An assessment of body force representations for compressor stall simulation

Abstract

This thesis examines an axial compressor body force representation constructed from 3D CFD calculations. The radial distribution of body forces is compared to that of a body force representation based on axisymmetric streamline curvature (SLC) calculations, and shown to be in qualitative agreement except in the vicinity of the blade tip. In terms of stall inception type and stall point, computations based on both representations exhibit agreement with rig test data. A parametric study is undertaken in which the magnitude of the forces in the blade tip region of both representations is reduced so as to obtain reductions in compressor pressure rise similar to those observed experimentally due to increased tip clearance. It is shown that on a back-to-back basis, a given change to the end wall forces produces similar effects on the computed stall point, whether the underlying body force representation derives from 3D CFD or SLC. Based on this result one route to capturing effects of tip clearance on stall prediction can be the development of a tip clearance body force model for use in conjunction with SLC calculations.