Numerical simulation of large scale hydrogen explosions in complex geometries

Large hydrogen air clouds represent a serious hazard during severe accidents in nuclear power plants as well as in facilities of the developing hydrogen technology. The accident scenarios are dominated by large time and length scales with complicated boundary conditions. The combustion can proceed as an accelerating turbulent flame with possibly transition to detonation. Such problems require a careful selection of the physical and chemical models as a fully detailed calculation is not yet feasible. An extension of the well known eddy break-up model together with the k--model was calibrated at a large set of experiments on different scales. It was demonstrated that this model gives good results for a large range of parameters.