间隙泄漏对透平级气动性能影响的数值研究
Numerical Investigation on Effects of Leakage Flow on the Aerodynamic Performance of Turbine Stages

为提高透平级气动性能设计水平,采用数值求解三维Reynolds-Averaged Navier-Stokes (RANS)方程和Spalar-Allmaras (S-A)方程湍流模型的方法,针对三级实验透平级开展了包括动叶叶顶间隙、静叶叶根与转轴间隙(隔板间隙)和动叶叶根与轮盘间隙(叶根间隙)的泄漏流动对透平性能影响的数值研究。研究结果表明:与不考虑所有间隙的纯通流三级透平相比,动叶叶顶和隔板间隙泄漏流使透平总静效率降低了0.62％,但同时动叶叶根与轮盘间隙泄漏流动使透平总静效率提高了0.28％,适当的叶根间隙泄漏有利于透平效率的提升;动叶枞树型叶根与轮盘的间隙泄漏影响叶根端区附近主流与泄漏流交互作用的方向;主流与泄漏流之间的“吸”与“漏”影响叶片端区附近二次流的分布与发展,进而引起叶片端区能量损失系数的变化。
Effects of the different leakage flows on the aerodynamic performance of a three？？stage test turbine are numerically investigated to improve the aerodynamic design of a real turbine. The three？？dimensional Reynolds？？Averaged Navier？？Stokes (RANS) and the S？？A turbulence model are used to analyze the leakage flows from the rotor tip clearance, the clearance between the stator hub and shaft, and the clearance between the rotor root and wheelspace disk. Results show that the three？？stage turbine efficiency decreases by about 0？？62％ when the rotor tip clearance and the stator/shaft clearance are considered, however, the efficiency rises 0？？28％ by considering the rotor root and wheelspace disk clearance leakage flow through a comparison with the case that only considers rotor tip and stator/shaft clearance leakage flow. The rotor root and wheelspace disk clearance leakage is beneficial for improving efficiency of turbines to some extent. The flow direction of the mainstream and the leakage flow at the hub is influenced by the leakage from the rotor root and wheelspace disk clearance. The distribution and development of the secondary flow is influenced by the “suction” and “leakage” near endwalls, causing the change of energy loss coefficient in endwall regions