Theory of Lifting-Lines for Cascade of Blades in Subsonic Shear Flow

Abstract

A theory of lifting-lines for a cascade of blades in subsonic shear flow is developed by assuming that the dependence of the local lift force upon the local upstream Mach number in a shear flow is same as that in two-dimensional flow. By comparing numerical examples with experimental results, the physical validity and the limit of applicability of the present theory are discussed. The effect of compressibility upon the mean characteristics of a cascade in shear flow depends upon the root of harmonic mean square of the upstream Mach number (M* ). Experimental correlation is not disappointing, as far as M* lies within the limit beyond which the small disturbance theory for two-dimensional flow through cascade shows poor validity. Significance of M* as a criterion for the mean characteristics was also confirmed experimentally.