Research On Smoke Prevention And Exhaust Of Shopping Mall Business Hall Based On FDS

With the rapid development of social economy,more and more shopping malls and business halls have been established.Because the business hall of shopping mall belongs to a large space,the fire has the characteristics of rapid and rapid spread,and it is difficult to Figureht the fire.Therefore,it is of great significance to study the smoke control and exhaust system of shopping mall business hall for fire rescue and protection of life and property safety,and to provide reference for the design and standard revision of smoke control and exhaust system of shopping mall business hall.According to article 3.2.1 and 3.1.3 of Technical Standard for Smoke Management Systems in Buildings(GB51251-2017)(hereinafter referred to as"Smoke Standard"),this paper studies the smoke prevention situation of shopping mall business hall and the smoke emission situation of shopping mall business hall according to the window layout of atrium which can open the outer window.The main research contents and conclusions of this paper are as follows:(1)This paper proposes a utility model patent:a heat dissipation and smoke exhaust for stairwell roof automatically open double flat window and has passed the examination to obtain the certificate.The utility model in the stairwell temperature reached 70℃when the fusible bolt in the bolt rod will melt,double fan flat window under the action of gravity to open down,can reduce the probability of the window can not be opened in time.(2)In the case of fire source on the first floor,FDS simulation was used to obtain that the area of the open outer window at the top of the stairwell set in accordance with the specification of 1.0m~2 does not meet the requirements,so the area of the open outer window at the top should be increased.When the fire source is in the middle layer and the top layer,the area set according to the specification is in line with the requirements.It is recommended to add in Section 3.2.1:for enclosed stairwells with natural ventilation,an open outer window or opening with an area of no less than 2.5m~2 should be provided at the highest part.(3)By changing the position of the fire source,the power of the fire source and the height of the building,the FDS simulation was used to analyze the visibility,temperature and CO concentration of the smoke-proof stairwell.It was found that the greater the power of the fire source,the less ideal the smoke-proof effect of the front room and the stairwell,and the shorter the time to reach danger.The smoke-proof method of the smoke-proof stairwell was related to the height of the building.It is suggested to add in section 3.1.3:natural ventilation system should be adopted in smoke-proof stairwells of shopping malls with building height between 24m and 32m;mechanical pressurized air supply system should be adopted in smoke-proof stairwells of shopping malls with building height over 32m.(4)By changing the location of fire source,environmental wind direction and environmental wind speed,FDS simulation is used to study the layout form of natural smoke exhaust in the atrium.The layout form of Windows is smoke exhaust at the top,smoke exhaust at the side and smoke exhaust at the top and side.The findings:(1)When the fire source location is different,the start time of smoke exhaust is very different.When the fire source is located in the atrium,the smoke exhaust time is the earliest and the smoke exhaust effect is the best at the top.When the fire source is in other floors,the start time of smoke exhaust is delayed compared with that when the fire source is in the atrium.There is little difference in the smoke exhaust effect of the three window layout forms.(2)The environmental wind will affect the efficiency of natural smoke exhaust.When the wind speed is 5m/s or 7m/s,the top smoke exhaust effect is the best,and the top smoke exhaust effect is less affected by the environmental wind.The lower the wind speed is,the difference of smoke emission of the three window layout forms is not significant,but with the increase of wind speed,the difference of smoke emission of the three window layout forms gradually increases.When the wind speed is 10m/s,natural smoke exhaust will fail.It is recommended to use mechanical smoke exhaust in cities with perennial wind and high wind speed.