Simulation Of Pantograph Pneumatic Noise Source And Noise Reduction Design For High-speed Trains

China’s railroad industry continues to develop,high-speed trains continue to break through new high speed,high-speed train operation induced by the pneumatic noise is also becoming more and more serious,and affect the comfort of passengers and the surrounding environment along the railroad line.The pantograph is the main source of pneumatic noise of high-speed trains,so it is meaningful to study the pneumatic noise caused by the pantograph of high-speed trains and control it to reduce the pneumatic noise of high-speed trains.This paper analyzes and studies the near-field and far-field aerodynamic characteristics of the pantograph area of CRH3 high-speed trains,and improves and optimizes the pantograph structure to reduce the aerodynamic noise of high-speed trains.The specific research contents are as follows.(1)Based on the CRH3 high-speed train,a three-crew high-speed train and an independent pantograph computational fluid dynamics model are established by applying Hypermesh,in which the three-crew train model includes the head car,intermediate car,tail car,pantograph(bow head,hinge,bottom frame,cavity)and six bogies,and the train is 76.4m long,3.3m wide and 3.6m high;the independent pantograph model consists of bow head The independent pantograph model is composed of bow head,hinge and bottom frame,and the independent pantograph is 2.4m long,1.9m wide and 1.6m high.(2)Fluent software is applied to simulate the aerodynamic characteristics of the three-formation train and the independent pantograph.Firstly,the steady-state flow field is calculated,and the surface pressure,turbulent kinetic energy and surface acoustic power of the three-formation train and the independent pantograph at different speeds are analyzed.The calculation and comparative analysis show that the pressure at the windward side of the pantograph head is the highest,the turbulent kinetic energy at the pantograph area is the highest,and the sound power level at the pantograph surface is the highest for the three-group train and independent pantograph models.(3)Based on the steady-state results,large eddy simulation(LES)is applied to calculate the transient flow fields of three-group trains and independent pantographs,and the FW-H model is applied to calculate and analyze the pantograph near-field aerodynamic noise characteristics at different speeds for three-group trains and independent pantographs respectively when the pantographs are used as noise sources.The calculation results show that the pantograph head is the main noise source in the pantograph area.(4)The far-field aerodynamic noise was analyzed when the pantograph,bowhead,hinge,underframe and cavity were used as noise sources for the three-group trains running at300km/h and 350km/h respectively,and the contribution of bowhead,hinge,underframe and cavity to the far-field noise of the trains was analyzed,and it was found that the contribution of bowhead was the largest among the pantograph-induced aerodynamic noise.(5)Based on the pantograph surface static pressure,turbulent kinetic energy,sound power level and train far-field aerodynamic noise distribution law,structural optimization was carried out at the pantograph head to reduce the pantograph aerodynamic noise by trapezoidal slotting of the lower part of the pantograph head.Through the comparison analysis of the pantograph aerodynamic noise before and after the optimization,the feasibility of opening trapezoidal slot in the pantograph head to reduce the aerodynamic noise is verified.