Prediction of three-dimensional compressible turbulent boundary layers on transonic compressor blades

Abstract

A small crossflow approximation to the full three dimensional compressible turbulent boundary layer equations for turbomachine blade rows is developed by taking advantage of the nature of blade geometry and inviscid flow field when an intrinsic coordinate system is used. The resulting system of equations is solved by Keller's box scheme, providing the capability of numerically calculating compressible turbulent boundary layers on transonic compressor blades to a good approximation. The scheme is checked with two known solutions of incompressible flow over unloaded zero thickness blades. It is then applied to the first stage of a NASA Low-aspect-ratio rotor blade for which the inviscid flow field is available. The results give insight to the three-dimensional boundary layer character of transonic compressor blades, caused by an imbalance of centrifugal and Coriolis forces within the boundary layer.