余高对不带冠涡轮转子尖区流动的影响

Effects of Recess Casing on Tip Flow of Turbine Rotor

在不带冠转子通道内部,叶尖泄漏流动与端区二次流相互作用,对涡轮性能有较大影响。本文通过改变机匣后台阶高度R,得到了不同的余高设计,并采用数值模拟方法对比分析了余高对涡轮性能和转子尖区流动的影响。结果表明,随着余高高度增大,马蹄涡压力侧分支强度增强,并向叶中迁移,加强了二次流动,进一步影响泄漏流动。对本文研究的涡轮转子,当余高高度为两倍间隙高度时,能够有效降低二次流和泄漏流损失,涡轮性能提高0.2%。

The tip leakage flow interacts with the secondary flow in the endwall inside the unshrouded rotor channel,which has a great influence on the turbine performance.In this paper,by changing the back step height R of the casing,different recess casing designs are obtained.And the effect of height on the turbine performance and the flow in the rotor tip is compared and analyzed using numerical simulation methods.The results show that as the height increases,the strength of the branch of the horseshoe vortex on the pressure side increases and migrates into the middle of the blade,which strengthens the secondary flow and further affects the leakage flow.For the turbine rotor studied in this paper,when the height of back step is twice the gap height,the secondary flow and leakage flow losses can be effectively reduced,and the turbine performance is improved by 0.2%.