Aerodynamics Simulation And Anti-Slip Analysis For EMUs Parking In Wind Area

In response to the EMUs station or interval unpowered stay sneak escape problems,the anti-slip measures of the EMUs are clearly stipulated in Railway Technology Management Discipline which was made by China's railway department.However,this method is not completely applicable to the trains running on the second double-line of Lanzhou-Xinjiang railway and Beijing-Zhangjiakou intercity railway,which are in strong winds or on steep sections of the line.Therefore,it is necessary to carry out the research on the comprehensive stress of the EMUs under the conditions of high wind area and large line slope and determine determine the number of hand brakes or iron shoes that need to be set when the vehicle staying without power under different conditions,Furthermore,the braking efficiency of the vehicles in the wind zone is improved to ensure the safety of the EMUs.Based on the analysis of the train aerodynamics and the train anti-slip principle,this paper analyzes the aerodynamic forces of the stationary EMUs in three different subgrade structures,by using the method of computational fluid dynamics(CFD),and studies the aerodynamic characteristics of the stationary emu in strong wind area.Finally,the detailed anti-slip measures are developed for all the possible slipping conditions of the staying EMUs.Compared with the existing anti-slip measures,the measures developed in this paper are more comprehensive and the anti-slip equipment setup is more efficient.This is of great significance for the railway departments to further improve and supplement the anti-slip management methods of high-speed trains operating in the wind zone,ensure the safe operation of high-speed trains in the wind zone,and improve the safety and work efficiency of railway operations in the wind zone.The aerodynamic simulation results of EMUs stopping in strong wind area show that the longitudinal force of EMUs stopping in three sections increases with the increase of wind speed under strong longitudinal wind and no wind direction.The longitudinal force is proportional to the second power of wind speed.In different subgrade structures,the longitudinal force of trains is within the range of 5 kN.Under the condition of strong longitudinal wind and wind direction Angle,the overall longitudinal force of three sections of emu decreases with the increase of direction Angle,while the air lift increases with the increase of wind direction Angle.The change of air lift is the most significant in embankment section,and the maximum air lift reaches 700 kN.However,for the flat section and the cutting section,the air lift shows a slow growth trend,the maximum value of the flat section is about 300 kN,and the maximum value of the cutting section is only 150 kN.The calculation results of anti-slip force when the emu stops in strong wind area show that:when the parking brake of EMUs is normal,the parking brake can meet the requirements of staying on the line with a wind speed below 40 m/s and a slope below 30 ‰,without slipping.When the slope is above 33‰,anti-slip measures must be externally applied.When parking brake fails,anti-slip force of EMUs under most working conditions is positive,so anti-slip measures must be externally applied.When the wind direction Angle is within the range of 0°?60°,the anti-slip force required for the EMUs to park safely at the three sections is positive.When the wind direction Angle is within the range of 60°?90°,the anti-slip force ratio of the EMUs decreased by about 20?50 kN.Under the same line slope condition,the most unfavorable wind directions of EMUs parked at different sections is analyzed,we could obtain the most unfavorable wind direction angle of EMUs parked at flat section is 20° and the most unfavorable wind direction angle of EMUs parked at embankment section is 20°,and the most unfavorable wind direction Angle of EMUs parked at embankment section is 30°.