FAN UNIT WITH A FREE RADIAL FAN IMPELLER

摘要

The invention relates to fan units with a free radial fan impeller which are mainly used in tube axial fans. Said invention makes it possible to increase the productive efficiency at high static pressure and to reduce a noise level. The inventive fan unit consists of a radial fan impeller (1) comprising front (3) and basic (4) discs, backward fan blades (5), which are located therebetween and provided with slats (24,) and of an input collector (2) having converging input (12) and output (13) segments and an additional segment (16), which is arranged therebetween and has a slight curve surface and a length L cw which is equal to or greater than 0.04 of the diameter D of the fan impeller. The front disc (3) and the output segment (13) of the collector (2) are located in such a way that a circular clearance, in front of which plates (18) are arranged, is formed. A straight line connecting an axis (6) to the leading edge (27) of the slat (24), when projected on a plane perpendicular the axis (6) of the fan impeller (1), does not fall beyond the limits of ±0.05 of the angular interblade pitch t of the blades (5) with respect to a straight line connecting the axis (6) to a point (29) where the blade, which is next in the rotational direction,is adjacent to the front disc (3)