A simple formula has been proposed to calculate the equivalent ventilation parameter of multiple openings. The formula intends to be used as a part of engineering fire resistance design, where the fully developed fire temperature is characterized by fuel load, compartment size, thermal inertia of enclosure walls and ventilation parameter of the compartment opening. As most of the existing approaches assume a single opening in a fire compartment, the equivalent ventilation parameter has to be evaluated prior to using these models. In this study, a simple, closed form formula was developed to calculate the equivalent ventilation parameter that gives same (or conservative) amount of airflow rate into fire compartment. The reasonable agreement of the formula was checked against numerical results changing the aspect ratios and area fractions of the windows in a wide range.

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This paper describes the required performance of numerical simulation of smoke movement in large volume spaces and the safety design of smoke control systems by using Computational Fluid Dynamics.
The relational studies which have been done up to date are reviewed and the performance of the two-zone model is evaluated through the basic analysis of smoke movement phenomena in large volume spaces of cubic geometric unit. The basic concept and the scope of numerical simulation of smoke movement is derived.

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A mathematical model is proposed to describe the spread rate of a smoke front under an inclined ceiling. The smoke flow is treated as a macroscopic density current, and the effect of buoyancy caused by the inclined ceiling is taken into consideration based on the horizontal spread model.
To substantiate the validity of this model, experiments are also carried out under various conditions. The experimental result shows that with an increase in the inclined angle of the ceiling up to 45 degrees the spread speed of the smoke front increases. However, when the angle exceeds 45 degrees, the spread speed is saturated and it happens that the spread speed slows down on the way of spread. This retardation of the smoke front is caused by the counter flow appeared in the closed space of a model corridor, and does not occur in the open space, which is obtained by taking off the floor. The location of the smoke front is also calculated and the results agree well with the experimental results. Thus, it is confirmed that the present model is valid to predict the spread rate of smoke front under the horizontal and inclined ceiling.

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