Abstract: Aiming at the unsteady characteristic of the stage interaction phenomenon of the multistage subsonic axial turbine，the Nonlinear Harmonic (NLH) method was used for calculation. The Spalart-Allmaras(S-A) turbulence model together with AGS(Abu Ghannam Shaw) transition model was used to simulate the transition characteristic. Comparison with the experiment results validates the reliability of computational results. Results show that the 4th harmonic NLH method could get a middle course between computation cost and time. The leading edge of the blade is the key area of heat transfer. High temperature of the vane mainly concentrated at the leading and the near-tip area while the high temperature of rotor blade concentrated at the near-tip leading edge area. Rotor blade，which cut the upstream wake of vane，periodically changed the blade cascade turbulent distribution. An obvious temperature fluctuant happened at the high temperature area of the blades in which a temperature fluctuant of 11K happened at the vane stage Ⅱ.

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

摘要： 针对多级亚声速轴流涡轮级间干涉的非定常现象，通过非线性谐波(NLH)法进行了非定常数值计算，加入AGS(Abu Ghannam Shaw)转捩模型的Spalart-Allmaras(S-A)湍流模型对转捩特性进行捕捉，与实验结果的对比验证了计算方法的可信性。研究结果表明，4阶谐波的NLH法在计算成本与计算精度间获得了较好折中；叶片前缘是关键的换热区域，静叶高温区主要集中在叶片前缘以及近叶顶区，转子叶片高温区主要集中在叶片前缘靠近叶顶区；转子叶片的相对运动不断切割静叶尾流，叶栅湍流场分布呈周期性变化，叶片高温区产生了明显的温度波动，其中Ⅱ级静叶高温区温度波动幅值达11K。

关键词: 非线性谐波法；多级轴流涡轮；非定常；叶顶间隙；数值计算