Aerodynamic Performance Of High-Speed Train With The Train Shape Design

Aerodynamic performance of high-speed train is closely related to its head shape. Besides considering aerodynamic drag, the aerodynamic configuration design of high speed train also should consider the impact of the aerodynamic lift, lateral force and torque on running smooth performance and stability. CAD, CFD and calculation of multi-body system dynamics were combined to implement Co-simulation of train shape-air-vehicle dynamics. Then, the relationship between aerodynamic performance and train shape was analyzed.The computational models for the properties of high speed train on basic aerodynamic, under crosswind, during passing events and passing tunnel were built by using CFD software FLUENT and multi-body dynamics software SIMPACK. The influence of the stream-lined nose length, the shape of fore- and after- body of the train, the lagest outline of train head and nose height on varies properties of aerodynamics and vehicle dynamics was deeply studied through these models. These conclusions can be abtained as follows:1. The properties of the train on basic aerodynamic, under crosswind, during passing each other and passing tunnel are improved significantly by increasing the length of the stream-lined nose.2. The horizon section line style has a greater impact on the basic aerodynamic characteristics while the longitudinal profile line shape has a larger influence on the performance of the train under strong crosswind and during passing each other. The basic aerodynamic performance is best when the fitted curve of the change rate in the cross sectional area of the train head is similar to an approximate linear function.3. The tail car with a double arched outline and a high nose will significantly reduce lift force and improve the lift performance of the end car. Increasing the nose height of tail car will slightly increase its drag. Increasing the train nose height will not improve the performance of trains crossing each other as the air pressure pulse and aerodynamic loads increase gradually with its nose height increases.4. The average drag of the train passing tunnel is increased 12% and the biggest drag in tunnel is increased 120% compared with the drag when it runs in open section. As the block ratio decreases, the aerodynamic loads, the pressure of train surface and tunnel wall will decrease by square. The pressure of tunnel wall and the peak to peak value of lateral force reduce in proportion of square relationship as the stream-lined length of the train head increases while high-speed train pass through a tunnel.5. The influence of the train head shape on vehicle dynamics is similar to its influence on the aerodynamic performance.