Mechanism Study of Stall Triggered by Hub Region Inception in a Transonic Compressor

A new type of stall inception starting from the hub region was found in the experiments. Full-annulus transient simulations were carried out to explore the characteristics of the initial disturbance and the dynamic development mechanism of the stall process. The simulation results show that the blockage area firstly forms in the stator hub region during the stall process, indicating that the disturbance initiates in the compressor hub region. The disturbance is consisted of six axisymmetric blockages which are rotating at 45% of the rotor speed. In the stall evolution, the blockages merge into a full-annulus separation zone, leading to more serious flow blockage at low blade height. Because of the hub region blockage, more fluid have to go through the tip region, resulting in the increase of tip region flow rate, so the tip region fluid is accelerated. Moreover, shock wave/tip leakage vortex interaction cause the formation of tip blockage. The tip region's blockage finally develops into rotating stall cells which lead to the compressor eventual stall.