基于POD方法的弯曲扩压通道分离流控制的时空特性分析

为了分析一种运用于压气机内分离流控制的无源脉冲射流控制技术的特点，基于弯曲扩压通道试验模型进行了脉冲射流控制的试验和数值模拟研究，结果均表明当射流频率接近通道内分离涡主频时控制效果最为明显；引入了本征正交分解（POD）技术对无控状态下通道内流场结构进行分析，得到了POD各阶模态的流动结构特征。在此基础上对比分析了定常及非定常控制特点，结果表明：非定常控制方式主要是重分配各阶模态之间的能量，有选择性地强化或削弱某阶模态；定常射流控制则是整体削弱高阶模态，压制通道内复杂流动现象；合理地构建脉冲射流可使能量从高阶模态向平均流模态进行转移，能量的转移通过空间流场结构的重构和模态时间演化特性的序化实现。最后针对POD分析结果进行了验证性试验研究，试验结果部分反映了时空特性的变化规律，提升了POD分析结果的可信度。

Spatiotemporal Characteristics Analysis for Controlling Flow Separation in Divergent Curved Channels with POD Method

In order to analyze the characteristic of a micro pulsed aspirated jet in a compressor, an experimental and numerical investigation is conducted about pulsed jet control, which is based on a divergent curved channels experimental mode. When the frequency of the pulsed jet is close to the characteristic frequency of the separation vortex, the control effects are obvious. In order to analyze the unsteady control mechanism, the proper orthogonal decomposition (POD) method is introduced, and the spatial and temporal flow characteristics are obtained. According to the POD analysis results of the steady and unsteady control methods, it can be noted that the main effect of the unsteady pulsed jet is reallocating the energy of each mode, and selectively strengthening or weakening certain modes; the effect of the steady jet is reducing in an overall manner the energy of high order modes. Based on the reasonable control parameters of the pulsed jet, the energy in higher modes will be transferred to the average flow mode, and the translation of modal energy comes from the reconstructing of spatial flow structurnd the ordering of modal evolution characteristics. Finally, experimental investigation is performed to validate the POD analysis. The results reflect partially the variation of spatiotemporal characteristics of a pulsed jet and the credibility of the POD analysis results is enhanced.