An air stream-generating curtaining unit (1) adapted for being included as one of several curtaining units situated in a row in an air curtaining installation. The unit comprises a fan unit (6) arranged.in a casing (5), the casing having inlets (7) and outlets (8) for a partial curtain forming air stream driven by the fan unit (6) for the air curtain. The outlet (8) of the curtaining unit is provided with a combined silencing and air distribution means having an air supply nozzle (9) which has a substantially rectangular through-flow cross section with long sides extending along substantially the entire curtaining length of the curtaining unit, and with short sides (12) of gradually decreasing length along the flow path of the partial air stream. At least one (13) of both the defining walls of the supply air nozzle which form said long sides has its profile convex shaped in the flow direction of the partial air stream, seen from within the nozzle. Both defining walls (13,14) each define one side of a box (15) filled with porous material exterior to and facing towards the nozzle (9), the box serving in a manner known per se as a resisfve arSd reactive silencer, the only open communication of the box (15) with the supply air nozzle (9) being a pierced portion (16) of the defining wall, this portion being at a distance from the inlet of the nozzle. Adjacent the inlet end there is an unpierced entry portion (17) for the partial air stream. The fan unit (6) has a plurality of fans (19), the outlets (20) of which are distributed in spaced relationship along the longitudinal extension of the inlet cross section of the nozzle (9) while the zones in the cross section of the inlet not utilized for outlets from the fan are blanked off.