Combining bionic blade design with fluidic oscillators for separation and loss suppression in high-lift low-pressure turbines

Flow separation on high-lift low-pressure turbine (LPT) blades under low Reynolds number conditions results in severe aerodynamic losses and performance degradation. To address this issue, an innovative combined flow-control strategy integrating bionic blade design with a fluidic oscillator (FO) is proposed in this study. Unsteady Reynolds-averaged Navier-Stokes (URANS) simulations are conducted for multiple blade configurations at a Reynolds number of 30,000. The simulation method is validated against low-speed wind tunnel experiments. The combined effects of the bionic structure and jet excitation, with a jet mass flow rate of 0.1% of the mainstream, on aerodynamic losses and suction-surface flow characteristics are evaluated using time-averaged results. The results demonstrate that the combined strategy outperforms the individual control methods in reducing total pressure loss coefficient, yielding an approximately 32% reduction. The dynamic influence of the unsteady jet on separation evolution is revealed through instantaneous flow-field analysis. The unsteady jet enhances near-wall momentum and periodically suppresses flow separation. However, the entrainment of low-momentum airflow by the jet increases aerodynamic losses in localized regions. Bionic structures promote spanwise momentum redistribution, mitigating the adverse effects of jet entrainment and enabling the combined strategy to exhibit superior performance.