Abstract: The internal flow structure within a low speed axial turbine is complex due to the underlying flow transition which may exist under low inlet Reynolds number. In order to analyze the three-dimensional flow structure under such condition，numerical simulations were performed on a low speed axial turbine. The three-dimensional structure of the flow field within the cascade passage was obtained. Comparing with the experimental results，the unsteady flow structure arising from the stator-rotor interaction and its influence on the aerodynamic performance of the turbine are analyzed in detail. Results show that the effects of the stator-rotor interaction on the stator flow are smaller than those on the rotor flow. The separated flow on rotor blade suction surface is located between midspan and tip. The tip passage vortex stretched in circumference under the press of separated flow. Thus，the periodic variations of the flow variables close to tip are larger than that close to hub.

Key words: Stator-rotor interaction；Non-linear harmonic method；Low speed axial turbine；Incompressible flow

摘要： 低速涡轮内部流动在低雷诺数进口条件下可能涉及流态转变，增加了流动的复杂性。为了分析低速涡轮在低雷诺数下的三维流动结构，对低速轴流涡轮内部流场进行了数值模拟，获得了叶片通道中的三维流场结构。在与实验结果进行对比确认的基础上，详细分析了由转静干涉效应引起的非定常流动现象及其对涡轮气动性能的影响。结果表明，低雷诺数状态下，转静干涉效应对低速轴流涡轮静叶通道内流动状况的影响小于对动叶通道内流动的影响；动叶表面的分离流区位置位于叶中和叶顶之间，使得顶部通道涡沿周向拉伸。这种拉伸运动使得气流参数在叶顶附近的周期性变化幅度大于叶根附近的变化幅度。

关键词: 转静干涉；非线性谐波方法；低速轴流涡轮；不可压缩流