| With the increasing service speed of high-speed railroads in China,the aerodynamic problems of high-speed railroads become more and more significant.Due to the complex geomorphology of China,high-speed trains running in open lines and running through tunnels are two typical phenomena in the aerodynamic problems of high-speed trains.The impact oscillation of the surrounding disturbed air when the train is running in the open line may lead to structural deformation or stress concentration of the train,which affects the train’s driving safety.The pressure wave generated when the train passes through the tunnel will cause drastic changes in the pneumatic pressure load inside the tunnel,which may cause some damage to the tunnel facilities and train structure.At the same time,the propagation and generation of pressure waves in the tunnel will also be affected by the form of train formation and train running speed.To address the above problems,this paper applies numerical analysis to study the aerodynamic characteristics of high-speed trains with different group lengths through the tunnel and the fluid-structure coupling of trains running in the open line.The main work and findings of this paper are as follows:(1)Based on the RNG k-ε two-equation turbulence model and combined with the dynamic grid technology,the three-dimensional fluid calculation model of train-tunnel coupling was established for 3,6,and 8 group high-speed trains passing through the tunnel,and the three-dimensional non-constant turbulent flow of different groups of trains passing through the tunnel was numerically analyzed;the pressure wave generation and superposition reflection propagation law when trains passing through the tunnel were focused on;and the pressure changes at different spatial locations in the tunnel and different locations on the train surface were analyzed.(2)The effect of pressure wave on the pressure distribution law and peak change law of the tunnel wall surface and train surface under different grouping conditions,as well as the effect on the change law of the train aerodynamic resistance,was compared and analyzed,and the peak-peak pressure in the most significant pressure change area of the tunnel wall surface increased by 7.5% and 0.3% respectively when the train grouping length increased from 3 to6 and then from 6 to 8.The results showed that the rate of increase of pressure amplitude at the inner wall of the tunnel was not linear,but showed a trend of first increasing and then decreasing.(3)The effect of pressure wave on the pressure distribution pattern and peak change pattern of the tunnel wall surface and the train surface when the 8-vehicle high-speed trains pass through the tunnel at 350km/h,400km/h,and 450km/h was studied,and the pressure amplitude values of the head car increased by 44.45% and 26.71%,the pressure amplitude values of the tail car increased by 43.06% and 30.61%,and the pressure amplitude values of the middle car The pressure amplitude of the middle car increased by about 34.5%,so it can be seen that the change of speed has a greater effect on the pressure amplitude of the head car and the tail car.The results of the study can provide the reference for the study of train crossing tunnel problems and the arrangement of safety facilities in the tunnel.(4)ANSYS Workbench was used to establish a fluid calculation model and a structural analysis model for the train open-line operation,and a one-way fluid-structure coupling analysis was conducted for the train open-line operation under six-speed conditions.The influence of the change of pneumatic load on the deformation and stress concentration of the train structure is obtained,which provides some reference for the evaluation of the structural design and operational safety of the train. |
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