Numerical Study On Aerodynamic Noise Of High-speed Train

Aerodynamic noise generated by high-speed trains is closely related to speed.With the increasing speed of national high-speed trains,aerodynamic noise generated by high-speed trains during high-speed operation becomes increasingly prominent,which becomes the main source of operating noise.Due to the limitations of experimental testing and analysis of aerodynamic noise generated by high-speed train operation,it is necessary to conduct numerical simulation analysis.The main research of this paper is as follows:aerodynamic noise generated by high-speed trains is closely related to the speed.As the national high-speed rail continues to speed up,the aerodynamic noise generated by high-speed trains during high-speed operation has become increasingly prominent,and it has become the main source of operating noise.Since the actual experimental test and analysis of the aerodynamic noise generated by the high-speed train running at high speed is time-consuming and labor-intensive,it is very necessary to do numerical simulation analysis on it.The main research of this paper is as follows:(1)The aerodynamic model of CRH3 high-speed train and independent pantograph with equal ratio of 1:1 is established.The geometric model is properly simplified,and the calculation model is three car formation,retaining the window deflector,bogie,air conditioning,windscreen,baffle and pantograph and other main geometric parts;The independent pantograph consists of bow head,hinge and base related parts.The reasonable fluid control domain is established and the simulation calculation is carried out.Simulate the independent pantograph.On the same steady-state results,select the large eddy simulation and the separated eddy simulation turbulence model for transient calculation,and compare and analyze the difference in aerodynamic noise generated by the pantograph simulated by the two turbulence models,the calculation results show that the separated vortex simulation produces large vorticity and high air velocity behind the pantograph,which results in a large noise value at the monitoring point.(2)The aerodynamic noise simulation of independent pantograph is completed.Firstly,the steady-state flow field of the pantograph is calculated.Based on the steady-state results,the large vortex model and the separated vortex model are selected respectively to carry out transient calculation,and the difference of aerodynamic noise generated by the pantograph of the two turbulence models is compared and analyzed.The calculation results show that the separated eddy simulation produces large vorticity and high airflow velocity behind the pantograph,and the noise value of the monitoring point is larger.Taking different parts of the train and different parts of the pantograph as the noise sources to study their contribution to the aerodynamic noise of the whole vehicle and the pantograph,the results show that the contribution of the whole vehicle from large to small is the leading car and the middle car.(3)Fluent and Star ccm+ were used to complete the numerical simulation of three marshals of high-speed trains.The surface pressure nephogram and sound power nephogram of trains at different speeds are analyzed,and the noise value of monitoring points is compared.The results show that there is little difference between the two software calculation results.From the perspective of maximum pressure and sound power,the result calculated by Fluent is larger,and the average sound pressure level of the vehicle monitoring point is less than 1.5d B larger than that of Starccm+.(4)Taking different parts of the train and pantograph as noise sources,the contribution of local structure to the vehicle and the pantograph aerodynamic noise was studied and analyzed.The results show that the contribution of the whole vehicle from large to small is head car,middle car,tail car,bogie,bogie compartment,pantograph and wind shield.Pantograph contribution in descending order is the bow head,pantograph cavity,base and hinge.(5)The flow characteristics of far field aerodynamic noise and surrounding flow field under three working conditions with bogie,without bogie and without bogie cabin are compared and analyzed.The results show that the far-field aerodynamic noise is the largest under the bogie condition,and the other two conditions have little difference.The bogie area affects both the flow field pressure and vorticity around the pantograph,and then affects the far field aerodynamic noise of the pantograph.