produced pressure oscillations, which propagated all the way up to the
inlet capture.
• The mean levels of static pressure downstream of the throat did not differ much for both the 20% and the 40% case, except for the 90 Phase injection configuration. A
small drop in pressure could be observed in the first three static taps during injection,
for the 40% injection case.
• The stagnation pressure at the exit increased during injection for the 20% case for allthe injection configurations independent of frequency. No specific trend was
observed for the 40% injection case.
• The mean stagnation pressure recovery at the exit is 0.3. The static pressure rise in the
inlet is about 15. This low-pressure recovery is a result of both shock system lossesand presence of large separation zones in the inlet. The inlet was operated at a
backpressure ratio of 0.2.
• The pressure oscillations downstream of the throat correlated well with the
backpressure excitation frequency.
• For a given injection mass flow and an injection configuration, lower backpressureexcitation frequency produced larger pressure oscillations while the higher
backpressure excitation frequency produced higher exit stagnation pressures.
• The schlieren and the oil flow visualization images confirmed these observations.
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APPENDIX ADATA ACQUISITION PROGRAM
LabVIEW programs were used to control the Wind Tunnel and the backpressure
excitation mechanism. This section describes the action of these programs in a flowchart
and later presents the front panels and block diagrams for these programs.
Start
Main
Stop
Continue
ConfigureRegister Calibration
data, channel info., etc
Channel info Acquire Data
Stop
Process DataCalibration const.
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Global Data
Display
Stop?yes no
Po set point
Tunnel?no yes
Tunnel control
Inj. Control
Main
Save
Data?
File path
no yes
Stop Tunnel
yes
no Injection?
Save Data
Figure A-1. Flowchart showing the data acquisition and experimental automation.26
The six primary modules that are triggered manually are Main.vi, Display.vi,
Acquire and Save.vi, Valve control.vi, Telnet to Freedom.vi, AOcontrol.vi and Injseq.vi.
Two computers are used for acquiring pressure data. One of them (Kronos) runs the
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Main.vi which further loads and runs the other five VI’s (modules) listed above. The
other computer (Freedom) runs the pressure scanner.vi, which handles the PSI9010
scanner pressure data. The sub-VI’s are presented in the order at which they are called.
Also, empty cases and cases where the data is passed through unchanged are not
included. The front panels and block diagrams are scaled to fit the page. The scaling is
different for each VI shown.
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Main.vi: Opens up and runs the other VI’s on Kronos
Front panel
Block Diagram
Startup.vi
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WriteNetVar.vi
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Shutdown.vi
Startup.vi
Front Panel
Block Diagram
WriteNetVar.vi
Front Panel
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Block Diagram
Shutdown.vi
Front Panel
Block Diagram
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Display.vi: The core user interface VI with controls for the tunnel, injection
mechanism and data saving. This VI, simultaneously acquires and plots
the High speed pressure data.
Front Panel
Block Diagram
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Msg2
Freed
Zer
Word.vi
Format
string .vi
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Zero.vi: Resets all read pressures to atmospheric pressure on all the pressure
transducers including the pressure scanner (by sending a signal to
Freedom).
Front Panel
Block Diagram
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Msg2Freedom.vi
Front Panel
Block Diagram
Format string.vi
Front Panel
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Block Diagram
Word.vi: Writes log file when update log is closed on display panel.
Front Panel
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Block Diagram
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Acquire and Save: Reads blocks of 250 high-speed data rows and saves to prescribed
file.
Front panel
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Block Diagram
Process Data.vi
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Process Data.vi: Applies calibration to read Pressure transducer data to convert
them to psi.
Front Panel
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Block Diagram
Valve control.vi: Controls the tunnel valve.
Front Panel
Block Diagram
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Telnet to Freedom.vi: Handles Telnet communication between Kronos and
Freedom.
Front Panel
Block Diagram
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Msg2Freedom.vi
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Injseq.vi: Controls the Injection mechanism by actuating the injection solenoids
accordingly.
Block Diagram
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AO Control.vi: Sends the Analog output (voltage) to the Relays as prescribed by
the Injseq.vi.
Front Panel
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Block Diagram
Droplet.vi: Used for capturing schlieren images.
Front Panel
Block Diagram
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Pressure Scanner.vi This program reads serial data from PSI9010 scanner on Freedom.
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Block Diagram
Read Mach 4
WT PSI9010.vi
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Read Mach 4 WT PSI 9010.vi
Front Panel
Block Diagram
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Global Controls.vi
Front Panel
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APPENDIX B
MATLAB PROGRAM FOR DATA REDUCTION
A MATLAB program was used to compile the pressure data obtained both from
the scanner and the High Speed Transducers (Omega). The program performs the
following operations:
1. The pressures are normalized with respect to the freestream stagnation pressure.
2. Mean and rms values of the normalized pressures are calculated for the time intervalsspecified by the user.
3. Makes the plots of wall mean static pressure and the fluctuation of static pressure,defined as the difference between the maximum and minimum pressures attained, to
the average pressure during injection, with X/L. (normalized axial coordinate
measured from the leading edge of the inlet), with the error bars.
4. Makes the plot of ordinate Y*-the non-dimensional distance of the location of thestagnation probe from the ramp, with the normalized mean stagnation pressure at the
exit, with the error bars
5. Makes the pressure time trace for all the wall static pressures measured in the inlet.
6. Plots are produced based on the transducer assignment provided by the user.
MATLAB Code
%M3_5compile.m
%reads and compiles pressure scanner and Kronos dataflnhs='F:/Raw data/11-13-02p'; %high-speed data file
dsc='//Freedom/PDE Inlet/Scanner data'; %scanner data directoryrunn=flnhs(end-8:end);
hssf=1000; %sampling frequency, high-speed data
bar=0.01; %bar length for std barsn=41; %high speed data points to calculate average over when using with scanner data
curr=cd;
%cd('curr');
% cd('C:\');
d=dir([dsc '/*' flnhs(end-8:end)]); %find matching scanner file
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skipt=0; %skip no transducers in hs data - plot them all
%%Also change statv and strutv below to assign transducers to correct taps.
%
if prod(runn(1:8)=='03-20-02')|prod(runn(1:8)=='04-08-02')|prod(runn(1:8)=='04-11-02'),
mode=17;elseif prod(runn(1:8)=='04-26-02')|prod(runn(1:8)=='04-29-02')|prod(runn(1:8)=='05-20-
02')|prod(runn(1:8)=='05-21-02')...
|prod(runn(1:8)=='06-10-02')|prod(runn(1:8)=='06-13-02')|prod(runn(1:8)=='06-14-02')|prod(runn(1:8)=='06-19-02')...
|prod(runn(1:8)=='06-20-02')|prod(runn(1:8)=='06-21-02')|prod(runn(1:8)=='06-24-
02')|prod(runn(1:8)=='07-02-02')...|prod(runn(1:8)=='07-05-02')|prod(runn(1:8)=='07-15-02')|prod(runn(1:8)=='07-16-
02')|prod(runn(1:8)=='07-17-02')...
|prod(runn(1:8)=='08-27-02')|prod(runn(1:8)=='08-28-02')|prod(runn(1:8)=='09-08-
02')|prod(runn(1:8)=='09-12-02')...
|prod(runn(1:8)=='09-16-02')|prod(runn(1:8)=='09-20-02')|prod(runn(1:8)=='09-22-02')|prod(runn(1:8)=='09-23-02')...
|prod(runn(1:8)=='09-24-02')|prod(runn(1:8)=='09-25-02')|prod(runn(1:8)=='09-27-02')|prod(runn(1:8)=='10-03-02')...
|prod(runn(1:8)=='10-05-02')|prod(runn(1:8)=='10-13-02')|prod(runn(1:8)=='10-15-
02')|prod(runn(1:8)=='10-19-02')...|prod(runn(1:8)=='10-20-02')|prod(runn(1:8)=='10-28-02')|prod(runn(1:8)=='10-31-
02')|prod(runn(1:8)=='11-01-02')...
|prod(runn(1:8)=='11-09-02')|prod(runn(1:8)=='11-10-02')|prod(runn(1:8)=='11-
13-02'),
mode=18;
else
mode=99;
end;
switch modecase 17,
sc1=5;
sc2=10;xv=([0.7 1 1.4 1.8 2.2 2.65 3.1 3.1 3.6 3.6])/5.1797;
rpmcol=12;
stagcol=6;
skipt=4; %%skip first 4 transducers in hs file - scxi datacase 18, %Mach 3.5 inlet
sc1=5; % vac line connected to sc 5 06-20-02
sc2=12;%xv=([1.2 1.7 2.1 2.5 2.9 3.1 3.5 3.9 4.3 4.7 5.1 3.9 4.3 4.7 5.1])/5.3041;%added
locations for cowl static taps
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xv=([1.2 1.7 2.1 2.5 2.9 3.1 3.5 3.9 4.3 4.7 5.1])/5.3041;
yv=[0.145 0.5 0.855]; %stag rake locations from the ramprpmcol=9;
stagcol=3;
skipt=0;
otherwise,
disp('Need parameters! Add in program for this case.'); break;
end;
if length(d)>1,disp('WARNING! More than one matching scanner file found!');
end;
flnsc=[dsc '/' d(1).name]; %file name of scanner file with search path
tsc=str2num(d.name(1:end-10)); %time stamp obtained from scanner file name
hs=load(flnhs);
sc=load(flnsc);[hsrows,hscols]=size(hs);
%scanner format: t, dt, selected ports (sc1-sc2)
%subtracting scanner start time from all time stamps in scanner data
sc(:,1)=sc(:,1)-sc(1,1);
sc(1,2)=sc(2,1)-sc(1,1);
stamp=find(hs(:,1)>0); %row numbers of rows in high-speed data carrying time stamp
(first in each batch)
ths=hs(stamp,1);
if length(tsc)==0, %for scanner files without a time stamp, use start of high-speed datatsc=ths(1);
end;
figure(1);clf;
% plot(sc(:,1)/1000,sc(:,3:end-1));
% hold on;% ha=plot((hs(stamp,1)-tsc)/1000,hs(stamp,2:end-1));
% %ha=plot((0:(length(hs(:,1))-1))/1E3,hs(:,2:end-1));
% for i=1:length(ha),
% set(ha(i),'LineWidth',2);% end;
x=(0:1:length(hs(:,1))-1)/1000;
plot(x,hs(:,2:end-1))grid on;
xlabel('t (s)');
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ylabel('p (psi)');
title([flnhs(end-8:end)]);% legend([num2str(1:11)']);
sc(:,1)=cumsum(sc(:,2)); %replacing time stamps on scanner data with higher-precision
values
hst=(0:hsrows-1)/hssf;dt=hs(1,1)-tsc; %time difference - start of high-speed data minus start of scanner data
switch runn, %manually set offset time between scanner and high-speed data
case '05-20-02c',dt=dt+840;
case '05-20-02c',
dt=dt+454;case '05-21-02c',
dt=dt+503;
case '06-10-02a',
dt=dt+1234;
case '06-10-02b',dt=dt+1462;
case '06-13-02a',dt=dt+1306;
case '06-14-02d',
dt=dt+1260;case '06-14-02e',
dt=dt+940;
case '06-20-02d',
dt=dt+1172;case '06-21-02a',
dt=dt+1300;
case '06-21-02i',
dt=dt+1280;
case '06-24-02d',dt=dt+1201;
case '06-24-02c',
dt=dt+1325;case '06-24-02e',
dt=dt+1478;
case '06-24-02h',dt=dt+1300;
case '06-24-02i',
dt=dt+1201;
case '07-02-02d',dt=dt+1323;
case '07-05-02a',
dt=dt+785;case '07-05-02b',
dt=dt+1282;
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case '07-15-02a',
dt=dt+1170;case '07-15-02b',
dt=dt+1328;
case '07-16-02b',
dt=dt+1587;case '07-16-02a',
dt=dt+1230;
case '07-17-02a',dt=dt+1380;
case '08-27-02a',
dt=dt+1260;case '08-28-02a',
dt=dt+1538;
case '09-08-02a',
dt=dt+246;
case '09-08-02b',dt=dt+1246+118;
case '09-12-02a',dt=dt+1297;
case '09-12-02b',
dt=dt+1575;case '09-16-02b',
dt=dt+1486;
case '09-16-02c',
dt=dt+1293;case '09-16-02d',
dt=dt+1198;
case '09-20-02a',
dt=dt+1020;
case '09-22-02a',dt=dt+1220;
case '09-22-02b',
dt=dt+1298;case '09-22-02c',
dt=dt+1268;
case '09-23-02a',dt=dt+1018;
case '09-24-02a',
dt=dt+1098;
case '09-24-02b',dt=dt+1476;
case '09-25-02a',
dt=dt+1286;case '09-25-02c',
dt=dt+1346;
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case '09-27-02a',
dt=dt+1346;case '09-27-02c',
dt=dt+1346+147;
case '10-03-02a',
dt=dt+1303;case '10-05-02a',
dt=dt+1473;
case '10-05-02d',dt=dt+1263;
case '10-05-02e',
dt=dt+1263;case '10-05-02f',
dt=dt+1343;
case '10-05-02g',
dt=dt+1343;
case '10-05-02h',dt=dt+1343;
case '10-05-02k',dt=dt+1365;
case '10-13-02a',
dt=dt+1400;case '10-13-02b',
dt=dt+1345;
case '10-15-02i',
dt=dt+1245;case '10-15-02n',
dt=dt+1473;
case '10-19-02b',
dt=dt+1123;
case '10-19-02m',dt=dt+1203;
case '10-19-02p',
dt=dt+1736;case '10-19-02q',
dt=dt+1219;
case '10-19-02r',dt=dt+1309;
case '10-19-02s',
dt=dt+1197;
case '10-20-02c',dt=dt+1107;
case '10-20-02d',
dt=dt+1294;case '10-20-02g',
dt=dt+1219;
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case '10-20-02i',
dt=dt+1337;case '10-28-02i',%[test e=1227,test f=1314,test g=1184,test h=1179,test i=1299]
dt=dt+1299;
case '10-31-02b',%[test b=1314 test c=1314,test f=1378,h=1137,a=1136]
dt=dt+1314;case '11-09-02n',%[a=1272 b=1197 i=1292 j=1318
dt=dt+1302;
case '11-10-02i',%[a=1302 j=1352 i=1268 d=1440 e=1476 f,h,i=1280 j=1354 k=1267m=1548 n=1256]
dt=dt+1280; %[o=1386 p=1277]
case '11-13-02p',%[a=1420 c=1204 d=1263 e=1342 g=1186 h=1524 i=1147 j=1418k=1249 l=1302 m=1500]
dt=dt+1545; %[n=1215 p=1545]
end;
maxdev=max((stamp-1)/hssf-(hs(stamp,1)-hs(1,1))/1000);disp(['Maximum time deviation in high-speed data ' num2str(maxdev) ' s']);
%build normalized highspeed matrix, keep rpm unchanged
%note that hsn lacks first column in hs (time stamps)
stag=hs(:,stagcol); %extracting high-speed data on stagnation pressures%hsn=hs(:,2:end); %not normalize (for plotting abs pressures)
hsn=hs(:,2:end)./(hs(:,stagcol)*ones(size(hs(1,2:end)))); %normalize
hsn(:,stagcol-1)=stag; %restore stagnation pressurehsn(:,rpmcol-1)=hsn(:,rpmcol-1).*stag; %restore rpm
%building a matrix of high-speed data with scanner sampling frequency
hs1=[];hsn1=[];
hsn1q=[];
n1=[];for i=1:length(sc(:,1));
p1=find(abs(hst-(sc(i,1)+dt)/1000)<(n-1)/2/hssf); %find corresponding high-speed data
if (length(p1)<2), p1=[];
hs1=[hs1; NaN*ones(size(hs(1,:)))];
hsn1=[hsn1; NaN*ones(size(hsn(1,:)))];
hsn1q=[hsn1q; NaN*ones(size(hsn(1,:)))];else
hs1=[hs1; mean(hs(p1,:))];
hsn1=[hsn1; mean(hsn(p1,:))];hsn1q=[hsn1q; sum(hsn(p1,:).^2)]; %store quadratic sums too for rms calculation
later
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end;
n1=[n1; length(p1)]; %no of samples in hsdata converted into single sc data pointend;
%normalize scanner data with stagnation pressure
scn=sc(:,3:end)./(hs1(:,stagcol)*ones(size(sc(1,3:end))));%scn=sc(:,3:end); % for plotting only pressures
figure(2);
clf;ha=plot(sc(:,1)/1000,[hsn1(:,skipt+1) hsn1(:,skipt+3:end-1) scn(:,1:end-1)]);
for i=1:length(hsn1(1,skipt+1:end-2)),
set(ha(i),'LineWidth',2);end;
grid on;
ax=axis;
%axis([0 ax(2) 0 1]);
xlabel('t (s)');ylabel('p/p_0');
title([flnhs(end-8:end), ' - thick hs, thin sc']);% legend([num2str(1:11)']);
figure(24);clf;
plot(sc(:,1)/1000,scn(:,6));
hold on;
sync=dt; %here is where the HST data is in sync with scanner HST1=hsn(sync:end,:);x=(0:length(HST1(:,1))-1)/1000;
plot(x,HST1(:,[1 5 7]));
pstag=[]; pstagrms=[];
pstat=[]; % tap location and scnm
pstatrms=[]; % tap location and scnrms pressure=[]; % rearranging the mean pressures for diff condns in the same run for
subplots
time=[];
% extracting the pressures and saving them in text delimited files
for j=1:3,
switch jcase 1,
%disp('vac sols open');
disp('without injection');case 2,
% %disp('vac sols closed');
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disp('injection');
case 3,disp('hinjection');
end;
%select excerpt to analyzet1=input( ' Start time ');
t2=input( ' Stop time ');
running=find(sc(:,1)/1000>t1&sc(:,1)/1000<t2);
%calculate mean and rms for normalized values during this time span
scnm=mean(scn(running,:));scnrms=std(scn(running,:),1);
hsn1m=mean(hsn1(running,:));
hsn1rms=sqrt((sum(n1(running))-1)/sum(n1(running)))*sqrt(1/(sum(n1(running))-
1)*(sum(hsn1q(running,:))-(n1(running)'*hsn1(running,:)).^2/sum(n1(running))));
% % make plots for the 3 cases
% HST=hs1(running,2:end-1);% scan=scn.*(hs1(:,stagcol)*ones(size(sc(1,3:end))));
% scan=[sc(running,1)/1000 scan(running,:)];
% press=[scan(:,1) HST(:,1) scan(:,2:end) HST(:,[5 7]) HST(:,[2 3 4 6])];% eval(['save ' runn num2str(j) '.txt press -ascii -tabs']); %saves the pressures in as a
text file in the current dir
%make plots for the cases press=[hsn1(running,1) scn(running,[1:8]) hsn1(running,5) hsn1(running,7)];taps=[1 2 3 4 5 6 7 8 9 10 11];
%making plot of stag rake pressures
stgrake=[scn(running,[9:11])];figure(j+10);
plot(sc(running,1)/1000,stgrake);
axis([t1 t2 0 0.5]);xlabel('t(s)');
ylabel('Po / Po1');
title([flnhs(end-8:end), ' - stagrake']);%
%make stagerred plots for static press vs time in the interval [t1 t2]
figure(7);for k=1:6,
if (j==1),
l=2*k-1;else
l=2*k;
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end;
subplot(6,2,l);
if (k==1),
T1=t1*1000;T2=t2*1000;
ch=[1 2 3 5 7];
h=plot(t1:0.001:t2,HST1(T1:T2,ch(k)),'k-');set(h,'linewidth',1.5);
end;
if (k>1),h=plot(sc(running,1)/1000, press(:,k),'k-');
set(h,'linewidth',1.5);
end;
if (l==(2*k-1)),
ha=ylabel('p/p_0');set(ha,'Fontsize',24,'Fontweight','bold');
set(get(gca,'YLabel'),'position',[(t1-0.2) 0.11 0]);set(gca,'yticklabel',{'0.04';'';'0.12 ';'';'0.20'});
else
set(gca,'yticklabel',[]);end;
set(gca,'ytick',[0.04:0.04:0.2]);
set(gca,'linewidth',1.5,'ticklength',[0.02 0.035]);
%title(['static tap' num2str(k)]);axis([t1 t2 0.04 0.20]);ax=axis;
set(gca,'xtick',[t1:0.2:t2]);
set(gca,'xticklabel',[]);
ha=text(0.7*ax(2)+0.3*ax(1),0.9*ax(3)+0.1*ax(4),['tap ' num2str(taps(k))]);set(ha,'Fontsize',20,'Fontweight','bold');
set(gca,'Fontsize',20,'Fontweight','bold');
if (l==1),hb=text((t1+(t2-t1)*0.1),0.24,'Without Injection');
set(hb,'Fontsize',24,'Fontweight','bold');
elseif (l==2),hc=text((t1+(t2-t1)*0.18),0.24,'With Injection');
set(hc,'Fontsize',24,'Fontweight','bold');
end;
if (l==11)|(l==12),
set(gca,'xticklabel',[t1:0.2:t2]);ha=xlabel('t (s)');
set(ha,'Fontsize',20,'Fontweight','bold');
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end;
end;
figure(8);
for k=1:5,if (j==1),
l=2*k-1;
elsel=2*k;
end;
subplot(5,2,l);
if (k<4),
h=plot(sc(running,1)/1000, press(:,k+6),'k-');
set(h,'linewidth',1.5);
end;if (k==4|k==5),
T1=t1*1000;T2=t2*1000;
ch=[1 2 3 5 7];
h=plot(t1:0.001:t2,HST1(T1:T2,ch(k)),'k-');set(h,'linewidth',1.5);
end;
if (l==(2*k-1)),
ha=ylabel('p/p_0');set(ha,'Fontsize',24,'Fontweight','bold');set(get(gca,'YLabel'),'position',[(t1-0.2) 0.11 0]);
set(gca,'yticklabel',{'0.04';'';'0.12 ';'';'0.20'});
else
set(gca,'yticklabel',[]);end;
set(gca,'ytick',[0.04:0.04:0.20]);
set(gca,'linewidth',1.5,'ticklength',[0.02 0.035]);%title(['static tap' num2str(k)]);
axis([t1 t2 0.04 0.20]);
ax=axis;set(gca,'xtick',[t1:0.2:t2]);
set(gca,'xticklabel',[]);
ha=text(0.7*ax(2)+0.3*ax(1),0.9*ax(3)+0.1*ax(4),['tap ' num2str(6+k)]);
set(ha,'Fontsize',20,'Fontweight','bold');set(gca,'Fontsize',20,'Fontweight','bold');
if (l==1),hc=text((t1+(t2-t1)*0.1),0.24,'Without Injection');
set(hc,'Fontsize',24,'Fontweight','bold');
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elseif(l==2),
hd=text((t1+(t2-t1)*0.18),0.24,'With Injection');set(hd,'Fontsize',24,'Fontweight','bold');
end;
if (l==9)|(l==10),
set(gca,'xticklabel',[t1:0.2:t2]);ha=xlabel('t (s)');
set(ha,'Fontsize',20,'Fontweight','bold');
end;
end;
disp('Average pressure ratios, p/p0');
disp(['scanner: ' num2str(mean(scn(running,:)))]);
disp(['remaining: ' num2str(mean(hsn1(running,:)))]);
for i=sc1:sc2,
disp(['Scanner port ' num2str(i) ': ' num2str(scnm(i-sc1+1)) ' rms: 'num2str(scnrms(i-sc1+1))]);
end;
switch mode
case {1,2,14,15,16,18} %No SCXI transducers during May 2001 and Nov 2001- tests
%note that stagcol now points to static pressure column after removal of first
columndisp(['Tunnel static: ' num2str(hsn1m(stagcol)) 'p0 rms: ' num2str(hsn1rms(stagcol))
' p0']);
disp(['->Mach number: ' num2str(sqrt(5*(hsn1m(stagcol)^(-2/7)-1)))]);
for i=0:6,disp(['Omega ' num2str(i) ': ' num2str(hsn1m(i+1)) ' rms: '
num2str(hsn1rms(i+1))]);
end;
otherwise %with SCXI transducers
for i=1:4,disp(['SCXI ' num2str(i) ': ' num2str(hsn1m(i)) ' rms: ' num2str(hsn1rms(i))]);
end;
%note: stagcol now points to static pressure since one col has been chopped off!
disp(['Tunnel static: ' num2str(hsn1m(stagcol)) ' rms: ' num2str(hsn1rms(stagcol))]);disp(['->Mach number: ' num2str(sqrt(5*(hsn1m(stagcol)^(-2/7)-1)))]);
for i=1:4,disp(['Omega ' num2str(i) ': ' num2str(hsn1m(i+6)) ' rms: '
num2str(hsn1rms(i+6))]);
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end;
end;
% disp(['RPM: ' num2str(hsn1m(rpmcol-1)) ' rms: ' num2str(hsn1rms(rpmcol-1))]);
% disp(['->f: ' num2str(hsn1m(rpmcol-1)/30) ' rms: ' num2str(hsn1rms(rpmcol-1)/30)]);
%build vectors for plots
switch mode
case 17, %2D inlet with rotating cylinder switch runn,
case '03-20-02a', %HST on static 1-5
statv=[hsn1m([1 4 5 6 7]) scnm([1 4 5])];statvrms=[hsn1rms([1 4 5 6 7]) scnrms([1 4 5])];
case '03-20-02b', %HST on static 6-10
statv=[scnm([1 2 3]) hsn1m([1 4 5 6 7])];
statvrms=[scnrms([1 2 3]) hsn1rms([1 4 5 6 7]) ];
case '04-08-02a', %HST on static 1,2,7,8statv=[hsn1m([7 8]) scnm([1:4]) hsn1m([9 10]) scnm([5 6])];
statvrms=[hsn1rms([7 8]) scnrms([1:4]) hsn1rms([9 10]) scnrms([5 6])];case '04-08-02b', %HST on static 3,4,7,8
statv=[scnm([1 2]) hsn1m([7 8]) scnm([3 4]) hsn1m([9 10]) scnm([5 6])];
statvrms=[scnrms([1 2]) hsn1rms([7 8]) scnrms([3 4]) hsn1rms([9 10]) scnrms([56])];
case '04-08-02c', %HST on static 5,6,7,8
statv=[scnm(1:4) hsn1m([7 8]) hsn1m([9 10]) scnm([5 6])];
statvrms=[scnrms(1:4) hsn1rms([7 8]) hsn1rms([9 10]) scnrms([5 6])];case '04-08-02d', %HST on static 7,8,9,10
statv=[scnm(1:6) hsn1m([7 9 8 10])];
statvrms=[scnrms(1:6) hsn1rms([7 9 8 10])];
case {'04-11-02e','04-11-02d'} %HST on static 7,8,9,10
statv=[scnm(1:6) hsn1m([7 8 9 10])];statvrms=[scnrms(1:6) hsn1rms([7 8 9 10])];
end;
case 18,% Mach 3.5 inlet with fluidic injectionswitch runn,
case '04-26-02f', %HST on static 1,2,3,10,11
statv=[hsn1m([1 4 5]) scnm(1:6) hsn1m([6 7])];statvrms=[hsn1rms([1 4 5]) scnrms(1:6) hsn1rms([6 7])];
case '04-29-02b', %HST on static 1,2,3,10,11
statv=[hsn1m([1 4 5]) scnm(1:6) hsn1m([6 7])];
statvrms=[hsn1rms([1 4 5]) scnrms(1:6) hsn1rms([6 7])];case '04-29-02c', %HST on static 4-8
statv=[scnm(1:3) hsn1m([1 4 5 6 7]) scnm(4:6)];
statvrms=[scnrms(1:3) hsn1rms([1 4 5 6 7]) scnrms(4:6)];case '05-20-02a', %HST on static 1,2,3,10,11,no extra block
statv=[hsn1m([1 4 5]) scnm(1:6) hsn1m([6 7])];
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statvrms=[hsn1rms([1 4 5]) scnrms(1:6) hsn1rms([6 7])];
case '05-20-02b', %HST on static 1,2,3,10,11,extra max blockagestatv=[hsn1m([1 4 5]) scnm(1:6) hsn1m([6 7])];
statvrms=[hsn1rms([1 4 5]) scnrms(1:6) hsn1rms([6 7])];
case '05-20-02c', %HST on static 1,2,3,10,11,no extra block
statv=[hsn1m([1 4 5]) scnm(1:6) hsn1m([6 7])];statvrms=[hsn1rms([1 4 5]) scnrms(1:6) hsn1rms([6 7])];
case '05-21-02c', %HST on static 1,2,3,10,11,no extra blockage
statv=[hsn1m([1 4 5]) scnm(1:6) hsn1m([6 7])];statvrms=[hsn1rms([1 4 5]) scnrms(1:6) hsn1rms([6 7])];
case '06-10-02a', %HST on static 1,10,11,U/D stream of inj.solenoid,no extra
blockagestatv=[hsn1m(1) scnm(1:8) hsn1m([5 7])];
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];
case '06-10-02b', %HST on static 1,10,11,U/D stream of inj.solenoid,no extra
blockage
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; %some taps loststatvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];
case '06-13-02a', %HST on static 1,10,11,U/D stream of inj.solenoid,no extra blockage
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])];
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];case '06-13-02b', %HST on static 1,10,11,U/D stream of inj.solenoid,no extra
blockage
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])];
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];case '06-14-02e', %HST on static 1,10,11,U/D stream of inj.solenoid,no extra
blockage
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % shorter sting
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];
case '06-19-02k', %HST on static 1,10,11,U/D stream of inj.solenoid,no extra blockage
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; %no TFE tubes,no SS tubes at the
back statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];
case '06-20-02d', %HST on static 1,10,11,U/D stream of inj.solenoid,no extra
blockagestatv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180
statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];% vac line on scnm(1)
case '06-21-02a', %HST on static 1,10,11,U/D stream of inj.solenoid,no extra
blockagestatv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180, no W/T run..
statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];% vac line on scnm(1)
case '06-21-02b', %HST on static 1,U/D stream of inj.solenoid,no extra blockagestatv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180,no W/T run
statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];% vac line on scnm(1)
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case '06-21-02c', %HST on static 1,U/D stream of inj.solenoid,no extra blockage
statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180,no W/T runstatvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];% vac line on scnm(1)
case '06-21-02i', %HST on static 1,U/D stream of inj.solenoid,no extra blockage
statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180,2 inj sols coupled
statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];% vac line on scnm(1)case '06-24-02c', %HST on static 1,U/D stream of inj.solenoid,no extra blockage
statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180,90 phase
statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];%case '06-24-02d', %HST on static 1,U/D stream of inj.solenoid,no extra blockage
statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180,2 inj sols coupled
statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];%case '06-24-02e', %HST on static 1,U/D stream of inj.solenoid,no extra blockage
statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180,4 inj sols coupled
statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];%
case '06-24-02h', %HST on static 1,U/D stream of inj.solenoid,no extra blockage
statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180, 90 phase offsetstatvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];%
case '06-24-02i', %HST on static 1,U/D stream of inj.solenoid,no extra blockagestatv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180,90 phase offset
statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];
case '07-02-02d', %HST on static 1,no inj,U/D stream of inj.solenoid,50% extra blockage
statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180
statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];
case '07-05-02a', %HST on static 1,no inj,U/D stream of inj.solenoid,20% extra blockage
statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180
statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])]; %90 phase offset
case '07-05-02a', %HST on static 1,no inj,U/D stream of inj.solenoid,20% extra
blockagestatv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180
statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])]; % 90 phase offset
case '07-15-02a', %HST on static 1,no inj,U/D stream of inj.solenoid,20% blockagestatv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180,90 phase offset
statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];
case '07-15-02b', %HST on static 1,no inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180
statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];
case '07-16-02a', %HST on static 1,no inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];
case '07-16-02b', %HST on static 1,no inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180,tripstatvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];
case '07-17-02a', %HST on static 1,no inj,U/D stream of inj.solenoid,
8/3/2019 Venkata Narasimham Nori- Unsteady Flow in a Mixed-Compression Inlet at Mach 3.5
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statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180,trip
statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];case '08-27-02a', %HST on static 1,no inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,bleed
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];
case '08-28-02a', %HST on static 1,no inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,bleed
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];
case '09-08-02b', %HST on static 1,no inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,bleed
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];
case '09-12-02a', %HST on static 1,no inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,bleed
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];
case '09-12-02b', %HST on static 1,no inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,no bleed
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];case '09-16-02b', %HST on static 1, inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,bleedstatvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%90 phase offset
case '09-16-02c', %HST on static 1, inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180, bleedstatvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% Symm coup
case '09-16-02d', %HST on static 1, inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180, bleed
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% Antisymmcase '09-20-02a', %HST on static 1, inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180, bleed
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%No inj
case '09-22-02a', %HST on static 1, inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,No bleedstatvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%Only Ramp
case '09-22-02b', %HST on static 1, inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,No bleedstatvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%Only Ramp
case '09-22-02c', %HST on static 1, inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleedstatvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%Only Ramp
case '09-23-02a', %HST on static 1, inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,No bleed
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%Only Rampcase '09-24-02a', %HST on static 1, inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,No bleed
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% No injcase '09-24-02b', %HST on static 1, inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,No bleed
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statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% No inj,stag tubes
case '09-25-02a', %HST on static 1, inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% No inj,stat tubes
case '09-25-02c', %HST on static 1, inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% No inj,stag tubes
case '09-27-02a', %HST on static 1, inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% inj,stat tubes
case '09-27-02c', %HST on static 1, inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% inj,stag tubes
case '10-03-02a', %HST on static 1, inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% inj,stat tubes
case '10-05-02a', %HST on static 1, inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,symm
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% inj,stat tubescase '10-05-02d', %HST on static 1, inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,symm
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% inj,stag tubescase '10-05-02e', %HST on static 1, inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,Anti-symm
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% inj,stag tubes
case '10-05-02f', %HST on static 1, inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,Anti-symmstatvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% inj,stat tubes
case '10-05-02g', %HST on static 1, inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,Anti-symm
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% inj,stat tubescase '10-05-02h', %HST on static 1, inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,Anti-symm
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% inj,stag tubescase '10-05-02k', %HST on static 1, inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,Anti-symm
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% inj,stag tubescase '10-13-02a', %HST on static 1, inj,U/D stream of inj.solenoid,
statv=[scnm(1) hsn1m([1 5 7]) scnm(2:8)]; % rotated by 180,
statvrms=[scnrms(1) hsn1rms([1 5 7]) scnrms(2:8)];%
case '10-13-02b', %HST on static 1, inj,U/D stream of inj.solenoid,statv=[scnm(1) hsn1m([1 5 7]) scnm(2:8)]; % rotated by 180,
statvrms=[scnrms(1) hsn1rms([1 5 7]) scnrms(2:8)];%
case '10-15-02n', %HST on static 1, inj,U/D stream of inj.solenoid,statv=[scnm(1:4) hsn1m(1) scnm(5:7) hsn1m([5 7]) scnm(8)]; % rotated by 180,
statvrms=[scnrms(1:4) hsn1rms(1) scnrms(5:7) hsn1rms([5 7]) scnrms(8)];%
8/3/2019 Venkata Narasimham Nori- Unsteady Flow in a Mixed-Compression Inlet at Mach 3.5
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case '10-15-02i', %HST on static 1, inj,U/D stream of inj.solenoid,
statv=[scnm(1:4) hsn1m(1) scnm(5:7) hsn1m([5 7]) scnm(8)]; % rotated by 180,statvrms=[scnrms(1:4) hsn1rms(1) scnrms(5:7) hsn1rms([5 7]) scnrms(8)];%
case '10-19-02b', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleed
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%90case '10-19-02m', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleed
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%AS-2case '10-19-02p', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleed
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%S-2case '10-19-02q', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleed
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%S-1
case '10-19-02r', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleedstatvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%AS-1
case '10-19-02s', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleed
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%AS-3
case '10-20-02c', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleed
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%AS-1
case '10-20-02d', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleedstatvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%AS-3
case '10-20-02g', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleed
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%S-1
case '10-20-02i', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleed
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%AS-2
case '10-28-02i', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,statv=[scnm(1:3) NaN NaN NaN NaN hsn1m(7) scnm(4:5) hsn1m([5 7])
scnm(6:8)]; % rotated by 180,with bleed
statvrms=[scnrms(1:3) NaN NaN NaN NaN hsn1rms(7) scnrms(4:5) hsn1rms([57]) scnrms(6:8)];%90
case '10-31-02b', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleed
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];case '11-09-02a', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,
statv=[scnm(1:6) hsn1m([1 5 7]) scnm(7:8)]; % rotated by 180,with bleed
statvrms=[scnrms(1:6) hsn1rms([1 5 7]) scnrms(7:8)];case '11-09-02n', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,
statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleed
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statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];
case '11-09-02j', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,statv=[scnm(4) scnm(1:3) hsn1m([1 5 7]) scnm(7:8) scnm(5:6)]; % rotated by
180,with bleed
statvrms=[scnrms(4) scnrms(1:3) hsn1rms([1 5 7]) scnrms(7:8) scnrms(5:6)];
case '11-10-02i', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleed
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];
case '11-13-02p', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleed
statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];
end;
otherwise
disp('Don`t know how to build strut and static profiles for this run - modify
program!');
break;end;
%building matrices of wall static mean and rms values for tecplot
build1=[xv' (statvrms./statv*100)'];
[x,m]=sort(build1); pstatrms=[pstatrms; 0 0; build1(m(:,1),:)];
build=[xv' statv'];
[y,i]=sort(build); pstat=[pstat; 0 0; build(i(:,1),:)];
%making matrices of rake stag mean and rms for tecplot
stag=[scnm(11) scnm(10) scnm(9)];
stagrms=[scnrms(11) scnrms(10) scnrms(9)];
make=[yv' stag'];
[a,b]=sort(make); pstag=[pstag; 0 0; make(b(:,1),:)];
makes=[yv' stagrms'];[p,r]=sort(makes);
pstagrms=[pstagrms; 0 0; makes(r(:,1),:)];
% if (j==3), %a plot for measure of variation of pressure about the mean value duringinjection
figure(j+6); % make sure that the fluc* columns correspond with that of statv
clf;fluc_peak=[ max(hsn1(running,1)) max(scn(running,1:8)) max(hsn1(running,[5
7]))];
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fluc_valley=[ min(hsn1(running,1)) min(scn(running,1:8)) min(hsn1(running,[5
7]))];% fluc_peak=[max(scn(running,1:3)) NaN NaN NaN NaN max(hsn1(running,1)
max(scn(running,4:5)) max(hsn1(running,5)) max(scn(running,6:8))
max(hsn1(running,7))];
% fluc_valley=[min(scn(running,1:3)) NaN NaN NaN NaN min(hsn1(running,[15])) min(scn(running,4:6)) min(hsn1(running,7)) min(scn(running,7:8))];
fluctuation=(fluc_peak-fluc_valley);
variation = fluctuation./statv;ma=plot(xv(1:11),variation(1:11),'s-');
var=[xv' variation'];
%hold on;%da=plot(xv(12:15),variation(12:15),'d');
set(ma,'linewidth',1.5);
%set(da,'linewidth',1.5);
ha=xlabel('x / L ');
set(ha,'Fontsize',14);ha=ylabel('(Pp-Pv)/Pav');
set(ha,'Fontsize',14);grid on;
axis([0 1 0 1]) ;
%end;
figure(j+2); %mean wall pressure plots
clf;
ri=plot(xv(1:11),statv(1:11),'s-');hold on;%pa=plot(xv(12:15),statv(12:15),'d');
set(ri,'linewidth',1.5);
%set(pa,'linewidth',1.5);
x1=[xv-5*bar; xv+5*bar; xv; xv; xv-5*bar; xv+5*bar];y1=[statv-statvrms; statv-statvrms; statv-statvrms; statv+statvrms; statv+statvrms;
statv+statvrms];
h=line(x1,y1);set(h,'Color',[0 0 1]);
ha=xlabel('x / L');
set(ha,'Fontsize',14);ha=ylabel('p/p_0');
set(ha,'Fontsize',14);
grid on;
ax=axis;axis([0 1 0 0.25]);
%ha=text(0.7*ax(2)+0.3*ax(1),0.9*ax(3)+0.1*ax(4),['f= '
num2str((round(hsn1m(rpmcol-1)/3)/10)) ' Hz']);%set(ha,'Fontsize',14);
ha=title(['static pressures, run ' runn ', ' num2str(t1) '<t<' num2str(t2) ' s']);
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set(ha,'Fontsize',14);
set(gca,'Fontsize',14);
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APPENDIX C
INLET DRAWINGS
The AutoCAD drawings of the two-dimensional, mixed compression, supersonic
inlet is presented here. The main components of the inlet are as follows:
1. Cowl
2. Ramp, which has the wall static pressure ports and also houses the bleed plenums for boundary layer suction.
3. Exit injection block, which enables air injection into the inlet at the exit.
4. Sideplates, which supports the cowl and ramp in the correct alignment.
5. Sting, which supports the entire inlet assembly in the Wind Tunnel.
All the components, except the sideplates and the sting are made of Aluminum. The
sideplates are made of Plexiglas for optical access and the sting made of carbon heat
treated steel for resisting bending in the high-pressure environment of the Wind Tunnel.
All the dimensions in the drawings that follow are in inches. The CAD drawings are
scaled to fit the page and the scaling is different for each drawing shown. All the angles
shown are measured with respect to the horizontal.
10o
Figure C-1. The cowl.
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Front View
Side V
Top View
Figure C-2. The inlet ramp.
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Table C-1. Coordinates of points relative to the leading edge of the ramp that make the
ramp profile
Point X(in) Y(in)
1 0 0
2 0.5 0.05
3 1 0.125
4 1.25 0.168
5 1.5 0.212
6 1.75 0.254
7 1.865 0.276
8 2 0.294
9 2.25 0.325
10 2.5 0.353
11 2.75 0.359
12 3 0.348
13 3.25 0.325
14 3.5 0.295
15 3.75 0.26
16 4 0.223
17 4.25 0.186
18 4.5 0.151
19 4.75 0.121
20 5 0.1
21 5.25 0.087
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(a)
Front View
Top View
Figure C-3. The sideplates
(b)
Figure C-4. The sting.
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Rear View
Sectional Views
Top View
Figure C-5. The exit injection block.
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Top View10
o
5o
Front View Sid
Figure C-6. The inlet assembly.
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APPENDIX DSCHLIEREN MOVIES
Schlieren was used to visualize the inlet flow field and the images were recorded
on a SONY camcorder. Short movies, capturing the inlet flow field during the injection
phase, were made with the help of MGI Video Wave – 4 software. Table D-1 lists the test
conditions and also gives the order in which they are found later in this section. The
injection configurations with their associated definitions are given in Chapter 2. For the
zoomed in terminal shock movie, the test conditions are S-2 injection configuration, 5 Hz
excitation frequency and 23% mass injection. Similarly for the zoomed in inlet capture
movie, the test conditions are 90 Phase coupling, 5 Hz excitation frequency and 47%
mass injection.
The following can be observed in the movies:
• The terminal normal shock oscillations can be clearly seen during injection. Itsimmediate return to the initial position when the excitation is stopped can be clearly
seen.
• In the zoomed in view of the terminal shock, its structure, being partly normal andterminating as lambda shocks on the cowl and the ramp walls can be observed. The
degree of separation on the ramp and the cowl can be observed.
• The shock-induced separation region translates along with the shock.
• The shock weakening as it moves upstream can be observed clearly in the 90 Phase
configuration movies.
• Higher mass injection case i.e., 40% case producing greater shock displacement and
increased spillage at the inlet capture can be observed.
• In the 10 Hz case, the increase in curvature of the shock can be seen in the maximumdisplacement position. The shock is fixed on the ramp but curves forward.
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Table D-1. List of schlieren movies.
Test Conditions
F=10 Hz ; Minj=20%
S-2 Coupling
AS-2 Coupling
90 Phase Coupling
F=5 Hz ; Minj=20%
AS-2 Coupling
S-2 Coupling
S-1 Coupling
AS-3 Coupling
90 Phase Coupling
F=5 Hz ; Minj=40%
S-1 Coupling
AS-3 Coupling
S-2 Coupling
AS-2 Coupling
90 Phase Coupling
Zoomed in views
Zoomed at Terminal Shock
Zoomed at inlet capture
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Object D-1.S-2 Coupling, Minj=20.7%, F=10 Hz.
Object D-2. AS-2 Coupling, Minj=20.7%, F=10 Hz.
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Object D-5. S-2 Coupling, Minj=18.5%, F=5 Hz.
Object D-6. S-1 Coupling, Minj=19.5%, F=5 Hz.
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Object D-7. AS-3 Coupling, Minj=19.5%, F=5 Hz.
Object D-8. 90 Phase Coupling, Minj=23%, F=5 Hz.
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Object D-9. S-1 Coupling, Minj=39%, F=5 Hz.
Object D-10. AS-3 Coupling, Minj=39%, F=5 Hz.
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Object D-11. S-2 Coupling, Minj=39%, F=5 Hz.
Object D-12. AS-2 Coupling, Minj=39%, F=5 Hz.
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Object D-13. 90 Phase Coupling, Minj=39%, F=5 Hz.
Object D-14. Zoomed view of terminal shock for the S-2 Coupling, Minj=23%, F=5 Hz
case.
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Object D-15. Zoomed view at capture for the 90 Phase Coupling, Minj=47%, F=5 Hz
case.
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LIST OF REFERENCES
1. Anthony B. Opalski and Sajben Miklos, “Inlet/Compressor System Response to
Short-Duration Acoustic Disturbances,” Journal of Propulsion and Power , Vol. 18,
No. 4, July-August 2002, pp. 922-932.
2. Mullagiri, S., Gustavsson, J.P.R., Segal, C., “Modeling of Air Intake and EngineInteraction in Pulse Detonation Engine Systems,” AIAA Paper 2001-1211,
Proceedings of the ISABE 2001 Conference, Bangalore, India, Sep 2001.
3. Mullagiri, S. and Segal, C., “Oscillating Flows in Inlets of Pulse Detonation
Engines,” AIAA Paper 2001-0669, 39th
AIAA Aerospace Sciences Meeting and
Exhibit , Reno, NV, January 2001.
4. Chen, C.P., Sajben, M. and Kroutil, J.C., “Shock Wave Oscillations in a Transonic
Diffuser Flow,” AIAA Journal , Vol. 17, No. 10, October 1979, pp. 1076-1083.
5. Bogar, T.J., Sajben, M. and Kroutil, J.C., “Characteristic Frequencies of Transonic
Diffuser Flow Oscillations,” AIAA Journal , Vol. 21, No. 9, September 1983, pp.1232-1240.
6. Sajben, M., Bogar, T.J. and Kroutil, J.C., “Forced Oscillation Experiments in
Supercritical Diffuser Flows,” AIAA Journal , Vol. 22, No. 4, April 1984, pp. 465-
474.
7. Bogar, T.J., Sajben, M. and Kroutil, J.C., “Response of a Supersonic Inlet toDownstream Perturbations,” Journal of Propulsion and Power , Vol. 1, No. 2, March-
April 1985, pp. 118-125.
8. Sajben, M., Bogar, T.J. and Kroutil, J.C., “Experimental Study of Flows in a Two-Dimensional Inlet Model,” Journal of Propulsion and Power , Vol. 1, No. 2, March-
April 1985, pp. 109-117.
9. Bogar, T.J., “Structure of Self-Excited Oscillations in Transonic Diffuser Flows,”
AIAA Journal , Vol. 24, No. 1, January 1986, pp. 54-61.
10. Hongprapas Sorarat, Kozak D. Jeffrey, Moses Brooks and Ng F. Wing., “A small
scale Experiment for investigating the stability of a supersonic inlet,” AIAA paper
97-0611, 35th
AIAA Aerospace Sciences Meeting and Exhibit , Reno, NV, January1997.
11. Dailey, C.J., “Supersonic Diffuser Instability,” Journal of the Aeronautical Sciences,Vol. 22, No. 11, November 1955, pp. 733-749.
12. Van Wie, D.M., Kwok, F.T. and Walsh, R.F., “Starting Characteristics of Supersonic
Inlets,” AIAA paper 96-2914, 32nd
Joint Propulsion Conference and Exhibit , BuenaVista, FL, July 1996.
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131
13. Fernandez Rene and Nenni P. Joseph., “Pulsed Detonation Engine Inlet Experimental
and CFD Results,” NASA TM 2002-211581.
14. Culick, F.E.C. and Rogers, T., “The Response of Normal Shocks in Diffusers,” AIAA Journal , Vol. 21, No. 10, October 1983, pp. 1382-1390.
15. Hsieh, T., Wardlaw Jr., A.B. and Collins, P., “Numerical Investigation of Unsteady
Inlet Flowfields,” AIAA Journal , Vol. 25, No. 1, January 1987, pp. 75-81.
16. Hsieh, T., Bogar, T.J. and Coakley, T.J., “Numerical Simulation and Comparison
with Experiment for Self-Excited Oscillations in a Diffuser Flow,” AIAA Journal ,Vol. 25, No. 7, July 1987, pp. 936-943.
17. Hsieh, T., Wardlaw Jr., A.B. and Coakley, T., “Ramjet Diffuser Flowfield Response
to Large-Amplitude Combustor Pressure Oscillations,” Journal of Propulsion and Power , Vol. 3, No. 5, September-October 1987, pp. 472-477.
18. Biedron, R.T., and Adamson Jr., T.C., “Unsteady Flow in a Supercritical Supersonic
Diffuser,” AIAA Journal , Vol. 26, No. 11, November 1988, pp. 1336-1345.
19. Hsieh Shih-Yang and Yang Vigor, “A Unified Analysis of Unsteady Flow Structuresin a Supersonic Ramjet Engine,” AIAA Paper 97-0396 , 35
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Meeting and Exhibit , Reno, NV, January 1997.
20. Pegg, R.J., Couch, B.D. and Hunter, L.G., “Pulse Detonation Engine Air Induction
System Analysis,” AIAA Paper 96-2918 , 32nd
Joint Propulsion Conference, Lake
Buena Vista, FL, July 1996.
21. NASA Glenn Research Center, Cleveland, Ohio, “Pulse Detonation EngineTechnology Project,” URL: http://www.grc.nasa.gov/WWW/AERO/base/pdet.htm,
March 21st
, 2002.
22. Bussing, T. and Pappas, G., “Pulse Detonation Engine Theory and Concepts,”
Developments in High-Speed-Vehicle Propulsion Systems, Progress in Astronauticsand Aeronautics, Vol. 165, 1996.
23. Heiser, W.H. and Pratt, D.J., “Thermodynamic Cycle Analysis of Pulse Detonation
Engines,” Journal of Propulsion and Power , Vol. 18, No. 1, January-February 2002, pp. 68-76.
24. Eidelman, S. and Yang, X, “Analysis of the Pulse Detonation Engine Efficiency,”
AIAA paper 98-3877, July 1998.
25. Bussing, T.R.A., Bratkovich, T.E. and Hinkley, J.B., “Practical Implementation of Pulsed Detonation Engines,” AIAA paper 97-2748, 1997.
26. Sudarshan Mullagiri, “Forced Nonuniform Oscillation of Backpressure on aSupersonic Diffuser,” University of Florida at Gainesville, MS thesis, August 2001.
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BIOGRAPHICAL SKETCH
Venkata Narasimham Nori was born on March 17, 1979, in India. He grew up in
the city of Hyderabad and completed his schooling from Atomic Energy Central School-
II (AECS-II) in 1994. He finished his high school studies from the Little Flower Junior
College (LFJC) in 1996. Nori graduated from the Indian Institute of Technology, Madras
(IIT-M), in 2001 where he obtained Bachelor of Technology in aerospace engineering.
He pursued graduate studies at the University of Florida from 2001 to 2002 and obtained
a Master of Science degree from the Department of Mechanical and Aerospace
Engineering.
His interests range from soccer to supersonics, from listening to music to absurd
theorizing, from poetry to photography, from star gazing to chasing wild dreams, from