A Study On The Effect Of The Ventilation Of High Speed Train Equipment Cabin On Downstream Boundary Layer Characteristics

With the rapid development of China's high-speed railway technology,the train speed increasing continuously,many aerodynamics problems which can be ignored in low speed are gradually exposed,such as the train aerodynamic drag,noise,micro pressure wave and crosswind.These phenomena seriously affects the safety of train and limit the speed of further improvement.The ventilation of the equipment cabin on the characteristics of the vehicle boundary layer largely affects the maximum running speed of the high speed train and the safe operation performance.Therefore,the influence of the ventilation of the equipment should be studied.The main purpose of this paper is to obtain the flow structure of ventilation port and downstream of the body near the wall,and analysis the influence of the ventilation of equipment cabin on the downstream body boundary layer characteristics,provide an important theoretical basis for the further study on the ventilation of equipment cabin and air dynamics of high speed trains.The main contents include:(1)according to the similarity principle,take the CRH3 train as a design blueprint,build a experimental system of studying the influence of the ventilation of the equipment cabin of high speed train on the boundary layer characteristics;(2)build a physical and mathematical model of the equipment cabin ventilation,select an appropriate computational domain,by writing a program to calculate the velocity field of around train;(3)analysize the influence of the ventilation of the equipment cabin of high speed train on the boundary layer characteristics.The following results are obtained:(1)A large number of vortices are generated from the outlet of the equipment compartment to the near wall region downstream.(2)As far away from the air outlet of the equipment cabin,the absolute longitudinal vortex flux firstly increases and then decreases gradually,and the influence of the ventilation of the equipment cabin on the boundary layer charactersitics decreases gradually.(3)The ventilation of the equipment cabin of high speed train has great effect on the boundary layer characteristics.