Fluid-Structure-Acoustic Interaction of Enclosed Radial Fans

该研究项目包括在螺旋外壳中运行的径流式风扇的声学。径流式风机在流体工程中有着广泛的应用，对声辐射的要求也越来越高，本研究的目的是通过实验和仿真相结合的方法，研究蜗壳内径流式风机流场声辐射的多物理相互关系。套管结构的激励路径必须分开处理：套管内既有流体动压波动，也有流致声压场。数值模拟方法进行了验证和验证实验获得的数据。随后，开发的方法被用来调查在风扇叶轮中的声音产生和由此产生的声音辐射通过螺旋外壳。这是通过变量研究完成的。这些变量是由不同的流入条件形成的径向叶轮，这会影响叶轮中的流致声产生，从而也会影响壳体激励和声辐射到远场。研究工作的创新源于这样一个事实，即第一次有可能开发一种封闭旋转系统的模拟方法，该方法映射了整个流-结构-声相互作用链。在与实验研究的补充方法中，有意识地分离声音产生的不同机制及其复杂的相互作用，导致具有较高的一般有效性的知识，这在封闭式径向风扇的文献中尚不可用。这些发现可以得出结论，机器的哪个部分（叶轮流动，壳体结构等）改变辐射声的影响参数。在开发过程中，这导致了对声学问题区域的特定处理。面向基本的调查有很高的普遍有效性，并形成未来的设计规则的基础上，减少噪音的径向风扇。耦合模拟方法提供了一种计算工具，允许在频域和时域中分析径向叶轮中的流致声产生及其传播。未来的工作将集中在降噪优化算法的使用上，该算法不仅考虑叶轮的流入条件及其与叶片前缘的相互作用，而且还考虑材料参数和壳体结构的形状。

The research project comprises the acoustics of a radial fan operated in a spiral housing. Radial fans have a wide range of applications in a wide variety of fluid engineering applications, in which the requirements for sound radiation are becoming increasingly dominant.The goal of the present application is to investigate the multiphysical interrelationships of flow-related sound radiation of radial fans in volute casings using a combined, experimental, simulation-based approach. It is important to treat the excitation paths for the casing structure separately: There are the fluid dynamic pressure fluctuations as well as the flow induced acoustic pressure field within the casing. The numerical simulation methods are verified and validated against experimentally obtained data. Subsequently, developed methods are used to investigate the sound generation in the fan impeller and the resulting sound radiation through the spiral housing. This is done by means of variant studies. The variants are formed by different inflow conditions to the radial impeller, which influence the flow-induced sound generation in the impeller and thus also the casing excitation and sound radiation into the far field.The innovation of the research work results from the fact that for the first time it is possible to develop a simulation method for enclosed rotating systems, which maps the entire chain of fluid-structure-acoustic interaction. In a complementary approach with experimental investigations, a conscious separation of different mechanisms in sound generation and their complex interactions results in knowledge with a high general validity that is not yet available in literature for enclosed radial fans. The findings allow conclusions to be drawn as to which part of the machine (impeller flow, casing structure, etc.) changes the radiated sound with which influencing parameters. In the development process, this results in a specific treatment of the acoustic problem areas. The basic-oriented investigations have a high general validity and form the basis of future design rules for noise-reduced radial fans. The coupled simulation method provides a calculation tool that allows the flow-induced sound generation and its propagation in radial impellers to be analyzed in the frequency and time domain. Future work will focus on the use of optimization algorithms for noise reduction, which consider not only the inflow conditions to the impeller and their interaction with the leading edge of the blade, but also the material parameters and the shape of the casing structure.