High-speed train cars in the tunnel will study the aerodynamic characteristics of the process

With the rapid development of high-speed railway, the line of technical standards and higher requirements for the number of tunnels makes a greater increase. High-speed train entering a tunnel, the train air pressure around the tunnel as the sudden the constraints of limited space a huge difference in a short time, resulting in increased resistance to traffic, passenger car comfort, decreased slightly in the tunnel's exports, such as air pressure waves kinetic effect. High-speed train cars in the tunnel will be the pressure generated by the process of change than the single moment when the train through the tunnel to be more severe, the resulting transient pressure, air resistance, lateral aerodynamic force, micro-pressure waves, aerodynamic noise and other more serious and complex, high-speed train in the tunnel the aerodynamic characteristics of the car will produce a comprehensive study of depth becomes extremely necessary.Based on three-dimensional, unsteady, compressible, viscous fluid flow equations and the NS two-equation k ~ ε turbulence model, using the finite element method simulation of the high-speed train car in the tunnel will be the pressure and aerodynamic changes.Multi-condition calculation, analysis of the speed, the tunnel length, the length of train formation, cross-sectional area of the tunnel, the train car in the tunnel location factors will be high-speed train in a tunnel on the car body and the tunnel wall will be the pressure changes and train the withstand aerodynamic changes, come to power and gas pressure changes and the relationship between factors, recommendations for improvement. In addition, the study of the hole effect on the train car in the tunnel will produce pressure changes; of the buffer structure on the pressure and aerodynamic changes. The results show that high-speed train cars in the tunnel will have the pressure is really a transient hole effect in the compression wave and expansion wave propagation, reflection, and superposition of pressure wave in the participating car complex wave system formed by the result of joint work and affected by many factors.Transient pressure and speed of the power function power values greater than 2, and with increasing the length of the tunnel decreases slightly; tunnel length train length of 2 to 4 times, the pressure amplitude is relatively large; when the two trains of 350 ~ 400km / h speed in cross-sectional area of 100m2 of the tunnel, the driver exceeded the maximum pressure change in the human body to withstand the limit, increasing the cross sectional area of the tunnel can significantly reduce the pressure change; two train cars at the tunnel midpoint of the pressure changes will maximum amplitude, the car will be the most dangerous situation. Air resistance on the train, on the transient pressure and body share the same trend, both at the same speeds the car will be much larger than the open-wire and a single train through the tunnel. Lateral force on the train and the car will lift the pressure wave is mainly affected by the impact, and vehicle speed proportional to the square, and the tunnel length, tunnel cross-sectional area, the location would have little car. Buffer structure can effectively reduce the high-speed train car in the tunnel will be changes in pressure and air resistance. 

Key words: high-speed train; tunnel; will car; aerodynamic characteristics; numerical simulation