Research On Windscreen And Pantograph Noise Control Technology For High-speed Trains

With the continuous improvement of high-speed train speed,the noise problem is more and more serious,in the current high-speed train running speed,the aerodynamic noise problem is the most prominent.At present,the workshop connection windshield of Fuxing high-speed EMUS adopts all-inclusive windshield,with holes left on the side of the windshield,through which the air flow is easy to form strong cavity noise.In addition,pantograph is the main flow receiving device on the roof,and its complex structure forms a large disturbance to high-speed gas,forming a large wind torrent noise.Therefore,noise reduction analysis of these two components is the key to solving the aerodynamic noise of high-speed trains.Based on Lighthill sound analogy theory,this paper adopts CFD and acoustic solver coupling research method to analyze the train outflow field and pantograph external field noise through numerical calculation.Different noise control measures are adopted to explore the noise control effect.The main achievements and conclusions of this paper are as follows:(1)Real vehicle noise test.The noise condition inside and outside the vehicle in the windshield area at 350 km/h was investigated through the real vehicle noise test,which provided data support for the establishment of the simulation model.The analysis of the sound pressure level spectrum in the car shows that the sound energy in the car is mainly distributed below 1000 Hz(2)Windscreen area noise control technology.Fluent software is used for numerical calculation to analyze the velocity and pressure of the train outflow field,and the surface dipole sound source distribution in the windshield area is obtained.Acoustic module in Virtual Lab software was used to explore the sound absorption and noise reduction effect of adding sound absorption materials to the end wall,and the noise reduction effect in the middle of the cavity reached nearly 10 d B.The space between the inner and outer windshields is also designed to absorb sound,and the noise reduction effect in the middle of the cavity is more than 15 d B.(3)Analysis of external flow field and external sound field in pantograph area.The velocity and surface pressure of flow field in pantograph area,the distribution of surface noise source in pantograph area and the external sound field of pantograph are analyzed by numerical calculation,including the directivity and transverse attenuation of pantograph noise.The directivity of different frequencies is very different,and the transverse attenuation rate of sound is fast first and then slow,which conforms to the law of geometric attenuation.(4)Pantograph area noise control technology.Firstly,the noise reduction effect of the pantograph surface with additional sound absorbing material is explored.After the addition of sound absorbing material,the acoustic radiation capacity of the pantograph is weakened.The noise reduction effect around the pantograph is above 1 d B,and the best can reach 1.57 d B.In addition,by opening jet holes on the lee side of the pantograph rod,it can be obtained that the acoustic radiation capacity of the pantograph is weakened at some frequencies after jet flow,and the sound pressure level around the pantograph decreases at different levels,and the sound pressure level in the monitoring point decreases by up to 2 d B.In addition,the active jet noise control effect of the pantograph under other different working conditions is also studied.