'; C a ; ' O k...wind tunnel confirmed this jet noise power level increase due to crossflow....
Transcript of '; C a ; ' O k...wind tunnel confirmed this jet noise power level increase due to crossflow....
s j z ~~~~~~~~~~, I r! ' ;
1,4i, , \: ', .r,!; *
... ;: ,t ''..' .'-r.\ ' ' ., ' . ''. ,' . . . ,
. [" , ./~~~~~~~~~~~Z
I I
I .. I
G
;,, " '/ !t-
':,,.. /- /,.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~..
N73-2132
Unclas;3/02. 69425 .
, ..y.
I . . ; 1 'I, 1 ,
!I I
'. ,'-;' ., .OF; ' ,.; ..
';AIRCWAT ~ l
0571) EFFECT OF CROSSFLOW
/" t;' /
~ .: . .
' ~L 'I b., , ;
;'." "" " '; "E'.
: . JE'.'i'B, .. .E..
,I 11,
I.:
,, I . , ,.I
. . , .., 4,
:, , , ;' :,.: , .; X
~~~~~~~~~~~~', !; "'/i '.t ..... - , .'. "?
("
4
'..(. t$,t. tS, ',}. ',,(.' ',';" t;S ' 't ';
-S~~t ; \.; . ........ 8~~~~~,,,6 , ,y4, ...... i
... ";;?'""'~ ':" ' ' , '/" L;' ',' '~ ~
,.'
10.''~~~~~~~~~~, '"., ,,'.' i' ' ' ' ' ' t , 1,~~~~' b~-"
'. ,., ';~ .,. ', - , .' , , ' . .', '' ,'
;~~~~~~~,,K.> .,t: .. \,'.; 0 wO A
t ' 1 ,;, \ ~~~~~..( '.. " .5. t\! ';
'~ ".'" "., ^','"" ' ; : '81 ,';'"' . '\ \' ' .'tf 1X'' & ' 6'}"'~ ~ ~ ' ,' ' ' k c~ -' ',, t; " 1
,.,, ! ,: ~ , * ,, , a .; .*,;...
·" ~' ,'' ' . ,' C' ' {' ,,' .'., :, " {t '~AT INAL
. D,.: x,,>tstets, .W R~~~~~~~~~~~..G , ,
- k wi .'~ , ~ * *-
E,NERAL 'ELE~C!,a~ ;'C"*
Orl
a,
~~~~~~~,,.,,'~ . .", ' 'i " :
.'" " " ; ' * .'~ .. '''
I , I, .. i
. "k
. I..
,i'· .',
, ,] ~
,, ., .
.. , ..
."''!, F
" ,! ,1r ,t
; i /r? ','
! .\~~~~,, ,: ;..; r'; , , .... .ii'',
.. ~ ~ ,, . ' ,.....
- preparev o -
"O .,,. "5 ' ' A .-D ,-,, .An~TNi 9TRATIONA iS. ~AN.D" ' ~ r' '.'i:kERONA T C .... , , l' " ';"'-
·;. .. ' ' ' "-; %, F,';is,~ ~~~~~~ ,, ,, i ; , ,/~. ,, · ;*
.. I.
)j I.
, %i'.;t, .'),# ""3*7,
,r . ,' ,
N - m eseach Center.,NASA-.AoesR
, Contract NAS2-"546.. r -b.'e--, Manager'" ~'
; ) , ~, . ,-~Y -'PinjC. .::, , ~ . js;, , :i ...' , " " ,
",',t,,' ,, '.I I I
,I t, , ,I1 ,! " ;.I
4 : '1 ii i' 1 , I i , i,f ilI ',;'i "
LOCITY ON THE GENERATION OF LIFT FANT NOISE IN VTOL AIRCRAFT (Generalectric Co.) 43 p HC $4.25 CSCL 01C
ASA-CR-114
,1 Report No. 2. Government Accession No. 3. Recipient's Catalog No.NASA CR 114571
4. Title and Subtitle 5. Report DateEffect of Crossflow Velocity on the Generation of Lift Fan Jet r Q7tNoise in VTOL Aircraft 6. Performing Organization Code
7. Authorzs) 8. Performing Organization Report No.D.L. Stimpert, R.G. Fogg
10. Work Unit No.9. Performing Organization Name and AddressGeneral Electric CompanyAircraft Engine Group 11. Contract or Grant No.Cincinnati, Ohio 45215 NAS2-5462
13. Type of Report and Period Covered12. Sponsoring Agency Name and Address Contractor Report
National Aeronautics & Space Administration 14. Sponsoring Agency CodeWashington, D.C. 20546
15. Supplementary NotesProject Manager, D.H. HickeyNASA Ames Research CenterMoffett Field, California
16. Abstract
Analytical studies based on a turbulent mixing noise prediction technique indicatethat jet noise power levels are increased when a jet is situated in a crossflow. V/STOLmodel transport acoustic test data obtained in the NASA Ames 40' x 80' (12.2 m x 24.4 m)wind tunnel confirmed this jet noise power level increase due to crossflow. Increases
up to 6 dB at a Strouhal number of 2.5 and crossflow velocity to jet velocity ratio of0.58 were observed. The power level increases observed in the experimental data confirm
the predicted power level increases.
17. Key Words (Suggested by Author(s)) 18. Distribution StatementCrossflow Velocity
Jet Noise Unclassified - Unlimited
Lift Fan
VTOL Aircraft
19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price'Unclassified Unclassified 36
* For sale by the National Technical Information Service, Springfield, Virginia 22151
FOREWORD
The authors wish to acknowledge the cooperation of D. Hickey, J. Kirk
and A. Atencio of NASA Ames in making available the data sources used in the
experimental analysis portion of this report.
ii
TABLE OF CONTENTS
Page
FOREWORD ii
LIST OF FIGURES iv
SYMBOLS vi
SUMMARY 1
INTRODUCTION 2
ANALYTICAL STUDY 3
Crosswind Adjustment to Jet Noise
EXPERIMENTAL ANALYSIS 6
V/STOL Model and Data Acquisition
Lift/Cruise Fans
Lift Fans
COMPARISON OF ANALYTICAL AND EXPERIMENTAL RESULTS 9
CONCLUSIONS 10
FIGURES 11
REFERENCES 36
iii
LIST OF FIGURES
Figure
1. Schematic of Jet in Crossflow
2. Predicted Power Spectra Change for Jetsin Crossflow
3. Microphone and V/STOL Model TransportLocation in Ames Wind Tunnel
4. V/STOL Model Transport Schematic
5. Effect of Crossflow onModel Lift/Cruise Fans
6. Effect of Crossflow onModel Lift/Cruise Fans
7. Effect of Crossflow onModel Lift/Cruise Fans
8. Effect of Crossflow onModel Lift/Cruise Fans
9. Effect of Crossflow onModel Lift/Cruise Fans
10. Effect of Crossflow onModel Lift/Cruise Fans
11. Effect of Crossflow onModel Lift/Cruise Fans
12. Effect of Crossflow onModel Lift/Cruise Fans
13. Effect of Crossflow onModel Lift/Cruise Fans
14. Effect of Crossflow onModel Lift/Cruise Fans
15.
16.
Page
11
12
13
14
15
16
17
18
19
50 Hz SPL of V/STOL(Downstream Microphones)
50 Hz SPL of V/STOL(Upstream Microphones)
100 Hz SPL of V/STOL(Downstream Microphones)
100 Hz SPL of V/STOL(Upstream Microphones)
200 Hz SPL of V/STOL(Downstream Microphones)
200 Hz SPL of V/STOL(Upstream Microphones)
400 Hz SPL of V/STOL(Downstream Microphones)
400 Hz SPL of V/STOL(Upstream Microphones)
800 Hz SPL of V/STOL(Downstream Microphones)
800 Hz SPL of V/STOL(Upstream Microphones)
20
21
22
23
24
25V/STOL Model Lift/Cruise Fan Jet Noise Directiv-ity Pattern at Vo/VJet = 0 and 0.396
V/STOL Model Lift/Cruise Fan Jet Noise Direc-tivity Pattern at Vo/Vjet = 0 and 0.396
26
iv
LIST OF FIGURES - Concluded
Figure PagU
17. Jet Noise Power Level Increase with Increased 27Crossflow at Various Strouhal Numbers
18. Jet Noise Power Level Change as a Function of 28Strouhal Number for Various Crossflow VelocityRatios
19. Effect of Crossflow on 100 Hz Signal from V/STOL 29Model Lift Fans (Downstream Microphones)
20. Effect of Crossflow on 100 Hz Signal from V/STOL 30Model Lift Fans (Upstream Microphones)
21. V/STOL Model Lift Fan Jet Noise Directivity 31Pattern at 100 Hz
22. Comparison of Crossflow Effect on Jet Noise 32Power Level of V/STOL Model Lift Fans andLift/Cruise Fans
23. Comparison of Measured and Predicted Power 33Spectra at Vo/VJet = 0.091
24. Comparison of Measured and Predicted Power 34Spectra at Vo/Vjet = 0.2
25. Comparison of Measured and Predicted Power 35Spectra at Vo/Vjet = 0.33
v
SYMBOLS
Units
2 2A(y) Jet area FT m
dj Diameter of jet at exit plane FT m
f Frequency Hz
K1
Empirical constant
K2 Empirical constant
P Power watts
PWL Sound Power Level Re 10 watts dB
r Radius FT m
Sn Strouhal number, fdj/VjetSPL Sound pressure level Re 0.0002 microbar dB
V Jet Velocity FT/sec m/sec
Vjet Jet Exit Velocity FT/sec m/sec
V(X,Y) Velocity distribution in a plane perpendicular
to the jet trajectory axis FT/sec m/sec
V Crossflow velocity FT/sec m/seco
V Relative velocity FT/sec m/secr
x Space coordinate parallel to crossflow velocity
in jet exhaust plane FT m
X Space coordinate in a plane perpendicular to
the jet axis FT m
y Space coordinate parallel to jet exhaust
velocity at jet exhaust plane FT m
Y Space coordinate in a plane perpendicular to
the jet axis FT m
a Jet trajectory slope, dy/dx Degrees
a1 V/STOL model transport yaw angle Degrees
V Exhaust louver angle of V/STOL model lift fans Degrees
aCN V/STOL model transport lift/cruise nozzle
exhaust exit angle Degrees
Jet trajectory coordinate FT m
vi
SUMMARY
Possible installations for lift fans in future V/STOL aircraft include
vertical mounting in wing pods, vertical mounting in the fuselage, and lift-
cruise mounting on the fuselage with the Jet being vectored for lift and cruise.
In all these possible configurations, the jet will experience various degrees
of crossflow during flight. An investigation was conducted into the effects of
crossflow velocity on the generation of lift fan Jet noise. This investigation
included an analytical study and an examination of experimental data, both of
which confirmed an increase in jet noise sound power level with increasing
crossflow velocities. The aero-acoustic analysis utilized a turbulent mixing
noise prediction technique which is based upon a velocity profile method that
was modified to handle deflected jet velocity profiles. Confirmation of the
aero-acoustic analysis was obtained by examining acoustic data recorded during
testing of a V/STOL model in the NASA Ames 40 foot by 80 foot (12.2m by 24.4m)
wind tunnel.
INTRODUCTION
Research is currently being directed toward the design of V/STOL air-
craft to be used as commercial subsonic transports. Many of the configurations
being considered by NASA and the airframe manufacturers incorporate lift fans
which are fixed in wing pods or mounted in the fuselage with the inlets oriented
vertically. During transition from vertical to horizontal flight on takeoff
or the reverse on landing, exhaust jets from these lift fans experience various
degrees of crossflow velocities.
During aerodynamic and acoustic investigations of a large scale lift fan
model in the NASA Ames 40' by 80' (12.2m x 24.4m) wind tunnel, sound pressure
levels in the jet noise region of the spectrum were observed to increase when
the jet was issuing perpendicular to the crossflow (Reference 1). This paper
reports on analysis of additional noise measurements taken in the NASA Ames
40' by 80' (12.2m by 24.4m) wind tunnel with a complete lift fan aircraft
model. The results were analyzed to give an empirical understanding of jet
noise in a crossflow and to provide verification of an analytical study.
2
ANALYTICAL STUDY
CROSS WIND ADJUSTMENT TO JET NOISE
The Jet noise adjustment used in the prediction model to account for in-
troducing a cross wind component to the Jet flow is based on several fundamental
theoretical noise relationships with modifying assumptions. This cross wind
adjustment factor is applied to the undisturbed Jet noise spectra to arrive at
a predicted Jet noise with cross wind.
The reference jet noise spectra is prepared using the method delineated
in Reference 2. The flight Strouhal curve is used as being representative of
the free field sound generating conditions experienced in aircraft flyover.
This Jet noise spectra is calculated for a Jet exhausting into an undisturbed
area with the assumption that complete mixing occurs between the fan and Jet
stream so that the characteristics of a single jet stream are used to obtain
the Jet spectra.
The evaluation of the acoustic power spectra of a Jet in a crossflow is
based on a turbulent mixing noise analysis using a velocity profile method as
outlined in Reference 3. To compute the acoustic quantities two basic
assumptions are employed:
1. For static Jets or Jets without crossflow, the sound power, P, generated
by a slice of a circular jet obeys Lighthill's eighth power law
dP X v8 dA (1)
where V is the mean velocity which varies with axial location y and radial
distance r from the Jet centerline and A (y) is the cross section area of the
Jet at the axial location y.
2. The nomdimensional sound frequency (Reference 3 and 4) is directly
proportional to nondimensional axial location as defined by the empirical
relationship
fd -K2fdj = (K1 y/d) (2)Vjet
3
where f is the frequency, dj the Jet exit diameter, Vjet the jet exit velocity,
and K1 and K2
are experimentally determined constants which have values of 1.25
and 1.22 respectively.
To evaluate equation 1, the velocity profiles at each axial location are
needed. In this way, the power per slice of Jet can be readily converted to
a power per frequency band (or power spectral level). For a jet in a cross-
flow, the trajectory, jet spread, and velocity profiles are computed from the
model of Bowley and Sucec in Reference 5. Their analysis treats the deflected
jet as a jet composed of two regions - an initial mixing region and a fully
mixed region. Figure 1 presents the coordinates and form of the deflected jet
characteristics.
Acoustically, the splitting of the jet into two aerodynamic regions
also splits the acoustic analysis represented by equation 1 into two regions.
There is a high frequency region associated with the initial mixing region
and a low frequency region associated with the fully mixed region of the de-
flected jet. The superposition of these regions results in the total power
of the jet.
The frequency location along the axis of the deflected jet is represented
by equation 2 where the axial location y for a static jet is replaced by the
deflected jet trajectory location i; therefore equation 2 becomes
fd -Ket = (K1 /dj) (3)
jet
By assuming that the static velocity profiles in equation 1 may be replaced
by relative velocity profiles of a deflected jet or
V R V (X,Y) - V cos a (4)R o
a complete computational system is set for calculating the power spectral
properties of a jet in a crossflow. In equation 4, VR is the relative velocity,
V (X,Y) is the velocity in a plane perpendicular to the deflected jet axis,
VO is the crossflow velocity, and a is the jet trajectory slope. As in Refer-
ence 5, the shape of the jet in a plane perpendicular to the deflected jet
4
axis is assumed rectangular. Typical results of these calculations are shown
on Figure 2 with the peak sound power level occurring at the transition point
between the initial mixing region and the fully mixed region. For V /V jet 0,
the spectra correspond to those predicted by reference 2. This sound power
level increment in decibels is assumed equal to the sound pressure level
change. Since this increment is based on the SAE reference acoustic angle of
135°, the increment is allocated to all acoustic angles using a jet spectra
directivity factor currently in use accounting for the deflection angle for
each frequency. Consequently, the result of the calculation is a noise spectra
in units of SPL for all frequencies and acoustic angles adjusted for cross wind
effects.
Preliminary analysis of predicted power level spectra had indicated a
crossover or decrease in power level at high frequencies as crosswind in-
creased. This was not consistent with experimental data (see Section IV) and
a modification to the method of reference 5 was made. This modification
assumed no deflection of the jet axis in the initial region or more specifi-
cally the deflection angle a = 90° and cos a = 0. Consequently, on the power
frequency plot presented in Figure 2, the lines representing varying cross
flow strengths are regular without any crossover in the range of frequencies
generated in the initial region. It is noted, however, that the transition
point on the jet axis between the initial and turbulent region still varies
as a function of crossflow strength.
5
EXPERIMENTAL ANALYSIS
V/STOL Model and Data Acquisition
A scale model aircraft configured as a V/STOL transport was tested in
the 40' x 80' (12.2 m x 24.4 m) wind tunnel at NASA Ames. The aircraft had
four X376B fans of which two were mounted in deep inlets in the nose and two
were mounted as lift/cruise fans near the tail. The exhaust of the lift/
cruise fans could be vectored downward simulating a lift mode. Exhaust from a
T58 gas generator drove the tip turbine of each 36 inch (.914 m) diameter fan.
Each fan had a design pressure ratio of 1.08 and a tip speed of 640 feet per
second (195 m/ sec). Figure 3 identifies the fan locations on the model and
the microphone locations in the wind tunnel, while Figure 4 is a schematic
of the V/STOL model transport.
Noise measurements were recorded on magnetic tape at various tunnel
speeds for various combinations of lift fans and lift/cruise fans in operation
by NASA Ames personnel. The data were processed at General Electric Edwards
Flight Test Center to give 1/3 octave band sound pressure levels at each micro-
phone for each test point. All data for this report were referenced to a
120 foot (36.5 m) radius by extrapolating the SPL's measured at each microphone
under the assumption of spherical divergence. No corrections for tunnel
reverberation effects are included in the data.
Lift/Cruise Fans
To understand the effect of crossflow on jet noise, data from runs with
the lift/cruise exhaust nozzle in the lift mode (6CN = 90° ) were analyzed for
various tunnel speeds. Figures 5 through 14 show the effect of crossflow
velocity (expressed here as the ratio of tunnel velocity to jet exit velocity)
on 1/3 octave band sound pressure levels at all microphones and at frequencies
of 50, 100, 200, 400 and 800 Hz. It should be noted that the levels measured
are above the tunnel "floor" or background noise. Reference 6 indicates that
the tunnel broadband noise floor is on the order of 80 dB up to velocity ratios
of 0.4. As tunnel velocity and therefore crossflow velocity ratio decreases,
the tunnel noise floor which is broadband in nature drops accordingly.
Reference 6 places the broadband floor at low tunnel speeds at 65 dB + 5 dB.
6
There is a definite increase due to crossflow indicated for all microphones
up to and including 400 Hz. 800 Hz data show only a slight increase in SPL
as crossflow velocity increases. For this frequency and presumably higher
frequencies, the noise may be dominated by fan broadband noise. Reference 7
has shown that the fan pure tone noise of the lift/cruise fans does not increase
with increasing tunnel velocity since the fan inlet is aligned with the flow
and does not experience a true crossflow. Assuming that the fan broadband
noise follows the same trend and that fan broadband noise is dominant at 800 Hz
would account for the data of Figures 13 and 14. The downstream microphones
(numbers 1 through 5) at 50 Hz exhibit large change in SPL with crossflow.
Whether this is an actual increase due to crossflow or the result of inaccuracies
involved in measuring low frequency noise is not certain at this time.
The data of Figures 4 through 14 were used to determine the change in
jet noise at selected crossflow velocity ratios for five 1/3 octave bands
(50, 100, 200, 400, and 800 Hz). The procedure is demonstrated for a cross-
flow velocity ratio of 0.396. Shown in Figures 15 and 16 are plots of 1/3
octave band SPL at frequencies of 50, 100, 200, 400, and 800 Hz both with
and without crossflow. The acoustic angles for each microphone were calcu-
lated relative to the lift/cruise fan exhaust axis. At each frequency, there
is a change due to crossflow which is approximately constant for all angles.
This means that one can assume that the power level change due to crossflow
is equal to the measured SPL change. With the exception of the 50 Hz data in
Figure 15, upstream and downstream microphones show the same increase with
crossflow.
Similar analysis at velocity ratios of 0.175 generated the curves shown
on Figure 17 which are the power level changes due to an increase in cross-
flow velocity at five frequencies. Each frequency was normalized to a
Strouhal number (S n de).jet
Figure 18 was generated by reading the APWL values of the lines drawn
through the data of Figure 16 and represents the measured power level in-
crease as a function of Strouhal number for various crossflow to jet
velocity ratios.
7
Lift Fans
Another source of Jet noise data was noise measurements taken with the
forward lift fans of the V/STOL model in operation at various tunnel speeds.
The data were evaluated in the same manner as the lift/cruise fans. Figures
19 and 20 show the change in 100 Hz 1/3 octave band sound pressure level for
increasing crossflow. To date, only the 100 Hz data has been analyzed. After
calculating the acoustic angle "seen" by each microphone relative to the ex-
haust axis of lift fan number one, the plots of Figure 21 were made. The data
points represent the value of the lines through the data of Figures 19 and 20
read at the corresponding crossflow ratio. For each crossflow ratio, there
is an SPL increase which is constant over all acoustic angles. As a result,
one can assume that the jet noise power level increase is identical to the
SPL increase. Figure 22 compares the Jet noise power level increase indicated
by the lift fan data of Figure 21 with the lift/cruise results obtained by
reading Figure 18 at S = 1.82. The resulting comparison is good although the
forward lift fan increase at this selected frequency is higher than that of
the lift/cruise fans.
8
COMPARISON OF THEORETICAL AND EXPERIMENTAL RESULTS
Figures 23, 24, and 25 represent a comparison of the analytical and ex-
perimental results of the lift/cruise fans. For these comparisons at three
crossflow velocity ratios, the experimental incremental change in power level
from Figure 18 was added to the zero crossflow curve of Figure 2. The result-
ing comparisons indicate that the predicted power level increase and experi-
mental increase due to increasing crossflow are in good agreement.
9
CONCLUSIONS
This investigation included both an analytical study and an examination
of experimental data to determine the effect of crossflow velocity on the Jet
noise generation of lift fans. It was found that an increase in Jet noise
power level is associated with an increase in crossflow velocity perpendicular
to the jet exhaust axis. This predicted increase is confirmed by experimental
data from wind tunnel tests of a V/STOL model. It is recommended that the
analytically predicted Jet noise power levels with crossflow effects be
incorporated into current prediction techniques.
10
y AXIS
Vo0
(CROSS WIND)
INITIALREGION -
high frequency noisegeneration region
JET AXIS
/low frequencynoise generationregion
- TRANSITION POINT
x AXIS
VJET
INITIAL JET
FIGURE 1 SCHEMATIC OF JET IN CROSS FLOW11
LIo r
l rH
~/ x
M~co
\\ 0
-@\
X
·
SEE
M
Al
01 :al Wp 'lEI~
0 000:
rvw cc'
J
ollv
H
o H
a H
H
m
12
40 0 K
0IL'
r.
n n
co o
C1
O
O
0 ;
'-4Z
M'-4
\ O
· --0 10
cO
.0
0r- -
IrC\jF
_
08g 0
OJ
8 HH
o o
i
1.4
SC
o cv-
13
.tLl'-:
-14f
0Um0coH
14
@E(
ca0h
cNH
4
PH
\ +
0 .2 .4 .6
V/STOL MODEL
* FANS 3 & 4 @ 3600 RPM* REFERENCED TO 120' RADIUS
(36.6m)
*· cn9i °O
.4
Vo/VJet
FIGURE 5 EFFECT OF CROSSFLOW ON 50 Hz SPL OF V/STOL MODELLIFT/CRUISE FANS (DOWNSTREAM MICROPHONES).
15
1001
A
a)
tO
8
0Lu'
MIKE 5
_~~~~~1 ,..6.2
100
0MIKE 6
90o
80
100
90
80
100
90
80
V/STOL MODEL
* FANS 3 & 4 @ 3600 RPM* REFERENCED TO 120' RADIUS
(36.6m)
* 61c0
· 6cn=90
Vo/VJet
FIGURE 6 EFFECT OF CROSSFLOW ON 50 Hz SPL OF V/STOL MODELLIFT/CRUISE FANS (UPSTREAM MICROPHONES)
16
8rnr-4
0
MIKB 8
I I I
V/STOL MODEL
* FANS 3 & 4 e 3600 RPM* REFERENCED TO 120' RADIUS
(36.6m)
* 5cn90 °* 6 in900cn
0 .2 .4 .6
Vo/VJet
FIGURE 7 EFFECT OF CROSSFLOW ON 100 Hz SPL OF V/STOL MODELLIFr/CRUISE FANS (DIWNSTREAM MICROPHONES).
17
100
90
0o;C-1
Y 80
h)
100
90
80Ec
r-
N
8r4
100
90
80
MIKE 5
I'- I- I
.2 .4
V/STOL MODEL
* FANS 3 & 4 @ 3600 RPM* REFERENCED TO 120' RADIUS
(36.6m)
· 6 =90 °
cn
.6 0 .2 .4 .6
Vo/VJet
FIGURE 8 EFFECT OF CROSSFLOW ON 100 Hz SPL OF V/STOL MODELLIFT/CRUISE FANS (UPSTREAM MICROPHONES).
18
jUL
9c-
O
MIKE 6
iL.
0)
8
Ec
-
MIKE 7
I L I
MIKE 8
I I I
10(
9( _
MKK 9
R I I I0
MIKE 11
I I I I
94
100
90
80
.00
MIKE 2
LO80
90MIKE 4
80
1
0 .2 .6 0
V/STOL MODEL
* FANS 3 & 4 @ 3600 RPM* REFERENCED TO 120' RADIUS
(36.6m)
·* 6 ,90· cn9O
.2 .4 .6
Vo/VJet
FIGURE 9 EFFECT OF CROSSFLOW ON 200 Hz SPL OF V/STOL MODELLIFT/CRUISE FANS (DOWNSTREAM MICROPHONES).
19
MIKE 1
I I I
C..
0
Cuk1
1
,d
C/)
DI
E
oorCuJ
MIKE 5
_ <o~
N
0
MIKE 7
0 .2 .4
V/STOL MODEL
* FANS 3 & 4 @ 3600 RPM* REFERENCED TO 120' RADIUS
(36.6m)
* 6 900cn
.6 0
Vo/VJet
.2 .4
FIGURE 10 EFFECT OF CROSSFLOW ON 200 Hz SPL OF V/STOL MODELLIFT/CRUISE FANS (UPSTREAM MICROPHONES).
100
90 o 0
MIKE 6
I I I
I-_
1;
00
$
100
i 90
E 8018
0ccm
90
80
MIKE 8
I I I
MIKE 9
I I I
MIKE 11
-- I I I
.6
20
.6 0
V/STOL MODEL
* FANS 3 & 4 @ 3600 RPM* REFERENCED TO 120' RADIUS
(36.6m)* alcr1
· 6cn=90°
.2 .4 .6
Vo/VJet
EFFECT OF CROSSFLOW ON 400 Hz SPL OF V/STOL MODELLIFT/CRUISE FANS (DOWNSTREAM MICROPHONES).
21
100
90
0.
c)
MIKE 1
I I I
'-4
8cn
8r-
80
100
90
80
100
90
80
MIKE 2
I I I
MIKE 4
I I I0
I I I
0
MIKE 5
-5 gO .2
FIGURE 11
V/STOL MODEL
* FANS 3 & 4 @ 3600 RPM* RVFERENCED TO 120' RADIUS
(36,6m)* aI 90 0
· 5cn=90°
.6 0
Vo/VJet
.2 .4
EFFECT CP CROSSFLOW O0 400 Hz SPL OF V/STOL MODELLIFT/CRUISE FANS (UPSTREAM MICROPHONES).
100
90
80
0Y~I;
MIKE 6
I I I
. 100
90
80
MIKE 7
~ -I I I
m
c
-4
MIKE 8
I i I
N 100
OO
90
80
MIKE 9
I I I
O
MIKE 11
, !- I ! I
.2 .4
FIGURE 12
.6
22
1001
90o
9C4
86
MIKE 4
- I I -
I
V/STOL MODEL
* FANS 3 & 4 @ 3600 RPM* REFERENCED TO 120' RADIUS
(36.6m)· al 0 °
1 6 900 cnm9
.4 .6 0
Vo/VJet
.2 .6
EFFECT OF CROSSFLOW ON 800 Hz SPL OF V/STOL MODELLIFT/CRUISE FANS (DOWNSTREAM MCRAOPONES).
23
C)DY:
MIKE 1
I I I
MIKE 2
I I X I
0
-0 0
MIKE 3
1 .1
Cr
'4
N
10n
MIKE 5
I I . I
.20
FIGURE 13
I
QiaI
.6 0
V/STOL MODEL
* FANS 3 & 4 @ 3600 RPM* RWEBfRCED TO 120' RADIUS
(36.6m)
*· 690°
0 cnW
.2 .4 .6
Vo/VJet
EFFECT OF CROSSFLOW ON 800 Hz SPL OF V/STOL MODELLIFT/CRUISE FANS (UPSTREAM MICROPHONES).
MIKE 6
0 Jp
I I I
100
90o I
110
100-
90 I I I
co
8
MIKE 8
0--I
I I--
100-
90o
0
MIKE 9
I I I
MIKE 11
I I I.2
FIGURE 14
24
V/STOL MODEL
* FANS 3 & 4 @ 3600 RPM* REFERENCED TO 120' RADIUS (36.6m)* SOLID SYMBOLS DENOE. DOWNSTREAM MICROPHONES V /e
t
* CY=' o Jet
* 6n =900 0 0Una 3 0.396- 0~~
50 Hz
Sn -.625
]--
O "-"
90 100 110 120 130
ACOUSTIC ANGLE RELATIVE TO EXHAUST AXIS
140
V/STOL MODEL LIFT/CRUISE FAN JET NOISE DIRECTIVITYPATTERN AT Vo/VE = 0 and 0.396.
25
ioo
.
90 _
80 _
(V
8
-4
FIGURE 15
I I II
v/s0
0
3TOL MODEL
FANS 3 & 4 @ 3600 RPMREFERENCED TO 120' RADIUS (36.6m)
SOLID SYMBOLS DENOTE DOWNSTREAM MICROPHONES
C1 = O°
6cn 90° Vo/Vjet
o0o 0.396
100
800 Hz
~~90 0 4 _S n - 10
I I I 140100 110 120 130
ACOUSTIC ANGLE RELATIVE TO EXHAUST AXIS
V/STOL MODEL LIFT/CRUISE FAN JET NOISE DIRECTIVITY
PATTERN AT Vo/VJET - 0 AND 0.396 ·
o
0
o0
..co
-4
90
FIGURE 16
26
V/STOL MODEL* FANS 3 & 4 @ 3600 RPM* REFERENCED TO 120' RADIUS (36.6m)
* 6cn=90* cn C
I , I , I IF .--
.2
Vo/VJet
50 Hz
Sn = .625
100 Hz
Sn = 1.25
200 Hz
Sn
= 2.5
400 Hz
Sn 5
800 Hz
Sn
- 10
.6
FIGURE 17 JET NOISE LEVEL INCREASE WITH INCREASED CROSSFLOWAT VARIOUS STROUHAL NUMBERS.
27
10
O
10
0
10
0
10
0
10
0
I I
F I I I I
oII9 I0.4
00
O
0~
~~
~~
~0
cn O
Z~~~~~~~~
Do ~ ~ ~ ~
~ ~
~ ~
~ ~
~ ~
~~
~o
I
0
MI
I I
I I
I _I.
m
U,
AS
~~~~~~~(U'
co 4
CM
H'-
* *
* H
0~
~~
~~
~~
~rl~
~~
p
I I I~
~~
~~
~~
~~
~~
8S
~~
~~
l
'I~~
~~
~~
~dV
~~
~8
28
cO
m;
r1-*
-O
* 0
so
9,
0o
O
0>0_
0 R
8
B-
o
00
0
0a\
0 a
~
coH
-
UV
GD
/3DI
8mOO'
:a
qpidS
I
BINVE
AVLDO V/I ZH 001
081to(v3D
o
II,.4
Oa 0
r4
b
0 *
* &
N
Z
a
29
to. 0H
P
CY')cu
cO r0
E--
rdv
bc
OM
HV-tO tO
IH
0o'0.
00r4
rtidE00'
:a.x gp
0 0
oa oa
aC
NM
aA
VI0
0
L/l ZH 001
to'.0
r4rr4H
00oo
0
0oI
ooC
Uo
o
kD
I>:Noc
;I0 :li
cu0
30
V/STOL MODEL* LIFT FANS 1 & 2 @ 3600 RPM* REFIIRNCED TO 120' RADIUS (36.6m)* SOLID SYMBOLS DENB!TE DOWNSTREAM MICROPHOIES
· vA
I I I
Vo/VJet
oo.2
0.4V.6
0
i m I I I I I
V
0
I I I I I I100 120 140 160
ACOUSTIC ANGLE REZATIVE TO LIFT FAN 1 EXHAUST EXIT AXIS, DEGREES
FIGURE 21 V/STOL MODEL LIFT FAN JET NOISE DIRECTIVITY PATTERNAT 100 Hz
90
80
70
090
80
70
100
90
I
,
2
..
80 _
70
31
I I I I
I .I I I I I II
I
V/STOL MODEL
* LIFT FANS 1 & 2 @ 3600 RPM· l-o4-av-o°
· 6cn900
0 .2 .4 .6
Vo/VJet
FIGURE 22 COMPARISON OF CROSSFLOW EFFBCT ON JET NOISEPOWER LEVEL OF V/STOL MODEL LIFT FANS ANDLIFT/CRUISE FAIRS
32
0Ul
/ -r.
I .
I~
o
I
trt -.
.S
I
/
SEC
. I
Eal4
',O:"
33
0uL\
Au
I
0i
//
'I//Q~
~~
~
a~
~~
~
0i
0
/0
a~
~~
~~
~~
/
/ //
/
/'L
'4
(~~
~~
!
0N~
0
~'~ 0
~',U
IN
zt
_-r
~ ~
~~
~
0
r4 rA
-- I
r- r4
N
34
/
/ / /
0tur
Fcr)
/~/ 0_ C
~/a
~~
~
o
0
/ C
,,~~
MC
Y
/ 1 qp 1
Iu
rcc,~
~~
~~
U~
so uoo
us
i
/~~
~~
4~
~~
~~
~~
~~
~4
0~
~~
~~
X
Lm*C
U
Hq H
H
M
SJ*Lf
At
Val
gp
'a
I
35
/'1
r4
REFERENCES
1. Kirk, J.V., Hall, L.P., and Hodder, B.K., "Aerodynamics of Lift Fan V/STOL
Aircraft," NASA TM X-62, 086, September 1971.
2. "Jet Noise Prediction," Aerospace Information Report 876, Society
of Automotive Engineers, Inc., July 10, 1965
3. Lee, R., et al, "Research Investigation of the Generation and Suppression
of Jet Noise," General Electric Flight Propulsion Division, Prepared
under Bureau of Naval Weapons, Contract #NOas 59-6160-C, June 1961.
4. NASA Report #1338, "Near Field Noise of a Jet Engine Exhaust."
5. Bowley, W.W., and Sucec, J., "Trajectory and Spreading of a Turbulent
Jet in the Presence of a Crossflow of Arbitrary Velocity Distribution,"
ASME Paper presented at Gas Turbine Conference & Products Show,.
Cleveland, Ohio, March 9 - 13, 1969.
6. Hickey, D.H., Soderman, P.T., and Kelly, M.W., "Noise Measurements
in Wind Tunnels," pp. 399-408, Basic Aerodynamic Noise Research,
NASA SP-207, July 14, 1969.
7. Stimpert, D.L., "Effect of Crossflow Velocity on VTOL Lift Fan Blade
Passing Frequency Noise Generation," NASA CR 114566, February 1973.
36