Research On Fire Smoke Movement Characteristics Of Super Tall Building Under Ambient Wind Condition

There are many kinds of super high-rise buildings in China,and most of them exist in the form of group of buildings,which have the characteristics of complex internal structure,densely populated office area,and various kinds of combustible materials.When a fire occurs,the chimney effect,piston effect,environmental wind and other coupling effects will affect the dynamic balance of the fire inside the building,resulting in the sudden change of the fire and the increase of the smoke spread speed,and to some extent affect the evacuation and the intervention of external rescue forces.If a fire occurs in super high-rise building,it is easy to cause mass death and mass injury and serious economic loss.The rapid development of super high-rise buildings has brought great challenges to building fire safety.The fire of super high-rise buildings under the joint influence of environmental wind speed and wind direction（wind Angle）is more special.Under the influence of ambient wind,how the fire smoke spreads and how the temperature field,concentration field and smoke visibility change are the key links to study the fire in super high-rise buildings.The research on fire smoke movement law of super high-rise building under ambient wind can provide theoretical basis and practical guidance for fire prevention design of super high-rise building as well as active evacuation and external rescue work,which has forward-looking and guiding significance.Taking a super high-rise building in Tianfu Business District of Chengdu city as the research object,this study uses computer simulation software and small-scale experiments to explore and analyze the smoke movement law of super high-rise building under environmental wind conditions.In the most unfavorable building fire half-close environment,based on the field survey data,simulation studies super-tall building under different wind speed and direction（Angle）wind plume flow characteristics,on this basis to explore high-rise building fire in the environmental wind conditions the change of wind speed and direction（Angle）wind of tall building convex type structure,the influence of fire smoke movement.Research shows that:（1）It can be known from comprehensive analysis of temperature field,concentration field and fire visibility.According to the analysis of temperature field under various working conditions,the weight order of the influence of ambient wind on stable temperature of fire site is wind speed > wind direction.In other words,the higher the wind speed,the lower the temperature stability value.When the wind Angle is 45°,the fire stability temperature of the northeast wind（45° e by north wind）is lower than that of the north wind（90°）under all wind speeds.It can be seen that when the wind Angle is 45 °,the peak of the fire can be suppressed.In the analysis of carbon monoxide concentration,it is concluded that the weight of environmental wind on the content of CO in the fire site is wind speed > wind direction.In other words,in each working condition,the higher the wind speed,the lower the peak value of carbon monoxide content in the fire site.According to the same wind speed and different wind Angle,there is no obvious direct correlation between carbon monoxide component content and wind direction.In the analysis of the visibility of the fire site,it is concluded that the stability value of visibility inside the fire site is the lowest under the condition of no wind,and when the wind direction is northeast（45° e by north）,the stability value of visibility with wind speed of 2m/s is lower than that of 4m/s.The higher the wind speed,the higher the visibility inside the fire site,and vice versa.When the wind direction is north（90°）,the greater the wind speed,the lower the visibility stability value.（2）"small size experiment explores the different wind Angle,wind speed under the condition of different fire temperature distribution and the regularity of smoke spreading,the results showed that under normal circumstances,the wind Angle from a different Angle to change interval 30 °to 45 °,and the spread of fire smoke is reduced,but the fire temperature peak will ascend,ascension is about 20 ℃ to 50 ℃.This study can provide model and data reference for improving the smoke control and exhaust system of super high-rise buildings,so as to ensure the safety of personnel and property,which has important practical significance.