Mechanism of Affecting the Performance and Stability of an Axial Flow Compressor with Inlet Distortion

The purpose of the investigation is to obtain the mechanism of affecting the performance and stability of an axial flow compressor with two kinds of multi distortion area. In the investigation, the compressor inlet distortion is made by the distortion generator, which is a column and is placed in the compressor rotor passage upstream. The five-passages unsteady numerical results show that the compressor performances for two kinds of multi distortion area are both lower than that for the clean inlet, and the compressor peak efficiencies for inlet distortions of 6×12 degrees and 6×24 degrees are about 3.5%, and 9.2% lower than that for the clean inlet, respectively. Further, two kinds of multi distortion area both reduce the compressor stability, and the stall margin improvements of −2.93% and −6.11% are provided by inlet distortions of 6×12 degrees and 6×24 degrees, respectively. The flow field analyses show that the flow conditions of the rotor tip inlet upstream deteriorate after the application of multi distortion area. The values of axial velocity and flow angle of incoming flows in some regions, which are near the shroud, become small due to the adverse effect made by the inlet distortion. So, the circulation capacity of the regions becomes low, and inlet blockages appear in some rotor tip passages. The bigger the distorted range is, the greater inlet blockages and corresponding flow losses are. When multi distortion area changes from 6×12 degrees to 6×24 degrees, there are obvious separations of the boundary layer near the blade suction surface in some blade tip passages, and the serious separations prevent the incoming flows from entering the blade tip passage. As a result, overflows occur at the leading edge of the blade tip. Furthermore, as the number of the distortion generator increases by a factor of one, the effects of inlet distortion on the amplitudes of the air relative velocity and static pressure in the rotor inlet upstream at the distortion generator passing frequency of 1076.5 Hz increase by a factor of about one.