Fractal Based, Scale-adaptive Closure Model for Darrieus-Landau Instability Effects on Large-scale Hydrogen-air Flames

Darrieus-Landau instability is an essential driving mechanism behind flame acceleration, especially in the absence of turbulence. Effectively quiescent initial conditions are particularly relevant for explosion safety in various process facilities or parts of nuclear power plants. Large-scale industrial facilities pose a considerable challenge for numerical modeling through CFD since applying methods that rely on resolving the internal flame structure to predict the flame dynamics is well outside the limits of today's computational resources. Therefore, in present work, a new scale-adaptive URANS (Unsteady Reynolds-Averaged Navier-Stokes) model for sub-grid closure is introduced. It is aimed at modeling the effects of the Darrieus-Landau instability at a significantly reduced computational cost. Model validation was performed using lean and stoichiometric hydrogen deflagration experiments at medium (similar to 1m) and large (similar to 10m) geometric scales.