Numerical Study On Aerodynamic Noise Of High-Speed Train

The aerodynamic noise generated by high-speed train is closely related to the running speed.With the increase of train speed,the aerodynamic noise value increases the most.When the running speed is higher than 300km/h,aerodynamic noise becomes the main noise source of high-speed train.On the one hand,aerodynamic noise can be reduced by structural modification in the design stage.On the other hand,it is convenient to adopt more targeted noise reduction measures in noise reduction work.The main research contents of this paper are as follows:(1)The 1:1 computational fluid dynamics model of CRH3 high-speed electric EMUS is established,which consists of one head car,one middle car and one rear car.The structure of bogie,pantograph,deflector plate and pantograph deflector is retained.In order to reduce the calculation time and improve the calculation efficiency,a calculation model based on middle face was established by taking the plane perpendicular to the ground,along the direction of the vehicle and passing through the center of the vehicle as the symmetric plane.According to the actual situation,the boundary conditions are applied to calculate the external steady flow field using the k-ε standard turbulence model.At the same time,the wide band noise source model is used to calculate the aerodynamic noise source on the car body surface.The distribution of surface pressure and sound power level is calculated.Through observation,it can be found that the nose and bogie bear the greatest surface pressure,and pantograph is the most concentrated part of sound power.(2)The transient calculation was carried out with the steady-state results calculated at different speeds as the initial conditions.The large eddy simulation method was adopted in the transient calculation,and the FW-H equation was used to set up 8 monitoring cross sections in the longitudinal direction of the vehicle,and 9 noise monitoring points were set up in each monitoring cross section.The total sound pressure level of the far-field monitoring points was calculated.The analysis shows that the locomotive,bogie and pantograph are the main noise sources.(3)A CFD model of aerodynamic noise dimension reduction for high-speed trains was established,and the steady-state external flow field characteristics were calculated at 300km/h speed using the k-ε standard turbulence model.Taking the steady state results of the CFD model of aerodynamic noise reduction of high-speed train as the initial conditions,the large eddy simulation method and ACTRAN-SNGR method were used to carry out aerodynamic and acoustic calculations respectively,and the sound pressure levels at the monitoring points were analyzed and compared.The results show that the ACTRAN-SNGR method can be used to quickly check the noise reduction effect and has practical application significance.(4)Based on ACTRAN-SNGR streamlined design optimization method for bogie package cabin,wrapped around the cabin damper and beneath the surface of the vertical plane is modified to streamline,add a radius of 0.2 m,Angle of 60 the rounded design,noise reduction design study,results show that the aerodynamic design optimization scheme can effectively reduce the surface pressure,It has good noise reduction effect.