Numerical Simulation Analysis Of Wake Field And Wake Vortex Characteristics Of High-speed Train In Vacuum Pipeline

With the continuous development of rail transit,people have higher and higher requirements for the running speed of trains.However,problems such as air resistance and aerodynamic noise have severely restricted the further development of traditional high-speed rail trains.In this regard,the construction of a vacuum tube high-speed train system has become a solution for the substantial increase in train speed.The operation of high-speed trains in vacuum ducts is a kind of aerodynamic problem of low-pressure and high-speed airflow.It is of great significance to explore the aerodynamic characteristics of trains in vacuum ducts.In this paper,a simplified model is constructed based on the CRH380 CL high-speed train,and the improved delayed separation vortex simulation method is used to perform transient simulation calculations for the high-speed train at a speed of 600 km/h on open-line working conditions and vacuum pipeline working conditions with a vacuum degree of0.01 atm.According to the calculation results,the turbulence characteristics and vortex structure of the train wake field are mainly explored.The research shows that through the Q criterion and Ω criterion,a pair of reverse spiral vortex pairs can be captured alternately from near the nose of the tail car of the train,and travel a long distance along the flow direction,and its movement and expansion have obvious three-dimensionality;Through the physical meaning of the vortex,it is found that the vortices with high vorticity are concentrated in the area near the nose of the tail car.And in the downstream area of the extensive wake,there are mainly weak vortices dominated by rotation and low dissipation;The distribution of the train wind in the wake field is closely related to the shedding and movement of the wake vortex,indicating that the wake vortex has a dominant influence on the turbulence characteristics of the wake field;The turbulent kinetic energy and Reynolds stress of the wake field are very prominent near the nose of the chaser,and they decay rapidly along the flow direction.It shows that the vortex near the nose of the chaser is subjected to strong shearing effect,and its dissipation is very significant;In the downstream far from the nose of the chaser,the interaction area between the vortex and the ground and the inner wall of the pipe also has low-level turbulent kinetic energy and Reynolds stress distribution.This interaction is described by weak shear vortex for energy to sustain itself;Condition and open wire plumbers vacuum conditions in the wake of the vortex shedding motion field,the train air distribution,the distribution of turbulent kinetic energy and Reynolds stress distribution are significantly different.