Characteristics of Buoyancy Driven Single-Sided Natural Ventilation through Horizontal Openings

An experimental study of the phenomenon of buoyancy driven natural ventilation through single-sided horizontal openings is described in this paper. The experimental analysis was performed in a full-scale laboratory test rig. The basic nature of air flow through the single-sided openings was investigated. The bi-directional air flow was measured using constant injection tracer gas technique. Variable parameters included the air flow rate, the air velocity, the temperature difference between the rooms and the dimensions of the horizontal openings. The measurements were made for opening ratios L/D in the range of 0.115 to 4.445, where L and D are the length of the opening and the diameter of the opening, respectively. The smoke visualization showed that the flow patterns are highly transient and unstable, and the air flow rates oscillate with time. The air flow rate can be obtained in the correlation between Froude number Fr (dimensionless air flow rate) and L/D ratio. The tendency of Fr with L/D is good agreement with Epstein’s formula obtained from brine-water measurements, but the Fr value shows considerable deviations between the air flow measurements and the Epstein’s formula. So, the full scale air flow measurements are quite important and much more reasonable than the scale brine-water measurements, even though the brine-water technique has some advantages.

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