基于POD的超声速尾喷焰流场时空降阶模型  

Spatiotemporal reduced-order model of supersonic exhaust plume based on POD

作　　者：孙傲 牛青林 王晓冰 SUN Ao;NIU Qinglin;WANG Xiaobing(School of Mechanical and Electrical Engineering,North University of China,Taiyuan 030051,China;Science and Technology on Electromagnetic Scattering Laboratory,Shanghai Radio Equipment Research Institute,Shanghai 200438,China)

机构地区：[1]中北大学机电工程学院,太原030051 [2]上海无线电设备研究所电磁散射重点实验室,上海200438

出　　处：《航空动力学报》2024年第7期274-284,共11页Journal of Aerospace Power

基　　金：国家自然科学基金(52006203,U22B2045);山西省回国留学人员科研资助项目(2021113)。

摘　　要：采用大涡模拟(LES)方法计算三维非定常喷焰流场,采用低通滤波器获得流场的低频、高能量的大尺度相干结构,利用傅里叶变换和本征正交分解(POD)在尾喷焰方位角上进行空间缩减,通过在主导POD时间模态中提取傅里叶模态进行时间缩减,建立超声速尾喷焰湍流的时空降阶模型(ROM).结果表明:低通滤波器与POD截断均可对尾喷焰的中高频、低能量的小尺度结构实现滤波;前两阶方位角模态占据了射流中80.9%的能量,且主导方位角模态下的压力POD空间模态因压缩波与激波的交互作用在射流核心区出现尖锐峰值现象;尾喷焰温度和组分的POD空间模态因复燃效应的发生在下游呈现出剧烈扰动,第2阶方位角模态的POD空间模态呈现出交替的波包结构,且具有稳定的波长;尾喷焰温度与组分的POD空间模态呈现出相似的波包结构;基于傅里叶模态能量选择的时间缩减方法不仅可以降低数值不稳定性而且重建精度高.该研究可为超声速尾喷焰流场演化规律和特征提取提供理论方法,也可为目标智能化特征工程应用提供支撑.Large eddy simulation(LES)was used to compute the three-dimensional unsteady plume flow field.Low-frequency and high-energy large-scale coherent structures in the flow field were extracted by using low-pass filters.Spatial reduction was achieved by Fourier transform and proper orthogonal decomposition(POD)in the azimuthal direction of the plume,while temporal reduction was achieved by extracting the Fourier mode from the leading temporal POD mode.Consequently,a spatiotemporal reduced-order model(ROM)for supersonic plume reaction turbulence was established.The results demonstrated that low-pass filters and POD truncation can successfully filter high-frequency and low-energy small-scale structures in the supersonic plume.The first two azimuthal modes accounted for 80.9%of the energy in the plume.In the dominant azimuthal mode,the pressure POD spatial mode showed sharp peaks in the core region of the jet due to the interaction between compression wave and shock wave.Furthermore,POD spatial modes of the component and temperature exhibited sharp disturbances downstream because of afterburning.An alternating wave packet structure with a steady wavelength was displayed in the POD spatial mode under the second-order azimuthal mode.The POD spatial mode of both components and temperature showed a similar wave packet structure.In addition to reducing numerical instability,temporal reduction based on Fourier mode energy selection guaranteed excellent reconstruction accuracy.This research can support target intelligent feature engineering applications by offering theoretical techniques for evolution laws and feature extraction on supersonic rocket exhaust plumes.

关 键 词：尾喷焰 时空降阶模型 本征正交分解 相干结构 时空模态 

分 类 号：V435[航空宇航科学与技术—航空宇航推进理论与工程]