Research progresses of stall precursor-suppressed casing treatment

Modern aeroengine has been developed for high thrust to weight ratio, so the fan/compressor must support higher blade loading. Under this situation, it becomes more and more difficult to meet stall margin requirements. The casing treatment is one of the most effective ways to enhance the stall margin. A kind of casing treatment, named stall precursor-suppressed (SPS), has been developed recently. The stall inception model can be used to determine the variation range of the stall margin improvement with the SPS casing treatment for both subsonic fan and transonic compressor. The model predicts that 7.6% and 6.8% of stall margin improvement (SMI) can be achieved in a subsonic fan TA36 and a transonic compressor J69 Stage, respectively. The effectiveness of the SPS casing treatment is investigated and the experimental results show that the SPS casing treatment can achieve 5.5% and 9.3% of the SMI in TA36 and J69 Stage, respectively. Due to the fact that the distributions of the total pressure ratio along the spanwise are kept the same as those of the solid wall casing at the same mass flow rate, the SPS casing treatments with a small open area ratio and large backchamber enhance the stall margin without an obvious efficiency loss and a change of the pressure-rise characteristics. Furthermore, the generation and the evolution of the stall inception waves are suppressed and the non-linear development of the stall process is delayed with the SPS casing treatment.