Detection of Aerodynamic Noise Sources over a Rotating Radiator Fan Blade for Automobile

To locate the sources of flow noise generated from the radiator fan for automobiles and to clarify the flow mechanism, we performed the noise source detection, flow visualization experiment, measurement of fl ow field around the blade, and measurement of cross-correlation between noise and air velocity fluctuation. The results indicate that the first noise sources are distributed around the leading edge on suction surface where flow separation and reattachment are observed. The second sources are around the trailing edge of the blade where tip vortices and vortex shedding exists.