Effect of the Leading-Edge Tubercles on the Aerodynamic Performance of Transonic Cascades under High Static Pressure Rise

Abstract

Under high static pressure rise conditions, flow separation in transonic compressor cascades is severe, exacerbating the performance degradation of the compressor cascades. Biomimetic flow control techniques, as a category of passive flow control technologies, hold promise for improving the performance degradation of transonic cascades under high static pressure rise conditions. Therefore, this paper takes the DLR transonic cascade L030-4 as the baseline cascade and investigates the impact of biomimetic leading-edge tubercles on the aerodynamic performance of transonic cascades under high static pressure rise conditions. This paper employs numerically simulated methods validated by experiments to obtain the variation laws of the total pressure loss coefficient and the leading-edge peak diffusion factor of the transonic cascade with biomimetic leading-edge tubercles as the static pressure rise increases. In the wavy leading-edge cascade, streamwise vortices and surface separation bubbles are observed, and the relationships between the development direction of streamwise vortices and static pressure rise, as well as between streamwise vortices and surface separation bubbles, are discovered. The study shows that biomimetic leading-edge tubercles can reduce flow separation at high static pressure rises by inducing the generation of streamwise vortices, thereby effectively reducing the total pressure loss and decreasing the leading-edge peak diffusion factor. Moreover, the effect of increasing static pressure rise is similar to that of increasing the angle of attack, both of which have the effect of changing the inlet angle of the blade. As the static pressure rise increases, the streamwise vortices gradually shift from developing along the pressure side to developing along the suction side. The streamwise vortices can cause the laminar separation bubbles induced by shock/boundary layer interaction to transition into turbulent separation bubble structures.