Experimental Study On Thermal Characteristics Near Fire Source And Plug-holing Phenomenon In Tunnel

Longitudinal ventilation combined with large-scale exhaust port sub-concentrated smoke,in the tunnel structure design and fire safety rescue embodied many advantages,representing the future direction of the tunnel construction,with a wide range of applications.In this paper,a 1: 20 scale fire safety experimental model platform is designed to focus on the thermal parameters of the near fire source and the smoke blocking effect under the coupling effect of the tunnel.The source of fire hazards in the fire source,whether it is the impact of hot flue gas on the tunnel structure,or the study of the source of heat for the surrounding objects,are inseparable from the characteristics of the fire itself,that is,the characteristics of the flame parameters.Based on the previous work,the author has continued to improve on the basis of the previous work.For the first time,the fluctuation of the flame is introduced into the flame geometric characteristic parameter.The influence of the fire intensity and the wind on the geometrical parameters of the flame is analyzed.In order to improve the applicability of the experimental conclusion,to better promote to the actual production to select a number of classic tunnel fire experimental model were compared for the text of the commonly used data were carried out dimensionless processing.The diffusion law of hot flue gas and the radiation characteristics of near fire source are discussed in detail,and the maximum temperature position of hot flue gas is presented in the form of probabilities for the first time,and the instability of flame is also given.The radiation coefficient k is defined,which combines the radiant heat flow with the total heat flow ratio to study the radiation characteristics of the near fire source.According to the experimental idea of Lubin water tank,the outflow of different density fluid orifice may cause the blocking effect,and the obstructive effect of hot flue gas and cold air caused by large difference in the density of large scale exhaust port is studied.With the increase of the intensity of the firesource,the amount of critical smoke is also increased,and it is suggested that the smoke efficiency can be maximized by measuring the temperature of the hot flue gas below the top wall and providing the response of the smoke.The relationship between the transverse wind speed and the critical smoke volume is analyzed.With the increase of the lateral wind speed,the critical smoke volume increases,and the minimum transverse wind speed should be given for the transverse wind speed should be satisfied when the flue gas is not countercurrent.