Research On Aerodynamic Noise Of High Speed Maglev Train Based On Surface Blowing/Sucking

With the advantages of fast running speed and good safety performance,maglev train has become one of the focus of future development in the field of rail transportation.However,as the speed of the train increases,the proportion of aerodynamic noise in the total radiated noise of high-speed train increases,which has a serious impact on the surrounding environment and the health of passengers.The problem of aerodynamic noise is one of the bottleneck problems that restrict the further speed of maglev trains.At present,the research on aerodynamic noise control of high-speed trains is mainly focuses on train streamlining design and local structure optimization,while the application of active flow field control technology in the field of aerodynamic noise reduction of trains is still in the initial stage.Therefore,this thesis adopts the method of numerical calculation to study the influence of different surface blowing/suction modes on the aerodynamic noise characteristics of 350km/h high-speed maglev train.The main research work is as follows:(1)The characteristics of turbulent flow field around high-speed maglev train were investigated by CFD numerical method based on large eddy simulation and FW-H sound analogy.The distribution of main noise sources and far-field radiation of high-speed maglev train were obtained,and the rear streamline part of the train was determined to be the main radiation sources of maglev train.According to the characteristics of flow field and sound field,a scheme of arranging blowing/suction holes at three positions at the rear of the train is proposed.(2)In the tail of train streamline transition position of blowing/suction holes,and the noise reduction effect is most obvious when the position to 0.1U speed blowing,and the maximum sound pressure level in the far field reduced by 1.53 d B(A).While in the suction mode only has a noise increasing effect,and the amount of noise increase gradually increases with the increase of suction speed.(3)In the tail end of train nose separation position of blowing/suction holes,and noise reduction effects were achieved when the position to less than 0.2U speed blowing and less than 0.3U speed suction,of which the maximum change in sound pressure level was most obvious to 0.1U speed blowing,and the maximum sound pressure level in the far field was reduced by 0.84 d B(A).Subsequently,the aerodynamic noise showed an increasing trend,and the noise enhancement effect became more significant with the increase of blowing/suction speed.(4)In the side edge of the trailing car streamline position of blowing/suction holes,the noise reduction effect in the blowing mode shows a trend of increasing first and then decreasing with the increase of blowing speed,among which the noise reduction effect is most significant to 0.2U speed blowing,and the maximum sound pressure level in the far field is reduced by 1.46 d B(A).However,in the suction mode,with the increase of suction speed,the law of first noise reduction and then noise increase,and the noise reduction effect is weaker than that in the blowing mode.(5)Based on the optimal blow/suction modes at three positions,the combined blow/suction research results show that the far-field maximum pressure level of high-speed maglev train is reduced by 1.66 d B(A),which has a certain optimization effect compared with the single position blowing/suction,but its reduction is not significant.The research results provide the theoretical basis and engineering and technical support for the development of new drag and noise reduction technology and the sustainable development of high-speed,energy-saving and environment-friendly maglev trains.