Study On The Influence Of Different Pressures On Fire Behaviors Of Typical Passenger Luggage

During the civil aviation transportation,the cabin and cargo compartment is in low pressure environment,and the change of environmental parameters will inevitably affect the combustion reaction,leading to the aviation fire appearing different from the atmospheric environment.Therefore,it is of great significance for civil aviation transportation safety and personnel protection to study the combustion characteristics of passenger luggage under different pressure environments.ABS plastic,PU leather,pure cotton and polyester were selected as test samples through the statistics of 500 pieces of passenger clothing and 300 pieces of suitcase in the paper.Three different experimental platforms were designed and built in Kangding airport（61 kpa）,Kangding county（75 kpa）and Guanghan（96 kpa）.The typical parameters such as burning rate,mass loss ratio,flue gas composition,smoke density and burning time were measured and analysed to investige the effect of pressure on the combustion characteristics of passenger luggages.The results of horizontal combustion experiments show that the smoke density of materials increases rapidly to the peak at first and then changes slowly at the stable stage,and the influence of environmental pressure on it is obvious.In the initial stage of combustion,the product was mainly converted to CO₂,while the CO increased rapidly in the later stage with multiple peak changes,and the FED toxicity evaluation of the material was rated as hazardous level.The flame rapidly enters the stable temperature zone after experiencing the rapid heating zone.At this point,the radial width and the oscillation frequency of the flame are positively correlated with the ambient pressure,while the flame height is approximately negatively correlated with it.The results of countercurrent fire spreading experiments show that the combustion time and mass loss are relatively small in unsteady combustion.While,after entering the stable phase,the fire spread rate and mass loss increases relatively with the environmental pressure and oxygen concentration goes up.The increase of air velocity will promote the diffusion of oxygen molecules to the front of the flame and maintain the flame combustion.But when the airflow speed is too high,the flame front will be suppressed or blown out due to blowout effect.The results of thermal radiation combustion experiments show that the combustion time is negatively correlated with the radiation ambient temperature.Besides,the influence of environmental pressure on the combustion is reduced in the high radiation temperature stage.When the fire enters into stable combustion,the radial width of the flame is negatively correlated with the radiation temperature,while the height of the flame is positively correlated with the ambient pressure.The peak time of each smoke component decreases with the increase of radiation ambient temperature,and the material is rated as hazardous with the FED toxicity assessment meathod.