Planform Dependency of Optimum Supersonic Airfoil for Wing-Body-Nacelle Configuration Using Multi-Fidelity Design Optimization
CHALLENGE - In this study, the design knowledge which had been obtained in a previous study was developed by considering the effect of the aerodynamic interference between the engine intake and the wing. Therefore, a supersonic wing design problem was solved for a supersonic transport (SST) with an integrated engine intake and a nacelle. The following two planforms were considered: a quadruple tapered wing with a large sweep-back angle and a single tapered wing with a small sweep-back angle.
SOLUTION - To consider the effect of the aerodynamic interference between the engine intake and the wing, a high fidelity solver is required, which is significantly time-consuming. To improve the design efficiency, in this study, a multi-fidelity design method, which combined a high-fidelity solver and a low-fidelity solver to render the design process efficient was applied. In addition, to reduce the calculation cost of the optimization, a hybrid surrogate model was used that combines the Kriging surrogate model4 with a radius basis function (RBF) model. The ANOVA, which is a multi-variate analysis method, was used for the evaluation of the contribution of the design variables. A genetic algorithm was used in the optimum search process using optimizer modeFRONTIER.
BENEFITS - Through optimum designs, two kinds of design knowledge are obtained. First, in airfoil design, the shape of the forward camber and the twisted angle have the largest influence on drag reduction. For a high sweep-back wing, an airfoil that has small positive camber and small twisted down angle were shown to be optimum. However, for a low sweep-back wing, an airfoil which has negative camber at the leading edge or higher twisted down angle as compared to that of a low swept-back wing was shown to be optimum. Second, the type of aerodynamic interference between the wing, engine, and fuselage depends on the planforms.