GB980623A - Improvements relating to cross-flow blowers - Google Patents

Abstract

980,623. Transverse-flow blowers. FIRTH CLEVELAND Ltd. Feb. 7, 1961 [Feb. 12, 1960], No. 4538/61. Heading F1C. [Also in Division F4] In a transverse-flow blower, the impeller comprises a series of flow-dividing elements secured to the blades and extending transversely thereof, adjacent elements being spaced in the axial direction by substantially less than the radial depth of a blade. This reduces noise. As shown in Fig. 3, wire 20 may be wound helically about the outer edges of the impeller blades 21, each turn of the wire comprising one of the flow-dividing elements. The wire may be replaced by a flat strip wound edgewise. Alternatively, thin rings of greater radial depth than the blades may be stamped with slots in which the blades are inserted so that the rings extend perpendicular to the impeller axis. The rings may be thickened at the pressure (i.e., concave) side of each blade to displace the fast portions of the flow into the region of the suction (i.e. convex) side. Fig. 4 shows an impeller in which rings 60 of serrated form are provided, whereby the channels formed between the rings are of greater depth adjacent the suction side 62 of each blade, where the velocity of flow is greater, than on the pressure side 63. The flow-dividing elements may instead comprise a series of fins 103, Fig. 5, carried by each blade 100. On the suction side of the blade, the fin is confined to the outer edge of the blade where breakaway of flow may occur. In a modification, the fins merge into each other at their outer edges to form a closed ring. Specifications 757,543 and 876,611 are referred to.