Experimental study of buoyancy driven natural ventilation through horizontal openings

An experimental study of buoyancy driven natural ventilation through single-sided horizontal openings was performed in a full-scale laboratory test rig. Measurements were made for opening ratios L/D range from 0.027 to 4.455, where L and D are the length and the diameter of the opening, respectively. The bidirectional air flow rate was measured using constant injection tracer gas technique. Smoke visualizations showed that the air flow patterns are highly transient, unstable and complex, and that air flow rates oscillate with time. Correlations between the Froude number Fr and the L/D ratio were in reasonable agreement with result in literature obtained from brine-water measurements, but the obtained Fr values show considerable deviations for a range of L/D ratios. The measurement results can be used in both simple calculation tools to give a rough estimate of the capacity for design of a ventilation system, but also be implemented in more detailed models, especially multi-zone models, for simulation of the performance of natural ventilation systems