Effect Of Wind And Rain Coupling On Operation Safety Of High Speed Train

With the rapid development of high-speed railways,the running speed of high-speed trains continues to increase,and train safety issues have become more pronounced.China has a wide range and across a variety of climate areas.Gale and rainfall are common meteorological environments in various regions,which can not be ignored for the safe operation of high-speed trains.When high-speed trains are operated under stormy weather,the aerodynamic loads of trains vary greatly due to strong wind and rainfall,and the safety indicators of trains will be worse.Therefore,it is of great significance to study the wind-rain coupling effect on the operation status and safety of high-speed trains.In this paper,the simplified model of the CRH3 high-speed train is adopted to study its aerodynamic characteristics and operation safety in the combined environment of wind and rain.First,a simplified model for trains with three compartments was established.In the FLUENT software,the high-speed train operating conditions was simulated to analyze the train surface pressure and the surrounding flow field changes.According to the different rainfall types,the uniform rain phase model,the M-P raindrop spectrum model and the Gamma raindrop spectrum model are used to compile the UDF program for the raindrop spectrum model,and then the rainfall environment is simulated by the discrete phase model.The three rainfall models are compared to analyze Variation of the aerodynamic characteristics of the high speed train with the rainfall intensity,as well as the changes of the aerodynamic load of the train under different crosswind speeds and different train speeds.Then the multi body dynamic model of train is established by using SIMPACK.The aerodynamic forces and moments of the train under the rainfall of the Gamma Raindrop spectrum were used as incentives to load the multi-body dynamic model of the train.The derailment coefficient,rate of wheel load reduction,axle lateral force,and wheel-rail vertical force of the train multi-body dynamic safety evaluation index were used to analyze the impact of wind-rain coupling on the safety of high-speed trains.The results show that the change of rainfall intensity has little effect on its aerodynamic characteristics when high-speed trains are operated under wind and rain conditions.Comparing the operating conditions of the following train with different rainfall models,under the conditions of uniform rainfall,the resistance of the train under the rainfall intensity of 100mm/h was increased by 11.8%and the lateral force increased by 5.2%compared to that in the absence of rain due the presence of crosswind.However,with the Gamma spectrum rainfall model,the resistance of the train is only increased by 5.8%and the lateral force is increased by 1.6%under the rainfall intensity of 100mm/h.Compared to the Gamma spectral rainfall model,the aerodynamic forces and moments of the train under the uniform rainfall model are significantly larger.Because the uniform rainfall of rain does not take into account the distribution of raindrop particles,the estimation of raindrops is relatively simple;while the Gamma spectrum rainfall takes into account the distribution of raindrops of different diameters,and the description of rainfall conditions is more realistic.The aerodynamic loads of the following train under the rainfall of Gamma spectrum were applied to the multi-body dynamic model of the train to obtain the safe speed of the high-speed train when it was operating under wind and rain conditions.Under the condition of rainfall intensity of 60mm/h,when the cross-wind speed is 28m/s,the train derailment coefficient and wheel load reduction rate are allowed to be 250 km/h at safety limits of 0.8.According to the operating safety area of the train,the maximum safe operating speed of the train is 250km/h under the condition of the cross wind speed of 28m/s,and the train is more safely at the speed of 360km/h when the cross wind speed is not more than 14m/s.