Research On Aerodynamics Of High Speed Trains In Strong Sand Environment

With the continuous development of science and technology,the moving speed of high-speed trains is increasing.During the high-speed operation of trains,the airflow around the vehicle body is disturbed by the near-ground,which makes the flow characteristics more complicated,thus generating interesting aerodynamics.Learn problems.However,at present,there are relatively few studies on the influence of strong wind and sand on the aerodynamics of high-speed trains.When the train runs on high speed,the law of the surrounding air flow field also has certain value during the train rendezvous.In this paper,the high-speed train is operated under strong wind and sand environment.Combined with the theory of aerodynamics,the aerodynamics of the train and its surrounding environment are studied.The dynamic grid technology is used to simulate the change of the flow field during the train rendezvous.The main research content includes the following aspects:(1)Establish a high-speed train physical model,select a mathematical solution model,and use a fluid-solid coupling method to simulate the dynamic behavior of a high-speed train running at a speed of 200 m/s at a high speed of 20 m/s,using the discrete phase model of FLUENT software(DPM).The discretization of sand and sand is carried out,and the airflow is continuously processed by the standard κ-ε turbulence model.The Navier-Stokes equation is solved by the Euler-Lagrangian method.The research shows that the pressure of the train is mainly at the front and the rear of the train.When the wind is affected by the wind,the surface pressure of the train will increase,the resistance of the train will increase,and the lift and viscous force will decrease.(2)Using the combination of theoretical separation and numerical simulation,the erosion characteristics of different particle sizes(0.1mm,0.3mm,0.5mm),different sand content on the front of the train,and the trajectory of the particles after the collision of the train are studied.Studies have shown that as the particle size increases,the erosion surface and erosion intensity increase,and the filling rate of sand content increases.From point erosion to surface erosion,the grinding increases;the sand is close.The car body and the nose tip are separated.When the sand elastically collides with the front of the car,it moves to both sides of the car body and above the car head,which is in good agreement with the theoretical analysis of the particles.(3)The aerodynamic model of the train rendezvous was established to study the flow characteristics around the air and the change law of pressure flow field under 7 different working conditions of the train rendezvous at different operating speeds(200km/h and 250km/h)in the calm environment.The research shows that the flow field of the train is complicated during the rendezvous,and the pressure value will increase with the increase of the speed of the rendezvous.The pressure distribution of the two vehicles has always maintained symmetry.The train’s inner wall surfaces changes little when the train meets and before the rendezvous.The pressure on the wall of the process will increase.When two cars are fully rendezvous,the pressure will reach the maximum,and the gas will be compressed during the rendezvous.