Study On Fire Ventilation & Smoke Exhaust System And Influencing Factors Of Cylindrical Underground Parking Garage

With the improvement of living standard and the change of travel mode,more and more people buy cars.The shortage of existing parking spaces causes the difficulty of parking cars.Underground parking garage is one of the effective means to solve the parking problem because of its high density parking space,but,when fire occurs in this kind of garage,it will cause incalculable property and personnel losses.Therefore,this paper mainly studies the problems of fire in the cylindrical underground parking garage.Firstly,this paper introduces the parameters of STAR-CCM+,and analyses the feasibility of using this software to calculate fire in underground parking comparing with the experimental data.The grid size of 0.05D* is selected for subsequent calculation through grid independence verification.Secondly,under the natural ventilation conditions,this paper selected the negative first-floor,negative sixth-floor and negative tenth-floor as the ignition points.It calculated out that,the deeper the fire source,the higher the center temperature of the roof.The temperature values are respectively 860℃,927℃ and 942℃.The center temperature of parking spaces on the same floor as the fire are all higher than 200℃.When a car get fired,its adjacent vehicles,upper vehicles and relative vehicles will be ignited at about 240 s,312s and 322 s.The deeper the fire source,the shorter the time it takes to ignite its nearby vehicles.Thirdly,three kinds of smoke exhaust systems are designed,which are top smoke exhaust system,the smoke exhaust system of parking spaces at the same height as fire source,and the smoke exhaust system of one smoke outlet.Under three kinds of smoke exhaust systems and natural smoke exhaust system,by comparing the changes of temperature,smoke concentration and thermal radiation on the surface of the vehicle,it is concluded that the smoke exhaust cooling effect of the third smoke exhaust system is better.At the same time,the effects of different air supply and exhaust volume on the performance of smoke exhaust system were compared.Without considering the influence of fire source,the increase of supplementary air volume and smoke exhaust volume will make the smoke exhaust cooling effect of smoke exhaust system better.Finally,the somke screen is introduced into the parking garage.By comparing the effect of the different height of somke screen under the natural ventilation and the mechanical ventilation,it is considered that the existence of somke screen can effectively prevent the diffusion of smoke in the same parking space of fire source and reduce the influence of fire sources on the same-level vehicles.