Aerodynamic Noise Source And Inner Aerodynamic Noise Research Of High Speed Train

Based on high-speed CRH3emu as the research object, this paper use CFD simulation software and related CAE finite element simulation tools to analyze the the causes of High-speed emu aerodynamic noise, the distribution regularity of noise source and the influence of interior acoustic environment.A CRH3CFD numerical calculation model of flow field is built,and calculate the pressure distribution on the surface of the body of emu respectively at different speed.Analysis results show that at the same speed, maximum static pressure point appear pantograph head.With the increasingt of running speed, the train surface pressure also increase rapidly,but the speed almost don’t change the surface pressure distribution,the biggest stress is proportional with the square of velocity.Broadband noise calculation showed that the surface acoustic power distribution similar to surface static pressure distribution, maximum surface acoustic power appears at curvature changes area as pantograph, bogie and car tip.All parts of the loudest power level Seems to have a linear relationship to the running speed.Extract Lighthill turbulence noise source of the car body area in the time domain through ICFD module,converte time domain turbulence noise to frequency domain through FFT,get all the parts of the acoustic pressure response and far field by acoustic frequency response results by Calculating the sound propagation.The simulation results show that pantograph, front, rear and bogie are the main noise source,and the maximum sound pressure level located at the pantograph bow and its head and supporting seat.Extract time domain of the side window wall pressure results from fluent transient result, and get frequency domain side window pressure through FFT.Take side window fluctuating pressure in frequency domain as boundary condition of acoustic response to get middle car cavity acoustic response.The calculation results show that aerodynamic noise is a kind middle frequency and high frequency noise.Acoustic energy is mainly distributed in the range of140hz-280hz.Laying of porous sound absorbing material on side walls,floor and roof of middle car can effectively reduce the size of the aerodynamic noise,especially for the high frequency noise peak has significant noise reduction effect,and sound-absorbing materials have smaller absorption effect on low frequency noise.