N. A. Cumpsty

TL;DR: In this paper, a linear cascade with tip clearance is complemented by numerical solutions of the three-dimensional Navier-Stokes equations in an investigation of tip leakage flow, and detailed comparisons show that the mechanism of leakage is primarily inviscid.

TL;DR: In this paper, a radial impeller-vaneless diffuser free-spool system was used to investigate turbocharger surge in the presence of a volute at the inducer tip, and two very different compression systems were employed to examine stall initiation phenomena as well as the behavior of the compressor characteristics when operating in surge.

Abstract: Experimental measurements in a linear cascade with tip clearance are complemented by numerical solutions of the three-dimensional Navier-Stokes equations in an investigation of tip leakage flow. Measurements reveal that the clearance flow, which separates near the entry of the tip gap, remains unattached for the majority of the blade chord when the tip clearance is similar to that typical of a machine. The numerical predictions of leakage flow rate agree very well with measurements and detailed comparisons show that the mechanism of tip leakage is primarily inviscid. It is demonstrated by simple calculation that it is the static pressure field near the end of the blade which controls chordwise distribution of the flow across the tip. Although the presence of a vortex caused by the roll-up of the leakage flow may affect the local pressure field, the overall magnitude of the tip leakage flow remains strongly related to the aerodynamic loading of the blades.Copyright © 1990 by ASME

TL;DR: In this paper, a simple model for loss created by the tip clearance flow in axial compressors is presented, based on an experimental program performed in conjunction with the Dawes three-dimensional Navier-Stokes calculation method.

TL;DR: In this article, a radial impeller-vaneless diffuser free-spool system has been investigated in a turbocharger surge and two very different compression systems, one with a large downstream volume and one with the smallest possible downstream volume, are employed to examine stall initiation phenomena as well as the behavior of the compressor characteristics when operating in surge.