An experimental and theoretical investigation of airflow through large horizontal openings.

The work was concerned with measuring natural convection through a large horizontal opening of different sizes and shapes located between two rooms in a building. Airflow rates between the two rooms were measured using a tracer-gas decay technique. Room 1 was heated to various temperatures in the range 18°C to 33°C using thermostatically controlled heaters; room 2 was unheated. A multi-point sampling unit was used to collect tracer-gas samples from each room. The concentration of SF6 tracer was measured using an infra-red gas analyser. The heat and mass flow rates between the two rooms were calculated from the tracer-gas concentrations and temperature differences. The coefficient of discharge of the opening was found to be a function of the temperature difference between the two rooms. The mass flow rate was increased by increasing the area of the opening. The mass flow rate of a circular opening was in most cases higher than that of a square opening. The work also describes CFD modelling of natural convection through horizontal openings. Results were compared with values obtained from experiment.