Effects of compressor endwall suction and blowing on stability enhancement

Abstract

An experimental investigation was carried out to examine the effects on stall margin of flow injection into, and removal out of, the endwall region of an axial compressor blade row. A main goal was to identify the mechanism by which wall treatment suppresses stall in turbomachines. To simulate the relative motion between blade and treatment, the injection and removal took place through a slotted hub rotating beneath a cantilevered stator row. Overall performance data and detailed (time-averaged) flow-field measurements were obtained. Both injection and removal increased the stalling pressure rise, but neither was as effective as the complete treatment. This implies that removal of high blockage flow is not the only reason behind the observed stall margin improvement in a casing or hub treatment, and that injection also contributes to stall suppression. The results also indicated that, for a given variation of injection, the increase in stall pressure rise is linked to the streamwise momentum of the injected flow.