Numerical Investigation of Forward Sweep Rotor Effect on Internal Flow under Inflow Distortion

Abstract

The effect of the forward sweep rotor on the internal flow under the inflow distortion condition was investigated by the unsteady DES analysis of full-annulus. The test rig in this research is a low-speed, single-stage axial flow compressor, which has two types of rotor blades: the radially stacked blade (Radial) and the forward-swept blade (Sweep). Under the inflow distortion, in the case of Sweep, a large separation vortex was generated in the mid span due to the effect of the distortion same as in the uniform inflow condition. However, a tip leakage vortex was not developed in the non-distortion region. On the other hand, in the case of Radial, the flow on the tip side is unstable due to the collapse of the leakage vortex caused by the strong incidence at the exit of the distortion area. The spillage was generated near the tip side, and induced the disturbance which rotated in the circumferential direction. It is assumed that this disturbance induced the spike type stall inception. Therefore, Sweep had better stall margin than Radial under inflow distortion condition because Sweep suppressed the generation of spillage that may cause spike type stall inception.