Turbulence and noise characteristics of a radial fan

A radial fan was numerically studied for flow and aerodynamic noise properties with both k and LES turbulence models. Transport equations were solved with a finite volume code and free field noise propagation was calculated with the Ffowcs Williams and Hawkings (FWH) model. The simulations were performed at a rotational speed of 1200 rpm for different turbulent perturbations at the fan inlet and five different static pressure outlet values from 5 to 25 Pa. The corresponding mass flow rates were used to construct the performance characteristics of the fan, which indicates that the optimum point occurs at 20 Pa with a mass flow rate of 70 lt/s. In order to investigate the effect of rotational speed on the performance of the fan, the simulations were also repeated for rotational speeds at 1800 and 2400 rpm. Acoustic calculations are performed for two receivers on the outlet surface. The results indicated that maximum sound pressure occurs at 225 Hz, which is the fundamental Blade Passing Frequency (BPF) of the fan.