An experimental investigation of the tip leakage flow for a highly-loaded turbine cascade is carried out in a low speed rectangular cascade wind tunnel .The flow field structure and aerodynamic performance of the turbine cascade are analyzed for four different tip clearances including 0 ,0 .5% , 1 .0% ,1 .5% of blade height and five different incidence angles including 0° , ± 5° and ± 10° .Total pressure ,yaw angles and velocity distribution are measured at an exit plane of the rectangular cascade by using a 5-hole probe .Meanwhile ,the static pressure distribution is also measured through surface static pressure taps at the mid-span and near the tip of the blade surface .The experimental results show that the secondary flow near the tip of the blade becomes strong and the flow gets complicated in a region of the upper half of the blade span due to the existence of tip clearance ,and the structure of vortex system changes .With increasing in the tip clearance ,the blade total pressure loss increases and the phenomenon of over turning and under turning of flow deteriorates . With the incidence angle increasing ,the blade total pressure loss increases .%针对一种高负荷涡轮叶栅，利用低速矩形叶栅风洞实验研究叶顶间隙泄漏流动．研究了不同叶顶间隙和不同来流冲角情况下，涡轮叶栅的流场结构和气动性能．研究工况包括无间隙，0．5％、1．0％、1．5％叶高间隙和±10°、±5°、0°冲角．通过五孔探针获得矩形叶栅出口截面上总压、气流角以及速度分布；通过叶片表面开设的静压孔，获得叶片中部以及靠近叶顶截面的叶片表面静压分布．实验结果表明：叶顶间隙的存在增强了叶栅顶部的二次流动，恶化了上半叶展的流动状况，涡系结构发生了改变．随着叶顶间隙的增大，叶栅总压损失增加，气流偏转不足/过偏现象加剧；随着冲角的增大叶栅总压损失增加．
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