CFD modelling of methane dispersion from buried pipeline leaks: Experimental validation and hazard distance estimation

The safe operation of buried pipelines necessitates an understanding
of potential leak dynamics and the subsequent formation of
flammable clouds defining hazard distances. This paper presents a
computational fluid dynamics (CFD) model and its validation against
experimental data on the dispersion of methane through a sand
layer of 100 mm thickness to the atmosphere. A leak orifice diameter
of 4 mm was considered for pipeline gauge pressures in the range of
10 to 300 kPa. This study describes the methane propagation in time
through the sand and the development of the flammable cloud in the
atmosphere. The simulations demonstrate a high degree of accuracy
in capturing the transient behaviour of methane propagation in the
sand and dispersion in the atmosphere when compared with a
60 s experiment. The model was applied to predict the development
and maximum spread of the flammable cloud; hazard distances are
also presented. The simulations provide insight into the development
of the flammable cloud. The validated CFD model can serve as a
predictive tool for hazard distance estimation in case of leaks from
buried pipes, informs safer pipeline design and improves emergency
response strategies for gas leaks.