Abstract: Numerical model of equal proportion comprehensive pipe gallery was established and the fire suppression of the cable cabin fire by water mist under the ventilation speeds of 0, 0.4, 0.8 and 1.2 m/s was simulated by FDS. The influence of wind speed on fire extinguishing and the smoke spread under the combined action of longitudinal ventilation and water mist were researched. The results showed that with the increase of longitudinal ventilation wind speed, although the oxygen content in the tunnel increases, the temperature at and above the fire source drops, which greatly reduces the vertical development trend of the fire source. The effectiveness of the high pressure water mist fire extinguishing system is proved by the results. When the water mist system is used in the urban comprehensive pipe gallery, it is more advantageous to apply the ventilation airflow with the wind speed no higher than 1.2 m/s to extinguish the fire by water mist.

Key words: utility tunnel, high pressure water mist, fire suppression effect, numerical simulation