Improvement in sealing effectiveness of air curtains using positive buoyancy

Air curtains are commonly employed in building applications to facilitate aerodynamic sealing against the exchange flow that occurs through an open doorway due to the density differences owing to buoyancy. Such situations often prevail due to temperature gradients across a doorway of an air-conditioned building, e.g., during the summer season in an Indian subcontinental situation. In the present study, we numerically investigate the performance of `positively buoyant' air curtains. In such installations, the density of the jet fluid is larger than the density of the fluid contained within the building space. Using the two-dimensional Reynolds-averaged Navier-Stokes (2D RANS) formulation, we compute the temperature distribution in the flow domain and estimate the associated sealing effectiveness for various values of positive jet buoyancy and operating velocities of the air curtain. These estimates of sealing effectiveness are compared with that of a neutrally buoyant air curtain to assess the influence of positive buoyancy. We report an increase in sealing effectiveness of up to 10%, whereas its peak value improves by about 5%.