Flame extension length beneath a horizontal eave due to excess fuel diffusion combustion outside compartment opening under ambient wind

Abstract

Fuel diffusion combustion through the opening outside the compartment is a fundamental scientific problem associated with complex fuel-air mixing/reaction, heat/mass transfer and fluid dynamics. This paper presents an experimental investigation and analysis on the flame extension behavior beneath the horizontal eave due to excess fuel ejected through an opening hence diffusion combustion outside the compartment under the ambient wind. Experiments were carried out in a reduced-scale model consisting of a compartment with an opening, a facade wall and a horizontal eave. The opening was set normal to the ambient wind provided by a wind tunnel. The flame extension lengths beneath the horizontal eave in the two directions (front direction- opposite to the wind; side direction- normal to wind) were quantified. The two flame extension lengths were measured under various horizontal eave heights, wind speeds and heat release rates. Results show that the flame extension lengths both decrease with increasing horizontal eave height or wind speed. The flame extension length in the front direction shows to be smaller than that in the side direction when the ambient wind is applied, which could be interpreted by the flow dynamics with the aid of CFD simulation. Based on the analysis of the controlling physics hence the associated non-dimensional parameters, correlations were proposed to describe the two flame extension lengths in relation to the horizontal eave height, heat release rate and wind speed.