斜切式叶顶形状下非均等流量射流对叶顶间隙泄漏流动的影响

Influence of Non-uniform Flow Jet on Tip Clearance Leakage Flow Under Oblique Blade Tip Shape

采用非均等流量射流的控制方式,即叶顶射流孔流量沿轴向弦长方向呈二次曲线分布,通过数值模拟方法探究LISA涡轮在斜切式叶顶形状下非均等射流对叶顶间隙泄漏流动的影响。结果表明:与前缘至尾缘间隙由小到大相比,前缘至尾缘间隙由大到小的叶顶形状下,非均等射流更有利于控制间隙流动,其相较于无射流下的涡轮等熵总总效率最大增幅可达2.20%,动叶出口质量平均总压损失系数最大降幅可达37.56%,间隙相对泄漏流量最大降幅可达48.57%;当射流比(总射流量占主流流量的比例)小于1.0%时,采用叶顶前缘单孔射流量大的分布方式,当射流比大于1.0%时,增加叶顶中部的单孔射流流量,这种非均等射流分布规律比均等射流控制效果更佳。

A control method of non-uniform flow jet was adopted,which meant that the flow rate of the tip jet hole was distributed in a quadratic curve along the axial chord length direction.Based on the LISA turbine,the influence of non-uniform flow jet on the tip clearance leakage flow under oblique blade tip shape was explored by numerical simulation.Results show that compared with the leading edge to trailing edge clearance from small to large,the non-uniform flow jet is more advantageous to control the gap flow in the tip gap with the leading edge to trailing edge clearance from large to small.Compared with no flow jet,the maximum increase of total isentropic efficiency of turbine can reach 2.20%,the maximum decrease of mass flow average total pressure loss coefficient on rotor outlet can reach 37.56%,and the maximum decrease of relative clearance leakage flow can reach 48.57%.When the jet flow ratio(the ratio of jet flow to main stream flow)is less than 1.0%,the distribution mode of large single-hole flow rate at the leading edge of the blade tip is adopted.When the jet flow ratio is larger than 1.0%,the single-hole flow rate in the middle of the blade tip is increased,and this non-uniform jet distribution pattern is more effective than the uniform flow distribution jet control.