The Dependence of Diffuser Performance upon Inlet Flow Conditions

Abstract

It was recently stated by Cockrell, Diamond and Jones(1) that attempts to correlate diffuser loss coefficients with the inlet boundary layer momentum thickness were generally unsatisfactory. In particular, it had proved impossible to align various results from diffuser tests which had been made with differing inlet flow conditions. The two methods of thickening the diffuser inlet boundary layer, using either(a) a length of parallel pipe, or(b) screen rings at inlet to the diffuserled to a corresponding variation in diffuser performance.The conclusion was drawn that “the manner by which an inlet boundary layer has been thickened is as significant in determining diffuser performance as is the thickness of the layer. No satisfactory inlet flow parameter is at present known”.