The Characteristics Of Aerodynamic Study On CRH380A High-speed Train

A strong aerodynamic effect is generated when two high-speed trains passing by each other,the pressure pulse may damage windowpanes,each compartment will be affected by aerodynamic forces and moments thus emerges driving instability,hunting movements and even rollover accidents.CRH380A,as a self-designed high-speed train,of which the running speed can reach 380km/h,occupies an important position in railway business.Whether its characteristics of aerodynamic are better than other high-speed trains,whether it will produce smaller pressure waves and aerodynamic forces,both of them should be compared and discussed.Thus in this paper calculate aerodynamic loads of CRH380A when two trains pass by each other in different situations by using CFD finite volume method and moving grid technology based on three dimensions,transient,compressible Navier-Stokes equations combined with k-? two equations turbulence model and compare CRH380A with CRH2,CRH3 and Germany Inter City Express trains' aerodynamic loads to determine aerodynamic characteristics of CRH380A.The results show that:1.The pressure pulse produced by two trains passing by each other in the open air is proportional to the square of speed,the maximum negative pressure may occur is a quadratic function of speed when two trains intersecting in a tunnel.Due to the existence of the entrance effect,the maximum negative pressure may occur in tunnel is much bigger than that in the open air at the same speed.2.The change of aerodynamic loads of each CRH380A's compartment is proportional to the square of speed under the open air condition.With the increase in the length of the train,posterior compartments will suffer more positive lift force and its pitch moment commutates many times,vertical forces become worse.3.The lateral force,yaw moment and rolling moment of CRH380A are proportional to the square of speed when two trains passing through in tunnel.Although the lift force and pitching moment do not follow this law,the amplitude of them is a quadratic function of speed.4.Pressure pulses of CRH380A crossing each other in the open air are much smaller than other high-speed trains due to the improvement of head train's shape,its running safety has been improved greatly.The maximum negative pressure may appear of CRH380A intersecting in a tunnel is the smallest but differs little compared with CRH2,CRH3 and ICE,the influence of head train's shape on pressure pulses becomes smaller.5.The amplitude of aerodynamic forces of CRH380A is the smallest when two trains rendezvous in the open air and in a tunnel respectively,which indicates CRH380A owns the best running stability.In addition CRH380A has the smallest amplitude of lift force,pitching moment and drag force,thus it has the best aerodynamic characteristics.