不同叶顶结构的间隙流场及对涡轮性能的影响

Influence of Tip Clearance Flow of Different Blade Tip Structures on Turbine Performance

为了给涡轮叶顶结构的选择提供参考,采用数值方法和标准k-ω方程湍流模型,分别研究了带冠和不带冠涡轮叶顶间隙泄漏流动状况及其对涡轮气动性能的影响,同时考虑不同间隙高度的影响。结果表明:不带冠涡轮的叶顶间隙流动是由近叶顶横向压差驱动,且在不同间隙下泄漏涡和通道涡的发展规律并不一样;而带冠涡轮的间隙流动是由上下游压差驱动,且泄漏流与主流掺混损失是泄漏损失主要组成部分。带冠涡轮叶顶间隙泄漏损失要小于不带冠涡轮的。

In order to provide reference for the choice of turbine blade tip structure in specific application, numerical study was performed by solving steady compressible Reynolds-averaged N-S equations in conjunction with the standard k-w two-equation turbulence model. The numerical simulation was performed to investigate tip leakage flow conditions and their effects on turbine aerodynamic performance in unshrouded and shrouded turbines, taking into account the effect of different gap heights. The results show that leakage flow is driven by the lateral pressure near the tip for unshrouded turbine tip. For different gap heights, the development law between the leakage vortex and the passage vortex are not the same. For shrouded turbines, the clearance flow is driven by the streamwise pressure difference, and the mixing losses between the leakage flow and the mainstream flow are a major component of the leakage losses. The blade tip leakage loss of the shrouded turbine is smaller than that of the unshrouded turbine.