Abstract: Turbine tip clearance has obvious effects on the aerodynamic performance of turbine. In order to study the unsteady effects of tip clearance on turbine efficiency and blade temperature field distribution，unsteady numerical simulation on multistage subsonic axial turbine was calculated by the Non-linear harmonic method. Effects of tip clearance on the turbine efficiency and blade temperature field distribution were analyzed. Results show that the fourth-order harmonic was fine enough between calculation resource and precision. When the tip clearance of R1 and R4 increased from 0.5% span to 1.5% span，the turbine efficiency will decrease by 0.44% and 0.76%，respectively. The near-tip region is the major high temperature region while the trailing edge has the sharpest temperature change. The rotor-stator interaction results in temperature periodic fluctuation of the high temperature field. Tip clearance height has no affect on the amplitude of temperature fluctuation but increased the fluctuation range. Vane has larger amplitude than blade does while the S2 has 11K fluctuation amplitude.

Key words: Non-linear harmonic method；Multistage axial turbine；Numerical simulation；Tip clearance；Temperature

摘要： 涡轮叶顶间隙对其气动特性产生非常明显的影响，为了研究叶顶间隙对涡轮效率以及叶片温度场分布的非定常影响，采用非线性谐波法对多级亚声速轴流涡轮进行了非定常数值计算，与实验结果进行对比后发现，对于本文研究对象，4阶次谐波是考虑计算成本与计算精度的优化值；R1叶顶间隙由0.5%叶高增大至1.5%叶高，涡轮效率降低了0.44%，R4叶顶间隙由0.5%叶高增大至1.5%叶高，涡轮效率降低了0.76%；叶片高温主要集中在近叶顶区域，尾缘温度梯度变化最为剧烈；叶栅级间干涉效应导致高温区温度的周期性波动，温度波动幅值不受叶顶间隙高度的影响但波动区间随间隙增大而升高，静叶相对动叶温度波动幅值较大，S2温度波动保持在11K左右。

关键词: 非线性谐波法；多级轴流涡轮；数值计算；叶顶间隙；温度