Laser Doppler Velocimetry Research of the Blowby Gas ...

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Master's Theses Graduate College

12-1992

Laser Doppler Velocimetry Research of the Blowby Gas Laser Doppler Velocimetry Research of the Blowby Gas

Characteristics in an Internal Combustion Engine Characteristics in an Internal Combustion Engine

Mark Kevin Coffill

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Recommended Citation Recommended Citation Coffill, Mark Kevin, "Laser Doppler Velocimetry Research of the Blowby Gas Characteristics in an Internal Combustion Engine" (1992). Master's Theses. 887. https://scholarworks.wmich.edu/masters_theses/887

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LASER DOPPLER VELOCIMETRY RESEARCH OF THE BLOWBY GAS CHARACTERISTICS IN AN INTERNAL COMBUSTION ENGINE

byMark Kevin Coffil'l

A Thesis Submitted to the

Faculty of The Graduate College in partial fulfillment of the

requirements for the Degree of Master of Science

Department of Mechanical Engineering

Western Michigan University Kalamazoo, Michigan

December 1992

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

ACKNOW LEDGM ENTS

There were many people who deserve credit for helping me in the many stages, to completion, of this thesis. First, to the members of my committee, Dr. Parviz Merati, Dr. Richard Hathaway, Dr. Iskender Sahin, and Dr. Jerry Hamelink, I extend my appreciation for their guidance and support. In addition to my committee members technical support and ideas were graciously donated by both Glen Hall and Joe Parker.

Secondly, to all of the loved people in my life who I turned to for both support and encouragement, I owe a debt of gratitude. In particular three people really stand out in'for this distinction: Melissa Needham, who was able tostand by me through long hours and even long distances giving me any support I required, and my parents, Larry and Bernice Coffill who through all of my projects, including this thesis, have supported me beyond recognition. To these three wonderful people I give my love.

To all the people who have helped me through this project I offer my thanks.

Mark Kevin Coffill

ii


LASER DOPPLER VELOCIMETRY RESEARCH OF THE BLOWBY GAS CHARACTERISTICS IN AN INTERNAL COMBUSTION ENGINE

Mark Kevin Coffill, M.S.Western Michigan University, 1992

The project was designed to measure a reciprocating engine fluid flow (blowby gases past the piston rings) using a laser doppler velocimeter (LDV). Blowby gases were obtained by introducing compressed air into an engine cylinder (piston held at TDC) to simulate engine combustion pressures. Beginning the proposed research included starting an LDV/reciprocating engine laboratory at Western Michigan University and determining the limits of the measurement devices (LDV system in particular).

The limitations which were found in the LDV system only allowed for limited results of in cylinder optical measurements. The results obtained were for cylinder pressures below 0.6 kPa'gauge pressure. The blowby gases were therefore analyzed using hot film anemometry. Various piston ring gap orientations were measured to see how the relationship of ring end gap alignment affected the blowby

gases. As expected when the ring end gaps were aligned the

blowby gases were at a maximum and when they were located 120° apart the blowby gases were minimized.


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Laser doppler velocimetry research of the blowby gas characteristics in an internal combustion engine

Coffill, Mark Kevin, M.S.Western Michigan University, 1992

UMI300 N. ZcebRd.Ann Arbor, M I 48106


T A B LE OF C O N TEN TS

ACKNOWLEDGMENTS ..................................... iiLIST OF FIGURES..................................... vCHAPTER

I. INTRODUCTION ................................. 1Objectives ................................. 1LDV/Reciprocating Engine Laboratory . . . . 1Blowby Gas Research ....................... 2Understanding the LDV System .............. 3

II. INSTRUMENTATION AND TEST A P P A R A T U S .......... 4Designed Test Setup ....................... 4Test E n g i n e ............................... 6

Engine Design ........................... 6Cylinder and Head D e s i g n .............. 7Piston and Piston Rings ................ 10

Air Flow Delivery and Measurements........ 12Pressure Delivery System .............. 12Mass Air Flow Measurements............ 12

Laser Doppler Velocimetry ................ 20Laser, Optics and Hardware ............ 20Particle Seeding ....................... 22

Limitations of the LDV System.......... 24

iii


Table of Contents— Continued

I I I . RESULTS....................................... 27Hotfilm Anemometry ..................... 27Blowby Estimates ....................... 27Effects of the Optical Window........... 28Quantifying Blowby Gases .............. 31

Laser Doppler Velocimetry ................. 39IV. RECOMMENDATIONS.............................. 42

Static....................... 42D y n a m i c ................................... 43

V. CONCLUSIONS.................................. 44A P P ENDICES......................................... 4 6

A. Engine Setup Data and Calculations........... 4 6

B. Calibration D a t a ............................. 52C. Results D a t a ............... 61

BIBLIOGRAPHY ....................................... 68

iv


LIST OF FIGURES

1. Test Setup and Equipment...................... 62. Rings Sealing with Optical Window and Slit . . . 93. Ring Locations on the CFR Piston.............. 114. Calibration Data of an Airflow out of a

1.27 cm P i p e ................................... 155. Hotfilm Air Flow Calibration.................. 176. Hotfilm and Pressure Transducer

Measurement Holder ............................. 187. Measurement Volume Dimensions ................ 228. Particle Seeder Design ........................ 239. An Unshifted and a Shifted Plot of a Particle

Burst Frequency Versus theCorresponding Velocity ......................... 25

10. A Comparison of the Blowby Gases With andWithout an Optical Window .................... 30

11. Volumetric Flow Rate of the Blowby Gasesfor Three Ring Orientations.................. 32

12. Mass Flow Rate of the Blowby Gases forThree Ring Gap Orientations.................. 34

13. Estimated Blowby Area Required Assuminga Choked Airflow Condition .................... 38

14. In Cylinder Measurements Using an LDV System . . 41

v


CHAPTER I

INTRODUCTION

Objectives

There were three main objectives which the project, Laser Doppler Velocimetry Research of the Blowby Gas Characteristics in an Internal Combustion Engine, proposed to achieve. The first goal was to expand the Laser Doppler Velocimetry (LDV) laboratory at Western Michigan University to include the study of reciprocating engine fluid flows. The first goal also includes designing a test engine which will allow continued research in the area of reciprocating engine flows after the completion of the present project. The second goal was to research a fluid flow, within a reciprocating engine, which has not previously been studied by an LDV system. The third' goal of the project was to acquire knowledge of an LDV system and determine the limitations ■ of the system as they apply to close wall measurements.

LDV/Reciprocating Engine Laboratory

Previously Western Michigan University (WMU) had started an LDV research laboratory to study the fluid flow

1


within an industrial fluid pump. The laboratory facilities and testing equipment (LDV system in particular) were expanded and used for the LDV research of the blowby gases in an internal combustion engine. The test setup used a complete combustion fuel research engine with the electric motor to allow continued research of both static and dynamic testing of the blowby gases in addition to allowing future tests to be conducted on other fluid flows within the reciprocating engine.

Blowby Gas Research

Considerable research has been carried out in the automotive industry on reciprocating engine fluid flow using Laser Doppler Velocimetry. Research has been conducted in the area of precombustion fluid motion (intake and flow within the cylinder before combustion), fuel vaporization and mixing, combustion interactions, flame structures, unburned hydrocarbon emissions, and particle formations, to name a few. One of the areas of interest which had been overlooked is the fluid flow near the piston rings and the blowby gases past the piston rings in a reciprocating engine.

The measurement of blowby gases past the piston rings in a reciprocating engine was determined to be the optimum starting area for LDV/reciprocating engine research at WMU. The measurement of these gases has not been done within the


3

cylinder using LDV measurement techniques and the results would be of interest to the industrial community. By gaining an understanding of the pressures and gas velocity that occur around the compression rings the volumetric efficiency of an engine could be increased (lower blowby gas losses) while maintaining minimum frictional losses.

Understanding the LDV System

In addition to understanding the behavior of the blowby gases the project was designed to find the limitations of the LDV system in close wall measurements. An innovative optical setup was used to obtain measurements within the small area between the piston ring end gaps. Measurements between the piston and the cylinder wall were also attempted.

The project additionally determined some of the limits of the current LDV signal processor. An understanding of how the processor calculates fluid velocities, given a particle burst frequency, for both shifted and unshifted frequencies, was learned. Application of the knowledge was used to measure beyond the limits of the processor's velocity measuring ability by using the measured frequencies only.


CHAPTER II

INSTRUMENTATION AND TEST APPARATUS

Designed Test Setup

The test setup was designed to introduce compressed air into the combustion chamber under static engine conditions (non reciprocating piston). The compressed air within the cylinder simulates the pressure the rings would experience during a combustion process. A pressure within the cylinder will cause a flow of the gases (blowby gases) from the cylinder past the piston rings and into the engine's crankcase, which is at atmospheric pressure. The engine's cylinder and head were completely sealed with the exception of the inlet air tube to assure the only gas losses were blowby gases. The pressure within the cylinder was then kept constant by a pressure regulator on the air inlet line thus keeping the total flow of the blowby gases constant.

The volumetric flow rate of the air delivered to the engine's cylinder was measured using a hot film anemometer. Measurement of the air pressure at the hot film's location, using a pressure transducer, allowed for the calculation of the mass flow rate of the air.

4


Finally the blowby gases were measured at various locations around the piston rings using the LDV system. With the local velocities around the piston rings known and the total mass flow rate of the blowby gasses known a relationship of gas velocity to local pressure on the piston rings could be achieved. A pressure distribution on the piston ring could then be obtained. The following calculations show the described relationships.

/ / P - 0

rh r»aT7 A ^^Pl^val,- PAVvel - — = — --- :

9 - TC ■ iti t l - A X) - g f V va l,

n imr

were p is the gas density, Vvel is the gas velocity, A is the area at the test location, m (dot) is the mass flow rate, P is the test pressure, Vvol is the volume, m is mass, R is the gas constant, T is the test temperature, and n is the number of test locations around the piston rings. The results of the tests would allow the optimization of the piston ring design by increasing ring tension at the high

pressure areas and decreasing ring tension at the low pressure areas thus decreasing the blowby gas losses


(increase volumetric efficiency) while minimizing the frictional power loses. A schematic of the overall test setup can be seen in Figure 1.

HollllmConvergingOpticsPhoto

DetectorPressureTransducer

P. D. Power

Oscilloscopt

OscilloscopeComputer

Figure 1. Test Setup and Equipment.

Test Engine

Engine Design

The test engine was a modified 1940 Combustion Fuel Research (CFR) engine. The cylinder and valve mechanisms

have been removed for a specially made cylinder and cylinder head. The rest of the engine was kept complete to


allow for possible future tests which may require the engine to be motored. An electric DC 1/4 hp motor is also set up on the engine test stand to drive the motor in

future tests. The electric motor could also be switched to work as a generator, absorbing power from the engine (like a dynamometer), if running engine tests are desired.

The entire engine stand was raised up 63.5 cm (25inches) off the floor to get the engine's cylinder at theheight of the laser. Thirty 12.7 x 12.7 cm (5 x 5 inch) wooden planks were used to raise the engine up the 63.5 cm. The wooden blocks are in two sets with each set tied together by two 0.317 cm (1/8 in.) cables to maintain a rigid engine stand.

Cylinder and Head Design

The test engine's cylinder was machined from A48 class 40 cast iron rough cylinder. The original dimension were11.43 x 7.62 x 24.76 cm (4.5 x 3.0 x 9.75 in.), outerdiameter, inner diameter, and height respectfully. Thetest cylinder was machined down to 10.795 x 8.331 x 23.495 cm (4.25 x 3.280 x 9.25 in). The inner cylinder was then honed out to 0.178 mm (0.007 in.) over the piston diameter 8.255 cm (3.250 in.) for an overall inner cylinder diameter of 8.273 cm (3.257 in.).

Several tests measuring the total blowby gases were run before the optical window was machined and installed


for the LDV measurements. The tests would allow a comparison of blowby losses with an optical window versus the losses without an optical window to determine if the installation of the window caused any changes in the blowby gas flow (tests and conclusions are under the results section).

After the tests were conducted a hole was machined in the cylinder's outer wall (for the optical window) using a Mazak computerized milling machine. The hole made in the outer wall of the cylinder is a 5.08 cm (2 in.) diameter hole with a flat bottom which is tangent to the inner cylinder wall. The center of the hole was located 3.967 cm (1.562 in.) down from the top of the cylinder. The configuration should allow a narrow vertical slit (apx. 2-3 mm) to appear in the machined hole to allow optical access to the inner cylinder at the height of the piston rings.

If the hole gets machined so the slit has very sharp edges, the out of roundness of the inner cylinder should be negligible and the rings would continue to seal as well as before the window was installed (see Figure 2) . The theoretical out of roundness of the cylinder would be 0.0121 mm (0.000476 in.) with a 2 mm slit (calculations are in Appendix A). However, as the Mazak milling machine got

close to the final cut on the bottom of the machined hole the cutting bit started to deflect the inner cylinder wall 0.051-0.102 mm (0.002-0.004 in.). After the Mazak milling


Optical f SlitOptical

WindowCylinder

Wall

PistonRing

■wa

Piston

Figure 2. Rings Sealing with Optical Window and Slit.

machine had reached the proper depth to allow the bottom of the hole to be tangent with the inner cylinder's wall the slit had not appeared. Enough material had been deflected to make the inner cylinder wall out of round. The cylinder was then rehoned to true the inner diameter thus increasing the inner diameter by an additional 0.051-.0765 mm (0.002- 0.003 in.) making an overall 0.254 mm (0.010 in.) clearance between the piston and the cylinder.

A small hand grinder was then used to open a slit at

the desired location in the hole. The edges of the slit and the flat area of the hole were then hand sanded to achieve the best possible finish. A clear plexiglass


r

window was then installed in the hole and sealed with Permatex aviation form-a-gasket.

The cylinder head which was used is a 1.25 cm (0.5 in.) flat steel plate which is bolted down to the cylinder using five evenly spaced 1/4-20 in. bolts. The head is sealed to the cylinder using Permatex aviation form-a- gasket. The cylinder head has three additional holes (drilled and tapped) to allow for the mounting of the incoming air tube, a pressure gauge and a thermocouple. The entire head and cylinder is held down to the engine's crankcase by three 1/2 bolts which go though the cylinder's head and screw into existing holes in the crankcase.

Piston and Piston Rings

The piston used for the tests is the original piston from the CFR engine. The piston design allows for 5 piston rings, 4 compression and one oil ring. During the blowby tests only 3 piston rings were used, 2 compression rings and 1 oil ring. The number of piston rings was limited to three because most passenger cars have only three, two compression rings and one oil ring. The arrangement of the piston rings on the piston can be seen in Figure 3. The ring end gap of the first compression ring (top) was 1.04

mm (0.041 in.) . The second compression ring had a ring end gap equal to 1.09 mm (0 .043 in.) . The oil ring end gap was 0.76 mm (0.030 in.) .


1 Compression Ring

2 Compression Ring

Oil Ring

Figure 3. Ring Locations on the CFR Piston.

During all of the blowby tests the piston was held at top dead center. An external mount was made to hold the flywheel at a fixed location which kept the piston at the desired location. The mount was made strong enough to keep the flywheel from turning for pressures up to 3.45 MPa (500 psi) with the piston held at a maximum torque configuration (crank is at a right angle to the piston rod).

With the piston at top dead center the distance between the top of the piston and the cylinder head was

1.63 cm (0.643 in.). With the CFR engine stroke of 11.43 mm (4.5 in.) the compression ratio of the engine during a

Idynamic test would be 8:1.


Air Flow Delivery and Measurements

Pressure Delivery System

The pressure reservoir used to deliver the compressed air was a welders gas tank which was initial filled with approximately 7.36 m3 (260 ft3) of compressed air at 16,550 kPa (2400 psi). Each pressurized tank has enough air for 10-15 tests depending upon the engine cylinder pressure used and the duration of the test. Most tests were run at 1380 kPa (200 psi) cylinder pressure for approximately 350- 400 seconds.

The air was regulated using a pressure regulator attached to the outlet valve of the compressed tank of air. The pressure regulator used was an Altec Trimline with an output line pressure rating of 0-3450 kPa (0-500 psi), and an inlet pressure rating of 28000 kPa (4000 psi) . The tubing which delivers the pressurized air to the engine's cylinder was a 1.27 cm (0.5 in.) steel pipe rated at 3.45 MPa (500 psi.). The compression fittings for the pipe are rated at 13.79 MPa (2000 psi) and screw into 3/8 in pipe fittings. The entire air flow delivery system was designed for test pressures of up to 3.45 MPa (500 psi.).

Mass Air Flow Measurements

The total airflow entering the combustion chamber was


13

initially to be measured using a square edged orifice flow meter. However, the pressure transducers which were available for use in the orifice were not sensitive enough to measure a small mass flow rate.

The flow measurement device was therefore modified to hold a hotfilm anemometer and a pressure transducer in the airflow. The hotfilm anemometer measured the volumetric flow rate and with a pressure transducer mounted next to the hotfilm the mass flow rate of the air can be achieved.

The hotfilm used was a DISA probe type 55. It was attached to a TSI model 1051-1 power supply and monitor, a model 1053A Anemometer and a model 1056 variable decade probe resistance bridge. The hotfilm was calibrated using a pitot static probe mounted at an open end of the 1.27 cm (0.5 in.) tubing of the air delivery system. The pressure change of the static and dynamic pressures of the pitot static probe was measured using a manometer. With the change in static and dynamic pressure known, the velocity at each location could be calculated using the equation:

V -N Pair

where V is the velocity, Ah is the change in the manometer height, yH20 is the specific weight of water and pair is the density of air. The pitot static probe was moved across


the airflow in 0.127 cm (0.05 in.) increments to get a velocity profile of the airflow exiting in the tube. Figure 4 shows the velocity profile for four different volumetric flow rates with each having a different maximum velocity. The shape factor of the airflow was then calculated for each flow condition.

It was found that up until a maximum flow velocity of 10 m/sec (32.8 ft/sec) the shape factor for the airstream was just below 1.0 with a maximum deviation of 4%. Between the maximum velocities of 10 m/s and 15 m/s (32.8 -49.2 ft/sec) the shape factor fluctuated just above 1.0 with a maximum deviation of 5%. Above 15 m/s the shape factor fluctuated above and below 1.0 deviating a maximum of only 2%. The shape factor used in calculating the average air velocity and the volumetric flow rate was averaged out tobe 1.0. The data for the shape factor calculations can befound in Appendix B. The average velocity was then calculated from the shape factor and the volumetric flow rate could be calculated using the equations:

“ - 5urn„ Q - uA - SuraaxA

were u (bar) is the average velocity, S is the shapefactor, unax is the maximum velocity, and Q is thevolumetric flow rate.


Reproduced

with perm

ission of the

copyright ow

ner. Further

reproduction prohibited

without

permission.

Air Exit Velocity from 1.27cm Dia. Pipe Using a Pitot-static Tube

14.00

Max. Vel. = 13.0712.00

Max. Vel. = 11.23

10.00 Max. Vel. = 9.68— X —

Max. Vel. = 7.27o(DOT£ 8.00 5ooc d 6.00 ><

4.00

2.00Pipe dia.

0.00+ —-1.27 -0.64 0.00 0.64 1.27

Distance from Nozzle Center^cm)

!

I Figure 4. Calibration Data of an Airflow out of a 1.27 cm Pipe.

Ui

The hotfilm was then calibrated for a volumetric flow rate of 0-0.0075 m3/s (0-16 CFM) which' was found to correspond to a hotfilm voltage reading of 0-4 volts. For the calibration of the hotfilm the pitot static probe was located at the center of the open end of the 1.27 cm (0.5 in.) tube. The manometer would then, indirectly, read the average velocity of the air flow past the hotfilm. The hotfilm voltage was read and recorded using an Analog to Digital board linked with a PC computer. A QuickBasic program was written to time average the voltage readings over a one second period and record the data in a file1.An instantaneous hotfilm reading was also obtained using adigital voltmeter during the tests. The volumetric flow rate was calculated using the pitot static probe data which was then correlated to the hotfilm voltage. The hotfilm voltage was curvefit to the volumetric flow rate using a program called polyfit2. The calculated polyfit equation is:

Q = (-0.01121 E* + 0.2111 E3 + 0.3396 E2 + 0.1341 E+ 0.00326) x 0.00047195

where Q is the volumetric flow rate and E is the corrected

1 Program created at WMU by Joe Parker and modified by the author of this text.

2 "In house" program created at WMU.


Reproduced

with perm

ission of the

copyright ow

ner. Further


without

permission.

o•~2.<

E,ZoEi-i

3o*CuuEJ3'o>

0.008

0.006

0.004i

0.003

0.0020.001

0

Hot Film Air Flow Calibration(voltage vs volumetric air How)

Tiis-M anom eter value

Hot film-Calculatcd

0.5 1.5 2 2.5Anemometer Voltage E-Eo (V )

3.5

Figure 5. Hotfilm Air Flow Calibration.

hotfilm voltage (E-E0) . The measured hotfilm voltage was then plotted versus the measured volumetric flow rate and the calculated (curvefit) volumetric flow rate (see Figure 5) . The calibration data and a graph showing a smooth curve of the hotfilm voltage versus the calculated volumetric flow rate can be found in Appendix B.

The volumetric flow rate could now be measured using the hotfilm anemometer. To obtain the mass flow rate of the air flow a pressure transducer was mounted next to the hotfilm anemometer (see Figure 6). The pressure transducer

1. Hotfilm(Volts)

2. Pressure/ (Volts)

Air Flow

Figure 6. Hotfilm and Pressure Transducer Measurement Holder.


used was a PCB Piezotronics Inc. quartz pressure transducer, model number 112A. The pressure transducer has a pressure range of 0-20.68 MPa (0-3000 psi.). The pressure transducer was connected to a PCB charge amplifier, model number 4 62A.

The pressure transducer sends a signal in pico Coulombs to the charge amplifier which converts the signal to a voltage (0-12 volts). The range setting on the charge amplifier was set at 14% of a full scale reading of 500 units/volt. Therefore, to calculate the pressure from the output voltage use the equation:

P = volts x (.14 x 500) .

The pressure transducer was then calibrated, at the mentioned charge amplifier's setting, using a dead weight pressure tester. During the pressure transducer's calibration tests the output voltage was read into a PC computer with the use of an Analog to Digital board. A Quickbasic program3 read the pressure voltage and took a time average of the readings and wrote the results to a file. The calibration equation with the given charge amplifier settings is:

3 Program created at WMU by Joe Parker and modified by the author of this text.


7-0.0848 " ’ "0.0T73"

with P equal to the pressure and V equal to the charge amplifier output voltage with the amplifier set at 14% of a 500 unit/volt full scale reading.

Laser Doppler Velocimetry

Laser, Optics and Hardware

The LDV experiments used a TSI 100 mW argon-ion laser with a light wave length of 514.5 nm. The laser was split into two beams using a beam splitter with a beam spacing of 50 mm. One beam undergoes a 40 MHz carrier shift from a crystal-controlled oscillator. A 0-10 MHz doppler frequency shift is achieved from a mix of the 40 MHz carrier shift and a 30-40 MHz mixing frequency subtracted from the photodetector's measured burst frequency before the signal reaches the signal processor. The photodetector used was linked to a TSI IFA 550 signal processor which is rated up to a particle burst frequency of 15 MHz. The signal processor is controlled by a PC computer with the software package Find (by TSI Company, n.d.).

Due to the small measurement volume requirements to get between the cylinder wall and the piston, the converging optics must have a very short focal length. Initially the converging optics used a signal 50 mm lens,


however, the lens was not an achromatic lens and it did not focus the laser beams to a single point. Therefore, three converging achromatic lenses were used to achieve the small measurement volume required. The focal lengths of the three lenses used were 600 mm, 210 mm, and 122 mm. The half angle k produced by the three lenses was measured to be 15.226°. The measurement volume size was then calculated using the following equations:

d - 4-ft. la - . d\, df - *•n <TT n " w\ V- •71 Dt̂ " tanK 1 2sinK

where d„ is the diameter of the measurement volume, ln is the length of the measurement volume, a£ is the fringe spacing, f is the focal length of the transmitting lens, D„_2 is the diameter of the beam, X is the wavelength of the laser light, and K is the half angle between the beams.

The measurement volume diameter and length were calculated to be 0.0184 mm and 0.1351 mm respectfully. The fringe spacing was calculated to be 0.9795 micron (distance between each fringe) . Therefore, with the given optical arrangement a measurement of a 1 MHz particle burst frequency corresponds to approximately 1 m/s. The calculations for da, la, and df can be found in Appendix B.

Figure 7 shows the measurement volume.


»•' CONTOUR

FRINGES

Ao PLANE

-0...

Figure 7. Measurement Volume Dimensions.

Particle Seeding

The particle seeding for the LDV system was accomplished with an orifice located between the hotfilm and the engine cylinder. The orifice was located downstream of the hotfilm so when particles are introduced into the airstream they will not break the measurement film of the hotfilm.

The orifice is in a 1.27 cm (0.5 in.) tube with an orifice size of 0.635 cm (0.25 in.) . A reservoir which holds the seeded particles was attached across the orifice using two tubes. The first tube was mounted 2.5 diameters

upstream of the orifice and the second tube was mounted at the vena contracta downstream from the orifice. Two valves were used, one on each tube, to open and close the airflow


Particles u Kept Here

Closing valveClosing valve

Air and Particles

Air Flow

Air Flow

Engine

Orifice

Figure 8. Particle Seeder Design.

from the particle reservoir and to control the particle flow rate. The maximum pressure the tubes and closure valves can withstand is 1.72 MPa (250 psi) . Figure 8 shows a schematic of the orifice particle seeder.

The orifice design was used due to the high pressures at which the tests were conducted. Any outside system which would introduce particles into the airstream would have to have a reservoir pressure above 1.38 MPa (200 psi) while not introducing any additional air into the airstream

(mass flow rate is measured upstream of the seeding). The orifice design was hard to control to achieve good seeding, however, a better system was not found.


The particles which were used was a 99% pure alcohol solution which was introduced into the airstream as small droplets in the vena contracta of the orifice. The droplets would then be partially atomized making a small detectable particle which could be measured by the LDV system. Initial particle seeding tests were conducted using an open ended tube (not attached to the engine cylinder) with the laser measurement volume located at the end of the tube. The orifice design was able to produce a fine mist of alcohol particles at sporadic intervals.

Some seeding tests were done using a mixture of polysteren (1 |im particles) and alcohol. The addition of the small particles made a much slower data rate than pure alcohol. It is believed the polysteren particles are smaller than the alcohol particles which causes some background noise. The noise decreases the signal to noise ratio and thus decreases the data rate. Pure alcohol (99%) was used for all in cylinder tests to achieve the highest possible data rate.

Limitations of the LDV System

Some initial results were achieved using the LDV system at low cylinder pressures (0-600 Pa above atm.).

During the tests the LDV measurement volume was located in the piston ring end gaps. The limitations of the LDV signal processor prohibited measurements of the blowby


10 MHz ShiftUnshifted PlotMHZ

•15

m/sFor the shifted plot:

C=i Velocity reading region

Particles are traveling with the fringes and are faster

Particles are traveling with the

fringes but are slowerParticles are Traveling

opposite the fringes

Figure 9. An (Jnshifted and a Shifted Plot of a Particle Burst Frequency Versus the Corresponding Velocity.

gases at higher pressures because of the corresponding higher gas velocities. As mentioned above a 1 MHz particle burst corresponds to approximately 1 m/s for the given optical configuration. With the IFA 550 signal processor the maximum particle burst which can be measured is 15 MHz which is approximately a velocity range of ±15 m/s without a frequency shift. Figure 9 shows an unshifted frequency- velocity plot and a 10 MHz shifted plot with the mentioned

optical setup.With a frequency shift of 10 MHz (max shift) the

signal processor can still read a 15 MHz particle burst but


because the fringes are now moving at 10 MHz the velocity range is -5 m/s to 10 m/s. The limited velocity range is due to the way the processor handles the shifted frequency information. When the processor gets a particle burst frequency which has been altered from frequency shifting the processor will convert the burst frequency to a velocity using only the line which crosses the flow reversal point (velocity = 0) .

In order to obtain higher velocity measurement (above 15 m/s) the fringes were given a doppler shift of 10 MHz in the direction of the air flow and the processor was told to give the output in terms of the measured frequency. Because it was known the flow was above 10 m/s the velocity could then be calculated using the frequency-velocity line which corresponds to the particles traveling in the same direction but faster than the fringes (refer to Figure 9). The method just explained would allow the measurement of a non turbulent (non flow reversal) flow with a velocity up to 25 m/s for the given optical setup.


CHAPTER III

RESULTS

Hotfilm Anemometry

Blowbv Estimates

The initial blowby calculations to determine the total mass flow rate, past the piston rings were determined by calculating a 5% mass loss of air. A standard in the automotive industry is a loss less than .3 CFM/liter at 1500 rpm4. The standard corresponds to a running engine where pressure within the combustion chamber undergo a cyclic pressure, unlike the tests which were conducted on the blowby gases.

The blowby gas tests conducted on the CFR test engine kept a constant cylinder pressure. Therefore the theoretical mass air loss which would occur was calculated by relating the losses in a reciprocating engine to the static test engine.

The total mass which would enter the test engines cylinder, if it was running, was calculated assuming the

cylinder would be completely filled with air on the intake

4 Standard used by Ford Motor Co. Engine Division27


stroke (ideal case). The volumetric air loss due to blowby past the piston rings was then calculated using the industrial standard stated above. The volumetric air loss was calculated to be 98.98 x 10'6 m3/sec (calculations in

Appendix A).Then, on a similar running engine5, the pressure

within the combustion chamber was averaged over one complete engine cycle. The average pressure was found to be 315 kPa (45.75 psi), which becomes the target cylinder pressure for the LDV static blowby tests. The averaged pressure graph of the running engine can be found in Appendix A. When the static engine's cylinder is pressurized to 315 kPa the blowby gases should be similar to an identical running engine.

Effects of the Optical Window

Before the optical window hole was machined and the optical window was installed the blowby gases were measured at various cylinder pressures 0-1378 kPa (0-200 psi) using the hotfilm anemometer. The results of the test can be found in Appendix A. The maximum blowby mass flow rate was found to be 0.100 kg/sec (13.25 lbn/min) which occurred at 1379 kPa (200 psi).

5 Test engine for the pressure measurements was a CFR engine with the compression ratio set at 8:1. Ignition occurred at 12° before top dead center.


After the optical window was installed in the cylinder a second test, identical to the first, was conducted to determine if the optical window affected the sealing ability of the piston rings thus affecting the blowby gas measurements. The results of the second test can be found in Appendix A. The maximum blowby of the test with the optical window installed was 0.107 kg/sec (14.15 lbm/rnin) which occurred at 1379 kPa (200 psi).

Figure 10 shows the results of the two tests plotted as the mass flow rate of the blowby gases versus the cylinder pressure. It was expected that if the installation of the optical window affected the blowby gases an increase in the mass flow rate would occur. If the optical window affected the sealing ability of the piston rings an increase in cylinder pressure would cause the mass air flow rate (of the second test) to increase linearly with respect to the mass flow rate of the first test. Thus a constant percent change in the mass flow rate would be expected given the conditions stated above.

However, the calculated percent air mass flow change decreases as the cylinder pressure increases. The conclusion is the measured increase in mass airflow is caused by a constant change in the instrumentation readings such as a non zeroed instrument. The installation of the optical window is therefore assumed to not cause a measurable change in the total blowby mass flow rate.


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Blowby ComparisonWithout Window versus Window Installed

0.11

0.1

^ 0.09-0- I 0.08-

o.o7- 2 0.06-

1 oxe\OQ COcd

^ 0.034

0.04- W ithout Window

Window Installedi_3 0.02

0.01-

600 1400200 400 800 1000 Cylinder Pressure (kPa)

1200

Figure 10. A Comparison of the Blowby Gases With and Without an Optical Window.

GJO

Quantifying Blowby Gases

The effects of the ring end gap alignment on the mass flow rates of the blowby gases was studied by measuring the total mass flow rates for several ring gap orientations. The ring end gap orientations which were studied were 120° separation between all three ring end gaps (desired alignment in a vehicle), alignment of the second compression ring end gap and the oil ring end gap and with the first compression ring rotated 180°, and all three ring end gaps in line with each other.

The volumetric flow rate past the piston rings was measured using the hotfilm anemometer. The change in the volumetric flow rate of the blowby gases was found to be a linear relationship to the in cylinder pressure. The relationship is plotted in Figure 11.

With the pressure transducer measurements taken at the hotfilm's location the mass flow rate could be calculated using the equation:

rti - pO - JL Q

where m = mass flow rate, p = density, Q = volume flow rate, P = pressure at volumetric flow rate measurement location, R = gas constant, T = temperature at volumetric flow rate measurement location. The mass flow rate of the blowby gases past the three ring end gap alignments is


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Quantify Blowby - Volumetric Flow RateThree Ring Gap Orrienlations

0.005

0.0045

0.004

0.0035-

0.003-

* 0.0025- oE 0.002-

§ 0.0015-120 deg Separation

2-3 Inline: 1 Op.

0.001 Ring Gaps Inline

0.0005

1400600Cylinder Pressure (kPa gauge)

800 1000 1200400200

Figure 11. Volumetric Flow Rate of the Blowby Gases for Three Ring Orientations.

CJro

plotted versus cylinder pressure in Figure 12. Tables 9, 10 and 11 in Appendix C show the measured data and the calculated results for each of the ring gap orientations.

It was expected that the maximum mass flow rate would occur with the ring end gaps in line. The in line ring gap orientation provides the least resistance (a straight line for the airflow) for the blowby air to travel through the end gaps to the engine crankcase. At a maximum cylinder pressure of 1372 kPa (199 psi) the blowby gas mass flow rate was .084 kg/sec (11.1 lbm/min).

With the rings oriented with an equal spacing between the ring end gaps (120°) the blowby gas flow was minimized. A maximum blowby gas mass flow rate for the 120° orientation was .063 kg/sec (8.33 lbm/rnin) at a cylinder pressure of 1379 kPa (200 psi) . The blowby gas mass flow rate was decreased by 25% for the 120° ring gap orientation over the in line ring gap orientation.

The third ring gap orientation (rings 2 and 3 end gaps in line) had a blowby mass flow rate of .066 kg/sec (8.73 lb^/min) at a maximum cylinder pressure of 1379 kPa (200 psi) . The data show the blowby mass flow rate is very close to the ring gap orientation of 120° separation. The results are closer to the 120° orientation for two reasons.

First the third ring (oil ring) had a much smaller ring end gap spacing than the compression rings (oil ring end gap = 0.76 mm, compression ring end gap = 1.04 mm and 1.09 mm).


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01<Dcd&ZOEi/icoas

0.09

0.08

0.07

0.06

0.05

0.04-

0.03-

0.02-

0.01-

0*-0

Quantify Blowby - Mass Flow RateThree Ring Gap Orrientations

120 deg Separation X

2-3 Inline: 1 Op.X

Ring G aps Inline

40 60 80 100 120 140 160 180 200Cylinder Pressure (kPa gauge)

Figure 12. Mass Flow Rate of the Blowby Gases for Three Ring Gap Orientations.

Putting the two largest ring end gaps in line would have a larger effect than aligning the small ring end gap with a larger ring end gap. Secondly, the compression rings are expected to seal most of the cylinders pressure and the oil ring then experiences only a small pressure drop across itself. Therefore aligning the oil ring end gap with a compression ring end gap does not have as large of an effect on the blowby gas flow rate as aligning the two compression ring end gaps.

The blowby gas mass flow rate data have been curvefit to the cylinder pressure for each of the ring end gap orientations. The function which was found was a nonlinear function due to the many conditions which change with the increasing cylinder pressure. Given the mass flow

t

rate equation shown above the mass flow rate is proportional to the cylinder pressure and the volumetric flow rate, while the mass flow rate is inversely proportional to the temperature. However, the temperature of the airflow through the ring gaps was not measurable and was assumed to be constant. The curvefit equations can be found in Appendix C .

Finally a theoretical area was calculated using the mass flow rate of the blowby gases and the total pressure

drop which occurs across all three rings. The following equations were used to calculate the estimated area:


3 6

4- - 0.8333TEl - 0.5283 El - 1.0

A -

P0.8333 itiRT

0.5283 P ̂ 0.8333 fRT

where A is the theoretical area, m is the mass flow rate, R is the gas constant (287 .2 J/kg°K for air), T is the temperature of the gases, P is the pressure drop and M is the mach number.

The theoretical area which is calculated corresponds to the total area required for the measured mass flow rate to flow at the corresponding pressure change at a choked airflow condition (M = 1). It is assumed the flow past the piston rings does not become supersonic due to the nonideal nozzle conditions. Choked flow occurs when

where Pb is the base pressure (atmospheric pressure in this case 101.3 kPa) and Pc is the tank pressure (cylinder pressure in this case). A choked condition is therefore expected for all cylinder pressures above 191.8 kPa (27.8 psi) .


h. 0.5283P

The theoretical blowby area requirements for a choked airflow condition were plotted with respect to the cylinder pressure (see Figure 13) . The graph shows how the area requirements increase linearly with the cylinder pressure. The static ring gap area (no pressure in the cylinder) is also plotted on the graph. Most of the blowby gases are not escaping through the ring end gaps as one would expect. The large area requirement could be caused by improper sealing of the rings against the cylinder wall. The blowbygases then could escape past other areas of the piston ringother than the ring end gaps.

The improper sealing could occur in the test engine because the engine could not be properly "broken in" and thus the rings did not get a chance to wear into the cylinder which would have increased the sealing ability of the rings. The piston rings were also oiled with a SAE10W-30 oil on only half of the ring to minimize the oilcontamination on the optical window for LDV testing.

A second possibility for the large blowby area requirements, as compared to the ring end gap area, could come from an undetected air leak downstream of the hotfilm measurements. A leak would cause an enlarged mass air flow rate measurement and thus a large blowby area would be

calculated to compensate for the loss. A leak would also explain the unexpected overall high mass flow rate as compared with the calculated value found in the Cylinder


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Estimated Blowby AreaThree Ring Gap Orricntations

CN<B,ca<o

2.5- 120 deg Separation

2-3 Inline: 1 Op.

Ring Gaps Inline10W©1-1 15to l.JG£ ,

0.5-

Static Rinc Gap Size

200 400 600Cylinder Pressure (kPa gauge)

800 1000 1200 1400

Figure 13. Estimated Blowby Area Required Assuming a Choked Airflow Condition.

00oo

and Head Design section in Chapter II. An air leak would explain two of.the project's problems but none were found and the size of the air leak which would be required to cause such a large change from the expected values should

be easy to find.

Laser Doppler Velocimetry

The laser doppler velocimeter was only able to measure the local gas flow velocities when the cylinder pressures were less than 0.6 kPa (.087 psi, gauge pressure) due to the limitations of the LDV signal processor (5 to 10 m/s for flow reversals with a 5 MHz shift) as explained in the Limitations of the LDV System section in Chapter II. The data were obtained with the measurement volume located in the first ring end gap. All three ring end gaps were in line for the LDV measurement tests. The air and alcohol was entered into the cylinder with the use of an airbrush. The airbrush was mounted on the cylinder head using a rubber grommet at the inlet hole for the 1.27 cm (0.5 in.) pipe.

The data obtained for each test were shown on a realtime histogram using the program Find. The data which were obtained had a very slow data rate (apx. 5 data points

per minute for most of the tests). The program Find would average the data for each of the LDV tests after enough data were collected. The average of the LDV tests were


then plotted versus the cylinder pressure (see Figure 14). The data obtained are shown to be very random in nature despite getting data in a bell shaped histograms in each individual test. A linear regression analysis was done on the data points and the corresponding line was plotted on the graph. The averaged data and the results of the regression analysis can be found in Appendix C.

Velocity measurements using the LDV system were also attempted at a location just below the first compression ring away from the ring end gap. Some data did show on the realtime histogram, however, the data rate was extremely low and the few data1 point which were collected appeared random.


Airbrush in CylinderMeasuremnet Volume in Ring End Gap

A

A

0.60.50.40.30.2Cylinder Pressure (kPa gauge)

0.1

Figure 14. In Cylinder Measurements Using an LDV System.

C H A P TE R I V

RECOMMENDATIONS

Static

The static tests on the blowby gases should be continued to obtain a pressure distribution around the piston rings and to determine the effects of different ring end gap sizes and shapes on the blowby gases. Some outside interest has been shown for the results of these tests. However, before they can be completed some test setup changes may need to occur.

First the blowby tests using the LDV system were severely limited by the limitations of the signal processor. Before further tests are conducted on the blowby gasses a different signal processor should be used with the capabilities of measuring much faster flow velocities.

Secondly a different particle seeding device may be needed. The one used in the current project was only used for out of cylinder testing. The particle seeding device worked, but it was hard to control and it gave a very low data rate under the optimum conditions. The entire airflow

delivery system should also be rechecked under very high pressures for a possible air leak which was not found at

42


200 psi. Lastly a single converging lens with a similar half angle may give a larger signal to noise ratio than the three lens configuration.

Overall the largest drawback of the project was the lack of outside funding for the project. However, during the project there was some interest shown once the test setup was completed and initial tests were successful. In the future getting the required sponsorship may prove much easier because the engine setup is already in place and the testing has been started.

Dynamic

Future dynamic tests will require some additional modifications to the engine and motor, however, the main equipment which will be required is already installed (complete crankcase, oiling system, flywheel and belt drive, and the electric motor).

Dynamic tests of the blowby gases may be possible using the LDV system. Before dynamic tests are attempted the static tests should be completed. Other dynamic tests such as the measurement of in cylinder fluid flows, intake or exhaust fluid flows and flows within a given manifold would be possible with only minor modifications to the

cylinder and head design. Very long term goals may even include the measurement of combustion fluid flow.


C H A P T E R V

CONCLUSIONS

The project laser doppler velocimetry research of the blowby gases in an internal combustion engine was designed to accomplish three main goals. The first goal was to expand the LDV research laboratory at WMU to include LDV/reciprocating engine measurements. A complete engine and electric motor stand was constructed for both static and dynamic LDV tests of a CFR engine. Future tests will be able to be carried out on the same experimental setup with only minor modification required for the given testing desired.

The second goal of the project was to research an engine fluid flow which has not been previously studied using the LDV technique. Some data measuring the blowby gases using the LDV system were collected. The main reason for the lack of LDV data came from the limitations of the LDV's signal processor. These limitations which were not expected and were only partial overcome by using frequency measurements in single direction flow and lower cylinder

pressures when turbulent flow was expected.

Most of the data collected was done by hotfilm

44


anemometry. The results collected from the hotfilm anemometer behaved as expected with the exception of the mass flow rate being larger than expected. However, the relationship between the data collected was very predictable.

The third goal of the project was to acquire knowledge of the LDV system and determine its limitations in close wall measurements. A very good working knowledge of the LDV system was accomplished as well as being able to put that knowledge to use in an innovative way (as explained above) to increase the capabilities of the LDV system.

The close wall measurements limitations were overcome by using a very small measurement volume for both minimum reflections from the measurement volume itself and a large signal to noise ratio from the intensity of the measurement volume.

Two of the three proposed goals were accomplished (starting an LDV/reciprocating laboratory, and understanding the LDV system and its limitations) as well as getting some preliminary data of the unfinished goal, measurement of the blowby gases using the LDV system. Overall the project was determined to be a success.


Appendix A Engine Setup Data and Calculations

46


Theoretical out of Roundness of Cylinder Due to Optical Window

h - r (1- cos^) - ^ tan-̂ ^ " cylinder out of roundness

S - 2 r s^n-j

5 - slit — 2 mmr - cylinder radius - 41.275 mm

<)> - 2 sin-1 (^.)

,|’ ' 2 sln'‘ (T7TnT7TT) ' °-0485 radh -2 tan 0. °4,85. - 0.0121 mm

Theoretical Blowby in a Reciprocating Engine

Vd - Engine Displacement Volume - 0.612 L 7C - Piston-Head Clearence Volume - 0.087 L

(.3°™) 0.612 L - 0.184 CFM - 98.98 x 10‘6 JULsec


4 8

Pressure Graph from Reciprocating CFR Engine

Figure 15. CFR Pressure Test During Compression and Ignition. Vertical Axis is 1249 kPa/div and the Horizontal Axis is 18 Degrees of Engine Revolution.


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Table 1

Measured and Calculated Data for the Blowby Gases without the Optical Window Installed

Calculated Effects

Time from Cylinder Hotfilm Tank-Line Hotfilm Corrected Hotfilm Volumetric Air MassBeginning Pressure Line Pres. Pressure Voltage Hotfilm V. Line Pres. Airflow Flow Rate

(sec) (kPa) (volts) (kPa) (volts) (volts) (kPa) (m ~ 3/s) (kg/sec)

64 344.738 1 365.4223 5.13 2.145 326.9882 0.001746 0.007123114 689.476 2.1 827.3712 5.77 2.785 735.8861 0.0032547 0.026557174 861.845 2.4 965.2664 5.97 2.985 820.0517 0.0038483 0.03925214 1034.214 3.05 1206.583 6.25 3.265 1055.506 0.0047832 0.058542274 1206.583 3.4 1310.004 6.42 3.435 1159.598 0.0054115 0.07727304 1378.952 4.05 1516.847 6.6 3.615 1400.951 0.0061279 0.100001

Base Values (No Flow)Start = 0 0 0 2.96End = 0 0.45 0 3.01

4*V£>

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Table 2

Measured and Calculated Data tor the Blowby Gases with the Optical Window Installed

Calculated Effects

Time from Cylinder Hotfilm Tank-Line Hotfilm Corrected Hotfilm Volumetri Air MassBeginning Pressure Line Pres. Pressure Voltage Hotfilm V. Line Pres. Airflow Flow Rate

(sec) (kPa) (volts) (kPa) (volts) (volts) (P2)-(psi) (m ~ 3/se (kg/sec)

62 344.738 1.1 . 5.29 2.3575 351.3455 0.002183 0.00890892 689.476 2.025 - 5.79 2.8575 694.2283 0.003463 0.028255

122 861.845 2.5625 - 6.11 3.1775 882.6763 0.004478 0.04567157 1034.214 3.1 - 6.25 3.3175 1066.83 0.004972 0.060856197 1206.583 3.45 - 6.48 3.5475 1171.962 0.005853 0.083575232 1378.952 4.4 - 6.65 3.7175 1520.514 0.00656 0.107048

Base Values (No Flow)Start = 0 2.925End = 0.5 2.94

CJ1o

5 1

Table 3

Comparison of the Blowby Gases with the Optical Window Installed versus Without

Percent Change

Air Flow Air Flow Calc.Cylinder Without With % Increase % Increase

.Pressure Window Window W.- W.O. W. - W.O.(kPa) (kg/sec) (kg/sec)

344.738 0.0071064 0.0089208 0.20338983 0.17140178689.476 0.0265356 0.0282744 0.06149733 0.10255263861.845 0.0392364 0.0456624 0.14072848 0.07411826

1034.214 0.0585144 0.060858 0.03850932 0.057030171206.583 0.0772632 0.083538 0.07511312 0.048805391378.952 0.1000188 0.1070496 0.06567797 0.04726887


Appendix B Calibration Data

52


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Table 4

Measurement and Calculation Data for the Shaping Coefficient for a Maximum Velocity of 13.07 m/sec

Integrated Results

Probe Ht. Manometer Velocity 2*r*(pi)*vel. Change r* Volume Shapingto Radius Reading of Air avg 2ru(pi) Flow Rate Coefficient

(cm) (in. H 20) (m/sec) (m ~ 2/sec) (m ~ 3/sec) (m ^ 3/sec)

1.27 0 0 0 01.016 0 0 0 00.762 0.02 2.853135133 -0.13660236 -0.000173480.508 0.15 7.813632359 -0.24940064 -0.000490220.254 0.26 10.28712502 -0.1641756 -0.00052524

0 0.42 13.07470771 0 -0.0002085-0.127 0.42 13.07470771 0.104331774 6.62507E-05-0.254 0.38 12.43652772 0.198478625 0.000192285-0.381 0.27 10.48308786 0.250954557 0.00028539-0.508 0.19 8.793953082 0.280691163 0.000337595-0.635 0.11 6.691194996 0.266967439 0.000347763-0.762 0.03 3.494362621 0.167303038 0.000275762-0.889 0.01 2.0174712 0.112691196 0.000177796 Q = S =-1.016 0 0 0 7.15589E-05 0.00175441 1.059249916

tnw

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Table 5


Integrated Results


(cm) (in. H 20) (m/sec) (m ~ 2/sec) (m ~ 3/sec) (m ~ 3/sec)

1.27 0 0 0 01.016 0.01 2.0174712 -0.12878994 -0.000163560.762 0.02 2.853135133 -0.13660236 -0.000337050.508 0.06 4.941775011 -0.15773482 -0.000373810.254 0.26 10.28712502 -0.1641756 -0.00040883

0 0.31 11.23280425 0 -0.0002085-0.127 0.31 11.23280425 0.089634004 5.69176E-05-0.254 0.27 10.48308786 0.167303038 0.000163155-0.381 0.21 9.245214486 0.221321116 0.000246776-0.508 0.12 6.988725242 0.223070717 0.000282189-0.635 0.05 4.511202746 0.179989411 0.000255943-0.762 0.02 2.853135133 *0.136602358 0.000201036-0.889 0.005 1.426567566 0.079684709 0.000137342 Q = S =-1.016 0 0 0 5.05998E-05 0.001393966 0.979633002

cn

Table 6


Integrated Results


(cm) (in. H20) (m/sec) (m ~ 2/sec) (m ~ 3/sec) (m ^ 3/sec)

1.27 0 0 0 01.016 0 0 0 00.762 0.01 2.0174712 -0.09659245 -0.000122670.508 0.08 5.706270265 -0.18213648 -0.000353990.254 0.2 9.022405492 -0.14399153 -0.00041418

0 0.24 9.883550022 0 -0.00018287-0.127 0.235 9.780054499 0.078041549 4.95564E-05-0.254 0.21 9.245214486 0.14754741 0.000143249-0.381 0.17 8.318246854 0.199130445 0.00022014-0.508 0.1 6.379804106 0.203634773 0.000255756-0.635 0.045 4.279702699 0.170752948 0.000237736-0.762 0.01 2.0174712 0.096592454 0.000169764-0.889 0.002 0.902240549 0.050397035 9.33383E-05 Q = S =-1.016 0 0 0 3.20021 E-05 0.001201549 0.959683229

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Table 7


Integrated Results


(cm) (in. H20) (m/sec) (m ~ 2/sec) (m ~ 3/sec) (m ^ 3/sec)

1.27 0 0 0 01.016 0 0 0 00.762 0.005 1.426567566 -0.06830118 -8.6742E-050.508 0.05 4.511202746 -0.14399153 -0.000269610.254 0.11 6.691194996 -0.10678698 -0.00031849

0 0.13 7.274095858 0 -0.00013562-0.127 0.13 7.274095858 0.058044841 3.68585E-05-0.254 0.12 6.988725242 0.111535358 0.000107683-0.381 0.1 6.379804106 0.152726079 0.000167806-0.508 0.055 4.731389356 0.151019589 0.000192878-0.635 0.025 3.189902053 0.127271733 0.000176715-0.762 0.01 2.0174712 0.096592454 0.000142154-0.889 0 0 0 6.13362E-05 Q = S =-1.016 0 0 0 0 0.000885436 0.960898567

Olo\

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Pitot-Static Pressure Measurement of Air Exit Velocity from a 1.27cm Pipe

45

40 Max Reading = .42

O35

SOE 30 co c >»"9 25o

Max Reading = .31

Max Reading = .24~ - X -Max Reading = .13

b<o3toto<DCL

Pipe Dia.

-1.27 -0.635 0.635 1.27Distance from Nozzle Center (cm)

Figure 16. Manometer Reading Versus Pipe Position to Obtain the Shape Factor.in-4

Table 8

Measured and Calculated Data for Calibration of the Hotfilm Anemometer

Curvefit Analysis

Hot Film Voltage

E(V)E-EO

(V)

Manometer Velocity delta h max from h

(in H20) (m/sec)

Shape Average Volumetric Factor Velocity Air Flow

(m/sec) (m ̂ 3/s)

2.92 0 0 0 1 0 03.98 1.06 0.02 2.85313513 1 2.85313513 0.000361434.08 1.16 0.06 4.94177501 1 4.94177501 0.000626014.26 1.34 0.08 5.70627027 1 5.70627027 0.000722864.28 1.36 0.07 5.33772707 1 5.33772707 0.000676174.37 1.45 0.09 6.0524136 1 6.0524136 0.000766714.49 1.57 0.125 7.13283783 1 7.13283783 0.000903574.51 1.59 0.13 7.27409586 1 7.27409586 0.000921474.65 1.73 0.18 8.5594054 1 8.5594054 0.001084294.73 1.81 0.22 9.46277871 1 9.46277871 0.001198724.76 1.84 0.23 9.67545198 1 9.67^45198 0.001225664.78 1.86 0.25 10.087356 1 10.087356 0.001277844.86 1.94 0.27 10.4830879 1 10.4830879 0.001327974.89 1.97 0.31 11.2328043 1 11.2328043 0.001422954.96 2.04 0.33 11.5894897 1 11.5894897 0.001468134.97 2.05 0.36 12.1048272 1 12.1048272 0.001533414.97 2.05 0.39 12.5991036 1 12.5991036 0.001596035.02 2.1 0.38 12.4365277 1 12.4365277 0.001575435.05 2.13 0.4 12.7596082 1 12.7596082 0.001616365.23 2.31 0.67 16.5137135 1 16.5137135 0.002091925.35 2.43 0.85 18.6001654 1 18.6001654 0.002356235.62 2.7 1.46 24.3771973 1 24.3771973 0.003088055.78 2.86 1.96 28.2445968 1 28.2445968 0.003577965.89 2.97 2.07 29.0263559 1 29.0263559 0.00367699

6 3.08 2.82 33.8791026 1 33.8791026 0.004291736.19 3.27 3.45 37.4728644 1 37.4728644 0.004746986.38 3.46 4.68 43.6445752 1 43.6445752 0.005528796.52 3.6 5.95 49.211412 1 49.211412 0.006233996.61 3.69 6.35 50.838673 1 50.838673 0.006440136.74 3.82 7.6 55.6178428 1 55.6178428 0.007045546.86 3.94 8.7 59.5068512 1 59.5068512 0.00753819


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Hot Film/Air Flow Calibration(voltage vs volumetric air flow)

0.006

0.005-

Hotfilni Calculated

S 0.004

0.003

0.002-

0.001-

0.5 1.5Anemometer Voltage E-Eo (V )

2.5 3.5

Figure 17. Hotfilm Calibration Curve Obtained from Polyfit Equation.(XIKO

Calculation of Measurement Volume Dimensions

D,_2 = The beam size at the converging optics = 1.60 mm X = Laser frequency = 514.5 nmf = focal distance of the converging optics = 90 mmtc = half angle of the converging beams = 15.334

d - 4 f k l - d” . df - ^ -“ 7tL>_2 “ tan K f 2 sin Kd - 4 (90) (514 .5 x 10;6) . 0.0184 ^" nrs '

I- - 0____°-1-84 -r - 0.1351 mma tan 15.334

df - 514.5 x - , , . - 0- 97 95 x 10"3 mmf 2 sin 15.334


Appendix C Results Data

61


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Table 9

Measurement and Calculation of the Blowby Volumetric Flow Rate, the Mass Flow Rate, and the Estimated Blowby Area

for a 120 Degree Separation of the Ring End Gaps

Calculated Results

Cylinder Time Hotfilm Corrected Line Line Volume Mass Est. BlowbyPressure Voltage Hotfilm Pressure Pressure Flow Rate Flow Rate Area

(kPa) (sec) (volts) (volts) (volts) (kPa) (m~3/s) (kg/sec) (m ~2)

0 0 2.92 0 0 0 0 0131.0004 43 4 41 1.49 0.54 171.5214 0.000755 0.001533 5.008E-06310.2642 103 4.67 1.75 0.99 337.0586 0.001087 0.004338 5.9837E-06406.7908 143 4.85 1.93 1.225 421.5115 0.001364 0.006802 7.1562E-06586.0546 193 5.11 2.19 1.75 619.2404 0.001834 0.013437 9.8131E-06703.2655 233 5.22 2.3 2.01 713.6569 0.002059 0.01739 1.0583E-05841.1607 293 5.37 2.45 2.44 871.2232 0.002393 0.024674 1.2555E-05979.0559 333 5.5 2.58 2.95 1065.275 0.002708 0.034142 1.4925E-051103.162 363 5.59 2.67 3.25 1177.934 0.002941 0.040991 1.5904E-051261.741 403 5.71 2.79 3.7 1348.073 0.003269 0.052149 1.769E-051378.952 433 5.83 2.91 4.05 1480.66 0.003619 0.063407 1.968E-05

End = 0.25

Ok

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! Table 10

Measurement and Calculation of the Blowby Volumetric Flow Rate, the Mass Flow Rate, and the Estimated Blowby Area

for Rings #2 and #3 Inline with #1 Rotated 180 Degrees

Calculated Results

Cylinder Time Hotfilm Corrected Line Line Volume Mass EsL BlowbyPressure Voltage Hotfilm Pressure Pressure Flow Rate Flow Rate Area

(kPa) (sec) (volts) (volts) (volts) (kPa) (m~3/s) (kg/sec) __(m_~2)__

0 0 2.92 0 0 0 0 0131.0004 64 4.26 1.34 0.475 132.9518 0.000597 0.000939 3.068E-06275.7904 104 4.76 1.84 0.9 288.2324 0.001221 0.004164 6.461 E-06434.3699 134 4.95 2.03 1.3 437.0743 0.001534 0.007935 7.819E-06551.5808 174 5.1 2.18 1.645 560.4716 0.001814 0.012031 9.336E-06

689.476 214 5.32 2.4 2.05 707.7814 0.002278 0.019084 1.185E-05861.845 254 5.53 2.61 2.55 892.9526 0.002784 0.029424 1.461E-05

958.3716 294 5.6 2.68 2.83 990.4448 0.002967 0.034770 1.553E-051110.056 324 5.76 2.84 3.29 1163.199 0.003412 0.046967 1.811E-051275.531 384 5.8 2.88 3.83 1357.262 0.003529 0.056685 1.902E-051378.952 424 5.89 2.97 4.15 1470.696 0.003802 0.066167 2.054E-05

End = 0.375

oiu>

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Table 11

Measurement and Calculation of the Blowby Volumetric Flow Rate, the Mass Flow Rate, and the Estimated Blowby

Area for an Inline Ring End Gap Onientation

Calculated Results

Cylinder Time Hotfilm Corrected Line Line Volume Mass EsL BlowbyPressure Voltage Hotfilm Pressure Pressure Flow Rate Flow Rate Area

(kPa) (sec) (volts) (volts) (volts) (kPa) (m ̂ 3/s) (kg/sec) (m~2)

0 0 2.92 0 0 0 0 0172.369 49 4.66 1.74 0.725 225.4071 0.001073 0.002863 7.1088E-06

268.8956 94 4.78 1.86 0.875 257.8771 0.001252 0.003819 6.0792E-06410.2382 139 5.18 2.26 1.3 399.9458 0.001975 0.009349 9.7535E-06586.0546 184 5.46 2.54 1.9 611.7593 0.002609 0.018886 1.3793E-05723.9498 214 5.53 2.61 2.3 752.9682 0.002784 0.024811 1.4668E-05854.9502 259 5.69 2.77 2.68 877.1026 0.003213 0.033347 1.6694E-05965.2664 274 5.82 2.9 3 995.5321 0.003589 0.042279 1.8747E-051110.056 319 5.98 3.06 3.43 1139.594 0.004087 0.055114 2.125E-051227.267 349 6.06 3.14 3.83 1280.802 0.004351 0.065944 2.2997E-051372.057 394 6.21 3.29 4.35 1460.733 0.004873 0.084232 2.6275E-05

End = 0.6

<xi

6 5

Mass Flow Rate Equations

Ring end gaps 120° apart:9.5 x 10-9 P4 - 3.4 x 10"7 P3 + 0.00022 P2 + 0.0028 P + 0.023

Ring end gaps #2 and #3 inline with ring #1 rotated 180°:-4.22 x 10-7 P3 + 0.00031 P2 - 0.0014 P + 0.034

All ring end gaps inline:-4.95 x 10‘9 P4 + 3.0 x 10'6 P3 - 0 .00062 P2 + 0.096 P +

0.016

In the equations P = cylinder pressure


Table 12

Laser Doppler Velocimer Measurements in Ring End Gap of #1 Compression Ring

Measured Data

Manometer LDV Cylinder Blowby CalculateReading Frequency Pressure Velocity Regresion(in H 20) (MHz) (Pa) (m/sec) Line

0.45 2.46 0.112128 2.40957 4.230970.5 4.4 0.124587 4.3098 4.269388

1 5.29 0.249174 5.181555 4.6535651.1 5.1 0.274091 4.99545 4.7304011.2 6.95 0.299009 6.807525 4.8072361.3 4.8 0.323926 4.7016 4.884072

1.72 5.4 0.428579 5.2893 5.2067811.8 4.5 0.448513 4.40775 5.268249

2 8.28 0.498348 8.11026 5.421922.2 4.85 0.548183 4.750575 5.5755912.2 5.1 0.548183 4.99545 5.5755912.2 5.6 0.548183 5.4852 5.5755912.3 4.5 0.5731 4.40775 5.652427

Regression Output:Constant 3.885211Std Err of Y Est 1.288115R Squared 0.142175No. of Observations 13Degrees of Freedom 11

X Coefficient(s) 3.083608Std Err of Coef. 2.283765

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Sample Doppler Burst of in Cylinder Testing Using The LDV System

1.5Sample Doppler Burst

-1.5 ■ ' ' ' 1 I I 1 L. I i l I I I i < I 1----- 1

10

Time (jis)IS 20

Figure 18. Sample Doppler Burst of Incylinder LDV Measurements of the Blowby Gases at a Cylinder Pressure of 0.44 kPa.


B IB L IO G R A P H Y

Asanuma, T., & Obokata, T. (1979). Gas Velocity Measurements of a Motored and Firing Engine by Laser Anemometrv. SAE Technical Paper 790096.

Hamady, F., DeFillppis, M., Stuecken, T., & Schock, H. (1991) Experimental Analysis of Blowbv and Flow Field Interaction in a Motored Rotary Engine. SAE Technical Paper 910893.

Jugal, K. Argarwal,& Johnson, M., (1981). Generating AerosolFor Laser Velocimeter Seeding. TSI Publication VII, 5-12.

Kjaer J., & Enni, B. (1987). LDA Measurements in Thin Channels. Dantec Information. 1-4.

Schock, H., Hamady, F., DeFillppis, M., Stuecken, T.,& Gendrich, C. (1991) . High Frame Rate Flow Visualization and LDV Measurements in a Steady Flow Head Assembly. SAE Technical Paper 910473.

TSI Company. (n.d.). Find Software. St. Paul Minnesota: Author

Yeoman, M. (1978). LDA Applications to Internal Combustion Engines. Proceedings of the Dynamic Flow Conference, 629-644.

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