The numerical and experimental analysis of upward flame spread over the flat surface and the wavy surface.

Highlights • Flame spread over the wavy surface of corrugated cardboard was modeled using direct numerical simulation. • Comparisons between flame spread on the flat surface and the wavy surface were made in detail. • The 'B' and 'C' flute cardboards were simulated to analyze the effect of wavy structure on the spreading flame. Abstract The corrugated cardboards have been widely used in warehouse where flame spread over its surface consisting of the flat layer and the wavy layer contributes more hazards once fire disaster happens. This paper therefore performs a numerical investigation to study upward flame spread over the cardboards with wavy structures. Comparisons between upward flame spread over the flat surface and the wavy surface of corrugated cardboards were made on the flame characteristics, flame spread rate, standoff distance, local burning rate and flame splitting. It is found that the flame gets closer to the wavy surface and a larger averaged temperature gradient is exerted on the surface, which causes the fuel to burn with a higher rate. The wavy structure is the main reason that causes a distinct difference between the flat surface and the corrugated surface, and it promotes the flame to split into more small flames, thus leading the flame to move faster. To validate the model results, experiments on the flame spreading over the fuel with wavy structure were conducted, which were in good agreement with the simulation. The results can provide a solid basis on which to guide the stacking of goods in warehouse in the future. [ABSTRACT FROM AUTHOR]