Prediction of the aeroacoustic noise of a radial fan using Lighthill’s analogy in frequency domain
* Presenting author
In this work, the aerodynamic and the aeroacoustic performance of a radial fan with backward curved blades is investigated. The experimental setup for the problem is built according to DIN ISO 5136, and the numerical simulations are performed in order to validate the experimental results. In a few previous articles by the current authors, the initial numerical results were presented based on a hybrid computational fluid dynamics and aeroacoustics (CFD/CAA) approach, where e.g. the Stress Blended Eddy Simulation was used for the computational fluid dynamics, and the pressure and the velocity calculated on a virtual interface at an intermediate region were taken as the input for the far field acoustic computations. In this current article, we investigate the effects of the quadrupole sound sources in the aeroacoustic computations. Namely, the quadrupole sound sources distributed throughout the volume are first calculated in time domain, are then transformed into frequency domain, and the frequency domain form of Lighthill’s wave equation is used in order to predict the noise spectrum in the far field. The comparison of the aeroacoustic results and the experimental values will be presented and the impact of the quadrupole sound sources on the overall sound spectrum will be discussed.