Design Studies of Thick Laminar-Flow Airfoils for Low Speed Flight Employing Turbulent Boundary Layer Suction over the Rear Part,

First the paper briefly reviews some computational tools, used at the authors institute, to analyse and design airfoils for low speed flight prediction of potential flow pressure distributions, laminar boundary layer flows, transition prediction using the esuperscript n- method and Heads entrainment method for the calculation of turbulent boundary layers. These tools are used in this paper to design pressure distributions and corresponding airfoil shapes producing long runs of natural laminar flow. Inevitably this results in airfoils with the maximum thickness far backwards, eventually leading to separation of the turbulent boundary layer over the rear part of the airfoil. This turbulent boundary layer separation is prevented by selecting a proper pressure distribution over the rear part andor suction of the turbulent boundary layer through slots or distributed perforations. Design charts are presented which help to select the required pressure distributions for laminar and turbulent flow. Author