Aerodynamic Analysis of a Slotted, Natural-Laminar-Flow Transonic Trussed-Braced Wing Aircraft Configuration

The integration of a slotted, natural-laminar-flow (SNLF) airfoil with a transonic, trussbraced wing (TTBW) configuration has been shown to offer significant benefits in comparison to other widely implemented designs for commercial transport applications. This work focuses on the computational aerodynamic analysis of an S207 SNLF TTBW vehicle flying at cruise conditions, with the study being supplemented by independent results of the S207 profile in two dimensions. The performance of the wing is largely dependent on the duration of laminar flow maintained across the chord length. Thus proper prediction of the transition from laminar to turbulent flow and its sensitivity to geometric changes is of top priority. Computations are performed in both two and three dimensions using Reynolds-averaged Navier-Stokes (RANS) solvers on unstructured grids with transition prediction models. Results in two dimensions agree well with the design performance metrics of the S207 SNLF airfoil, and also illustrate the sensitivity of this airfoil to flap positioning. Results in three dimensions were used to identify geometric inconsistencies in wing sweep transformations, which led to a redesign with improved performance. However, predicted transition locations on the current configuration occur earlier than expected by design, thus leading to less than optimal performance. CFD simulations point to the need for wing geometry modifications and/or alleviation of flow separation at the fuselage-wing fairing location.