We investigated noise reduction with a thin condenser cooling fan for automotive air conditioners. A new type of fan having a forward skew and large camber was developed, and the noise level of the new fan was 5 dB (A) lower than our previous fan. The internal flow behavior of the fan was investigated by flow visualization in order to achieve further noise reduction of the new fan. It was found that turbulence near the trailing edge of a prototype of the new fan was high. Trailing edge serrations are provided on the new fan to suppress the turbulence and the noise level is 2 dB (A) lower than the base value. The trailing edge serrations are effective for noise reduction without any deterioration in fan performance.
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