Numerical Simulation Study Of Smoke In High-rise Building Stairwell And Tunnel Shaft

The continuous development of high-rise buildings on the surface and the development of underground tunnels have been implemented in cities across the country to relieve urban pressure in the current environment of rapid economic development and population growth in the world.However,the ensuing problems are the hidden dangers of various high-rising buildings and tunnels in the city.A large number of fire accidents show that 85% of the people died in the fire because of asphyxiating effect of toxic and harmful smoke.For high-rise building and tunnel fires,studying the characteristics of hot smoke and efficient smoke exhausting methods have great significance to reduce casualties and start rescue.Therefore,this paper will use theoretical analysis and full-scale simulation experiments to study the characteristics of the smoke temperature,the smoke concentration,the smoke speed in high-rise building stairwells and tunnels,as well as the efficiency of vertical shaft exhausting with the influence of different ambient temperature,heat release rate,opening height,ventilation velocity and presence or absence of baffles.The main contents are the following:1.Using numerical simulation and theoretical analysis to study the temperature,concentration and velocity of the smoke in the high-rise buildings with the influence of different ambient temperature,heat release rate,opening height,environmental wind speed and baffles.The main conclusions are the following: As the height increasing,the temperature rise of smoke on the longitudinal centerline of the stairwells will increase firstly and the decrease.To a certain extent,the spread of smoke can be suppressed after installing baffles on stair steps.It isn’t conducive to evacuation because broken windows will accelerate the spread of smoke.2.Using numerical simulation and theoretical analysis to study the smoke temperature distribution,concentration and velocity under the tunnel ceiling with the combined action of longitudinal ventilation,fire source location and shafts.The main conclusions are the following:The decay rate of temperature rise of the downstream fire source will increase with the increase of the longitudinal ventilation speed.A certain speed of the longitudinal wind can be introduced into the tunnel,which can reduce the temperature and carbon monoxide concentration.3.Using numerical simulation and theoretical analysis to study the vertical shaft smoke exhaust efficiency,smoke layer thickness,temperature distribution,vertical shaft smoke exhaust,overflow smoke volume and penetration phenomenon with the influence of the vertical ventilation,fire source location,etc.The main conclusions are the following: The increase of the longitudinal ventilation speed will increase the thickness of smoke layer,but it can suppress the phenomenon of suction through the shaft to a certain extent.Therefore,there is a critical longitudinal wind speed,which can not only prevent the occurrence of the phenomenon of suction and penetration,but also obtain a better smoke exhaust effect.The longitudinal position of the fire source has a significant effect on the exhaust volume of the shaft.However,the horizontal position of the fire source hasn’t obvious effect on the exhaust volume of the shaft.