Analysis Of Smoke Movement And Control In Fire Elevator Shafts Of High-Rise Buildings

High-rise building fire will cause serious casualties and property losses for its long evacuation routes and high spread speed. In order to solve the difficult evacuation problem, some domestic and foreign experts have put forward the idea of evacuation by elevators. China fire code provides that elevators cannot be used for fire evacuation, but evacuation by the way of combing stairs and elevators will shorten evacuation time if the elevators can be ensured safety in the process of evacuation. Elevator safety including many aspects, such as power supply facilities, smoke control systems. The aspect of smoke control by elevator shaft pressurization is mainly analyzed in this paper.Firstly, the characteristics of fire smoke spread in high-rise buildings, driving forces, FLUENT software are introduced briefly. Then the influence of piston effect, stake effect, buoyancy force on elevator shaft pressurization system is analyzed. Study of the influencing factors of elevator shaft pressurization system in high-rise buildings considers the elevator under different working conditions including elevator car fixed, upward and downward moving, different elevator speed. Elevator shaft pressurization pre-experiment was conducted in the high-level test tower of Sichuan Fire Research Institute. The fire is diesel oil burning and the air supply outlet is on the top of elevator shaft. Pressure values of elevator shaft, elevator rooms and corridors on some representative floors are tested. To judge whether the smoke control system is effect, smoke detector is used. The main purpose of experiment is analyzing the possible problems such as other smoke spread ways, fan, elevator running and pressure relief. Meanwhile, compared the results of the two methods with the same conditions, the rationality of simulated results is verified.The method of FLUENT numerical simulation is adopted mainly to study elevator shaft pressurization smoke control system. Elevator car moving is simulated by dynamic mesh. The numerical analysis is realized in terms of variable steps, e.g. creating and meshing the mode by gambit, defining boundary condition and choosing computation mode. Finally the total supply air and the critical pressure difference which can keep smoke under effective control are obtained.On the basis of computational and experimental study of smoke control in the elevator shaft, smoke moving under different conditions and the pressure difference varying of elevator shaft, elevator lobby and corridor are analyzed. Finally the critical parameters of preventing smoke into the elevator shaft effectively are obtained through simulation, In a word, this paper achieves important practical meaning and economic value, will play an important role in standard improving, and provide technology demonstration for fire fighting and evacuation by elevators in high-rise buildings.