间隙和进口边界层厚度对跨音速涡轮叶顶流动换热特性影响的数值研究

Numerical Investigations on the Flow and Heat Transfer Characteristics of the Transonic Turbine Blade Tip

采用求解三维Reynolds-Averaged Navier-Stokes(RANS)和标准k-ω紊流模型的方法数值研究了跨音速流动条件下涡轮叶片顶部的流动传热特性,分别研究了跨音速流动条件下叶顶间隙高度及进口边界层厚度对叶顶流动换热特性的影响。研究结果表明:在气流进口总温及出口静压一定时,跨音速流动时叶顶平均换热系数远大于亚音速流动,跨音速流动时叶片前缘附近存在高换热系数区且再附着线附近的高换热系数区靠近压力面侧。在跨音速流动条件下,叶顶间隙高度对叶顶平均换热系数影响较小,但随着叶顶间隙高度的增大压力面侧分离线附近的高换热系数区和吸力面侧附近的低换热系数区面积均增大。进口边界层厚度对叶顶换热影响很小,但对吸力面侧换热有一定影响。进口边界层厚度较大时,叶顶间隙泄漏较小而横向二次流强度较大同时泄漏涡在二次流的挤压下更加靠近吸力面侧,最终分离线附近产生高换热系数区。

Numerical investigations on the flow and heat transfer characteristics of the transonic turbine blade tip using the three-dimen- sional Reynolds-Averaged Navier-Stokes（RANS） and standard k -ω turbulent model based on the CFD software ANSYS-CFX was pres- ented. The effect of the tip gap and inlet boundary layer thickness on the heat transfer characteristics of the transonic turbine blade tip was conducted. The numerical results show that averaged heat transfer coefficient on the blade tip at transonic condition is greater than that at subsonic case and the region near the blade leading edge obtains great heat transfer coefficient and the high heat transfer coeffi- cient region near the reattachment line moves towards pressure side for the transonic flow condition by comparison of the subsonic case with same total inlet temperature and outlet pressure. The influence of tip gap on the blade tip averaged heat transfer coefficient is limit- ed, but areas of the high heat transfer coefficient region near reattachment line and the low heat transfer coefficient region near suction side expands with the increase of blade tip gap. The endwall boundary layer thickness has little influence on the blade tip heat transfer performance, but noticeable impact is observed for the heat transfer coefficient of the blade suction side surface. With thicker inlet boundary layer, tip leakage vortex is weaker and more attached to the suction-side surface by the force of secondary flow, so the area near the separation line attains high heat transfer coefficient.