Design of adaptive transonic laminar airfoils using the γ-Re˜θt transition model

This paper examines the design of adaptive laminar airfoils in the transonic flow regime using the γ-Re˜θt model as a transition prediction method. A robust solution procedure for the transition model is described and a grid convergence study is presented. Predictions from the model are then compared to an extensive set of experimental results containing transition measurements on a morphing airfoil. It is shown that the sensitivity of the γ-Re˜θt transition model with respect to shape variations allows its use in a design framework. Using a multi-point optimization strategy, the model is then used to design transonic airfoils suitable for a range of flow conditions. The potential improvement in drag associated with the implementation of adaptive airfoil technology is then carefully quantified using single-point optimization with the multi-point designed airfoil as a reference. Structural design constraints are taken into account to obtain a realistic estimate of possible drag reduction through airfoil morphing using current wing construction technology. Airfoil drag improvements of up to 4.6% are obtained through morphing of the section of upper surface located between the wing spars with respect to the baseline multi-point design in flow conditions typical of large business jet operation.