In this work, a series of experiments were conducted to study the suppression effects of high-pressure water mist on smoke spread in a tunnel model with dimensions of 20m in length, 5m in width, and 5m in height. The main conclusions are shown as follows: (1) After the oil pool is ignited, the black smoke gathers beneath the tunnel ceiling, forming a ceiling jet that spreads towards both ends of the tunnel. A stable smoke layer is formed at 120 seconds with a settling height of about 3m. Moreover, 50°C can be considered as the standard for the smoke layer. (2) The ceiling temperature drops slightly after adding mechanical smoke exhaust. The temperature at the x0y0 position in the center of the fire source without longitudinal ventilation is 227°C, while the temperature drops to 181°C and 102°C with longitudinal ventilation of 1.3m/s and 3m/s. (3) High-pressure water mist can effectively block the spread of hot smoke. The temperature drops sharply and does not exceed 50°C after passing through the high-pressure water mist system, which indicates that High-pressure water mist can effectively protect the evacuation of personnel.

tunnel fire; full-scale experiment; high-pressure water mist; smoke barrier