Abstract: This article takes the scenes of hydrogen energy vehicles releasing hydrogen in four different directions and immediately igniting it in a tunnel as the research objects. Fluent software is used to numerically simulate the temperature field generated after hydrogen is released and immediately ignited. The influence of hydrogen leakage direction and tunnel ventilation speed on the maximum temperature of jet flame and the distribution of high temperature zone is analyzed, providing scientific basis for the setting of ventilation speed in the tunnel and the fire prevention design of the inner walls of the tunnels. The results show that under these four working conditions, increasing the longitudinal ventilation speed of the tunnel has a limited effect on reducing the maximum temperature of the jet flame, but it can significantly reduce the volume of the high-temperature zone, thereby reducing the damage caused to the tunnel walls by the high-temperature zone of the jet flame. Therefore, in the tunnel design stage, it is recommended to increase the longitudinal ventilation speed of the tunnel appropriately, with the optimal ventilation speed of 5.0~8.0 m/s. It is also possible to consider adding an emergency lane on the far right side of the tunnel to increase the safe distance between the tunnel walls and vehicles, thereby protecting the tunnel structure and the safety of vehicle personnel.

Key words: hydrogen cars, tunnels, fire, temperature fields