Assessing the influence of real releases on explosions : selected results from large-scale experiments

Abstract : The research activities in the project Assessing the Influence of Real Releases on Explosions (AIRRE) included a unique series of large-scale explosion experiments with ignited high-momentum jet releases directed into congested geometries. The primary objective for the AIRRE project was to gain improved understanding of the effect realistic releases and turbulent flow conditions have on the consequences of accidental gas explosions in the petroleum industry, to develop methodology that can facilitate safe and optimal design of process facilities. This paper presents selected results from experiments involving ignition of a highly turbulent gas cloud, generated by a large-scale, pressurised release of natural gas. The paper gives an overview of the effect on maximum explosion overpressures of varying the ignition position relative to the release point of the jet and a congested region placed inside the flammable cloud, with either a high or medium level of congestion. For two of the tests involving a jet release and the medium congestion rig, the maximum overpressures significantly exceeded those obtained in a quiescent reference test. The paper presents detailed results for selected tests in the campaign. The effects on the relevant explosion phenomena from introducing initial turbulence, initial flow momentum and concentration gradients, as generated by the realistic release, are discussed.