Aerodynamic Noise Reduction by Use of a Cooling Fan with Winglets

For the purpose of reducing the aerodynamic noise from a cooling fan for automobiles, we installed a winglet on each blade of the fan. To verify the effect, using two cooling fan units in actual use condition with and without winglets on the fan blades, we analyzed the noise and fan wake velocity distribution. As a result, the overall noise decreased due to the use of winglets by approx. 1dB and the noise spectrum changed. It was also found, through flow visualization with smoke and measurement of wake velocity by PIV that the influence of winglets appeared in the tip vortex that was generated at the blade tip.