Numerical investigation on propagation characteristics of inlet total-pressure distortion in a centrifugal compressor

The propagation characteristics of inlet total-pressure distortion in a centrifugal compressor are investigated by fullannulus unsteady three-dimensional numerical simulation. The inlet distortions considered in the paper are the total-pressure distortions covering a 60-deg sector (60deg distortion) and three 20-deg sectors (3∗20deg distortion), respectively. One is the classical distortion form, and the other is to simulate the downstream flow of the axial section of a centrifugal-axial combined compressor. By analyzing the distributions of flow parameters, the propagation of the total-pressure distortion in the centrifugal compressor is interpreted. The results show that, with the distortion propagating to the downstream, the lowpressure region produces a phase deviation along the streamwise direction relative to the opposite direction of impeller rotation direction, and the range of distortion region is reduced. Additionally, the propagation of the inlet distortion makes the three-dimensional characteristics of airflow more complex. The flow angle increases with different amplitudes along the direction of blade height corresponding to the distorted sector. The distortion region affects the location of blades which are in a low-pressure area, and the intensity of the distortion affects the increase of the flow angle. The distortion region causes more local relative flow losses, especially near the leading edge of blade suction surface.