Internal flow mechanism in a supersonic expander-rotor

Abstract

This article proposes a numerical investigation into the internal flow structure in the supersonic expander-rotor (SER). In order to reveal internal flow mechanism, the significant influencing factors in the flow structure are identified, and the solutions to improving the integrated performance of the SER are developed. According to the numerical results, the wave structure of the expansion wave and the oblique shock wave is what characterizes the flow in the mainstream region of the SER. In addition, the expansion wave and the oblique shock wave impose control on the pattern of static pressure distribution in the 3-D channel and then the 3-D flow structure. The formation and breakdown of the tip leakage vortex are the main form that the motion of vortex takes in the SER. The concentration, recirculation, and separation of the boundary layer; the low energy fluid mixing with mainstream; and the interaction between the oblique shock waves and the boundary layer are the crucial motion tracing near the endwall. Compared with the traditional turbines, the flow structures in the tip region of the SER are relatively simpler; the essential motion tracing is the airflow near the leading edge of the strake wall moving from the PS through the tip gap to the SS as a result of the transverse pressure difference.