GB788550A - Improvements in centrifugal or radial flow fan impellers - Google Patents

Abstract

788,550. Centrifugal fans. AEREX, Ltd. Jan. 2, 1956 [Jan. 18, 1955], No. 1498/55. Class 110 (1). A radial-flow impeller, for a fan having an inclined radial-inlet casing which forms a streamlined extension of the axial inlet, comprises aerofoil blades which define passages located only in an outer annulus of the impeller and are formed and mounted as cantilever beams extending from an inclined portion of a back or centre plate. Aerofoil blades d, of tapering width and thickness, are each welded to a shouldered disc e which is clamped, in angularly adjusted position, in a shouldered hole f in an inclined rim c<SP>1</SP> by means of a shouldered clamping disc g and screws h. A fairing c<SP>2</SP> is provided. In the embodiment shown, a shroud ring l, of thin sheet metal, is attached to each blade by a screw k at the blade pivot axis x-x, and forms a continuation of the casing inlet wall a<SP>1</SP>, a<SP>2</SP>. Leakage through the clearance between the ring l and the wall portion a<SP>2</SP> is reduced by flanges, as shown, of sufficient depth to give a sealing effect. The inlet wall a<SP>1</SP>, a2 may be continued to cover the blade tips, the shroud ring then being unflanged or omitted; this extension, like the rim c<SP>1</SP>, may be either of conical or spherical form. The centroid of each blade may be placed in the mean radial plane of the impeller. The fan may be of double inlet type and may have fixed blades.