Investigation of Forward and Backward Sweep Axial Fan Noise Sources using Lattice Boltzmann Method

Low speed axial fan used in automotive industry contributes to rising noise pollution levels in the environment that is necessary to mitigate. In this study, we simulated the impact of sweep on noise levels and compared with unswept fan by using Lattice Boltzmann method. Different inlet configurations study showed that in the experiment the strong inflow distortion is present. The quality of an incoming flow field is also responsible for higher broadband levels and tonal noise in absence of a stator in the spectra. The leading edge and trailing edge flow field details agrees very well with experimental recordings. The analysis showed that the swept blades alter the aerodynamic flow field. The backward sweep exhibit reduced blade loading near tip and increased leakage flow. The weak turbulent structures formed due to roll up of leakage flow that interacted with the blade near tip and acts as a major noise source. The standard deviation of pressure contours on blade suggest the potential noise sources. Finally, the noise spectra from simulation is validated with experiment showed a very good agreement