Study on the impact of interstage seal inlet and outlet angles on the vortex structure and aerodynamic performance of compressor cascades

This study investigates the effects of interstage seal structures with various inlet and outlet angles on the vortex structure and performance of high-load cascades. The analysis indicates that an increase in the angle between the interstage seal outlet and inlet and the incoming flow direction reduces total pressure loss and interstage leakage. As the inlet angle increases, the spanwise concentrated shedding vortex diminishes due to the suction effect generated by the interstage seal inlet. Concurrently, the passage vortex expands pitchwise, increasing root blockage and associated losses. However, the flow loss within the mid-span mainstream region is observed to be considerably reduced. As the outlet angle increases, the airflow aligns more closely with the flow direction. This results in the recirculation zone and the suction surface vortex shifting toward the leading edge root. Consequently, the pitchwise separation vortex expands while its height decreases, which reduces loss within the mid-span. The interstage seal outlet and inlet are oriented at 150° to the incoming airflow direction, effectively decreasing the corner separation height. This configuration minimizes flow loss in the mid-span and enhances the flow capacity. The reduction in total pressure loss demonstrates superior performance compared to single action, with a total pressure loss decrease of 2.29% relative to the original scheme. Furthermore, the enhancement of the passage vortex results in a deterioration of the vortex near the root. This change reduces the pressure difference between the interstage seal outlet and inlet, consequently decreasing interstage leakage.