Calculating Combined Buoyancy- and Pressure-Driven Flow Through a Shallow, Horizontal, Circular Vent: Application to a Problem of Steady Burning in a Ceiling-Vented Enclosure.
Calculating Combined Buoyancy- and Pressure-Driven Flow
Through a Shallow, Horizontal, Circular Vent:
Application to a Problem of Steady Burning in a
Cooper, L. Y.
Fire Safety Journal, Vol. 27, 23-35, 1996.
fire research; vents; buoyancy; pressure; ceilings;
enclosures; algorithms; equations; energy release rate;
ships; wood; ceiling vents; oxygen concentration
A model was developed previously for calculating
combined buoyancy- and pressure-driven (i.e., forced)
flow through a shallow, circular, horizontal vent where
the vent-connected spaces are filled with fluids of
different density in an unstable configuration (density
of the top fluid is larger than that of the bottom). In
this paper, the model is summarized and then applied to
the problem of steady burning in a ceiling-vented
enclosure where normal atmospheric conditions
characterize the upper-space environment. Such fire
scenarios are seen to involve a zero to relatively
moderate cross-vent pressure difference and
bidirectional exchange flow between the enclosure and
the upper space. A solution to the problem leads to a
general result that relates the rate of energy release
of the fire to the area of the vent and the temperature
and oxygen concentration of the upper portion of the
enclosure environment. This result is seen to be
consistent with previously published data from
experiments involving ceiling-vented fire scenarios.