The Flow in S-shaped Ducts

Abstract

SummaryMeasurements are presented of total pressure, static pressure, surface shear stress and yaw angle in the flow through several S-shaped ducts, each with a thin turbulent boundary layer at entry. The results show that the region of low total pressure in the exit plane, found by previous workers, is due to expulsion of boundary-layer fluid by a pair of contra-totating vortices in the boundary layer. The generation of these vortices is explained: similarly-produced vortices, with similar effects, occur in some types of wind-tunnel contraction and possibly in other three-dimensional flows.