Abstract: In order to guide the design of helium turbines with high load and low aspect ratio， the passage vortex migration mechanism of the first stage of a multi-stage helium turbine was numerically analyzed. The effects of bow blades on the aerodynamic performance of the turbine were also studied. The results show that the airflow deflection close to stator root increases， which is due to the influence of the hub passage vortex. It results in the increasing of incidence angles at rotor leading edge close to hub region. The blade load at that region is raised， and then the meeting point of the passage vortex moves close to the rotor leading edge. The hub passage vortex migrates to the blade tip region. The interaction between passage vortex and tip leakage vortex increases flow losses of the tip region. The effects of bow blades on performance of turbine blades with low aspect ratio and large turning angle are significantly different from those of traditional turbines. The positive bow blade reduces the rotor tip loading. The intensity and loss of the tip leakage vortex and passage vortex are decreased， and the turbine performance is improved. The negative bow blade enlarges the rotor tip loading， which increase the loss of the tip leakage flow. The low momentum fluid from the hub region also moves to the blade tip， which caused by larger radial pressure gradient compared with the one of the positive bow blade. The flow losses thus significantly increase and the turbine efficiency deteriorates.

Key words: Helium turbine;High load;Low aspect ratio;Passage vortex;Bow blade

摘要： 为指导高负荷低展弦比氦涡轮设计，以多级氦涡轮第一级为研究对象，借助数值模拟技术对低展弦比涡轮动静叶通道涡迁移机制进行研究，并考察了叶片弯曲对涡轮气动性能的影响。结果表明：受轮毂道涡影响，导叶出口近叶根处气流过偏转，导致转子前缘近轮毂区正攻角变大；叶片根部负荷增大，致使马蹄涡压力面分支与吸力面分支交点前移；轮毂通道涡径向迁移至近叶顶区，其与叶尖泄漏涡相互影响致使叶顶区粘性损失显著增大。弯叶片对低展弦比大折转涡轮叶片的作用效果与传统涡轮具有明显差别：叶片正弯时叶顶负荷减小，导致叶顶间隙泄漏涡与通道涡强度及损失显著下降，涡轮性能得到改善；叶片反弯时叶顶负荷增大，致使叶尖泄漏损失增大，且强径向压力梯度作用下下端壁低能流体向叶顶汇聚，损失显著增大。

关键词: 氦涡轮;高负荷;低展弦比;通道涡;叶片弯曲