Study On Air Volume Matching Of Personalized Air Supplement System Based On Smoke Flow Characteristics Of Atrium Fire

As the society progresses and the economy develops,people’s demand for building functions increases,and atrium-style buildings with integrated functions and multi-story connections with open views emerge.However,due to the lack of smoke partitions between floors of the atrium,once a fire occurs,high temperature toxic smoke will spread rapidly in the atrium,seriously threatening the life safety of people.According to the flow characteristics of fire smoke and the behavioral characteristics of personnel evacuation,this study adopts a combination of breathing zone air supply and downward air supply in the atrium with personalized make-up air to achieve smoke control in the evacuation channels of each floor of the atrium.This study analyzed the effect of this personalized make-up air system on CO concentration,temperature and visibility distribution at each floor in the atrium fire,and analyzed the smoke control effect under different make-up air ratios at each floor to determine a more reasonable make-up air distribution ratio.The main findings of the study are as follows:（1）It was found that the personalized make-up air method combining breathing zone and downward air supply could achieve smoke control in the evacuation passages of each floor.When the fire source is located at the bottom center of the atrium,the height of the make-up air system affects the combustion of the fire source compared to the natural fill state,thus affecting the heat release rate of the fire source.The heat release rate of the fire source in the natural filling state is Q₀,and the heat release rate of the fire source is 1.16 Q₀,1.09 Q₀,0.87 Q₀,and 0.81 Q₀ when the height of the make-up air system is 0%,25%,50%,and 75%of the total height of the atrium,respectively.（2）When the make-up air volume of each floor is equal,the CO concentration in the evacuation passages on the third and fourth floors cannot meet the requirements for safe evacuation of people.According to the ratio of CO concentration in each floor when the fire smoke is filled naturally,the make-up air volume of different floors is redistributed.It was found that when the distribution ratio of make-up air volume from one to four floors was 1:1.21:1.43:1.52,the smoke control effect on each floor was better,and the CO concentration,temperature and visibility of each floor could meet the requirements of safe evacuation of personnel.（3）The proportion of make-up air increases with the increase of make-up air height,but when the proportion of make-up air is too large,the effective area of personalized make-up air system will be reduced,so the proportion of make-up air at 16.5 m should not exceed 30%of the total amount of make-up air,and the proportion of make-up air at 11.5 m height should not exceed 28%of the total amount of make-up air;after determining the proportion of make-up air at the higher floors,the remaining make-up air will be allocated to the lower floors as needed.After determining the proportion of make-up air in higher floors,the remaining makeup air will be distributed to lower floors as needed.It is calculated that the proportion of makeup air at 1.5 m height should not be less than 15%of the total make-up air volume,and the makeup air flow rate at 6.5 m height should not exceed 27%of the total make-up air volume.