The Simulation of Axial Compressor Performance Using an Annulus Wall Boundary Layer Theory

Abstract

This paper summarizes the development of a computer program to simulate axial compressor performance. The program incorporates a well-established technique for cascade performance prediction and a modified radial equilibrium method of calculating the mainstream axial velocity distribution. The program’s most important feature is a new theory of annulus wall boundary layers which predicts annulus boundary layer development and losses. The empirical input to the present annulus wall boundary layer model is very restricted and involves well defined quantities: shape factor, skin friction, and leakage coefficients. Special provision is made for cases where the annulus wall boundary layers are merged; this aspect needs improvement however. Theoretically derivable losses due to the annulus wall, in combination with cascade losses, yield overall compressor efficiency. In the interest of being abstemious with empiricism, no attempt has been made to introduce high Mach number cascade loss corrections at this time and the values of the empirical parameters in the boundary layer theory are held fixed. Considering the very restricted empirical content of the model and the absence of adjustable parameters, the current predictions of compressor performance are quite good.