Air curtains are widely employed in domestic and industrial buildings to provide aerodynamic sealing against buoyancydriven exchange flows that occur through an open doorway due to the density differences. Such exchange results in undesirable heat and moisture losses through the doorway, as well as an inflow of uninvited substances e.g. pollutants, viruses, micro-organisms, dust, odours etc., which could deteriorate the indoor air quality of a building. Essentially, an air curtain is a planar turbulent jet produced by a fan unit that is blown through the nozzle, typically downwards, with a suitably high velocity. The performance of an air curtain, a parameter of importance from an engineering perspective, is largely dictated by its ability to inhibit this buoyancy-driven exchange flow.
In the present study, we report two-dimensional numerical simulations of air curtain flows based on the Reynoldsaveraged Navier-Stokes (RANS) formulation. These computations are shown to be in good agreement with the experiments conducted in a similar facility on a laboratory scale. Based on these simulations, we quantify the optimum velocity (in the form of a deflection modulus) at which the aerodynamic sealing (quantified as effectiveness) of the air-curtain is maximum. We also found that a higher effectiveness may not imply a larger fraction of domain being aerodynamically sealed.