The Smallest Size of a Spanwise Surface Corrugation which affects Boundary-layer Transition on an Aerofoil

Abstract

The effect of a spawise surface corrugation on the position of transition from laminar to turbulent flow in the boundary layer of an aerofoil depends on the local disturbances caused by the corrugation and on the stability of flow in the boundary layer beyond. The report describes wind-tunnel experiments made for bulges, hollows and ridges on an aerofoil and on a flat plate to obtain relations for the minimum height of a spanwise surface corugation which affects the position of boundary-layer transition, and so the drag, of a laminar-flow aerofoil.