基于POD方法的跨声速轴流压气机转子叶顶间隙流场分析

以跨声速轴流压气机转子NASA Rotor 36为对象,研究了叶顶间隙流场的非定常流动特性。在数值模拟结果的基础上,采用本征正交分解(POD)方法获取POD模态和时间系数分布规律,进一步分析了近失速工况下叶顶间隙流场的流动特性。结果表明:在近失速工况下,叶顶间隙流场的主导频率为叶顶泄漏涡频率,约为0.6倍转子通过频率;能量较高的POD模态决定了叶顶泄漏涡的波动频率和幅值,低能量的高阶涡则影响流场的细微结构;同时发现,前5阶POD模态就可以很好地重构流场,这为低阶模型的应用提供了一定的理论指导。 

Analysis of transonic axial compressor tip clearance flow field with POD method

The unsteady flow phenomenon of a transonic axial compressor NASA Rotor 36 was investigated. Based on the unsteady simulation results, proper orthogonal decomposition (POD) modes and time coefficients were obtained with POD method, and the flow characteristics of the tip clearance flow field at near stall conditions were further analyzed. Results showed that: at near stall condition, the dominant frequency of tip clearance flow field was the tip leakage vortex frequency, about 0.6 times blade passing frequency; the POD mode with higher energy determined the fluctuation frequency and amplitude of tip leakage vortex, and the POD mode with lower energy determined the fine structure of the flow field; the first 5 POD modes reconstructed the flow field very well, providing a theoretical guidance for the establishment of the low-order model.