Study On Flame Spread Characteristics Of Typical Wood Surface Under Multi-parameter Coupling

Forest fires,building fires,and industrial fires are the main types of fires classified according to the scene of the fire.In these types of fires,fires such as wood,a typical carbonizable solid combustible,are ubiquitous.The flame spread characteristics of the carbonizable solid surface are very complicated.Therefore,scientific understanding of this property is an important part of the study of fire science.Understanding the occurrence and evolution of fire spread,scientific and control of fire will have important guiding significance.Understanding the occurrence and evolution of fire spread,scientific and control of fire will have important guiding significance.In order to study the influence of various parameters coupling on the flame spread characteristics of wood surface,two typical woods,Chinese fir and camphorwood,were selected as research objects,and a small-scale experimental platform was built to carry out the fire propagation experiment under the coupling of various factors in this paper.Analyze the variation law of each flame propagation characteristic parameter in this process,explain its cause and reveal the influence and internal mechanism of each influencing factor on this process.In this paper,the theoretical analysis of the flame spread on the solid surface is first carried out.Through the derivation of the classical theoretical model formulas,the evolution mechanism of the flame propagation process on the solid surface is understood.The analysis of the downstream fire spread and countercurrent fire spread model provides a theoretical guidance for the experimental research.This paper then builds a small-scale experimental platform.Using the platform,two typical woods of Chinese fir and camphorwood are selected as research objects,and the effect of the width effect on the critical angle of accelerated propagation of the solid surface is experimentally studied.The variation of each characteristic parameter with width and angle.It is found that with the increase of width and angle,the fire spread rate,mass loss rate and flame area increase;The mass loss rate per unit width increases with increasing width and tilt angle at positive angles,and decreases with increasing width and tilt angle for negative angles.;the width of the sample promotes the acceleration of the fire propagation on the inclined surface,and the larger the width,the smaller the critical angle at which the acceleration spread occurs.In this paper,the experimental platform was used to select the camphorwood as the research object,and the effects of different altitudes and placement angles on the surface flame propagation characteristics were studied.It is found that the characteristic parameters of Wuhan area are larger than those of Lhasa,such as fire spread speed,flame height,flame pulsation intensity,mass loss rate,etc.,and as the angle increases,the dimensionless velocity also increases,and the dimensionless flame height instead Decrease;the gas-solid phase temperature change trend is basically the same,and the gas phase flame temperature in Wuhan area is longer.The reason of the above law is related to the difference of atmospheric pressure and air density in the two places.The higher the altitude,the lower the atmospheric pressure and the air density,so the convection intensity decreases,and during the flame spread progress,the convection has a greater impact on it.Therefore,various regularities are produced.