A Study On The Aerodynamic Characteristics And The Operational Safety Of A High-speed Train Under The Effect Of Crosswind And Rain

With the rapid development of high-speed railways and the continuous improvement of running speed,the aerodynamic performance and operational safety of high-speed trains have increasingly become a hit that cannot be ignored.Due to Chinese vast territory as well as complex and changeable climate,high-speed trains are prone to encounter severe weather such as strong wind and rain when running,resulting in the worse aerodynamic performance and operational safety.Therefore,it is of great significance to study the aerodynamic characteristics and the operational safety of high-speed trains under the effect of crosswind and rain.In this paper,the multiphase flow calculation in the rain is carried out,and the accuracy of the Eulerian-Lagrangian approach is verified.Based on this method,the length in the front and the windward side of the train is studied.What's more,the accuracies of aerodynamic models with wind and no wind are verified.The aerodynamic models of the high-speed train under rain and wind-driven-rain environment are respectively established,then the aerodynamic characteristics of the train with different train speeds and rainfall intensities are analyzed,and the aerodynamic characteristics of the train with different yaw angles,rainfall intensities and resultant wind speeds are analyzed.Then the fitted relationship of these are given.In addition,the system dynamic model of the vehicle is established,then the influence of different rainfall intensities on the operational safety zone is studied.The results show that the length in the front and the windward side of the train should reach more than 1.5 times of the horizontal distance of raindrops movement.Comparing to no rain environment,the drag force coefficient of the head vehicle increased by 13.59% and the lift force coefficient of the tail car increased by 12.7% in rain environment,at the train speed of 200 km/h and the rainfall intensity of 500 mm/h.In wind-driven-rain environment,the resultant wind speed will affect aerodynamic coefficients.At the yaw angle of 10.2°,the lateral force coefficient,lift force coefficient and roll moment coefficient around the top of the leeward side rail will increase by 4.7%,6.29% and 8.56% respectively.Aerodynamic coefficients of the vehicle can be approximately fitted as polynomials of the rainfall intensity,the resultant wind speed and the yaw angle.Vehicle system dynamics analysis shows that,when the rainfall intensities is from 100 mm/h to 500 mm/h,the operational safety zones of high-speed train decrease by about 0.56% to 3.2%.