Back-swept leading edge effects on aerodynamic performance of small scale transonic centrifugal compressor

Four transonic compressors with swept blades and wing-type diffusers are designed by a fully three-dimension CFD technique. And numerical simulation is also carried out to investigate the influence of back-swept leading edge on the flow field of compressor. The results show that the blades with back-sweptness can increase the choke mass flow, enhance ability of circulation, at the same time, back-sweptness can improve the distribution of the low energy mass flow; but because of the blade's chord reduced, which will reduce the surge margin, and it also can increase the leading shock wave angle and strengthen the shock wave in the channel. Back-sweptness has greater effect on the secondary flow at S3 section near the impeller inlet than the outlet. For the cases of different back-swept angles, it is found that, as the back swept angle is smaller, the pressure difference between suction side and pressure side will become much smaller, simultaneously, the flow field will be more stable; when the back swept angle is greater, the separation zone becomes weaker and weaker, although the shock wave is stronger; the smaller back swept angle can suppress the formation of separation vortex near the diffuser outlet.