Modeling of Gas Explosion Phenomena

Abstract

This paper presents the results of a study on scale modeling for simulating an accidental gas explosion in an enclosure. Discussion has been concentrated on modeling of main processes of a gas explosion. Those include flammable mixture formation and pressure rise. Of various parameters, on which the flammable mixture formation depends, those representing the enclosure size, gas flow in it, ventilation, and turbulence generated at the flammable gas leakage are pointed out to be the most important for scale modeling. It is indicated that in a large enclosure, the flammable gas scarcely becomes uniform. For simulating the mixture formation in a scale model, the velocity of leaked gas should be increased by a factor inversely proportional to the reduction factor and the time should be reduced by a factor square of the reduction factor. The pressure rise depends on flame behavior, which is closely related to the flammable gas concentration. The difficulties for scale modeling of the pressure rise are indicated to be attributable to the non-uniformity of the mixture and independence of burning velocity from the enclosure size. Despite of those difficulties, the pressure rise can be simulated by controlling the time at break as it is proportional to the representative dimension. For establishing reliable scale modeling, there remain many other issues to resolve.