Buoyancy distribution in a filling box segmented by a planar jet

Abstract

Air curtains are produced by thin vertical planar air jets and are used to prevent exchange flows between two fluids with a horizontal density gradient. They have been shown to work effectively provided the deflection modulus (DM) is greater than a critical value (DM = 0.14). Herein, results are presented from an experimental and modeling study of the initial transient development of the buoyancy distribution within an enclosure containing a round buoyant turbulent plume that is segmented by a co-flowing planar turbulent jet. A theoretical model based on filling box theory is developed to predict the leakage of buoyant fluid across the planar jet and the time at which the planar jet is no longer able to contain the buoyant plume outflow. Results from a series of analog salt-bath experiments are also presented that show that the model accurately predicts the rate of transport of buoyant fluid across the planar jet up until DM falls below the critical value of 0.14. The experiments show that, following the breakdown of the model there is a transition period after which the horizontal distribution of buoyant fluid throughout the enclosure is the same as it would be in the absence of the planar jet.