Research on the Impact of Exterior Cab Shape Parameters on Drag Characteristics of Double-Arch High-speed Trains
The aerodynamic performance of a high-speed train is intimately linked to its head shape.In order to reduce the aerodynamic drag during the operation of high-speed trains,five distinct head types with varying parameters are developed for double-arch trains and numerical calculation models for high-speed trains are established by modifying the cab height and front window transition shape of the double-arch high-speed train.The three-dimensional,steady,incompressible N-S equation and RNS method are used to simulate the flow field of five models running at a constant speed in open air,the influence of train cab height and front window transition shape on resistance characteristics of the double-arch train in the stable operation of the open air is comparatively analyzed.The following conclusions are drawn:under the same running conditions,the pressure difference in the flow field around the train mainly occurs in the transition area at the front window of the driver's cab and above,and the external geometric parameters of the driver significantly affect the aerodynamic drag of double-arch high-speed trains.The aerodynamic drag coefficient decreases as the height of the design position of the curvature transition of the front window of the train head increases,the maximum difference is 14.5%,and the distribution range of high pressure in the head car is reduced.The design inclination of the front window of the cab is reduced and the maximum pressure on the front window of the cab is lowered,resulting in a 13.4%decrease in the train's aerodynamic drag coefficient.When the plane is chosen to replace the curved surface as the transition surface of the train cab's front window,the positive pressure at the front window of the cab can be reduced,but the negative pressure above the cab will be intensified,and the aerodynamic drag coefficient of the train is decreased by only 3%.To achieve optimal drag reduction,it is recommended to raise the driver's cab height within a reasonable range and decrease the inclination of the front window surface on double-arch high-speed trains.
high-speed traindouble arch head typeexterior shape of the cabnumerical simulationpneumatic drag
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