Experimental and modeling study on the burning behavior and burning characteristics of aviation kerosene pool fire at sub-atmospheric pressure

In recent years, the development of the economy in plateau areas has resulted in the increase in the flights in plateau areas, resulting in a large demand for aviation kerosene. However, the occasional aviation kerosene pool fire that occurs in plateau areas poses a great threat to the safe storage of aviation kerosene. The burning behavior and the corresponding characteristics of liquid fuels, such as aviation kerosene, are different because of the influences of sub-atmospheric pressure and oxygen amount. Moreover, the available reports in the literature concerning sub-atmospheric pressure are mainly based on small-scale experiments, which are greatly affected by heat convection and heat conduction. Furthermore, the burning characteristics are far from the practical fire conditions in plateau areas, which are mainly controlled by heat radiation. Thus, the burning characteristics of liquid fuel pool fires at large scales remain unclear. This study aims to clarify the difference between the burning characteristics of aviation kerosene pool fire under sub-atmospheric pressure and that under atmospheric pressure as well as develop the corresponding prediction models under sub-atmospheric pressure.

A series of pool fire experiments using aviation kerosene with different pool diameters under sub-atmospheric pressure (69 kPa) were carried out. The burning behavior during the whole burning process was analyzed. Moreover, the evolution of some important parameters (including mass burning rate, flame height, and radiative fraction) with the pool diameter were measured and analyzed in detail, and the corresponding prediction models were proposed.

The results showed that the burning rate of aviation kerosene under sub-atmospheric pressure was lower than that under atmospheric pressure for the same burning scale and that the ratio of the rate under sub-atmospheric pressure to that under atmospheric pressure was about 0.58. This result is primarily the result of the heat radiation and heat convection feedback between flame and fuel surface under sub-atmospheric pressure being lower than those under atmospheric pressure. Furthermore, a prediction model of the burning rate was proposed based on the heat feedback. The flame height under sub-atmospheric pressure was higher than that of the same burning scale under atmospheric pressure, primarily because the net oxygen content in the air under sub-atmospheric pressure was reduced and more air was required for fuel burning. In addition, based on the flame entrainment theory, a prediction model of the dimensionless flame height of aviation kerosene under sub-atmospheric pressure was obtained. The radiative fraction decreased slightly with the increase of pool diameter under sub-atmospheric pressure. And at the same burning scale, the radiative fraction under sub-atmospheric pressure was slightly lower than that under atmospheric pressure, primarily because of the reduction of soot particles generated during fuel burning under sub-atmospheric pressure. Subsequently, a prediction model of radiative fraction was developed by modifying the key parameters.

The evolution of the burning characteristics of radiation-dominated aviation kerosene pool fires under sub-atmospheric pressure with pool diameter was found to be consistent with those under atmospheric pressure; however, the values of different burning characteristics changed substantially. The results enrich the large-scale aviation kerosene pool fire data under sub-atmospheric pressure and have practical significance for ensuring the use and storage safety of aviation kerosene in plateau areas.