The Influence Of Ambient Temperature And Wind Speed On Wood Fire Spread And Burning Traces

With the rapid development of social economy and urbanization,the types and quantities of combustibles used by people are increasing,leading to frequent fire accidents,causing huge economic losses and a large number of casualties,and also affecting the climate,environment and the earth’s ecology.The system causes varying degrees of damage and affects the development of society.The fire spreading process of combustibles determines the scale of fire development and the losses caused,so in-depth exploration of the solid fire spreading process plays an important role in the prevention and control of fires.At the same time,the mixture of heat,flame and smoke generated in the process of fire spread acts on the surface of the object to form fire traces,which bears witness to the whole process of fire from occurrence to development and extinguishment,so it helps us analyze the point of fire.As well as the cause of the fire,it is of great significance to the fire investigation.This paper studies the spread of fire on the surface under downwind,explores the influence of ambient temperature and wind speed on the process of fire spread,and analyzes the difference between fire traces formed under different ambient temperatures and wind speeds and explores its laws.Wood is very ubiquitous as a solid combustible.This article takes blockboard,a typical wood,as the research object,and uses the Steiner tunnel furnace built according to"ASTM-E84-06 Test Method for the Surface Combustion Characteristics of Building Materials"as the experiment Platform to study the influence of ambient temperature and wind speed on the spread of blockboard fire,and make theoretical analysis.First,conduct a systematic analysis of the fire spread process of solid combustibles,and theoretically derive the classic fire spread model to understand the evolution mechanism of solid combustibles,which provides a theoretical basis for the subsequent experimental research and analysis.This paper uses the Steiner tunnel furnace experimental platform to study the influence of ambient temperature and wind speed on the spread of solid fires,and analyze the effects of CO concentration,CO₂ concentration,NO concentration,NO_x concentration,fire spreading rate,fire spreading distance,heat release rate,and smoke production rate.Change characteristics,analyze fire spread from the perspective of heat and mass transfer,and establish a fire spread model.Observe the fire traces formed under different environmental temperatures and wind speeds,analyze the changes of traces on the surface of the blockboard;at the same time,observe the microscopic appearance of the burned embers with a scanning electron microscope（SEM）,and analyze the environment from a microscopic point of view.The effect of temperature and wind speed on the spread of fire along the wind.The main research conclusions are as follows:The influence of ambient temperature on the fire spread and fire traces of blockboard:（1）With the increase of ambient temperature,the distance and speed of fire spread gradually increase,and the relationship between fire spread speed and ambient temperature is approximately linear;（2）With the increase of ambient temperature,the peak value of smoke generation rate becomes smaller and smaller,the peak value of heat release rate gradually increases,and the time to reach the peak value of heat release becomes shorter and shorter.As the ambient temperature increases,the output of CO and CO₂ is increasing,and the production rate is getting faster and faster.The output of SO₂ and NO_X does not change much with temperature.（3）With the increase of ambient temperature,the size of the carbonized block of blockboard gradually increases,the tracheid fiber structure and lignin of blockboard are burnt and damaged more seriously,and the smoking traces become more and more dense.The influence of environmental wind speed on the fire spread and fire traces of blockboard:（1）With the increase of wind speed,the fire spread rate increases.At 1.6m/s,the fire spread rate increases sharply,approximately exponentially;（2）When the wind speed is0.4m/s-1.6m/s,the fire spread distance increases with the increase of wind speed;（3）The increase of ambient wind speed will cause the output of CO and CO₂ to increase,and the output of SO₂ and NO_X will increase with the increase of wind speed.The wind speed does not change much;（4）At low wind speeds,the wind plays a role in supporting combustion;after a certain range,the wind blows out;（5）The increase in wind speed will cause the ignition time of the blockboard to become longer.As the wind speed increases,the fire source ignites the blockboard further back.