Experimental study on the burning behavior and combustion toxicity of corrugated cartons under varying sub-atmospheric pressure

An approved fire-protection method for in-flight freighter aircraft is aircraft depressurization. The objective of this study was to evaluate the influence of depressurization on the burning characteristics of typical combustibles based on large-scale corrugated cartons test data, which is believed to be valuable for aircraft fire safety engineering. The fuel mass loss, pressure, CO concentration, and axial temperature distribution were investigated in comparative tests conducted in a newly designed hypobaric chamber to simulate a depressurization process from 100 to 60 kPa with respective rates of decrease of 91, 182, and 328 Pa/s. The depressurization experimental results show that the fire plume temperature, burning rate and pressure have a good power function correlation. A theoretical analysis of the sub-atmospheric pressure dependence relationship on the burning rates was conducted to predict the burning behavior, showing good agreement with the experimental results. Two kinds of pressure effects on the burning control mechanism were proposed. For the convective heat feedback control, a 2/3 power law with pressure was formulated with experimental validation. For the radiation heat feedback influenced by soot emissivity and mean beam length, a 3/2 power law with pressure resulted.