Influence of Water Mist Nozzle Characteristic Parameters on Oil Pool Fire Extinguishing in Confined Space

In order to explore the effect of characteristic parameters of water mist nozzle on oil pool fire in confined space, mathematical model and physical model of oil pool fire in confined space were established. The effects of nozzle characteristic parameters such as water mist atomization cone angle, spray speed, droplet size and spray flow on fire extinguishing in a naturally ventilated room were discussed by using large eddy method and Lagrange method. The research illustrates that when atomization cone angle is in a certain range (80°–110°), fire extinguishing time is gradually shortened, and cooling effect of water mist is improved with the increase of atomization cone angle. When spray speed is 5–20 m/s, the greater the spray speed, the better the cooling effect. When droplet size is 100–300 μm, there is a positive correlation between droplet size and fire cooling rate. When the droplet size is greater than 300 μm, there is a negative correlation between droplet size and fire cooling rate. The inhibition of water mist on heat release rate increases with the increase of droplet size. The water mist with small particle size has a good cooling effect on the ceiling because of its overflow effect. In a naturally ventilated room, the water mist with the droplet size of 300 μm has a good cooling effect on the oil surface, and the reasonable droplet size is 300 μm. When the spray flow is 10–20 L/min, the greater the spray flow, the better the extinguishing effect.