What happens during a gas explosion?
The detonation of a cloud of flammable gas is very rapid but also an extremely complex mix of chemistry and physics. The rapidity makes determining exactly what happens all the more challenging. Working on the task was the EU-funded project 'Advanced numereical study of flame acceleration and detonation in vapour cloud explosions' (DETONATION). The aim was to model the complex processes in flame acceleration and to transfer that knowledge to Europe. In particular, the model would focus on the path of flame around single and multiple obstacles. The study fell under the Seventh Framework Programme's (FP7) Marie Curie International Incoming Fellowships (IOF) sub-programme, and ran over two years to July 2013, completing all planned objectives. First, the study developed a technique for modelling large-scale hydrogen combustion and explosion. The method combines single-step chemistry and air flow parameters. In addition to combustion, the model incorporates the exploding gas's interaction with obstacles in open space, using modified OpenFOAM code. The study also simulated propagation of a detonation wave under various physical contexts, including U-bends and a flat semi-confined layer. The model developed for hydrogen showed good agreement with test measurements. The steps laid important groundwork for developing a large-scale chemistry model. A modified version was developed for liquefied natural gas (LNG), illustrating how changes to pipe diameter affect flame motion. The LNG calculations also agreed with testing. The study's models incorporate complete chemical reaction mechanisms for hydrogen–air and propane–air mixtures. In addition, the simulation incorporated eddy dissipation parameters for single and multiple fuels, and a sub-model concerning soot. As a result of the DETONATION project, the chemical and physical action of explosions in flammable gases is more completely understood. The work has both academic and industrial applications.
Keywords
Gas explosion, hydrogen, natural gas, detonation, flammable gas, chemistry, physics, flame acceleration, vapour cloud, combustion, air flow, OpenFOAM, liquefied natural gas
