基于SPOD方法的压气机转子叶顶区域非定常流动分析

为了研究叶顶区域非定常流动特性,对跨声速轴流压气机转子NASA Rotor37在多工况下进行了三维非定常数值模拟,采用谱本征正交分解（Spectral Proper Orthogonal Decomposition,SPOD）方法从叶顶区域流场中提取出时空耦合的单频相干结构进行分析。研究结果表明：相比于常规分析方法,SPOD方法能够高效地从非定常流场中识别出流动特征,有助于揭示叶顶区域流动规律;在“小流量”工况下叶顶区域流动呈现出强的非定常性,且随着质量流率的减小叶顶区域非定常流动增强、波动范围增加、波动频率呈现出“阶跃式”下降;造成叶顶区域流场非定常周期性波动的主要原因是叶顶间隙泄漏涡破碎区的扰动以及叶顶间隙泄漏涡破碎后与主流相互作用所形成的叶尖二次涡的波动。

Analysis of Unsteady Flow in Tip Region of Compressor Rotor based on SPOD Method

In order to study the unsteady flow characteristics in tip region, a three dimensional unsteady numerical simulation of a transonic axial compressor NASA Rotor37 under multiple operating conditions was carried out. Spectral proper orthogonal decomposition (SPOD) method was used to extract the spatiotemporally coupled single frequency coherent structure from the flow field in tip region for analysis. The research results show that compared with the conventional analysis method, SPOD method can quickly identify the flow characteristics from the unsteady flow field, which is helpful to reveal the flow law in tip region; under the "low mass flow" condition, the flow in tip region shows a strong unsteadiness, with the decrease of mass flow rate, the unsteady flow in the tip region increases, the fluctuation range increases, and the fluctuation frequency shows a "step like" decrease; the main reason for the unsteady periodic fluctuation of the flow field in tip region is the disturbance of tip clearance leakage vortex breakage area and the fluctuation of tip secondary vortex formed by the interaction between the breakage of tip clearance leakage vortex and the main flow.