Study On The Smoke Spread Pattern And Smoke Control Measures In The High-rise Building Fire

High-rise buildings become inevitable choice with the development of urbanization in our country. However, once they are in fire, flame and smoke will spread quickly due to the special features such as multiple floors, more complicated of interior and exterior wall materials, crowded occupations and so on, which results in fatal threaten to the safety of human evacuation. Therefore, it has important practical significance to research the mechanism of smoke spreading and the effect of smoke controlling measurement when high-rise buildings are in fire.The fire dynamics software FDS, which is recognized internationally in the fire research and engineering field, is used to establish the fire model of high-rise building, which occur inside and outside separately. Two measurements are applied and studied to control the fire smoke spread, saying, the positive pressure air supply system in antechamber and water spray system. In order to realize the optimization on the best way to control the smoke spread of high-rise building fire, the relevant datas are analyzed, such as the fire source heat release rate, indoor temperature and carbon monoxide concentration and so on. As a result, the mechanism of smoke spread in high-rise building fire inside and outside and the effects of the corresponding smoking control measures are analyzed and compared.Firstly, the effect of different installation height of positive pressure air supply outlet in the evacuation stairwell antechamber is analyzed to control the high-rise building fire smoke. Five different heights of positive pressure air supply outlets are insatalled in the evacuation stairwell antechamber such as250mm,750mm,1250mm,1750mm and2250mm aiming to control the fire smoke spread which is produced by three kinds of inside fire source such as2.5MW,5.0MW and7.5MW. By comparing and analyzing the change trend of the characteristic parameter as carbon monoxide concentration, temperature in the antechamber, it illustrates that the different effects exist with the different installation heights of the positive pressure air outlet in evacuation stairwell antechamber with the change of the fire source. Comparing comprehensively, the positive pressure air outlet with the height of750mm is the best, which is recommended to use in the practical design.Furthermore, the smoke spread mechanism of high-rise building fire which is ignited by the external insulation materials is studied. The following parameters such as indoor and outdoor air temperature, wind, fire location, etc, and their effects on the outdoor fire smoke spread are compared. It illustrates that the fire smoke spreading outside the building is aggravate with the increase of the temperature difference inside and outside of the high-rise building; the outside fire smoke spreads with the increase of the outside wind speed when the fire is in the windward surface, the outside fire smoke spreads with the outdoor wind speed decreases due to topical negative pressure effect when the fire is in the leeward side.Finally, water sprayer is installed on different position inside and outside of the building to find the smoke control effect on the external wall insulation materials fire of high-rise building, which aims to discuss the applying feasibility of the outside water spray system. Through the comparison on indoor carbon monoxide concentration, temperature and other parameters change, it is found that water spray system of spraying droplets can effectively settling fire smoke particle, the sprayer which is installed above the window inside can prevent the outdoor fire smoke into and guarantee the indoor temperature best. The sprayer which is installed outside can restrain the development of the fire source outside, and the effect on the controlling of smoke and fire is better, which can make up the shortage of the working height of the fire fighting equipment. It has a certain practical value and can do a lot to improve the performance of the prevention and control of high-rise building fire.