导流叶片两端间隙不同分配对可调向心涡轮性能影响

针对现有可调涡轮产品缺少喷嘴环叶片两端间隙约束机构现状,选取三种典型喷嘴环叶片间隙分布模型,用数值方法研究喷嘴环叶片两端间隙不同分配对涡轮级性能影响,并找出导致涡轮性能变化的相关机理,为提高可调向心涡轮在非设计工况下性能提供参考. 研究结果表明:在小开度情况下导流叶片两端间隙变化导致涡轮级效率差别至少为4％,且流动损失变化主要集中在转子段;导流叶片间隙泄漏流中气体气流角小于主流气体,因此间隙分布变化可以改变转子叶片吸力面前缘附近分离涡位置,从而改变转子叶轮通道内部流动损失,最终影响涡轮性能. 

Effect of Different Matching States of Both Nozzle Vane's Clearances on the Performance in a Variable Geometry Turbine

Up to now there is no design structure limiting the matching states of nozzle vane's clearances at both hub and shroud sides in a variable geometry turbine, so this research work was carried out by numerical simulation to evaluate the effect of different matching states of nozzle vane's clearances on the turbine performance and provide help for improving turbine performance at off-operation in the future. The results indicate that: for close condition, the difference in turbine efficiency indicated by numerical results among three matching states of vane's clearances reaches up to 4 percentage at least, and the flow loss change appears mainly in rotor section; the matching states of nozzle vane's clearances can change the location of separate vortex on suction side of rotor blade near leading edge due to the flow angle in the leakage of nozzle vane is lesser than that in free stream, resulting that flow loss in the rotor channel changes and then turbine performance is influenced.