An analysis of the subsonic flow past symmetrical blunt-trailing-edge aerofoil sections at zero incidence, in the absence of a vortex street

Abstract

A simplified analysis is presented of the subsonic non-periodic flow past symmetrical blunt-trailing-edge sections at zero incidence. The pressure distribution is determined, with the base pressure as parameter, by an analysis of the inviscid flow past a displacement surface representing the section, the attached boundary layer, and the wake. The shape of the downstream part of the displacement surface presented by the wake is specified by pressure criteria established from a study of the pressure distribution downstream of a rearwardfacing step. The solution is rendered unique by the estimation of the base pressure. An analysis is made of the flow in the wake, invoking the condition that the wake momentum thickness must asymptote to a value at infinity downstream which is proportional to the total drag of the section. The viscous solution can be regarded as a logical extension to blunt-trailing-edge sections of the method of Squire and Young for the estimation of the drag of conventional aerofoils. A few examples are submitted to illustrate the application of the method.