Axial Compressor Stall, Circumferential Groove Casing Treatment, and the Tip-Clearance Momentum Flux

Abstract

The stall margin and pressure ratio of an axial compressor can both be increased with the use of circumferential groove casing treatments over the rotor. Performance and stall point measurements were obtained in a single-stage high-speed axial compressor with seven different casing treatment configurations. The different configurations were designed to investigate the effects of the number and placement of circumferential grooves. The results demonstrated that the stall margin extension caused by individual grooves could be added together to obtain the value obtained with the equivalent multigroove configuration. Furthermore, the relationship between stall margin extension and the tip-clearance momentum flux was considered. A Reynolds-averaged Navier–Stokes computational solution from the smooth-wall configuration was used to obtain the momentum flux of the reverse flow at the tip. The results showed a linear relationship between the measured stall extension and the computed smooth-wall momentum flux integrated over the region occupied by the grooves.