| With the continuous increase in the running speed of China’s high-speed trains,the aerodynamic problems during the train operations are become more and more significant.Especially under crosswind,the body of the high-speed train vibrates laterally due to the lateral aerodynamic forces,thereby changing the attitude of the train on the line.This will jeopardize the stability of the running train and the comfortableness of the passengers in the train,more seriously,will lead to the derailment or rollover accident of the train.In this thesis,numerical simulations are conducted to study the effects of different train speed,rail embankment structures,wind speed,yaw angles and wind models on the aerodynamic performances of the high-speed train in crosswinds The aerodynamic loads and the flow around the high-speed train are analyzed,and the results show that:(1)The aerodynamic forces and moments of the high-speed train in crosswinds vary greatly with the increase of the train speed,among which the head car is most affected by the change of the train speed;The maximum positive pressure on the train appears near the windward side of the train nose,and its value increases gradually with the train speed;The pressure coefficients on the high-speed train vary greatly in the streamlined front and rear part of the train,on the contrary,the vary slightly in between the front and the rear part of the train.(2)In crosswinds,the embankment structures have different effects on the aerodynamic performances of the high-speed train.On the half-cutting embankment,the high-speed train is subjected to the minimal aerodynamic forces and moments comparing with the other conditions.The pressure distributions in the flow field on the leeward side of the train differ when the highspeed train is running on different embankment structures.The minimum pressure in the flow field on the leeward side appears on the half-cutting embankment condition and attenuation of the pressure is weak on the double-track embankment.(3)On the double-track embankment,the aerodynamic forces and moments of the train increase with the increment of the speed and the yaw angles of the crosswinds.the train is subjected to the largest aerodynamic forces when the yaw angle is 90°.The maximum positive pressure on the head of the train offsets to the windward side.The flow velocity on the windward side of the train gradually increases,and the velocity magnitude in the far field does not change along the vertical direction.The vortex structures around the train increased significantly,and the strength of the vortex increased gradually.(4)The exponential crosswind model lead to smaller aerodynamic forces and moments of the train comparing with the uniform wind model;The pressure at different positions in the flow field on the leeward side of the train is small and attenuate faster along the transverse direction.The incoming flow velocity magnitude on the windward side of the train increases along the vertical direction The velocity magnitude and vortex strength around the train are small comparing with which under uniform crosswind model. |
