Influence Of Bogie On Aerodynamic Characteristics Of High-Speed Trains

With the increase of train speed, aerodynamic forces have great effects on the safe operation of high-speed train and train slipstream effects may cause critical influence on the surroundings. At the same time, the force of wheel/rail becomes enhanced and the energy consumption of high speed train increases too. As a result, a higher demand is put forward for vehicle design and operation control. Due to the complication of bogie modeling and the huge amount of elements, the effort of bogie on aerodynamics was ignored in the past. In fact, the presence of bogie not only impacts the train's aerodynamic characteristics, but also has a great effect on cross-ventilation. Correspondingly, the wheel/rail interaction and the temperature of wheel are influenced. So there is an intricate ground effects between the train bottom and ground which is distinguished from plane aerodynamics. As a result, the results of the simplified model can not meet the demand of modern high-speed train development. In this paper, based on the previous research, a more detailed model is established to analyze the flow field and the influence of bogie on the train aerodynamic characteristics by numerical method. On the one hand, more accurate data is provided for the train design and operation control, on the other hand, a foundation is set up for the further researched on the thermal stress between wheel and rail and the influence of ground effect.According to the flow characteristics in the opening circumstance, on the basis of Navier-Stokes equation and k-εtwo-equation turbulence model, the numerical model of three-dimensional turbulent flow field is established. The aerodynamic characteristics and external flow field characteristics of the trail with and without bogies under different cross wind and train velocities are mainly studied by the commercial CFD software STAR-CD. The visual graph results are obtained. The flow velocity and pressure distribution around train and the characteristics of trail wake under different operating conditions are given. Taking the windshield into consideration, the pressure distribution on the windshield groove department is achieved. The drag force of the model with windshield decreases 3.4% compared with the model without windshield. In addition, the rotate motion of wheelset is realized in the numerical model through the node coincidence is controlled by programming, the velocity and pressure distribution characteristics around the wheelset with different rotation speed is analyzed by moving mesh technology.A more detailed bogie model is introduced into the train numerical aerodynamics, and the rotation of wheelset is realized by moving mesh technology in the paper, the effect of bogie model on aerodynamic force of high-speed train and the effect of wheelset rotation on flow field are numerically simulated under different train-speed and wind-speed, the data provides a reference for design and operation of high-speed train.