Multipoint Aerodynamic Shape Optimization of a Truss-Braced-Wing Aircraft

The truss-braced-wing (TBW) aircraft is a promising innovative design for the next-generation airliner. Nevertheless, for a full TBW wing–body–tail configuration, it is still a challenge to perform the comprehensive refined aerodynamic design. Especially, the complex mutual interference among the wing, struts, and fuselage should be analyzed in detail. Meanwhile, for its one-design cruise condition with Ma 0.70 and C_L 0.77, the aerodynamic explorations and performances of drag divergence and near-buffet-onset condition are also fateful. To address these issues, we utilize high-fidelity Reynolds-averaged Navier–Stokes solver and gradient-based optimizer to conduct aerodynamic optimization designs, including a single-point optimization, a two-point optimization, and a three-point optimization. Results indicate that the single-point design obtains a nearly shock-free configuration with an approximate elliptical lift distribution and an L∕D of 24.09. Also, the refined local aerodynamic analyses lead to a good understanding of the complicated interactions with several junctions. For multipoint optimizations, both optimized configurations have the same level aerodynamic behavior on cruise condition compared with the single-point result, and they have a satisfying performance of drag divergence. Moreover, the three-point optimization design shows excellent aerodynamic efficiency with some extra off-design points evaluations, whereas the two-point optimization still has an undesirable off-design result.