Numerical Simulation Of Fire Smoke In An Underground Comprehensive Pipe Corridor

Underground comprehensive pipe corridors play an increasingly important role in China's urbanization construction.Its use can not only greatly alleviate the dilemma of urban land use,but also avoid the frequent excavation of urban roads due to maintenance and the increase of municipal pipelines.Problems such as waste of funds and inconvenient transportation,thus ensuring the aesthetic appearance of the city.Because the integrated pipe corridor is laid on the ground,the space is narrow and long.Once a fire occurs,it is easy to cause heat and smoke to accumulate and spread along the pipe cabin to the distance,thereby causing huge economic losses and bad social impact.Therefore,the study of the smoke spreading rules and the spatial and temporal distribution characteristics of the pipe corridor fire in the early stage can provide data support for the pipe corridor fire detection,help to realize the very early recognition and control of the fire,and reduce the economic loss and social impact of the pipe corridor fire.In the process of fire detection,smoke is the most commonly used detection parameter.Scholars at home and abroad have already started to study the fire detection technology of pipe corridor fire and established some fire detection systems,but these fire detection systems have problems and are not suitable for comprehensive promotion.In other places,research scholars often use detection methods based on multi-sensor signal fusion,which can greatly reduce the false alarm rate and cost,and accurately identify the occurrence of early fires.This paper can provide data support for the multi-sensor coupled extremely early fire detection technology in the integrated pipe corridor by studying the spread of smoke in the early fire and the change of detector signal.The specific research contents are as follows:(1)By changing the type of fire source and the location of the fire source,study the early smoke spreading behavior of the comprehensive pipe corridor fire.The study found that under the same fire source location,the spread speed,temperature,and concentration of fire smoke are affected by the type of fire source.The speed of the flue gas spread from fast to slow is ethanol fire,n-heptane fire,polyurethane fire,wood fire,nylon fire;the order of flue gas temperature from high to low is n-heptane fire,polyurethane fire,ethanol fire,Wood fire,nylon fire;the order of smoke concentration is polyurethane fire,nylon fire,n-heptane fire,wood fire,ethanol fire.(2)Analyze the spreading law of smoke in the early stage of the comprehensive pipecorridor fire,and obtain the space-time distribution law of smoke field.The first is the time distribution law of smoke.When the distance between the measurement point and the fire source is fixed,the temperature and concentration of fire smoke increase with time,and the curve fitting of temperature and concentration with time conforms to a certain fit.relationship.Then there is the spatial distribution law of flue gas.At a specific moment after the fire,the temperature and concentration of the fire flue gas decrease as the distance between the measuring point and the fire source increases,and the relationship curve between temperature,concentration and distance conforms to a certain fit relationship.(3)Analyze the change law of the smoke signal of the detector to obtain the influence of the type and position of the fire source on the signal.In the case where the distance between the detector and the fire source is fixed,the detector signal is affected by the type of fire source,and the detector signal increases with time.When the fire occurs 100 s after the fire,each fire source causes the detector signal to change The order of strength from strong to weak is: polyurethane fire,nylon fire,n-heptane fire,ethanol fire,wood fire.Under the condition that the distance between the measuring point and the fire source is fixed,the intensity of the signal change of the detector at the working position of the fire source at the edge of the pipe corridor is greater than that at the center position of the fire source.When the position of the fire source is fixed,the signal change rule of adjacent detectors has a strong correlation,which can provide a basis for the identification of fire alarms.This paper has 18 pictures,5 tables and 74 references...