Stall and stability enhancement mechanisms of transonic compressor with inlet total temperature distortion

Inlet total temperature distortion refers to the nonuniform distribution of the total temperature at the inlet of the aero-engine, which is one of the external destabilizing factors that have the most remarkable impact on the stability of an aero-engine. In this study, the stalling process of the Darmstadt transonic compressor is investigated under the total temperature distortion of 180 deg circumferential extent and 500 K intensity by full-annulus unsteady numerical simulation. The analysis shows the addition of inlet total temperature distortion deteriorates the compressor stall margin from 22.7% to 17.0% with a considerable decrease in the pressure ratio. The type of compressor stall inception under temperature distortion conditions remains spike. Pressure perturbations and radial vortex formation are first clearly detected when the rotor rotates into the high temperature distortion region. The circumferential propagation of the stall cells under the total temperature distortion is 66% of the rotor speed, which is faster than that under uniform condition whose value is 44% of the rotor speed. The optimized casing treatment (CT) has extended the stall margin of the rotor without producing efficiency loss under uniform condition. The anti-distortion ability of CT is first verified despite its negative impact on efficiency under total temperature distortion. The adoption of CT could obviously push the shock wave into the blade passage under total temperature distortion condition. In addition, it can reduce the tip blade loading, thus removing the low Mach number area in the tip region, while increasing the blade loading below 80% span.