A mixed numerical-experimental study of the outdoor wind effects on the indoor air distribution under the multi-nozzle air curtains

Abstract

The infiltration of cold air through the open doors is controlled using air curtains, resulting in lower thermal loss and higher energy efficiency in the buildings. Meanwhile, severe outdoor conditions affect the performance of the air curtains drastically. In this context, the performance of a multi-nozzle air curtain with two different geometries has been investigated under various outdoor conditions using validated CFD. The air curtain system creates a thermal barrier with a specific sequence of large nozzles, small nozzles, and holes that blow air downward at different speeds. A half scale (1:2) model located above a door in the middle of the wind tunnel at the University of Sherbrooke is used for the hot wire measurements of the critical characteristics for different wind velocities (0, 4, and 9 m/s). Also, the SST k−ω turbulence model has shown the highest accuracy during the turbulence model sensitivity analysis and is used for complementary studies. Despite all the similarities, the results indicate that Fifth Order Polynomial Nozzles are more resistant against the high-velocity front winds, comparing the Arc Shape Nozzles, due to 3.6% augmentation of the exit velocities at large nozzles and shorter convergence areas. Also, this fact is proven by the studies of the impact point of these air curtains.