Abstract: An air outlet unit (101) for a large blower assembly comprising an outlet tube member (103) with an upstream inner end in flow communication with the pressure side of an impeller of the blower asembly and a downstream outer end for connection with a duct and a mainly cylindrical inner tube member (105) arranged coaxially to the outlet tube member (103) and having an inner end substantially aligned with the inner end of the outlet tube member (103) and a downstream outer end, the inner tube member (105) being closed by a closing means (106). The inner tube member (105) has an open downstream end (8114) projecting in the downstream direction beyoud the downstream outer end of the outlet tube member (103) to thereby achieve a reduced pressure loss and a more uniform velocity profile.

Abstract: An impeller (1) for an axial flow fan comprises a hub (2) supporting the blades (3). The hub (2) has bores (5) in its peripheral surface, whereby each bore (5) has a first radially inner section (10) with larger diameter than a second radially outer section (6). Each blade (3) has a substantially circular foot section (4) allowing adjustment of the blade pitch. Mach blade foot section (4) is mounted in a corresponding bore (5) by means of two connecting plates (8, 9) which in the first bore section (10) are spaced apart and face each other along substantially the entire diameter of the bore (5).