The Flow Mechanism and Loss Characteristics of High-Lift Low-Pressure Turbine Based on the Bionics Principle

The aerodynamic performance of a high-lift low-pressure turbine is closely related to the flow characteristics on the suction surface. In this study, the biomimetic blades inspired by the whiskers of harbor seals were designed to suppress laminar separation on the suction surface and reduce flow losses. Experiments comparing the aerodynamic performance of cascades with biomimetic blades and straight blades were conducted on a low-speed wind tunnel test bench under low Reynolds number conditions. The pressure values at the cascade outlet in the middle region of the blade were measured, and the flow losses of cascades were calculated based on the results. The mechanism of biomimetic blades on suction surface flow was analyzed by using a large eddy simulation. Two special sections along the blade span are used to analyze the flow characteristics of the biomimetic low-pressure turbine blade. Considering the great influence of laminar separation on the suction surface flow, the flow phenomena in the separation region were analyzed in detail. On the surface of the biomimetic blade, a separation region with a shorter average axial length was observed. A pair of counter-rotating vortices was induced on the suction surface of the biomimetic blade, which promoted the redistribution in the spanwise direction and altered the external characteristics of the separation bubble. The interaction between separated flows and counter-rotating vortices led to a rapid breakdown of the vortex tube structure, thereby accelerating the transition process.