Abstract: Aiming at the improvement of gas turbine blade tip seal performance，research on a circular groove labyrinth seal was carried out. Flow structure inside the shrouded tip and the outlet of a 1.5 stage turbine was simulated and the seal mechanism was analyzed. Relationship between the tip clearance and leakage coefficient and mixing loss coefficient was given. Results show that the cubage effect caused a small turn degree of the leakage flow and decreased the leakage loss and mixing loss. When the seal clearance was 0.3mm or 0.5mm separately，location of the vortex was changed by the circular groove. Leakage coefficient increased by 53.3% without the groove when seal clearance changed from 0.3mm to 2mm and it increased by 47.7% when the groove exist. The mixing loss increased obviously when seal clearance reached 1mm. The decreased mount between the two seal type retained at 0.044.

Key words: Turbine；Seal clearance；Circular groove；Aerodynamic performance；Numerical simulation

摘要： 针对涡轮叶顶密封性能的提高，对圆形凹槽式迷宫密封的密封特性进行了研究。通过数值模拟一级半涡轮叶冠内及转子出口处的流场结构，分析了密封作用机理，密封间隙变化与泄漏损失以及掺混损失之间的关系。结果表明，圆形凹槽的容积效应促使泄漏流发生小角度偏转，降低了泄漏损失与掺混损失；密封间隙分别为0.3mm，0.5mm时，凹槽的存在改变了腔室内涡流涡核的位置；不存在凹槽时，间隙由0.3mm增大到2mm，泄漏系数增大53.3%；存在凹槽时，泄漏系数增大47.7%；间隙增大到1mm，掺混损失明显增大，凹槽密封掺混损失相对于光滑面密封掺混损失减少量保持在0.044左右。

关键词: 涡轮；密封间隙；圆形凹槽；气动性能；数值模拟