In this paper the 3-dimensional viscous numerical calculation is applied to explain the mechanism of extending stability of circumferential grooved casing and hub treatments. A new index which can quantitatively evaluate the ability to extend stability of circumferential grooved casing and hub treatments is proposed with flux of gas through the treatment grooves. The influences of the geometric parameters on improving stall margin are discussed. The conclusions are the same as those of experiments.
A circumferential grooved hub treatment is designed and tested beneath the stator blade row in a single stage axial flow compressor. The upstream and downstream 3-dimension flowfields are measured carefully in optimum operation condition and near stall margin condition by a combined three-hole probe and a mirco-five-hole probe which has 1.5mm diameter. It is shown that stall margin can be improved not only for the single stage compressor, but also for the rotor. Through a lot of experimental investigations and theoretical analyses, the mechanism of extending stability of circumferential grooved casing and hub treatments are systematic and comprehensive explained.