This study presents the interplay of flow and acoustics within tandem deep cavities, focusing on the resonance mechanism occurring between turbulent shear layers and acoustic eigenmodes. The arrangement inside the tandem deep cavities includes both close and remote configurations. A combined fully coupled and decoupled aeroacoustic simulation strategy was devised. Employing an advanced high-order spectral/hp element method in conjunction with implicit large eddy simulation, the nonlinear compressible Navier–Stokes equations were solved to acquire internal flow–acoustic resonant field. In parallel, the linearized Navier–Stokes equations were tackled to determine coherent shear layer perturbations with external acoustic forcing. Based on acoustic measurements, the mainstream Reynolds number approaches approximately $R{e_{in}} = {O}({10^5})$ , where we identified the presence of frequency lock-in and a resonance range. Aeroacoustic noise sources were examined by implementing spectral proper orthogonal decomposition to decompose the pressure fields into hydrodynamic and acoustic components. As feedback intensified, the flow characteristics by the acoustic forcing effect and the flow-interactive effect were categorized according to the development of concurrent turbulent shear layers. Subsequently, the alternating and synchronous behaviours of concurrent shear layers resonated with the out-of-phase and in-phase acoustic eigenmodes were identified, and the corresponding large-scale counter-rotating vortex pairs and co-rotating vortex structures at the cavity entrances were extracted. The acoustic power generated by the Coriolis force was calculated using Howe's vortex-sound analogy, and the aeroacoustic energy transfer mechanism between large-scale shear layer vortices with acoustic eigenmodes was further explored. Finally, a linear response of coherent perturbations of the concurrent shear layers by external acoustic forcing was established. The amplification of flow in the streamwise direction toward the main duct led to the formation of coherent vortex structures, accompanied by separation bubbles into the main duct.

中文翻译：

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串联深腔中的流声共振机制与湍流剪切层中的声本征模态耦合

这项研究介绍了串联深腔内流动和声学的相互作用，重点关注湍流剪切层和声学本征模之间发生的共振机制。串联深腔内的布置包括近距离和远程配置。设计了一种组合的全耦合和解耦气动声学仿真策略。采用先进的高阶光谱/生命值采用单元法结合隐式大涡模拟，求解非线性可压缩Navier-Stokes方程，获得内部流声共振场。同时，处理线性纳维-斯托克斯方程以确定外部声强迫下的相干剪切层扰动。根据声学测量，主流雷诺数大约接近 $R{e_{in}} = {O}({10^5})$ ，我们确定了频率锁定和共振范围的存在。通过实施谱适当正交分解将压力场分解为流体动力和声学分量来检查气动声学噪声源。随着反馈的加强，声学强迫效应和流动相互作用效应的流动特性根据并发湍流剪切层的发展进行分类。随后，识别了与异相和同相声学本征模式共振的同时剪切层的交替和同步行为，并在腔入口处相应的大尺度反向旋转涡对和同向旋转涡结构提取的。利用豪涡声类比计算科里奥利力产生的声功率，进一步探讨了具有声本征模态的大尺度剪切层涡之间的气动声能传递机制。最后，建立了外部声强迫对并发剪切层的相干扰动的线性响应。流向主管道的流动放大导致形成相干涡流结构，并伴随着分离气泡进入主管道。