Maximum ceiling temperature and longitudinal distribution in a corridor-like enclosure with opening

Abstract

This paper reports a quantitative study on the effects of a side opening on the transition between the fuel-controlled and the ventilation-controlled condition and temperature distribution in a corridor-like enclosure fire. A side opening was introduced to simulate breakage of glass window in case of fire. Experiments were carried out in a 1/8 model tunnel with the dimensions of 3.14 m×0.42 m×0.368m(length×width×height), including 56 test conditions arising from variations of heat release rates (HRR) and opening sizes. The results showed that the transition was correlated with the fraction of the heat released to the heat convected through the opening and the ratio of the heat lost through enclosure boundary to the heat convected through the opening. The maximum temperature rise in the fuel-controlled condition was positively correlated with the fire heat release rate, but it was negatively correlated with the opening aspect ratio. There were two combustion stages in the ventilation-controlled condition, one with flame oscillation inside the corridor-like enclosure and the other with persistent flame ejection through the opening. The maximum temperature rise in the stage of flame oscillation inside the compartment was positively correlated with the air mass supply through the opening and negatively correlated with the heat loss through the corridor-like enclosure boundary. Non-dimensional correlations between the maximum temperature rise and the heat release rates (HRRs), opening sizes and the heat loss were proposed. Moreover, a piecewise equation was proposed to predict the longitudinal decay along the centerline of the corridor-like enclosure with an opening. All the proposed correlations were found to fit well with the experimental data, which established a basic relationship to quantify the (i) temperature variation, (ii) critical heat release rate and (iii) transition for various opening sizes and HRRs in a corridor-like enclosure fire. These new findings and the proposed non-dimensional model provide the basis for understanding fire growth and temperature distribution inside a corridor-like enclosure with opening.