Study On Smoke Filling And Control Strategy Of Fires In Full-scale Ship Engine Room

Ship fire is one of the hazardous shipwreck and a vital issue of ship safety.The ship fire can occur someplace where contain combustible such as engine room,cargo hold,passenger compartment and deck.When fire occur in some of them(engine room,cargo hold,passenger compartment),it defines as enclosed chamber fire.The smoke of enclosed chamber fire is more dangerous,it makes evacuation more difficult.The combustible that contain in engine room is far more dangerous than that contain in cargo hold and passenger compartment,the fire triggered by it is the most common fire pattern.Due to the complexity and particularity of ship engine fire,researchers are lack of knowledge about the process of the development of it,and smoke management about it has achieved little progress.Thus it is significant to study smoke movement and management of ship engine room fire.In this paper,experiments of smoke natural filling and mechanical exhaust control were carried out in the experimental compartment,and the size was 22 m(length)× 12 m(width)× 14 m(high).To reveal the law of smoke movement,smoke natural filling experiment was carried out with different fire sizes and different fire locations.Mechanical exhaust control experiment was conducted to study the effect of the location of the vent,the start-up time of exhaust fan and smoke volume on smoke control.By analyzing the mass loss rate of fuel,the distribution of smoke temperature and the descending process of smoke layer in the engine room,the following conclusions are drawn:The effect of different fire sizes and different fire locations on smoke descending process and smoke temperature were analyzed.It was found that the smoke temperature in the engine room increased with the increase of the fire scale,and the smoke descending rate increased with the increase of the fire scale.When the fire scale was too small,the smoke temperature of ceiling was too low to trigger the sprayer.When the fire source was moved to the wall the temperature and the rate of smoke descending process were reduced;when fire was lifted by 4m,the ceiling temperature was higher,the sprayer could start up,the height of smoke entrainment became smaller,the smoke generation reduced,the rate of smoke layer descending slowed down and stabilized at 8m high,thus lifting the fire source was beneficial to evacuate the staff on the ground.In the experimental engine room there were different sizes of obstacles,and the prediction model of smoke layer descending in the cabin filled with obstacles was developed.Compared with the model derived from the previous study,found that the model deduced in this paper was more accurate than the predecessor model in predicting the time of smoke layer descending.The influence of the location of the vent,the start time of the fan and the volume of exhaust fan was analyzed.The results show when the vent was at 1.5m high the rate of smoke descending was accelerated and smoke control effect was poor;when the vent was at the height of 5m the flame inclined and it had a cooling effect,the effect of smoke control appeared to be good;when the vent was at 9.5m high,it had a cooling effect to smoke layer.Compared with fan starting immediately and fan starting after 90s when the pool was ignited,the experiment that fan started immediately had a slower rate of smoke layer descending,so when fire was spread out the fan should start as soon as possible.Through the analysis of the effect of the volume of exhaust fan,we could see that the effect of smoke extraction had not always increased with the increase of volume,when volume increased from 34.57m3/s to 47.11m3/s,the temperature drop and the rate of smoke layer descending was not significant,so the best exhaust volume was 34.57m3/s.