Abstract: In order to investigate the influence mechanism of the rotor tip clearance effect on the transonic rotor performance，a commercial software NUMECA is adopted for a transonic axial compressor stage to solve three dimensional steady simulations. The results show that both the peak efficiency and the mass flow at the choke condition decrease with the increase of tip gap，and the sensitivity curve in rotor peak efficiency is found to be approximately linear with an increase in tip clearance when the tip gap size is higher than the value of 0.5τ([τ]represents the design tip clearance). Considering both the stall margin and efficiency change with the variation of tip clearance size，there exists an optimum tip gap of 0.5τ for this compressor，and the peak efficiency and stall margin are improved by about 0.22% and 3.1% respectively compared with the designed tip clearance. The tip leakage flows along the whole blade chord can be divided into three parts according to the flow structures，i.e. ，primary leakage zone，secondary leakage zone and common leakage zone. Each leakage zone plays a different role in the tip leakage flow structures and mechanisms. The dominant factors in the process of stall are different for the different tip clearances.

Key words: Transonic stage；Tip leakage flow；Tip leakage vortex；Double-leakage；Shock wave structure

摘要： 为了研究叶尖间隙效应对跨声速转子性能的影响机制，以一跨声速级轴流压气机为对象，采用商用软件NUMECA进行三维定常数值求解。结果表明:随着叶尖间隙的增加，峰值效率下降，堵塞流量减小，当叶尖间隙大于0.5τ(τ代表设计间隙)时，峰值效率敏感度曲线与叶尖间隙呈线性关系；综合考虑喘振裕度和峰值效率，该压气机存在最佳叶尖间隙0.5τ，此时的峰值效率和喘振裕度较设计间隙下分别提高约0.22%和3.1%。根据流动特点的不同可以将整个叶尖弦长范围内的叶尖泄漏流分为三个部分，分别为主泄漏区、二次泄漏区和普通泄漏区，且每个泄漏区在叶尖流动结构中的作用各不相同。不同叶尖间隙下压气机的失速过程的主导因素会发生改变。

关键词: 跨声速级；叶尖泄漏流；叶尖泄漏涡；二次泄漏；激波结构