Experimental study on fire thermal characteristics of flammable gases leakage underwater

With the rapid development of offshore oil and gas industry, the length of submarine pipelines installed globally continues to increase significantly. Due to the complex maritime environment and the difficulties in rescue operations, accidents including submarine pipeline leaks, fires, and explosions often result in significant disasters, such as the gas pipeline fire in Gulf of Mexico during the July 2021. This underscores the importance of advancing safety measures and risk management strategies for submarine pipelines in the context of sustainable offshore energy development. In this study, the fire experiment for flammable gases leakage underwater was carried out, where the flame centerline temperature and the radiative heat flux were measured. It was found that flame temperature for flammable gases leakage underwater was relatively low, about 770-870 K, and the classic prediction model of fire plume temperature was inapplicable. Then, the dimensional analysis is employed for investigation on fire radiation of flammable gases leakage underwater, where the correlation between dimensionless radiative heat flux and dimensionless distance was fitted. In addition, it was also found that the radiation fraction is lower than that of a free jet flame or pool fire, due to the water vapor on the surface diffusing into the combustion zone. Finally, the thermal hazards for fire on the ocean surface in the south of the Gulf of Mexico was analyzed using the fire radiation model introduced in this study. The research results significantly enrich the current theoretical knowledge of fire dynamics, and provide theoretical and data support for fire prevention of offshore energy industry.