Open cavities at transonic speeds can result in acoustic resonant flow behavior with fluctuating pressure levels of sufficient intensity to cause significant damage to internal stores and surrounding structures. Extensive research in this field has produced numerous cavity flow control techniques, the more effective of which may require costly feedback control systems or entail other drawbacks such as drag penalties or rapid performance degradation at off-design condition. The current study focuses on the use of simple geometric modifications of a rectangular planform cavity with the aim of attenuating the aeroacoustic signature. Experiments were performed in an intermittent suck-down transonic wind tunnel by using a typical open flow rectangular planform cavity, which was modularly designed such that the leading and trailing edge geometries could be modified by using a family of inserts. The current work focused on a variety of recessed leading edge step arrangements. Configurations were tested at transonic Mach numbers spanning the range Mach 0.7–0.9, and unsteady pressure measurements were recorded at various stations within the cavity in order to obtain acoustic spectra. The most effective configuration at Mach 0.9 was the leading edge step employing a step height to step length ratio of 0.4. This configuration achieved a tonal attenuation of up to 18.6dB and an overall sound pressure level (OASPL) reduction of approximately 7.5dB. This is a significant level of noise suppression in comparison with other passive control methods. In addition, it offers the additional benefits of being a simple geometric feature, which does not rely on placing flow effectors into the high-speed grazing flow.

1.
ESDU
, 2005, “
Aerodynamics and Aero-Acoustics of Rectangular Planform Cavities, Part I: Time-Averaged Flow
,” Datasheet 02008.
2.
Heller
,
H.
, and
Delfs
,
J.
, 1996, “
Cavity Pressure Oscillations: The Generating Mechanism Visualised
,”
J. Sound Vib.
0022-460X,
196
(
2
), pp.
248
252
.
3.
Vakili
,
A.
, and
Gauthier
,
C.
, 1994, “
Control of Cavity Flow by Upstream Mass-Injection
,”
J. Aircr.
0021-8669,
31
(
1
), pp.
169
174
.
4.
McGrath
,
S.
, and
Shaw
,
L.
, 1996, “
Active Control of Shallow Cavity Acoustic Resonance
,” AIAA Paper No. 96-1949.
5.
Cattafesta
,
L.
,
Williams
,
D.
,
Rowley
,
C.
, and
Alvi
,
F.
, 2003, “
Review of Active Control of Flow-Induced Cavity Resonance
,” AIAA Paper No. 2003-3567.
6.
Ukeiley
,
L.
,
Ponton
,
M.
,
Seiner
,
J.
, and
Jansen
,
B.
, 2003, “
Suppression of Pressure Loads in Resonating Cavities Through Blowing
,” AIAA Paper No. 2003-0181.
7.
Sarno
,
R.
, and
Franke
,
M.
, 1994, “
Suppression of Flow-Induced Pressure Oscillations in Cavities
,”
J. Aircr.
0021-8669,
31
(
1
), pp.
90
96
.
8.
Cabell
,
R.
,
Kegerise
,
M.
,
Cox
,
D.
, and
Gibbs
,
G.
, 2002, “
Experimental Feedback Control of Flow Induced Cavity Tones
,” AIAA Paper No. 2002-2497.
9.
Stanek
,
M.
,
Raman
,
G.
,
Kibens
,
V.
,
Ross
,
J.
,
Odedra
,
J.
, and
Peto
,
J.
, 2000, “
Control of Cavity Resonance Through Very High Frequency Forcing
,” AIAA Paper No. 2000-1905.
10.
Smith
,
B.
,
Welterten
,
T.
,
Maines
,
B.
,
Shaw
,
L.
,
Stanek
,
M.
, and
Grove
,
J.
, 2002, “
Weapons Bay Acoustic Suppression From Rod Spoilers
,” AIAA Paper No. 2002-0662.
11.
Rockwell
,
D.
, and
Naudascher
,
E.
, 1978, “
Review—Self-Sustaining Oscillations of Flow Past Cavities
,”
ASME J. Fluids Eng.
0098-2202,
100
(
2
), pp.
152
165
.
12.
Sarohia
,
V.
, and
Massier
,
P.
, 1977, “
Control of Cavity Noise
,”
J. Aircr.
0021-8669,
14
(
5
), pp.
833
837
.
13.
Charwat
,
A.
,
Roos
,
J.
,
Dewey
,
C.
, and
Hiltz
,
J.
, 1961, “
An Investigation of Separated Flows—Part II Flow in the Cavity and Heat Transfer
,”
J. Aerosp. Sci.
0095-9820,
28
(
6
), pp.
457
470
.
14.
Rossiter
,
J.
, 1964, “
Wind-Tunnel Experiments on the Flow Over Rectangular Cavities at Subsonic and Transonic Speeds
,” RAE Technical Report No. 64037.
15.
Heller
,
H.
,
Holmes
,
D.
, and
Covert
,
E.
, 1971, “
Flow Induced Pressure Oscillations in Shallow Cavities
,”
J. Sound Vib.
0022-460X,
18
(
4
), pp.
545
553
.
16.
Bilanin
,
A.
, and
Covert
,
E.
, 1973, “
Estimation of Possible Excitation Frequencies for Shallow Rectangular Cavities
,”
AIAA J.
0001-1452,
11
(
3
), pp.
347
351
.
17.
Heller
,
H.
, and
Bliss
,
D.
, 1975, “
The Physical Mechanism of Flow-Induced Pressure Fluctuations in Cavities and Concepts for Their Suppression
,” AIAA Paper No. 75-491.
18.
Plentovich
,
E.
,
Stallings
,
R.
, and
Tracy
,
M.
, 1993, “
Experimental Cavity Pressure Measurements at Subsonic and Transonic Speeds
,” NASA Technical Paper No. 3358.
19.
Zhang
,
J.
,
Morishita
,
E.
,
Okunuki
,
T.
, and
Itoh
,
H.
, 2001, “
Experimental and Computational Investigation of Supersonic Cavity Flows
,” AIAA Paper No. 87–0166.
20.
Tracy
,
M.
, and
Plentovich
,
E.
, 1997, “
Cavity Unsteady-Pressure Measurements at Subsonic and Transonic Speeds
,” NASA Technical Paper No. 3669.
21.
Komerath
,
N.
,
Ahuja
,
K.
, and
Chambers
,
F.
, 1987, “
Prediction and Measurement of Flow Over Cavities—A Survey
,” AIAA Paper No. 87-0166.
22.
Ukeiley
,
L.
,
Ponton
,
M.
,
Seiner
,
J.
, and
Jansen
,
B.
, 2003, “
Suppression of Pressure Loads in Resonating Cavities Through Blowing
,” AIAA Paper No. 2002-0661.
This content is only available via PDF.
You do not currently have access to this content.