Study On The Coupling Effect Of Enclosure Space Fire And Its Environment In Ship Cabin

In the ship's cabin,because of the fuel leaking caused by the pipe wear and collision,an oil pool fire is formed after ignition at a high external temperature,and then caused the ship fire.As a confined space environment,the ship's cabin has a poor circulation with outside world,resulting in a lower oxygen concentration in the space than in the standard environment.The combustion of the flame is a process in which the fuel reacts with oxygen under high temperature.When the oxygen concentration in the cabin is low,the development process of the fire will change.In this paper,the combustion experiments of small-scale enclosed diesel pool fires under different initial oxygen concentration conditions are carried out to analyze the changes of the flame combustion state and the physical parameters in the environment during the combustion process of the oil pool fire.The purpose is to reveal the law of coupling between the combustion of the oil pool fire and the environment in a ship closed space.The experimental cabin size is 1500mm?L?×1500mm?W?×1000mm?H?,the oil pool with a diameter of 12cm is adopted,and the diesel pool fire experiment is carried out at the condition of initial oxygen concentration of 18%,18.5%,19%,19.5%,20%,20.5%and21%.The experimental process focuses on the coupling changes of oil pool fire combustion and the cabin environment under different initial oxygen concentrations,and sums up the law of distribution of temperature and smoke under different oxygen in the enclosed space.At the same time,the changing rule of fuel mass loss rate and flame height non-dimensional empirical formula at different initial oxygen concentrations are presented.The 8cm and16cm oil pool fire experiments are used to verify the flame height.In order to study the law of internal gas flow and change in the cabin to supplement the experiment process,the temperature field and flow field of the flame combustion process is analyzed by the numerical calculation method in the closed cabin.The results show that:?1?When an oil pool fire occurs,a large amount of fuel evaporates at 17%oxygen concentration of the combustion zone,and the oxygen concentration in the combustion zone is insufficient to support full combustion of the fuel vapor,resulting in combustion of fuel vapor away from the oil pool at a position satisfying the combustion conditions,then the fire escapes from the main flame area.When the oxygen concentration in the combustion zone drops to about 12%,the flame will exhibit self-extinguishing behavior.?2?The lower the initial oxygen concentration in the experimental cabin,the greater the generation rate of CO and C_xH_y caused by flame combustion,but no difference in initial oxygen concentration is found to have a significant effect on the change of CO2concentration.?3?When the oil pool fire enters the stable combustion stage,the flame height and fuel mass loss rate under different initial oxygen concentrations are quite different.In the study,it was found that the flame height is affected by the oxygen concentration in the combustion zone and the rate of fuel mass loss.The dimensionless heightH/Dandm'?(10X_O2-.1)1²are increasing exponentially.?4?During the numerical simulation,it was found that the temperature of the same height layer of the enclosed cabin is basically the same,the oxygen concentration is low around the wall and high in the middle.Affected by heat buoyancy and entrainment,the gas flow in the area below the oil pool fire is poor and the temperature is always low.During the whole experiment and numerical simulation of the closed cabin,the boundary of the smoke layer is not obvious.