Gas explosion is commonly defined as a premixed fuel-oxidiser combustion process with rapid increase of pressure.
Premixed flame can propagate in two modes: deflagration and detonation. Usually premixed flame propagate in deflagration mode, where flame propagates at subsonic speed relative to the unburned gas. Under certain conditions, deflagration may locally transits into detonation where flame propagates at supersonic speed.
Accidental gas explosions can be very destructive. To prevent accidental gas explosion, a good understanding of gas explosion mechanism is very essential. However, gas explosion is an extremely complex process, with strong interaction between fluid dynamics and chemical reaction kinetics. There is no analytical solution for prediction of gas explosion.
With proper numerical solution method and proper models, CFD simulation can be a very useful tool for modeling of gas explosion. Presented below are examples of Simtec simulation of high pressure H2 leak and gas explosion.