基于高频响TR-PIV和线列动态压力传感器同步测量的深腔涡声耦合机理实验研究

The phenomenon of vortex-acoustic coupling is widely happened in the key components of industrial facilities, such as the lift system of an aircraft, the piping system of first loop of a nuclear power plant and the gas transport piping. The coupling between the separated shear flow inside the piping system with the acoustic standing wave of the deep cavity would bring severe problems to the industrial facilities, such as the aerodynamic noise, structural vibration and even acoustic fatigue damage. Present study focuses on the self-sustained oscillations of the aeroacoustically coupled flow field in a deep cavity, and tries to give an insight on the temporal-spatial evolutions of the coherent vortex structures, revel the relationship with the phase change of the acoustic standing wave, and delineate the energy transfer between the flow field and acoustic field. Towards this end, the synchronous measurement technique combining the high-frequency time-resolved PIV with the parallel dynamic pressure transducers are employed to capture the instantaneous flow field with high temporal-spatial resolution in the deep cavity. The advanced flow decomposition techniques, i.e. POD, EPOD and DMD, are used to identify, capture and quantify the dominant coherent structures. The Howe acoustic theory is used to analyze the energy transfer between flow field and acoustic field. The achievements of present study can provide the theoretical directions to control the aerodynamic noise and acoustic fatigue for the relevant industrial applications.

当深腔分离剪切流动与其声学驻波特征相互耦合时，会产生强烈的噪音辐射和结构振动，甚至声疲劳破坏等严重问题。在相关流动管路布置规划中，必须谨慎规避深腔结构的涡声耦合问题；然而，目前对其耦合机理及影响因素的科学认识尚且不足，严重制约着相关工程设计水平。本项目将首先开展高频响TR-PIV和线列动态压力传感器的同步测量实验，获取高时空分辨率的深腔非定常流场。采用涵盖POD、EPOD和DMD等的先进流场数据分析体系，提取深腔涡声耦合旋涡结构的时空演变特征及其与驻波模态的动态相位响应关系。最后，通过基于霍尔气动声学理论的深腔涡声能量传递输运分析，获取旋涡结构时空演变过程、自持振荡流场与声学驻波场之间的能量传递输运过程。本项目的相关研究成果将揭示深腔分离剪切流动与其声学驻波模态之间的耦合机理，为抑制流激噪声和缓解声疲劳损伤等相关工程应用提供重要的理论指导。

当腔体分离剪切流动与其自身声学模态特征（如深腔驻波模态、浅腔圆周声模态等）相互耦合时，会产生强烈的噪音辐射和结构振动，甚至声疲劳破坏等严重问题。在相关设备（如固体火箭发动机、燃烧室、汽轮机控制系统、核电一回路管路等）布置规划中，必须谨慎规避腔体结构的涡声耦合共鸣问题；然而，目前对其耦合机理及影响因素的科学认识尚且不足，严重制约着相关工程设计水平。本文首先采用基于FPGA（可编程逻辑门阵列）锁相技术的 PIV（粒子图像测速法）测量方法同步捕捉到受激发的声波特征和共鸣下的旋涡动力学特征。实验中，在 NI-CompactRIO实时采集控制平台基础上，综合应用压力传感器阵列信号的模态分解和FPGA硬计算，触发 PIV同步器获得非定常流场的时空演化过程，其相位捕捉误差低于2.5°。后续采用数据同化的思想并结合集合卡尔曼滤波技术，将实验数据驱动传统数值模型，获取了最优化的湍流数值模型并精确模拟涡声耦合共鸣场。最后，基于霍尔气动声学理论，深度分析了腔体涡声耦合下的涡声能量传递输运传递过程。研究成果将揭示深腔分离剪切流动与其声学驻波模态之间的耦合机理，为抑制流激噪声和缓解声疲劳损伤等相关工程应用提供重要的理论指导。