Train Aerodynamic Characteristics And Optimization Measures Of Bridge And Other Types Of Line Transition Section

In case of the crosswind,bridges,tunnels,embankments and cuttings have different influences on the distribution of the wind field above the tracks.They also affect the aerodynamic characteristics of the high speed train and the safety of train operation.As the train passes the transition sections of bridge-tunnel,bridge-cutting and bridge-embankment,the aerodynamic force of train must vary in different range.First,the models of the transition sections of bridge-tunnel,bridge-cutting and bridge-embankment have been built.After the process that the train passes through the transition section is simulated with the dynamic mesh technique,the results have been compared with the wind tunnel test,which has verified the rationality of the simulating method in this paper.The aerodynamic characteristic of three transition sections of bridge-tunnel,bridge-cutting and bridge-embankment at the train velocity of 250km/h under five different kinds of wind speed is calculated and the aerodynamic characteristic of the train at the wind speed of 25m/s under five different kinds of vehicle speed is also calculated.The extreme value of the aerodynamic force has been collected when train passes the transition section,the change rules of the transverse and lift force at the head train,the middle train and the tripper train under different kinds of the train speed and the wind speed have been explored.Considering wind barriers are put on both sides of the bridge,train’s aerodynamic force is optimized when passing the transition section.The results of the transverse and lift force have been compared with the results without wind barrier.The research shows:there are greater differences in aerodynamic force when the train passes different transition sections and the change rule of aerodynamic force vary at the head train,the middle train and the tripper train.The wind speed has greater influence in transverse and lift force and lesser impact on the train speed.The head train,the middle train shows a clear change law in terms of different wind speed and train speed,while the tripper train shows a complex rule.Wind barrier on both sides of the bridge can decrease the change of the amplitude of the transverse and lift force when the train passes transition section,the increase of wind barrier can effectively optimize the train’s aerodynamic force through the transition section.