Simulation and Validation of Centrifugal Impeller Shock Wave and Acoustic Power Prediction
In this paper, we describe the development and validation of a simulation based methodology for predicting centrifugal impeller rotor locked noise generated at supersonic relative tip speeds when shock waves dominate the acoustic field. Propagating shock waves were calculated in the compressor inlet with a RANS code using an acoustic quality grid to track the sound power as the shocks transition from non-linear to linear propagating wavefronts. The predicted shocks were compared with unsteady pressure measurements obtained from sensors installed on the impeller shroud wall as part of the validation procedure. Calculated shock signatures compared well with the directly measured pressure field propagating over the shroud wall. An independent measurement of acoustic power was also conducted in the free field outside of the test cell. The predicted acoustic power compared within 1dB of the direct measurement validating the simulation based methodology for centrifugal impeller rotor locked shock noise. The resulting study provides both prediction and measurement of the generation, evolution, and far field acoustic power of centrifugal impeller blade passage shock wave noise.