Abstract

VON BACKSTROM, T.W.. Relative-eddy Induced Slip in Centrifugal Impellers for Engineering Students. R&D j. (Matieland, Online) [online]. 2007, vol.23, pp.21-27. ISSN 2309-8988.

The paper presents a new method for deriving the relative-eddy induced slip factor in centrifugal impellers in an engineering teaching situation. The simple analytical method derives the slip velocity in terms of a single relative eddy (SRE) centered on the rotor axis instead of the usual multiple (one per blade passage) eddies. Features of the method are: the application of basic fluid dynamics to a consistent control volume and logical determination of empirical constants. The method shows correct limiting behaviour for zero blades and for 90° blade angle combined with unity radius ratio, and excellent agreement with the accurate analytical method of Busemann. The SRE method meets the main criteria for presenting slip factor in an engineering teaching situation. It is suggested as a replacement in the teaching situation for the commonly used methods of Stodola, Stanitz and Wiesner.

Keywords : Engineering education; slip factor; centrifugal impeller; eddy-induced slip; pump.