Abstract: In order to study the effect of nozzle installation angle on the effect of water mist extinguishing fire in the utility tunnel, a physical fire test platform was built, and the effects of water mist on smoke temperature and smoke layer height under seven sprinkler installation angles were simulated by FDS. The results show that the temperature of the fire field in the side-jet wireless trough
is lower and the cooling effect is better; when the nozzle installation angle ≤50̊, the fire extinguishing time is less and the fire extinguishing effect is better. When the sprinkler installation angle >50̊, the fire extinguishing time increases, and the fire extinguishing effect becomes worse; The installation angle of the sprinkler has a certain relationship with the average temperature drop, but it does not show a linear relationship. Considering the cooling effect and the height of flue gas layer, it is suggested that the installation angle of water mist nozzle should be 50̊.

Key words: water mist, fire extinguishing system, utility tunnel;fire, sprinkler, installation angle, smoke temperature, numerical simulation