Experimental Research On The Relative Flame Spreading Characteristics Of PMMA Based On Combustion Interaction

Fire is one of the most frequent and easily threatening public property and life safety disasters,and the flame spread process in its development stage is the most important part of fire processes.In the process of flame spread in real fires,there are generally multiple fire sources acting together,resulting in greater fire losses.On the basis of the research on multiple ignition sources of discrete combustibles,it is of great practical significance to study the flame spread of the same solid combustibles under the combustion interaction.This paper takes the polymethyl methacrylate plates as the research object,and conducts the relative flame spread experiments of PMMA with different widths.By observing the experimental phenomenon,qualitative and quantitative analysis of the flame spread characteristic angle,fire spread speed,mass loss rate,radiation heat flux and other parameters,The main findings are as follows:(1)Under the interaction of combustion,the process of relative flame spread has obvious stage changes.Influenced by the limited air entrainment and the enhancement of radiant heat feedback,after the flame spread process enters the stable stage,it is promoted again due to the coupled combustion.However,in the pre-flame fusion stage,some parameters such as the characteristic angle of flame spread,flame spread rate of center flame front and the radiant heat,have special changes that decrease.(2)In the width range of 5-9 cm,the spread of relative flame is obviously affected by the width,and the specific performance is as follows:There is a negative linear relationship between the characteristic angle α,the average mass loss rate m ? and the aspect ratio L/w,the maximum length of the pyrolysis zone increases with the width in the process of relative flame spread,the holding time of the relatively stable stage decreases with the increase of the width,and the maximum length of the pyrolysis zone increases with the increase of the width in the interaction stage.(3)In terms of heat transfer of relative flame spread,the effect of blocking thermal conduction on relative flame spread will increase the numerical fluctuation of mass loss rate,delay the maximum length of the plate pyrolysis zone,etc.,and has no obvious effect on the phase change of the flame shape and fire spread characteristic law.For the radiation heat which plays a leading role in the process of flame spread,it is found that the maximum value of the radiative heat flux density for the relative flame spread is about twice the unilateral flame spread,but it is not a simple superposition effect,which is significantly affected by the view factor of flames.At the same time,the theoretical model analysis of the radiative heat transfer of the flames on both sides to the preheating zone under the action of coupled combustion is carried out.