INCOMPRESSIBLE-FLOW IN CONTRACTING DUCTS

This paper describes the incomPressible flow through contracting ducts as used in windtunnel circuits. The value of the velocity gradients t hat are critically adverse to the boundary layer development are speci fied and the contraction profile is derived for two-dimensional flow. Solutions to the flow through three-dimensional contractions of circul ar, square, and square to rectangle shape are obtained. These lead to simple rules for scaling the profile of two-dimensional flow to provid e three-dimensional shapes having short lengths with the required velo city distributions. The development of both laminar and turbulent boun dary layers is calculated to provide criteria for the avoidance of sep aration.