Variations in Upstream Vane Loading With Changes in Back Pressure in a Transonic Compressor

Abstract

Dynamic loading of an inlet guide vane (IGV) in a transonic compressor is characterized by unsteady IGV surface pressures. These pressure data were acquired for two spanwise locations at a 105 percent speed operating condition, which produces supersonic relative Mach numbers over the majority of the rotor blade span. The back pressure of the compressor was varied to determine the effects from such changes. Strong bow shock interaction was evident in both experimental and computational results. Variations in the back pressure 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 span and 95 percent chord. Radial variation effects caused by the spanwise variation in relative Mach number were measured. Comparisons to a two-dimensional 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 study indicate that significant nonlinear bow shock influences exist on the IGV trailing edge due to the downstream rotor shock system. [S0889-504X(00)00303-2]

Flex Circuit Sensor Array for Surface Unsteady Pressure Measurements

“…The previous instrumentation by Probasco et al cost $1250/sensor. 1 Second, the cost associated with the added complexity of connecting four individual wires for each sensor to the data acquisition system is significant when compared to utilization of the flexible circuit substrate, which only requires two connections. Although an exact dollar value cannot be calculated, the savings in terms of time and potential errors and failure modes are significant.…”

“…Conventional sensor dies use thin aluminum wires for the connection from the die to the electrical 1 Because these sensors are to make nonintrusive surface pressure measurements, the surface of the sensor array was specified to be as smooth as practicable. A lamination of a thin, rubber sheet and Kapton tape with cut outs at the sensor locations facilitated this goal by filling in the bulk of the recessed area left over once the sensor dies were attached.…”

Assessment of the Severity of Unsteady Mach Number Effects in a 3-Stage Transonic Compressor

“…Others compare steady and unsteady results but only for a single stage and at design speed [7][8][9]. Further single stage unsteady simulations have been presented for part speed calculations [10][11][12] and at design speed [13][14][15][16][17], including Large Eddy Simulations (LES) [18], however, none of these compare the unsteady simulations to steady simulations.…”