A numerical simulation study on the formation and dispersion of flammable vapor cloud in underground confined space

A transient numerical study on the formation and dispersion of fuel vapor clouds in confined space was conducted. A liquid-gas phase-change model for fuel vapor formation was developed to better understand safe methods for fuel operation and storage. A liquid fuel leak was exposed to air, and a flammable fuel vapor-air mixture was formed. The simulation of the low-speed flowing and plum-like fuel vapor clouds was based on large eddy simulation. A typical case of gasoline leakage in underground fuel storage was also analyzed in detail. The results showed that following a gas leak in an underground storage tank, the vapor-air mixture will fill the space from the edges to the tank chamber exit and from the bottom up. In addition, the volume fraction at the top of the tank chamber remained below the 20% low explosion limit (LEL). The volume change in the vapor-air mixture with a volume fraction above 20% LEL can be divided into three periods: linear growth, space constraints, and critical increasing. This study provides an important insight for assessing flammable atmosphere risks after fuel leakage in a confined space and for determining the proper rescuing means and time.