Study On Stairwell Positive Pressure Ventilation In High-rise Building Fire Using CFD Simulation

When a high-rise building is on fire, the stair shaft will become the main vertical evacuating route way. Positive pressure ventilation is a new smoke control technique for high-rise building stairwells. So whether the conduct of positive pressure ventilation is appropriate will directly influence the evacuation of occupants in the building and the rescue of fire department. This paper analyses factors which influence smoke spread and flow in high-rise building, which consists of stack effect, buoyancy, thermal expansion, natural wind, HVAC systems and elevator piston effect. Then various smoke control measures are discussed. Based on fire experiments in real building, the performance of stairwell positive pressure ventilation in high-rise building fire is evaluated using the mature fire simulation software FDS.According to the real experiments of stairwell positive pressure ventilation, the 3D model of stairwell and fire floor is constructed using the FDS modeling software Pyrosim. The virtual environment contaminated by fire smoke is formed by changing parameters of the fire source. Then, the performances of four different styles of stairwell positive pressure ventilation are simulated in series of FDS experiments. Finally, the most effective ventilation style is picked out through comparison.Positive pressure ventilation in high-rise building has not been studied systematically in China so far. The study validates the effect of positive pressure ventilation in high-rise building, and determines the best ventilation measure, which provides reference material for carrying out positive pressure ventilation tactics in high-rise building in china.