Experimental study on upwards blowing air curtain jet.

Upwards blowing air curtain includes usually a shaped inlet, a fan, an outlet duct, sound attenuators, an underground plenum and a nozzle. Warmed air or outdoor air is blown from the nozzle forming a jet which travels the width of the doorway and run into the upper edge of the doorway. Upwards blowing air curtains are normally used in doorways to protect workers and processes from cold outdoor air and to reduce energy and maintenance costs of the industrial buildings (1,3). Design requirements of the upwards blowing air curtain are substantially different from those of the air curtains in entrance doors of the commercial buildings ( 1,2,4). Achieving the required momentum, the nozzle exit velocity can raise up to 40 m/s. To prevent the penetration of cold outdoor air through the air curtain, it is important that the air flow from the nozzle is evenly distributed through the full width of the doorway (1,3). In this study the main objective of the experiments was to develop an underground air plenum and the nozzle which would achieve an evenly distributed nozzle exit velocity using as low pressure loss as possible.