CFD evaluation against a large scale unconfined hydrogen deflagration

In the present work, CFD simulations of a large scale open deflagration experiment are performed. Stoichiometric hydrogen-air mixture occupies a 20 m hemisphere. Two combustion models are compared and evaluated against the experiment: the Eddy Dissipation Concept model and a multi-physics combustion model which calculates turbulent burning velocity based on Yakhot's equation. Sensitivity analysis on the value of fractal dimension of the latter model is performed. A semi-empirical relation which estimates the fractal dimension is also tested. The effect of the turbulence model on the results is examined. LES approach and k-ε models are used. The multi-physics combustion model with constant fractal dimension value equal to 2.3, using the RNG LES turbulence model achieves the best agreement with the experiment.