Noise Reduction Of The Electric Locomotive Traction Fan

Electric locomotive has become an important transportation carrier in China’s railway construction because of its advantages of high power,high speed and high energy utilization rate.In order to ensure the normal operation and work of locomotive equipment,the ventilation system needs to ventilate and cool the electrical components,and the noise of fan,especially the exhaust noise of traction fan,is a main noise source of electric locomotive.Therefore,the aerodynamic noise of traction fan is of great significance and industrial application value.This paper takes the traction fan of an electric locomotive as the research object through numerical simulation of the characteristics of the flow field in the fan and volute.The flow field source is applied to the sound field as the excitation source,and the internal and external noise characteristics of the air duct are obtained by Fourier transform of the boundary data of the rotating domain of the flow field.Two schemes are proposed to improve the structure of the fan from two aspects of blade trailing edge and volute size,and the characteristics of flow field and sound field after improvement are compared.The main conclusions are as follows:The pressure changes greatly at the leading and trailing edges of the fan blades,and an obvious vortex is formed between the outer boundary of the impeller and the volute.There is a very large pressure fluctuation in the cochlear tongue region,and the turbulent kinetic energy is the largest near it.But the distribution law of turbulent kinetic energy varies greatly with the height of impeller.At the inlet and outlet monitoring points,the peak value of the first and second order blade rotation noise is the most obvious.The rotation noise has high sound pressure level but narrow band width.The continuous noise generated by eddy current has low sound pressure level but wide bandwidth,which still accounts for a heavy total sound pressure level.For the three types of fans,the maximum difference of flow rate is 1.33%,and the pressure pulsation is reduced by 0.03% and 0.22% respectively after the maximum improvement at the volute tongue.The pressure pulsation at the volute tongue is obviously improved by the large volute,and the toothed trailing edge is obviously improved by the leading and leading edges of the blades and the vortex between blades.At the exhaust port,the sound pressure levels of modification 1 and modification 2 are 2.5d B(A)and 6.6d B(A)compared to the prototype.Both improvements have good noise reduction effect,improvement 2 has better effect on rotating noise of inlet and outlet.