An analysis of the drag of two annular aerofoils

Abstract

An analysis of the drag and pressure measurements made in subsonic wind-tunnel tests on two annular aerofoils is described, The relation between the design pressure distribution in incompressible flow and the pressure distribution on the aerofoil at high speed, is discussed. An attempt has also been made to see what changes in the flow field are associated with the drag rise and whether the drag-rise Mach number can be predicted by methods similar to those used for ordinary aerofoils and bodies of revolution. A comparison has been made of the measurements on a two-dimensional aerofoil and the annular aerofoils; no significant differences in the structure of local regions of supersonic flow were found at Mach numbers near the drag rise.