A theory for wind tunnel wall corrections

Wall correction theories for two-dimensional airfoils in wind tunnels with partly open walls are examined. Conventional wall correction theories are linearized theories, valid only for small thin models of slight camber at low angles of attack. Such theories are shown to be useless for the prediction of the required wall corrections for large models, models at high angles of attack, or models developing high lift. An exact numerical theory is presented in which it is not necessary to make these assumptions. The airfoil and any solid wall sections are represented by surface source and vortex singularities as in the method of A.M.O. Smith. Aerodynamic lift is determined by numerical integration of the calculated pressure distributions around the airfoil contour. The theory indicates that certain wall configurations will require small or negligible wall corrections for tests on lifting airfoils.