可调涡轮叶片在变工况下的端区优化研究

Study on the Vane End Zone Optimization of Variable Geometry Turbine under the Varying Conditions

为了使变几何涡轮在大子午扩张流道内可以自由转动,则需要在端壁处保持很大的间隙,但会增大间隙泄漏损失。故为了减小大子午扩张涡轮的间隙损失,需要对此可转导叶的端区进行改造。通过利用三维数值模拟的方法,本文对平面叶栅3种端区结构——叶顶开槽,叶顶迷宫密封结构和叶顶蜂窝密封蜂结构进行的流场进行计算研究,并对比分析了3种涡轮全工况性能的优劣。并在此基础上将研究的结果应用在大子午扩张变几何涡轮上。其计算结果显示:蜂窝密封结构能够有效抑制间隙泄漏流动,减小间隙泄漏损失,而在大子午扩张变几何涡轮中端区优化结构对间隙泄漏流动也具有良好的抑制作用。并且变几何涡轮端区进行蜂窝密封结构处理后,其具有较高的全工况性能。

To ensure the variable geometry turbine can freely rotate in the large meridional expansion flow passage,a large gap in the end wall is usually required,while it increases the clearance leakage loss. To reduce this clearance loss,modification to the end zone of the rotating guide vane is needed. In this paper,by using the three-dimensional numerical simulation method,three end zone structures of the turbine cascade,tip slotting,tip labyrinth seal structure and tip honeycomb seal structure,were simulated,and corresponding flow fields were analyzed and the turbine performance at the full range of operating conditions was compared. The calculation results showed that the honeycomb seal structure can effectively limit the clearance leakage flow,reducing clearance leakage loss,and also leads to a relatively high turbine performance at all operating conditions.