Experimental study of flame extinction with fuel diffusion combustion inside a wall-opening compartment under reduced ventilation conditions

Abstract

The present study investigates experimentally the transient flame extinction behavior with fuel diffusion combustion inside a wall-opening compartments at reduced ventilation condition. The characteristic parameters to quantify the flame extinction mechanism include the Global Equivalence Ratio (GER) extinction time and critical gas temperature right before extinction. Their coupling effect on the dynamic process of flame extinction with fuel diffusion combustion inside compartments of various scales and opening sizes is quantified and formulated. It is found that: (1) flame extinction is easier to occur for smaller opening size or relatively larger compartment scale which could be well represented by two non-dimensional quantities i.e. the GER and non-dimensional heat loss; (2) the time to reach flame extinction is shorter as the fuel supply flow rate is higher while it is longer as the opening size is larger; (3) the gas temperature inside the compartment when flame extinction is reached first increases with fuel supply rate until a plateau is reached. A formula is established to describe the critical gas temperature right before extinction as a function of a newly defined non-dimensional integrated parameter including both fuel combustion heat release and heat loss factors in which the fuel supply rate opening ventilation compartment scale and transient extinction time scale are involved in general to reflect physically their interplay in controlling the flame extinction inside the compartment. The present study provides new observation quantification and formulation of the mechanism of flame extinction with fuel diffusion combustion inside a wall-opening compartment under reduced ventilation condition.