Simulation Of Aerodynamic Noise In 600km/h Vacuum Tube High Speed Train

With the rapid development of China's economy and the continuous improvement of people's living standards,people have put forward more and more high requirements for the quickness,convenience and comfort of transportation.The current transportation situation has gradually failed to meet the high demand for travel.We know that the running speed of the ground high-speed vehicle is affected by the dense atmosphere,and the maximum economic running speed of the train running under the normal atmospheric pressure is not more than 400km/h.According to the experimental data,the aerodynamic resistance of the train is proportional to the quadratic power of the train running speed,and the aerodynamic noise generated by the train running is directly proportional to the sixth to eighth power of the train running speed.Therefore,vacuum pipeline high-speed train is a potential development direction in order to realize ultra-high-speed train running on the surface of the earth.Vacuum piping trains avoid the impact on the surrounding environment,Therefore,aerodynamic noise to the interior noise has become the focus of vacuum pipeline train research.In this paper,the characteristics of near-field aerodynamic resistance,near-field aerodynamic noise and in-vehicle aerodynamic noise of vacuum pipeline trains under low pressure are simulated and analyzed by means of simulation and test verification.The main tasks accomplished are:(1)The basic theory of fluid acoustics and aerodynamic acoustics is studied,the source of aerodynamic noise of train is analyzed,and the main factor causing aerodynamic noise of train is found out that the fluctuating pressure of train surface is the main factor,which also lays a theoretical foundation for the following simulation work.(2)Analysis of aerodynamic Resistance in two-dimensional train model.According to the combination of different atmospheric pressure,different train speed and different pipeline blocking ratio,the aerodynamic resistance is analyzed and the relationship among them is determined.According to the requirements of the paper,the atmospheric pressure is 0.2atm and the running speed is 600km/h.The optimal blocking ratio is determined for subsequent analysis.(3)Analysis of near-field aerodynamic noise of train.The three-dimensional model of pipeline train is established by CATIA.After the grid is divided,the steady-state flow field is analyzed by Fluent,and the static pressure distribution and sound power distribution on the train surface are obtained.Secondly,the transient analysis is carried out to obtain the pulsating pressure at the position of the measuring point,which can be used as a sound source for the analysis of the interior noise of the vehicle,so as to analyze the interior noise of the vehicle.(4)Determine the sound insulation amount of the car body material under low pressure and normal pressure.Firstly,the sound insulation of aluminum alloy is simulated under the condition of 1atm and 0.2atm,and then the accuracy of the simulation results is confirmed by experiments.Then,according to the requirements of the paper,the sound insulation of the carbon fiber is simulated and analyzed under two kinds of atmospheric pressure,and the sound insulation of the carbon fiber is obtained for the follow-up analysis.(5)Simulation of aerodynamic noise in vacuum pipeline train.The acoustic simulation software Va One is used to simulate the aerodynamic noise in the train.Firstly,the acoustic simulation model of the train is established.Then the sound source and the insulation amount of the car body material obtained before are loaded on the model,and the internal noise condition of the train is calculated.According to the evaluation standard of the interior noise level,the aerodynamic noise in the vehicle is analyzed.