An investigation of annular aerofoils for turbofan engine cowls

Abstract

Three annular aerofoils suitable for use as short fan cowls on turbofan engines of high bypass ratio have been tested at zero incidence over a range of subsonic Mach numbers and also in static conditions. Comparisons are presented with experimental results from a conventional type of 'pipe' rig, and with predictions from a linearised and a non-linearised theory. The results show that the effect of the cowl afterbody is fairly small and can be calculated theoretically. Both types of theoretical methods give good predictions of the surface pressure distribution, but the comparison between theoretical and measured mass flow through the cowl deteriorates as Mach number increases.