为了直观地揭示扩压器内部非稳定流动的周向传播和发展过程，采用本征正交分解（Proper Orthogonal Decomposition,POD）对数值模拟得到的非稳定流场进行分解，辨识出不同阶的扰动模态，对成对和孤立模态在空间分布和时间变化上进行了分析，成对模态在周向空间分布上存在相位差，在时间变化上具有相近的振动幅度和周期，在时域上表现出周向传播的特性。孤立模态为“过渡态”，代表对平均流动的修正，表示平均流动从一个状态过渡到另一个状态。重构了各阶模态在不同时刻的幅值信息，并对各阶模态幅值变化进行了傅里叶变换，得到对应的频率信息，并与线性稳定性方法预测结果进行了对比。

In order to reveal the circumferential propagation and development process of unsteady flow in the diffuser visually,the unsteady flow field obtained by numerical simulation is decomposed by Proper Orthogonal Decomposition (POD),and the disturbance modes of different orders are identified.The spatial distribution and time variation of the paired and isolated modes are analyzed.The paired modes have a phase difference in the circumferential spatial distribution,similar vibration amplitudes and periods in time variation,and exhibit the characteristics of circumferential propagation in time domain.The isolated mode is a "shift mode",which represents a correction to the average flow,indicating that the average flow transitions from one state to another.The amplitude information of each mode at different times is reconstructed,and the Fourier transform is performed on the amplitude changes of each mode to obtain the corresponding frequency information,which is then compared with the predicted results with the linear stability method.

TK474.8

国防基础科研计划资助（B1420110136）