Study On The Formation Mechanism Of Aerodynamic Drag Of Higher Speed Trains On The Open Air

With the rapid acceleration of high-speed trains,the problem of aerodynamic drag of trains becomes more prominent.The speed of the train further increased,making the aerodynamic drag contribute more and more to the total Aerodynamic DragThe drag of high-speed trains in stable operation can be roughly divided into two categories: basic drag and additional drag,and the former can be further divided into mechanical drag and air drag.Additional drag is due to ramps,line curves,and additional drag produces when the train passes through the tunnel.The mechanical drag is mainly the friction among the mechanical parts of the train,the rolling friction between the wheel pair and the track,the relative sliding friction between the wheel pair and the track,and the impactive drag of the train passing through the track connection.In this paper,the computational fluid dynamics CFD calculation software STAR-CCM+ based on the finite volume method(FVM)is used to numerically solve the formation mechanism of the aerodynamic dragin the steady operation of high-speed trains,including the effect of bogies,pantographs and rails on the aerodynamic drag of trains.And the aerodynamic drag of the train under different speeds and different grouping conditions.Research indicates:(1)For a entire train,the head and tail suffered the biggest drag,occupying 32.84% of the total vehicle drag.The main drag in the bogie system comes from differential pressure drag,and the pressure differential drag of each bogie is more than 90% of its own drag.Pneumatic aerodynamic drag accounts for about 5.3% of the aerodynamic drag of the train.The aerodynamic drag occupies the largest proportions of the pressure difference drag.The pressure drag of each component(except the balance bar and the lower arm)accounts for more than 90% of the total drag,both the balance bar and lower arm differential pressure drag also accounts for about 70% of its own drag..(2)Under different speed conditions,the aerodynamic drag,differential pressure drag and frictional drag of the train curve head gradually increase with the increase of speed,and the pressure differential drag ratio is basically stable at approximately 70%.(3)The aerodynamic drag coefficients of the 6 trains and the 8 train high-speed trains correspond to the trains,the curve heads,the curve tails and the straight bodies.