A compact equation for the prediction of eddy-induced slip in centrifugal impellers

Abstract

The single relative eddy (SRE) method for the prediction of relative-eddy-induced slip in centrifugal impellers proposes the existence of only one slip-inducing eddy in a rotating impeller, compared with the commonly assumed multiple eddies, with one eddy per blade passage. In the SRE method, the eddy-induced slip factor depends on the blade solidity, weighted by an auxiliary coefficient F that is a function of blade angle and blade number. The paper presents a series of increasingly accurate new expressions for F. The best fit leads to a compact equation for slip factor, giving very good agreement (within 0.003) with the numerically calculated slip factors of Busemann for impellers with four or more blades and reasonable agreement (within 0.02) for single-bladed impellers for any blade angle from 0° to 90°.

Keywords

centrifugal impellers slip factor eddy-induced slip

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