Application of Wavenumber-frequency Method for Characteristic Frequency Prediction of Cavity Noise at Subsonic Speeds

IF 1.1 4区工程技术 Q4 MECHANICS

Journal of Applied Fluid Mechanics Pub Date : 2024-02-01 DOI:10.47176/jafm.17.02.2081

W. Lu, L. Wei, Y. Wang, G. Yang, G. Zheng, Z. Sun

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Abstract

Flow-acoustic feedback is one of the main types of noise in a cavity, is caused by the instability of the cavity shear layer and is enhanced through an acoustic-wave feedback mechanism. The flow characteristics of the cavity boundary/shear layer and the characteristic frequencies of the flow-acoustic feedback in the cavities are studied numerically, with aspect ratios ranging from 1/2 to 4/3. The freestream Mach number is equal to 0.11, corresponding to an Re-based cavity length of 2.1×10 5 . Improved Delayed Detached Eddy Simulations combined with Ffowcs Williams-Hawkings acoustic analogy are used to simulate the flow and noise characteristics of the cavities. Auto-correlation analysis of flow field fluctuations is used to establish a link between the boundary/shear layer pressure fluctuations and flow-acoustic feedback noise. For the low aspect ratio cavities investigated in this paper, convection velocities along the shear layer development direction are obtained using wavenumber-frequency analysis. The deeper the cavity, the lower the shear layer flow velocity. Correspondingly, the characteristic frequencies of the narrowband noise generated by the flow-acoustic feedback shift linearly toward the low frequency band as the cavity depth increases. The results of the predicted noise characteristic frequencies obtained using wavenumber-frequency analysis and Rossiter'

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应用文波数频率法预测亚声速空腔噪声的特征频率

流声反馈是空腔中的主要噪声类型之一，由空腔剪切层的不稳定性引起，并通过声波反馈机制得到增强。对空腔边界/剪切层的流动特性和空腔中流声反馈的特征频率进行了数值研究，长宽比从 1/2 到 4/3。自由流马赫数等于 0.11，对应的再基空腔长度为 2.1×10 5。改进的延迟分离涡模拟与 Ffowcs Williams-Hawkings 声学类比相结合，用于模拟空腔的流动和噪声特性。流场波动的自动相关分析用于建立边界/剪切层压力波动与流声反馈噪声之间的联系。对于本文研究的低纵横比空腔，采用波频分析法获得了沿剪切层发展方向的对流速度。空腔越深，剪切层流速越低。相应地，随着空腔深度的增加，流声反馈产生的窄带噪声的特征频率线性地向低频段移动。利用波数频率分析和罗西特噪声分析法预测噪声特征频率的结果如下

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Applied Fluid Mechanics THERMODYNAMICS-MECHANICS

CiteScore

2.00

自引率

20.00%

发文量

138

审稿时长

>12 weeks

期刊介绍： The Journal of Applied Fluid Mechanics (JAFM) is an international, peer-reviewed journal which covers a wide range of theoretical, numerical and experimental aspects in fluid mechanics. The emphasis is on the applications in different engineering fields rather than on pure mathematical or physical aspects in fluid mechanics. Although many high quality journals pertaining to different aspects of fluid mechanics presently exist, research in the field is rapidly escalating. The motivation for this new fluid mechanics journal is driven by the following points: (1) there is a need to have an e-journal accessible to all fluid mechanics researchers, (2) scientists from third- world countries need a venue that does not incur publication costs, (3) quality papers deserve rapid and fast publication through an efficient peer review process, and (4) an outlet is needed for rapid dissemination of fluid mechanics conferences held in Asian countries. Pertaining to this latter point, there presently exist some excellent conferences devoted to the promotion of fluid mechanics in the region such as the Asian Congress of Fluid Mechanics which began in 1980 and nominally takes place in one of the Asian countries every two years. We hope that the proposed journal provides and additional impetus for promoting applied fluids research and associated activities in this continent. The journal is under the umbrella of the Physics Society of Iran with the collaboration of Isfahan University of Technology (IUT) .