Study On The Running Safety Of Train Under Rain And Sandstorm Conditions

The aerodynamic characteristics and operational stability of high-speed train will change significantly under the action of crosswind. Our country vast in territory, the running high-speed trains will often encounter storms and sandstorms, so it is necessary to study the aerodynamic characteristics and operational stability under the extreme weather conditions.With the real CRH3 type EMUs as the object of study in this paper, their aerodynamic characteristics and operational stability under the extreme weather conditions are analyzed. Based on the 3-D steady incompressible Navier-Stokes equations and standard turbulence model, the discrete phase model and Eulerian two-phase model are respectively used to simulate the high-speed train running under the conditions of storms and sandstorms. This thesis establishes and numerical calculates a dynamic simulation model of high-speed train by using software FLUENT, and it also analyzes the external flow field characteristics and aerodynamic characteristics of the train. A multi-body system dynamic model is established by using the multi-body system dynamic simulation software SIMPACK based on the computational multi-body dynamics theory. Then the loads, obtained by simulation calculating of the train running under the extreme weather, were dealt with as the external loads on the multi-body system dynamic model. With reference to the safe operation criteria for high-speed trains, this paper gives the running security domain of high-speed trains under the conditions of storms and sandstorms.The research results shows that in the wind driven rain condition, rainfall intensity has little effects on the aerodynamic characteristics of the high-speed train, and aerodynamic loads with the increase of rainfall intensity increases slightly. Compared with no rainfall condition, the train surface pressure and aerodynamic loads increase significantly under the rainfall condition. In the sandstorm condition, the train surface pressure and aerodynamic loads also increase significantly compared with no dust conditions. With the increase of dust concentration, aerodynamic loads have a tendency to increase, but the growth is small.After analyzing the safety indexes of high-speed train running under the conditions of storms and sandstorms, this thesis gives the running security speed. Under the crosswind speed less than 12m/s, the running security speed of train is under 400km/h in rainfall intensity of 60mm/h. When the operation speed of train less than 230km/h, the train can run safely in the crosswind condition, which speed is less than 30m/s. However, under the crosswind speed less than 13m/s, the running security speed of train is under 400km/h in strong sandstorm condition. When the operation speed of train less than 220km/h, the train can run safely in the crosswind condition, which speed is less than 30m/s. The maximum safe running speed set according to the rate of wheel load reduction is the most conservative, but the train running speed set according to the vertical force of wheel/rail is very high that the train is more easily to overturn. The results of the high-speed train running under the conditions of storms and sandstorms in the thesis provide reference to the safe operation of high-speed trains.