Analysis of aerodynamic load law of intercity EMU with different length under cross-wind
Crosswinds play a significant role in the sway and instability of operating intercity electrical multiple units(EMU)trains.To improve the safety and stability of EMU trains and determine the optimal train formation,this paper intended to investigate the aerodynamic loads on EMU trains under crosswinds.Based on the three-dimensional unsteady incompressible DES turbulence model,a new intercity EMU train was adopted to study the influence of characteristic loads on the train with different lengths under crosswinds or without crosswinds.By analyzing the change of flow field around each carriage when the train is running on the viaduct,the variation law of aerodynamic loads on the train was explored.The results show that without crosswinds,head and tail cars experience higher drag force coefficients compared to middle cars,with little change as speed increases.The lift force coefficient of the tail carriage is slightly greater than the head and middle carriages,and changed insignificantly with increasing train speed.With crosswinds,the drag force coefficient of the head carriage increases reversely,and the drag force coefficient of the tail carriage increases positively.Additionally,the force coefficient of the head and tail carriages decreases with increasing train speed,while the middle carriages remain basically unchanged.The lift force coefficient of the head carriage is slightly smaller than the tail and middle carriages.The longer the formation,the smaller the fluctuation in the lift force coefficient of the middle carriages,and the lift force coefficient decreases with increasing train speed.For the side force coefficient,crosswinds cause the largest side force coefficient on the head carriage,followed by the middle carriages,and the smallest on the tail carriage.The longer the formation,the smaller the fluctuation in the side force coefficient of the middle carriages.Crosswinds cause the largest overturning moment coefficient in the reverse direction on the head carriage,then the middle carriages,and finally the tail carriage,which decreases with increasing speed.In addition,trains with different formations have different aerodynamic characteristics during operation.Long formation trains have better stability and comfort under the same conditions,and the train head has the largest fluctuation in various loads,which needs special attention.The research can provide scientific basis for optimizing train design and improving the operation safety and stability.In the design and formation of intercity EMU trains,long formations would be preferred to ensure safe and stable train operation.
国家科技期刊平台
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