Non-Uniform Flow in Multistage Axial Compressors

Abstract

It has been suggested by the author that some aspects of severely distorted flow into multistage compressors may be examined utilizing an integral technique. The general idea of the proposed technique is clear enough; the appropriate equations of motion and energy are integrated peripherally and radially, using reasonable assumptions for the distributions of velocity and thermodynamic properties, and thereby reduced to ordinary non-linear differential equations for the parameters that describe the distributions. The questions that arise are whether the cascade characteristics may be described appropriately over wide variations of inlet angle, including stall, and whether the profiles may be characterized by a sufficiently small number of parameters to make the technique attractive. The present paper examines a specific example of distorted inlet flow through the two-dimensional annulus of a multistage compressor which can be solved completely. It is shown that the essential features of this exact solution, including stall, may be described by a two-parameter family of profiles and that an integral technique, utilizing these elementary profiles, will yield essentially the same results. While it is not clear that comparable success would hold for the three-dimensional problem, the results confirm the contention that the two-dimensional problem may be treated with acceptable accuracy by an integral technique.