Application of Tandem Cascade to Design of Fan Stator with Supersonic Inflow

This article proposes a tandem cascade constructed to tackle the thorny problem of designing the high-loaded stator with a supersonic inflow and a large turning angle. The front cascade adopts a supersonic profile to reduce the shock wave intensity turning the flow into subsonic, while the rear cascade adopts a subsonic profile with a large camber offering the flow a large turning angle. It is disclosed that the losses would be minimized if the leading edge of the rear cascade lies close to the pressure side of the front cascade at a distance of 20% pitch in pitch-wise direction without either axial spacing or overlapping in axial direction. The 2D numerical test results show that, with the inflow Mach number of 1. 25 and the turning angle of 52°, the total pressure loss coefficient of the tandem cascade reaches 0. 106, and the diffusion factor 0. 745. Finally, this article has designed and simulated a high-loaded fan stage with the proposed tandem stator, which has the pressure ratio of 3. 15 and the efficiency of 86. 32% at the rotor tip speed of 495. 32 m/s.