Abstract. The contribution deals with quantification of natural gas leak from a domestic low pressure pipe to a confined space in relation to formation of explosive concentration. Within the experiments, amount of leak gas was determined considering the character of pipe damage. Leakage coefficients, natural gas expansion and time before reaching the lower explosive limit of a gas-air mixture were taken. Conducted experiments were then modelled using CFD software and the results were verified. In numerical model, several models of flow were used and afterwards following issues were analysed: leakage velocity, spatial distribution of the mixture in a confined space, formation of concentration at the lower explosive limit etc. This work should contribute to better understanding of propagation and distribution of gaseous fuel mixtures in confined spaces and thereby significantly reduce the risk of fires or explosions or prevent them.

Abstract. Very rapid physical and chemical processes during the explosion require both quality and quantity of detection devices. CFD numerical simulations are suitable instruments for more detailed determination of explosion parameters. The paper deals with mathematical modelling of vented explosion and turbulent flame spread with use of ANSYS Fluent software. The paper is focused on verification of preciseness of calculations comparing calculated data with the results obtained in realised experiments in the explosion chamber.

The contribution deals with leakage of natural gas from domestic low-pressure piping. Spreading of the leaked natural gas in the confined space is deals with and the areas are defined where local hazardous concentrations are formed. Mathematical CFD models provide broad overview of spreading of natural gas, in dependence on the elapsed time from the start of leakage. The contribution should improve the understanding of spreading and distribution of mixture of gaseous fuels in confined spaces, and thus leads to significant reduction of the risk of occurrence of fire or explosion or to prevention of these hazards.

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Spreading of natural gas during its leak from a domestic low pressure pipeline in a confined space is a complicated issue depending on many factors. In relation to possible explosion, created dangerous concentrations could be identified effectively by numerical simulations using mathematical CFD models. It is suitable to verify the results of numerical simulations by real experiment, even if it is a simplified one. Verified mathematical model could then offer detail picture of spreading of gas in a whole focused space. In executed numerical analysis, several mathematical models of gas flow were applied and they were compared to the results of experimental measurements. This paper deals also with formation and propagation of critical concentrations of natural gas in the whole observed space in the cubical experimental chamber. All above-mentioned matters could be applied in the fields dealing with safety of persons, technologies and objects, and it could be also used for explanation of accidents related to leakage and explosion of gas.