Variations in upstream vane loading with changes in back pressure in a transonic compressor

Dynamic loading of an inlet guide vane (IGV) in a transonic compressor is c haracterized by unsteady IGV surface pressures. These pressure data were ac quired for two spanwise locations at a 105 percent speed operating conditio n, which produces supersonic relative Mach numbers over the majority of the rotor blade span. The back pressure of the compressor was varied to determ ine the effects from such changes. Strong bow shock interaction was evident in both experimental and computational results. Variations in the back pre ssure have significant influence on the magnitude and phase of the upstream pressure fluctuations. The largest unsteady surface pressure magnitude, 40 kPa, was obtained for the near-stall mass flow condition at 75 percent spa n and 95 percent chord Radial variation effects caused by the spanwise vari ation in relative Mach number were measured. Comparisons to a two-dimension al nonlinear unsteady blade/vane Navier-Stokes analysis show good agreement for the 50 percent span results in terms of IGV unsteady surface pressure. The results of the the study indicate that significant nonlinear bow shock influences exist on the IGV trailing edge due to the downstream rotor shoc k system. [S0889-504X(00)00303-2].