Vortex shedding mechanisms in relation to tip clearance flows

Abstract

This paper outlines the importance of tip leakage flows in axial fans as a source of loss and relates the dimensionless loss analytically to a range of dimensionless parameters by application of a jet loss theory due to Rains. Improved vortex shedding models are also presented. From these models theor- etical predictions of lift coefficient reduction are compared with published experimental data for isolated rectangular plates, with experimental tests for a single aerofoil adjacent to a wall with an on-coming boundary layer and correlations due to Lakshminarayana.