Experimental and theoretical study on the characteristics of the spill plume in a compartment fire with high-low opposing openings

This paper presents the characteristics of the spill plume in a compartment fire with high-low opposing openings. Three sizes of doors (low openings), six sizes of windows (high openings), and three heat release rates were adopted. Mass flow rates through the openings were calculated with new length scales considering the effect of bidirectional airflow at the door, and then the expression of the neutral plane height was derived. The calculated results had good agreement with the experimental results. To reveal the effect of the opening sizes on the energy proportion, the heat fluxes from the openings were calculated based on the new length scales, and the heat lost through compartment boundaries was also obtained. It was found the size variation of any opening would affect the proportion of each part of the energy and the ratio of heat flow through openings can be represented by the 5/2 power of the ratio of the new length scales. The fire spill plume thickness is related to the horizontal velocity of the plume ejected from the window, and one linear relationship was established. Moreover, the heat flux along the facade and the temperature distribution of the fire spill plume outside the window were given with the new length scale.