NUMERICAL STUDY ON THE PROPAGATION CHARACTERISTICS OF CIRCUMFERENTIAL TEMPERATURE DISTORTION IN A COMBINED COMPRESSOR

It is normal practice to design aero compressors under the assumption of uniform inlet flow. However, the distortion of temperature or/and other parameters at compressor inlet frequently occurs during actual operation due to surrounding environment. The aerodynamic stability and efficiency of compressor are often decreased by the inlet distortion. The researches on total temperature distortion are currently primarily concerned with the impact on overall performance, and the related flow mechanisms are not fully understood yet. Therefore, in this paper, the unsteady three-dimensional numerical simulations are conducted to study the influence of total temperature distortion on the compressor flow and its propagation characteristics in an axial-centrifugal combined compressor. The inlet distortions considered in the paper are the total-temperature distortions covering a 60-deg sector (60deg distortion). The results indicate that the circumferential distortion lowers the efficiency and pressure ratio of compressor. By analyzing the variation trend of the distortion index along the flow direction and the influence of distortion on the flow structure of the end-wall zone, the propagation law of total temperature distortion in the axial centrifugal combination compressor was explained. The results show that the total temperature distortion index decreases along the flow direction, and shows the characteristics of decreasing in the rotor blade row and changing slightly in the stator blade row. The distortion causes the rolling position of the axial rotor leakage vortex to migrate downstream, and the direction of the leakage vortex trajectory changes. In addition, the distortion leads to an increase in turbulence kinetic energy and loss in the blade tip region of the centrifugal impeller.