An experimental study on temperature evolution inside compartment with fire growth and flame ejection through an opening under external wind

Abstract

This paper investigated experimentally the temperature evolution inside the compartment as well as the transitions of fire growth from stratified phase to well-mixed case; and the critical conditions for flame ejection outside the opening, under different external wind speed. The characteristic parameters including the temperature inside the compartment, the heat release rate (HRR) of fire growth reaching well-mixed phase, as well as the critical heat release rate (HRR) for flame ejection were measured and discussed. It is found that: (1) For the stratified phase with lower heat release rate, the temperature difference between the upper part and lower part inside the compartment was reduced with increasing wind speed. (2) The maximum temperature that can be reached at the upper part as well as its corresponding HRR was lower when the wind speed was higher. (3) The critical total heat release rates corresponding to reaching the intermittent flame ejection and the continuous flame ejection at the opening both showed to first increase and then decrease with increasing wind speed. The corresponding transitional wind speed for this variation was shown to increase with increasing opening size or ventilation factor (AH). (4) The well-mixed condition was reached after the continuous flame ejection happens with no wind, however, it was reached before the continuous flame ejection shows up for the cases with external wind. The critical HRR for reaching the well-mixed condition decreased with increasing wind speed, which, in a non-dimensional form, correlated well against the wind Froude number by a linear function. These new findings provide a fundamental base for understanding fire growth dynamics inside a compartment with an opening subjected to external wind.