Computational Investigation of Unsteady Flow Mechanisms in Compressors With Embedded Supersonic Rotors

Abstract

An investigation of unsteady flow mechanisms in compressor stages with supersonic relative Mach numbers at the inlet to the embedded rotors is presented. Measurements of shock-stator vane interactions, discussed in the prior paper Langford et. al. (2005), form the basis for the validation of a modeling approach using the unsteady CFD code MSU TURBO. The experiment highlighted some unsteady flow processes that occur near the stator trailing edge as the shock from a downstream rotor interacts with the stator. The shock induces a time varying loading on the stator that results in a shed vortex. Comparisons between velocities derived from instantaneous flow measurements using Digital Particle Image Velocimetry (DPIV) and unsteady CFD at a similar instant in time show very good agreement. Details of the vortex circulation and vorticity distributions as computed by the CFD simulation also agree favorably with test measurements. The CFD technique used to match the cascade data was then applied to a 3-D embedded transonic stator-rotor stage. Details of the loss associated with the shed vortices are investigated.