Response of a two-dimensional cascade to an upstream disturbance

Abstract

Time-accurate Euler simulations of the flow through two-dimensional cascades were used to provide data on the response of the flow entering a compressor to an upstream disturbance. These data were then used to evaluate several compressor face boundary condition hypotheses intended for supersonic inlet stability simulations. An accurate outflow boundary condition for time-accurate Euler/Navier-Stokes simulations of inlet flows is needed to determine the stability margin of an inlet that encounters an atmospheric disturbance. The boundary condition must provide an approximation of the response from the compressor when a disturbance from upstream passes through the inlet and into the compressor face. In the cascade analysis, the blade stagger angle, solidity, shape, and loading; axial Mach number; and disturbance strength were each varied through a representative range. It was found that the response of a cascade to an acoustic disturbance is almost nonreflective for blade geometry parameters characteristic of the compressor hub region and almost at a constant velocity condition for blade geometry parameters characteristic of the blade tip region.