Numerical Simulation of Homogenous/Inhomogeneous Hydrogen-air Explosion in a Rectangular Channel

Hydrogen is one of the promising energy sources in the future, because it has the advantages of clean combustion products, high efficiency, and renewable energy. However, hydrogen has the characteristics of low ignition energy, wide flammable range (4% -75%), and fast burning flame speed, which can cause explosion hazards. Typically, the accidental release of hydrogen into confined or semi confined enclosures can often lead to a flammable hydrogen-air mixture with concentration gradients and possible flame acceleration and deflagration-to-detonation transition (DDT). The present study aims to test the capability of our in-house density-based solver, ExplosionEngFoam, for flame acceleration (FA) and deflagration-to-detonation transition (DDT) in homogenous/inhomogeneous hydrogen-air mixtures. The solver is based on the open source computational fluid dynamics (CFD) platform OpenFOAM and uses the modified Weller et al.’s combustion model taking into account LD and RT instabilities, turbulence and non-unity Lewis number etc. Numerical simulations were conducted for both homogeneous and inhomogeneous mixtures in a long enclosed channel with 5.4 m in length and 0.06 m in height. The predictions demonstrate good quantitative agreement with the experimental measurements in flame tip position, speed and pressure profiles by Boeck et al. The flow characteristics such as flame fine structure, wave evolution etc. were also discussed.