Fluid-Structure-Acoustic Interaction of Enclosed Radial Fans

• Applicant: Professor Dr.-Ing. Stefan Becker
• Subject Area: Fluid Mechanics ; Acoustics ; Hydraulic and Turbo Engines and Piston Engines
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 468338100

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.

• DFG Programme: Research Grants
• International Connection: Austria
• Partner Organisation: Fonds zur Förderung der wissenschaftlichen Forschung (FWF)
• Cooperation Partner: Professor Manfred Kaltenbacher, Ph.D.