A method of noise reduction for the cooling fans used in locomotives

This paper aims to develop a method of noise reduction for cooling fans fitted to the 4000 class locomotives. Particular attention was given to eliminating the noise at its source. The source of the noise from fans is directly proportional to the blade bypass frequency. Due to the turbulence created at the blade tip, this is where the majority of noise is generated. The effect of directing air away from the fan blade tip at the inlet was tested. Methods of testing of cooling fans were devised in order to quantify the noise reduction achieved by different modifications. It was found that by reducing the amount of air passing across the fastest moving part of the blade, the noise level could be reduced to within allowable limit of 85 dB(A). Modifications put forward in this study can be implemented during the routine maintenance of the locomotives.