Research On Aerodynamic Noise And Noise Reduction Of Pantograph Of High Speed Train

With the rapid development of China’s railway industry,the running speed of high-speed trains is increasing,and noise pollution is becoming more and more serious.The results show that when the train speed reaches 300km/h,the aerodynamic noise increases sharply and becomes the main noise source,which is obviously larger than the wheel-rail noise.Pantograph aerodynamic noise is one of the important sources of high-speed train aerodynamic noise,so it is of great significance to study the generation mechanism and control of pantograph aerodynamic noise.In this paper,the pantograph of high-speed train is taken as the main research object,the near and far field aerodynamic noise of the pantograph is calculated and analyzed and the noise reduction measures are taken.The main research work is as follows:(1)Establish a computational fluid dynamics model for acoustic simulation and analysis of high-speed trains.According to the geometric model of CRH3,the aerodynamics simulation models of high-speed trains with and without bogies are established respectively.There are 16.9 million fluid units with bogies in consideration,and 15.8 million fluid units without bogies in consideration.In order to improve the calculation accuracy,three fluid boundary layers were considered to refine the complex regional mesh such as pantograph.(2)Based on the model,the steady flow fields of the high-speed train at speeds of250km/h,300km/h and 350km/h with or without bogies were calculated.The surface pressure,turbulent kinetic energy and surface acoustic power of the train were obtained under the two conditions.The calculation results show that the maximum surface pressure is located at the pantograph slide.The turbulent kinetic energy at the pantograph reached the maximum when the bogie was taken into account,and the turbulent kinetic energy at the head barrier pullover reached the maximum when the bogie was not taken into account.The maximum acoustic power of the train surface is located on the pantograph surface under the two conditions.(3)Taking the steady-state solution of the train as the initial condition,large eddy simulation(LES)was used to calculate the transient state.Taking pantograph as noise source,the near and far field aerodynamic noise of pantograph is calculated and analyzed by FW-H equation.The aerodynamic noise characteristics of pantograph at speeds of 250km/ H,300km/ H,350km/ H and with or without bogies are compared and analyzed.The total sound level and noise spectrum of monitoring points are obtained.The results show that the pantograph carbon slide plate,base and insulator are the main noise sources of the pantograph,and the overall aerodynamic noise of the pantograph without considering the bogie condition is reduced to a certain extent compared with considering the bogie condition.(4)The noise reduction design of pantograph is studied,and the structure of carbon slide plate of pantograph head is improved and sound insulation board is added on both sides of pantograph.The lower part of the pantograph is treated with trapezoidal groove and fillet,and the noise reduction effect of the pantograph is analyzed after the structural shape optimization.The research shows that the improved structure of the carbon slide can effectively reduce the barrier of the pantograph to the airflow,reduce the vortex falling off,and then reduce the aerodynamic noise.Secondly,the sound insulation board is added on both sides of the pantograph,which also has a good noise reduction effect.