Numerical Simulation of a Ceiling Jet Fire in a Large Compartment

The ceiling jet phenomenon of a 15 m long test hall fire with 1.5 MW was reconstructed by an in-house large eddy simulation (LES) model which incorporates fully coupled sub grid-scale (SGS) turbulence, combustion and radiation models. Fire spread of an enclosure fire is typically caused by the ceiling jet behavior when radically-outward gas motion produced by impingement of a rising fire plume on a horizontal ceiling allowing hot gas to travel along the ceiling transfer energy to the lower portion of the hall by gas radiation. The non- equilibrium combustion caused by microscopic mixing processes was modeled by a scalar dissipation conditioned combustion model coupled with SGS turbulence model. The performance of the two sub grid-scale (SGS) turbulence models, Smagorinsky SGS model and Wall Adapting Local Eddy Viscosity (WALE) model, were assessed by comparing predicted transient gas temperatures and velocities at various spatial locations.