Fluid-Structure-Acoustic Interaction of Enclosed Radial Fans

In this research project, the fluid-structure-acoustic interaction in a radial fan, operated in a spiral casing, is investigated. The sound field radiating to the outside via the structural vibrations of the casing can be excited in two different ways. The excitation can occur on the one hand through the transient flow field within the casing (classical fluid mechanics - structural mechanics interaction), and on the other hand by acoustic pressure fluctuations in the interior of the casing generated by the flow (flow-acoustics and then acoustic structure mechanics interaction). In doing so, the research project focuses on the complex, multi-physical problem involving fluid mechanics, structural mechanics and acoustics including their couplings. The noise generated in radial fans, operated in a spiral casing is still an open problem. Therefore, we apply and develop methods, which are able to separate the flow induced sound from the vibrational generated sound. This is not possible by just applying experimental measurements. In doing so, the methods developed in this research project leads to a full understanding of the sound generation mechanisms, and further on will allow for a physical based optimization to reduce the noise of radial fans. The main objective is to investigate the multi-physical interrelationships of the flow-related sound radiation of radial fans in volute casings by means of a combined experimental-simulation based approach. The numerical simulation methods are verified and validated against experimental data. Subsequently, the developed methods are used to investigate the sound generation in the fan impeller and the resulting sound radiation.