## Abstract

A two-dimensional computational study was conducted to characterize the density wake induced force and moment fluctuations on a compressor blade row. The flow simulations indicate unsteady blade excitation generated by: (1) density wake fluid directed to the blade suction surface, (2) axial deflection of the blade passage shock wave position and (3) formation of a separation bubble on the blade suction surface. The blade force and moment fluctuation amplitudes are found to scale with the nondimensional density wake width $w/c$ and a nondimensional density parameter $ρ*.$

1.
Basic Research Issues in Aerodynamics, Structural Dynamics and Control of High Cycle Fatigue. Summary of a Workshop held at the Gas Turbine Laboratory, MIT, October 1995.
2.
Kerrebrock, J. L., and Mikolajczak, A. A., 1970, “Intra-Stator Transport of Rotor Wakes and its Effect on Compressor Performance,” ASME Paper No. 70-GT-39.
3.
Valkov, Theodore V., 1992, “Control of Unsteady Flow in a Stator Blade Row Interacting With Upstream Moving Wakes.” S. M. Thesis, Massachusetts Institute of Technology, Department of Aeronautics and Astronautics; also GTL Report No. 255, May.
4.
Platzer, M. F., 1978, “Unsteady Flows In Turbomachines—A Review of Current Developments,” AGARD CP-227, Paper 33.
5.
Marble
,
F. E.
,
1993
, “
Response of a Thin Airfoil Encountering a Strong Density Discontinuity
,”
ASME J. Fluids Eng.
,
115
, pp.
580
589
.
6.
Ramer, B. E., Wijesinghe, H. S., Tan, C. S. and Covert, E. E., 1997, “Aerodynamic Response of Turbomachinery Blade Rows to Convecting Density Wakes,” Proc. ASME Aerospace Division, ASME AD-Vol. 55.
7.
Wisler, D. C., 1977, “Core Compressor Exit Stage Study, Volume I—Design Report,” NASA CR-135391, NASA Lewis Research Center, Dec.
8.
Hoying, D. A., 1996, “Blade Passage Flow Structure Effects on Axial Compressor Rotating Stall Inception,” Ph.D. thesis, Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, Sept.
9.
Tam
,
C. K. W.
, and
Webb
,
J. C.
,
1993
, “
Dispersion-Relation-Preserving Finite Difference Schemes for Computational Acoustics
,”
J. Comput. Phys.
,
107
, pp.
262
281
.
10.
Chieng
,
C. C.
, and
Launder
,
B. E.
,
1980
, “
On the Calculation of Turbulent Heat Transport Downstream From an Abrupt Pipe Expansion
,”
Numer. Heat Transfer, Part A
,
3
, pp.
189
207
.
11.
Giles, M. B., 1988, “Non-Reflecting Boundary Conditions for the Euler Equations,” CFDL-TR-88-1, Computational Fluid Dynamics Laboratory, Massachusetts Institute of Technology, Feb.