This paper discusses the structure of the flow within the engine inlet of an uninhabited combat air vehicle (UCAV). The UCAV features a top-mounted, serpentine inlet leading to an engine buried within the fuselage. The performance of the inlet is found to depend strongly on a flow separation that occurs within the inlet. Both the time-averaged and the unsteady structure of this separation is studied, and an argument relating the inlet performance to the behavior of this separation is suggested. The results presented in this paper also suggest that there are considerable aerodynamic limitations to further shortening or narrowing of the inlet. Since there are substantial, system level benefits from using a smaller inlet, the case for separated flow control therefore appears clear.

Issue Section:
Technical Papers
Keywords:
aircraft, aerospace engines, flow separation, aerodynamics
Topics:
Flow (Dynamics), Pressure, Flow separation, Separation (Technology), Engines, Unmanned combat air vehicles
1.
Seddon, J., and Goldsmith, E. L., 1999, “Intake aerodynamics,” 2nd edition, AIAA education series, AIAA.
2.
Anderson, B. H., Miller, D. N., Yagle, P. J., and Truax, P. P., 1999, “A study of MEMS flow control for the management of engine face distortion in compact inlet systems,” Proc. 3rd ASME/JSME Conference, San Francisco, ASME paper no. FEDSM99-6920.
3.
Ng, W., and Burdisso, R. A., 2001, “Active acoustic and flow control for aeropropulsion,” 39th AIAA Aerospace Sciences Meeting & Exhibit, Reno, AIAA paper no. AIAA 2001-0220.
4.
SAE Committee S-16, 1977, “ARP 1420-Gas turbine engine inlet flow distortion guidelines.”
5.
Warfield, Z., 2001, “Active control of separation induced distortion in a scaled tactical aircraft inlet,” M.S. Thesis, Massachusetts Institute of Technology.
6.
Schlichting, H., 1979, “Boundary layer theory,” McGraw-Hill, New York.
7.
Abbott, I. H., and von Doenhoff, A. E., 1959, “Theory of wing sections,” Dover, New York.
8.
Perry
,
A. E.
, and
Chong
,
M. S.
,
1986
, “
A series expansion study of the Navier-Stokes equations with applications to three-dimensional separation patterns
,”
J. Fluid Mech.
,
173
,
207
–
223
.
9.
Horton, H. P., 1969, “A semi-empirial theory for the growth and bursting of laminar separation bubbles,” ARC current papers, no. 1073.
10.
Gad-el-Hak
,
M.
,
1990
, “
Control of low speed aerodynamics
,”
AIAA J.
,
28
, no.
9
, pp.
1537
–
1552
.
11.
Lubcke
,
H.
,
Schmidt
,
St.
,
Rung
,
T.
, and
Thiele
,
F.
,
2001
, “
Comparison of LES and RANS in bluff-body flows
,”
J. Wind. Eng. Ind. Aerodyn.
,
89
,
1471
–
1485
.
12.
Brear
,
M. J.
,
Hodson
,
H. P.
, and
Harvey
,
N. W.
,
2002
, “
Pressure surface separations in low pressure turbines-part 2: interactions with the secondary flow
,”
ASME J. Turbomach.
,
124
,
402
–
409
.
13.
Brear, M. J., 2000, “Pressure surface separations in low pressure turbines,” Ph.D dissertation, Cambridge University.
14.
Brear
,
M. J.
,
Hodson
,
H. P.
, and
Harvey
,
N. W.
,
2002
, “
Pressure surface separations in low pressure turbines-part 1: midspan results
,”
ASME J. Turbomach.
,
124
,
393
–
401
.
15.
Castro
,
I. P.
, and
Epik
,
E.
,
1998
, “
Boundary layer development after a separated region
,”
J. Fluid Mech.
,
374
,
91
–
116
.
16.
Braddom, S., 2002, “Design and Characterization of Robust Hot Film Sensors for Tactical Aircraft Inlets,” M.S. Thesis, Massachusetts Institute of Technology.
Copyright © 2004
 by ASME
You do not currently have access to this content.