Effect of inert gas injection on gas explosion in the process of sealing fire zone

In order to study the influence of inert gas injection to gas explosion in the process of fire zone sealing, tunnel fire model was established by COMSOL software, and numerical simulation is carried out to study change laws of flow field and concentration field in the process of fire zone sealing. Through comparing the distribution law of flow field and concentration field whether the inert gas injection and different flows, obtained the influence of inert gas injection to gas explosion in the process of fire zone sealing. As the decrease of entrance average wind speed, the maximum wind speed in the centre vertical section of tunnel gradually reduces. when the entrance average wind speed is 1m/s, counter current layer is produced near the fire resource, length and thickness of counter current layer and maximum current speed rises with the declining of the entrance average wind speed, and swirl will be formed when the entrance average wind speed is less than 0.01m/s. In the process of fire zone sealing, the maximum gas concentration in the fire area and on the side of leeward goes up with the declining of the entrance average wind speed, the nitrogen concentration will gradually increase with the declining of entrance average wind speed.