旋涡主导流动的直接数值模拟及其噪声产生机理分析

发布时间：2018-11-18 07:12

【摘要】：旋涡是流场的重要结构,它不仅对流体介质的动力学有重要影响,同时是气动噪声的重要源泉.本文从描述流体介质运动的N-S方程出发,通过较系统的推导、归纳和总结,建立了描述气动声学的广义方程.针对广义气动声学方程,提出两种数值方法通过自定义函数作为度量工具,量化分析了胀量方程右端各项的量级大小,研究了不同项在噪声产生过程中的贡献,为深入研究气动噪声产生机理奠定了基础.通过将无粘Phillips方程和无粘Lilley方程右端源项分解为线性部分与非线性部分之和,并用度量工具量化分析,得出了线性部分与非线性部分在主要发声区域的量级变化规律.采用高阶精度数值方法通过直接数值模拟,系统研究了包括二维可压缩同向旋转涡对合并、激波与剪切层相互作用、超声速剪切流和亚声速时间发展混合层等气动声学问题,分析了噪声产生的根源,验证了前面的数学分析结果.
[Abstract]:Vortex is an important structure of flow field, which not only has an important influence on the dynamics of fluid media, but also is an important source of aerodynamic noise. Based on the N-S equation for describing the motion of fluid medium, a generalized equation for describing aerodynamic acoustics is established through systematic derivation, induction and summarization. For the generalized aero-acoustic equations, two numerical methods are proposed to quantitatively analyze the magnitude of each item in the right-hand end of the expansion equation by using the custom function as a measurement tool, and to study the contribution of different terms in the process of noise generation. It lays a foundation for further research on the mechanism of aerodynamic noise. By decomposing the source terms at the right end of the nonviscous Phillips equation and the nonviscous Lilley equation into the sum of linear and nonlinear parts, the order of magnitude of linear and nonlinear parts in the main vocal regions is obtained by quantitative analysis with measurement tools. By means of direct numerical simulation with high order accuracy, the aerodynamic acoustics including the combination of two-dimensional compressible co-rotating vortices, the interaction between shock wave and shear layer, the supersonic shear flow and the subsonic time development mixed layer are systematically studied. The source of noise is analyzed, and the results of mathematical analysis are verified.
【学位授予单位】：中国空气动力研究与发展中心
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O35

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