GB1164353A - Improvements in Bodies for Immersion in Fluid Streams. - Google Patents

Abstract

1,164,353. Boundary layer control. H. PAPST. 30 June, 1967 [1 July, 1966], No. 30314/67. Heading F2R. An aerofoil 3 has an outer surface along which a boundary layer develops when the aerofoil is placed in a fluid stream, the surface having at least one channel 4 extending transversely to the direction of flow of the fluid stream, the channel being partially covered by a strip 5 which has a sharp edge 13 facing the flow, the angle between the faces forming the edge being less than 60 degrees (preferably less than 45 degrees), the edge 13 forming the rear edge of a slot 6 extending along the channel, so that boundary layer air may enter the channel, there being means (e.g. ports 11) to convey the boundary layer air from the channel to elsewhere outside the aerofoil. The edge 13<SP>1</SP> may be raised out of the outer surface into the flow by an amount e about equal to the width d of the slot 6. The slot 6 may be either cut as a series of short slots in the strip 5, formed between the edge 13 and the upstream wall of the channel, or formed between two strips held in spaced relationship by a series of elements 16 of rectangular, circular or segmental section, which bridge the slot at regular intervals. The channel 4 may be formed with recesses 7 to house the strips 5 so that the outer surfaces of the strip lies flush with that of the aerofoil 3. The recesses may be undercut and filled with selfhardening material 18. To avoid the slots 6 clogging with ice, the strips 5 may comprise material which acts as a heating element when an electric current is passed therealong, the strips 5 being insulated from other metallic parts of the aerofoil by a thin foil of plastics material.