Numerical Simulation Of Flooding Water Mist Extinguishing Fire In Cabin

In recent years,offshore oil resources have received more and more attention from countries in the world and have promoted the development of marine life platform serving multiple offshore oil drilling platforms.The cabin is the power device for the marine life platform.There are many equipment and pipelines of various systems in the cabin.Once a fire occurs,it is much difficult to save.It is considered to be one of the world's most difficult fires to extinguish.Due to the advantages of a wide range of water mists and high fire-extinguishing efficiency,the water mist has a broad application prospect in fire extinguishing.The article takes the cabin of the deep-water semi-submersible support marine life platform as the research object.Firstly,the article designs a flooding water mist fire extinguishing system according to the relevant rules of the International Maritime Organization(IMO).The water mist nozzles and temperature detectors in the cabin were arranged.Secondly,the Fire Dynamics Simulator(FDS)software is applied to establish the physical model of the cabin.The numerical simulation of the interaction process between the flooding water mist and the fire in the cabin was carried out.Through the comparison of with or without water mist,the effects of the water mist fire extinguishing system on some physical parameters were discussed,including the heat release rate of fuel,the temperature inside the cabin room,the concentration of oxygen and carbon dioxide near the fire source,and the height of the smoke layer in the cabin room.The fire extinguishing mechanism of diesel pool fire and diesel jet fire was analyzed.Through the study of the characteristics of the water mist nozzle,the water mist particles with the droplet diameter of 300 ?m and the atomization cone angle of 60° has the best extinguishing effect.In the study of water mist extinguishing the diesel pool fire,it was found that the water mist fire extinguishing system has good fire extinguishing effect on oil pools of different sizes and locations,and the larger of the fire,the sooner of the detection and startup time of the water mist system.The effect of different pre-ignition time on the fire extinguishing of the water mist system was compared.It was found that the extinguishing time increases firstand then decreases with the increase of pre-ignition time.There is a critical value.The water mist has the longer extinguishing time and the worse fire extinguishing effect when the obstruction covers the lager area of the oil pool.In the study of water mist extinguishing the diesel spray fire,the fire extinguishing conditions of the water mist system under different fire source power,different spray opening height and different ventilation conditions were discussed.It is found that the greater of the fire power source,the earlier of the starting time the water mist system;the smaller of the fire power source,the longer of the fire extinguishing time of the water mist.The fire detection time and the extinguishing time is shorter when the higher the height of the spray exit from the bottom of the cabin.Under ventilation conditions,the flow of air in the cabin accelerates the disturbance between the water mist and the flame,shortening the extinguishing time of the water mist system.