Research On Influence Of Two-phase Wind-sand Flow On Aerodynamic Performance Of High-speed Train

The Lanzhou-Xinjiang High-speed Railway is the first high-speed railway in Northwest of the country that pass through the windy areas and the desert Gobi.The environment along the line is extremely harsh,and strong winds and sands occur frequently.In this dissertation,Fluent software is used to compare and analyze the changes in the aerodynamic performance of the vehicle under different working conditions such as crosswind,sandstorm and windbreak wall.First,establish a three-dimensional simplified model of a highspeed train consisting of three cars,create the calculation domain of the train’s external flow field,and divide the unstructured grid with good quality.Secondly,a calculation model of twophase wind-sand flow is established,and the relevant boundary conditions are defined by a custom function to numerically solve the aerodynamic performance of the train.Study the changes of wind speed and vehicle speed on the aerodynamic performance of trains,and compare and analyze the changes in crosswind conditions and wind-sand conditions.Finally,in order to prevent the train from overturning,a windbreak wall is added to compare and analyze the changes in aerodynamic performance of high-speed trains.Through numerical simulation calculation,the results show that:(1)In crosswind conditions,wind speed has a greater influence on the lateral force and overturning moment.For example,when the vehicle speed is 200km/h and the wind speed is increased from 10m/s to25m/s,the lateral force of the leading vehicle has increased by 270.19%,and its overturning moment has increased by 340.13%.The leading vehicle has poor smooth operation.The speed of the train has a greater influence on the resistance of the train.(2)The addition of the sand phase in the wind-sand flow increases the collision between the airflow and the train,increases the load of the train,and intensifies the asymmetric distribution of the pressure between two sides of train,so that the aerodynamic pressure difference becomes larger and the lateral force and overturning increases significantly.Taking the vehicle speed of 200km/h and the wind speed of 20m/s as an example,the lateral force of the leading vehicle under the wind and sand conditions has increased by 7.76% compared with the crosswind conditions.(3)After the windbreak wall is installed,most of both sides of the train are in the negative pressure area,the pressure force from both sides has little difference,and the reduction of overturning moment is great.For example,when the vehicle speed is 200km/h and the wind speed is 20m/s,lateral force is decreased for the leading vehicle by 92.22%,and the stability of the train is better.Therefore,the train can still run at high speed in the wind and sand environment.