Influence of Airway Structures on Engine Cooling Fan Noise

The influences of air way structures in engine cooling system on fan discrete noise were investigated. Each structures such as stays, horns and air leak preventive duct, affect the uniformity of inflow air distribution and the non uniformity of inflow air causes to fluctuate the lift of fan blades.

This lift fluctuation results in the increasing of the discrete noise level from the fan.

It is found that the exponent functional relations between discrete noise level and the velocity defect in the wake of structures. The possibility of predicting method of noise level from the engine cooling system was mentioned by using this functional relation.