. 5 i i , C i I NASA TECHNICAL MEMORANDUM M v\ cv N 9 x z a c v) U z N 0 I e N67 11336 IACCESSION NUMBER1 /2 WAGES1 NASA TM X-52253 GPO PRICE $/ EXPERIMENTAL INVESTIGATION OF ACOUSTIC LINERS TO SUPPRESS SCREECH IN HYDROGEN-OXYGEN ENGINES by John P. Wanhainen, Harry E. Bloomer, and David W. Vincent Lewis Research Center Cleveland, Ohio TECHNICAL PAPER proposed for presentation at Third Combustion Conference sponsored by the Interagency Chemical Rocket Propulsion Group Kennedy Space Center, Florida, October 17-21, 1966 . NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON, D.C. 1966 https://ntrs.nasa.gov/search.jsp?R=19670002007 2020-06-11T14:28:23+00:00Z
Transcript
. 5
i i , C
i
I
N A S A T E C H N I C A L M E M O R A N D U M
M v\ cv N 9 x z a c v) U z
N 0
I
e
N67 11336 IACCESSION NUMBER1
/2 WAGES1
NASA TM X-52253
GPO PRICE $ /
EXPERIMENTAL INVESTIGATION OF ACOUSTIC LINERS TO SUPPRESS SCREECH IN HYDROGEN-OXYGEN ENGINES
by John P. Wanhainen, H a r r y E. Bloomer, and David W. Vincent Lewis Research Center Cleveland, Ohio
TECHNICAL PAPER proposed for presentation at Third Combustion Conference sponsored by the Interagency Chemical Rocket Propulsion Group Kennedy Space Center, Florida, October 17-21, 1966
.
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON, D.C. 1966
by John P. Wanhainen, Harry E. Bloomer, and David W. Vincent
Lewis Research Center Cleveland, Ohio
TECHNICAL PAPER proposed for presentation at
Third Combustion Conference sponsored by the Interagency Chemical Rocket Propulsion Group
Kennedy Space Center, Florida, October 17-21, 1966
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
EXPE€UMETI”T INVESTIGATION OF ACOUSTIC LINERS TO
SUPPFBSS SCREECH IN HYDROGEN-OXYGEN ENGINES
By John P. Wanhainen, Harry E. Bloomer, and David W. Vincent
National Aeronautics and Space Administration Lewis Research Center
Cleveland, Ohio
INTRODUCTION
As a part of an extensive investigation being conducted at the Lewis Research Center to explore the combustion dynamics of hydrogen-oxygen combustion systems, an experimental study of the use of acoustic liners to suppress screech was conducted in the Rocket Engine Test Facility. Liner design variables of open area ratio, liner thickness, liner back- ing distance, liner length and aperture shape were studied in a 10.78- inch diameter cylindrical combustor at a chamber pressure of 300 psia. The effects of changes in liner design parameters were evaluated by ramping the hydrogen injection temperature down into screech and deter- mining the change in hydrogen temperature stable operating limits.
f l r r r / o a APPARATlTs
The heat-sink combustor (fig. 1) used in the investigation was com- prised of a concentric tube injector, a cylindrical external pressure jacket, a perforated plate acoustic liner and a convergent-divergent exhaust nozzle with a contraction ratio of 1.89. The chamber internal diameter was 10.78 inches and the combustion chamber length from the injector to the throat was about 18 inches. The absorbing liners were 9 inches in length. The heat-sink acoustic liners tested included both circular (fig. 2) and noncircular aperture configurations (fig. 3). Circumferential partitions were used to minimize steady flow behind the liner and, thus, the flow through the apertures to simplify the calcula- tion of liner absorption coefficients.
A 487 element, uniform pattern concentric-tube type injector (fig. 4) was used in this phase of the investigation. The fine pattern injector was selected because of its poor stability characteristics or high hydro- gen screech transition temperature (fig. 5) to provide as severe a test as possible for the absorbing liners. The predominant mode of instability encountered was first tangential with a peak-to-peak amplitude of about 140 psi.
IiESULTS AND DISCUSSION
The Pratt-Whitney acoustic liner program, based on Helmholtz resonator theory, was used to calculate the absorption coefficients for the various liner configurations tested (fig. 6). The coefficients were calculated
TM X-52253
L E-3605
f o r an a r b i t r a r y value o f sound pressure l e v e l of 190 db, a wave f r e - quency (3250 cps) corresponding t o the first t angen t i a l mode f o r t h e engine and no flow past or through the apertures. I n the 3/16-inch w a l l th ickness , t he l i n e r s t e s t e d had open areas of 5, 10, 15 and 20 percent. The 10 percent open area l i n e r w a s the bes t configuration, s t a b l e i n a l l t e s t s a t hydrogen in j ec t ion temperatures about 60° R ( f i g . 7 ) . With t h i s l i n e r , t h e screech amplitude which reached values of 140 p s i peak-to-peak without a l i n e r , was l e s s than 10 p s i ( f ig . 8 ) .
*
The va r i a t ion i n s t a b i l i t y with the various 3/16-inch w a l l l i n e r s i s a combined e f f e c t of open area r a t i o and l i n e r cavi ty gas temperature on absorption cha rac t e r i s t i c s because the temperature var ied between con- f igu ra t ions ( f i g . 9 ) . There w a s a considerable va r i a t ion i n temperature depending on t h e locat ion behind the l i n e r and an increase i n t h e average value from 600° t o 1000° R as the open area w a s var ied from 5 t o 20 per- cent. This variance i n gas temperature undoubtedly r e s u l t s from d i f f e r - en t amounts of combustion gas rec i rcu la t ion behind the l i n e r . I n addi- t i on , one might a l so expect a var ia t ion i n cavi ty gas temperature with in j ec to r element s i ze , spacing and the propellant combination. Thus, unless a means of cont ro l l ing cavi ty gas temperature i s found, such as a gas bleed, the designer i s faced with an experimental program t o optimize the f i n a l acoust ic l i n e r design,
Analyt ical predict ions based on acoustic theory were i n agreement with experimental results only when flow past t h e apertures w a s included i n t he ca lcu la t ion of l i n e r absorpt ivi ty . Without flow pas t t h e aper- t u re s included, an anomoly exis ted i n the s t a b i l i t y correlat ion. Two configurations with the same calculated absorption coef f ic ien ts (0.15 and 0.2 open area r a t i o s ) o f 0.099 provided d i f f e r e n t hydrogen temperature s t ab le operat ing l i m i t s ( f i g . 10). To obtain a reasonable agreement be- tween theory and experiment, it was necessary t o use a flow ve loc i ty of 280 f e e t per second past t h e apertures in t h e ca lcu la t ion o f absorption coef f ic ien t , minimum coe f f i c i en t of about 0.25 calculated including flow past t h e apertures w a s required t o s t a b i l i z e t h e combustor used a t a hydrogen in- j ec t ion temperature of 60° R ( f ig . .11). the r e s u l t s of t h i ck and t h i n wall l i ne r s w a s not obtained even when the e f f ec t s of a 280 f e e t per second f l o w veloci ty pas t t he apertures was used i n t he absorption coef f ic ien t calculat ions ( f i g . 1 2 ) . Possibly, t he e f - f e c t s of flow pas t change with Liner thickness and aperture diameter.
The s t a b i l i t y cor re la t ion indicated t h a t a l i n e r with a
A s a t i s f a c t o r y agreement between
The e f f e c t of l i n e r length w a s evaluated with a 10 percent open area, 3/16-inch w a l l l i n e r , the most successful f u l l length configuration. p a r t i a l length l i n e r s were evaluated positioned a t t h e i n j e c t o r end of t h e t h r u s t chamber. t he f u l l length configuration without a f fec t ing t h e s t a b i l i t y character- i s t i c s of t he combustor ( f i g . 13). placement of resonators i s a t the in jec tor end of t h e t h r u s t chamber.
The
The length of the l i n e r w a s reduced t o 1 7 percent of
It appears t h a t t he most e f fec t ive
The s l o t t e d and cross l i n e r s tes ted t o determine the e f f e c t of aper-
The 10 percent open t u r e shape on absorption cha rac t e r i s t i c s demonstrated r e s u l t s s imi la r t o c i r c u l a r aper ture l i n e r s o f t he same w a l l thickness. a rea l i n e r again provided the b e s t s tab le operat ing range ( f i g . 14). cross l i n e r s which were designed for an open area of 10 percent were s t ab le
Both
2 E-3605
s o the e f f e c t of per ipheral length on absorpt ivi ty w a s not evaluated. However, these r e s u l t s indicate t h a t aperture shape does not have a f i rs t order e f f e c t on l i n e r absorpt ivi ty .
SUMMARY
1. High frequency combustion i n s t a b i l i t y i n hydrogen-oxygen engines of t h e s i z e investigated can be suppressed using a properly designed a r r a y of Helmholtz resonators.
2. Liner cavi ty gas temperature which varied with l i n e r var iables such as aperture s ize , open area r a t i o and a x i a l posit ion, has a s t rong e f f e c t on l i n e r absorption charac te r i s t ics . d i c t i n g o r control l ing cavi ty temperature i s found, no r a t i o n a l design procedure is possible.
Thus, unless a means of pre-
3. Analytical predictions based on acoust ic theory were i n l imited agreement with experimental r e s u l t s providing the e f f e c t s of flow past the apertures of 280 feet per second was included i n the calculat ion of absorption coeff ic ient . Additional data evaluating t h e e f f e c t of flow past t h e apertures a r e required before l i n e r absorption charac te r i s t ics can be predicted.
4. Liners with absorption coeff ic ients of 0.25 o r higher, calculated including flow past t h e apertures, were required t o eliminate screech i n t h e combustor used i n t h e tests a t a hydrogen in jec t ion temperature of 60' R (minimum avai lable) .
5. F u l l combustor length l i n e r s were not required t o suppress acoustic mode i n s t a b i l i t y f o r t h e par t icu lar combustor used i n the investigation. A 1 7 percent p a r t i a l length l i n e r positioned a t the i n j e c t o r end of the t h r u s t chamber provided s tab le combustion t o a hydrogen in jec t ion temper- a ture o f 60' R.
6. Liner designs need not be limited t o c i r c u l a r apertures; f u l l length s l o t s appeared t o be j u s t as ef fec t ive as c i r c u l a r apertures.
E-3605 3
L
ENGINE ASSEMBLY
L O X -..
m 0 W m I w
Figure 1
T Y P E S OF ACOUSTIC L N E R S T E S T E D
MP
S S U R E
4970
' I O N
( A I 3 / 1 6 I N . - T H I C K N E S S
Figure 2
( B ) 3 / 4 I N . - T H I C K N E S S CS-4)980
L
.
T Y P E S O F A C O U S T I C L I N E R S T E S T E D
( A ) S L O T L I N E R . ( B ) C R O S S L I N E R .
Figure 3
FACEPLATE VIEW OF I N J E C T O R
CS-40971
Figure 4
I w
a. A B S O R P T I O N
STABILITY CHARACTERISTICS WITHOUT LINER
. 5 - T H I C K N E S S - 3 / 1 6 IN. HOLE D l A M - 1 / 4 IN .
. 4 - S P L - 1 9 0 d B C A V I T Y GAS FREQ - 3 2 5 0 C P S TEMP, FLOW P A S T - 0 O R
1 2 0 0 . 3 -
,
H 2
O R
I N J E C T I O N TEMP, 120 14/
100
8 0 3 3 4 5 6 r 8
O X I D ANT-FUEL R AT10 CS-4969
Figure 5
LINER ABSORBING CHARACTERISTICS
LD 0 u)
COMBUSTION STABILITY LIMITS 3116- IN. WALL L i N E R S O P E N AREA
1 / 4 - I N . APERTURES 1 4 0 r
R A T I O 0 0. 2
/’ 0 ’ STABLE
0
H2 1 0 0 U N S T A B L E
I N J E C T I O N TEMP,
0 A
0 STABLE + A 0
U N S T A B L E
O R
0. 15 0. 1 0 0. 05
STABLE
3 4 5 6 7 8 O X I D ANT-FUEL R AT10
cs-40978
Figure 7
ANALYSIS OF PRESSURE OSCILLATWS
1 5 0 r
5 0
A M P L I T U D E , P S I
( A ) WITHOUT LINER.
20
FREQUENCY, C P S x 1 ~ - 3
( B ) WITH 3116- IN. WALL, 0 . 1 O P E N
cs-43977 AREA R A T I O LINER.
Figure 8
LINER CAVITY GAS TEMPERATURES
6oo-
4 0 0
I I I
COMBUSTION STABILITY CORRELATION
, 1 1
0 T R A N S I T I O N TO T H I C K N E S S - 3 / 1 6 I N .
STABLE s PL SCREECH HOLE D l A M - 1 / 4 I N .
- 1 9 0 dB - 3 2 5 0 C P S 1 2 0 FREQ
FLOW PAST - 0
l o o C \ ~ ~ ~ ~ ~ ~ ~ ~ LINER "2
I N J E C T I O N
R - .05 :a - . 1 \
To - . 2 \ b
:o 9 . 15 1 '*
' L D 0 W M
I u H 2
I N J ECTlO TEMP,
OR
' N
COMBUSTION STABILITY CORRELATION
T H I C K N E S S - 3116 IN. HOLE O l A M - 114 IN. s PL - 190 d B
FLOW P A S T - 280 F T l S E C 1 2 0 r W I T H O U T LINER FREQ - 3 2 5 0 C P S k
0 T R A N S I T I O N TO
m STABLE SCREECH
STABLE
r a . . 0 5
a - .h
6 0 0 .1 . 2 . 3 . 4 . 5 . 6
CALCULATED A B S O R P T I O N COEFFICIENT, a CS-40961
Figure 11
COMBUSTION STABILITY CORRELATION
FREQ - 3250 C P S s PL - 190 d B FLOW P A S T - 280 FT lSEC
0 WITHOUT L INER 0 314- IN. W A L L A 318-IN. W A L L 0 3116- IN. W A L L
H 2
OR
I N J E C T I O N TEMP,
C A L C U L A T E D - A B S O R
Figure 12
0 T R A N S I T I O N TO SCREECH
STABLE
r O . 1 5 a - . 1 a ' . 1 7
.. ION COEFFICIENT, a
cs-4l968
EFFECT OF LINER LENGTH
T H I C K N E S S , 3 / 1 6 IN. ; HOLE OIAM, 114 IN. ; O P E N AREA, 10%
