Numerical Investigations of Rack Storage Fires

A number of numer~cal simulations of rack storage fires have been carr~ed out, with various fuel types and burner outputs. Both the standard buoyancy-modified k E turbulence model and a recently developed turbulence model which significantly improves the consideration of the buoyancy effect on turbulence and turbulent transport, were used to study the turbulence of the buoyant flow. The flamelet concept. coupled to a prescribed probability density function, was employed to model the non-premixed combustion process. Sooting was modeled by solving the balance equations for mass fraction and number density considering nucleation, surface growth, coagulation and oxidation. The discrete transfer method was used to calculate radiation, with the radiation properties of the main radiating species carbon dioxide, water vapour and soot, provided by a fast, narrowband model. The results, including heat flux and gas temperature profile, were analyzed and compared with experimental measurements. The comparisons showed considerably improved agreement for the new model.