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An efficient aerodynamic design tool has been developed adopting a surface mesh movement method for body-installation junctions and an unstructured adjoint method. A three-dimensional unstructured Euler solver is used for flow analysis. Sensitivity analysis is conducted by a discrete adjoint solver. For the geometric modification around body-installation junctions, surface mesh points on aircraft components are moved directly on the curved body surface without any mapping or regeneration of the surface and volume mesh. The present design approach has been applied to ONERA M5 and DLR-F6 wing-body-nacelle-pylon configurations at transonic flow conditions. For ONERA M5, juncture between main wing and fuselage was redefined with wing geometry modification. For DLRF6, juncture between wing and pylon was redefined with modification of both wing and pylon geometries. In both design examples, shock wave strength was remarkably reduced by the design process. The successful design results validate effectiveness and efficiency of the present design approach for complex configurations with junction interference effects. DOI: 10.2514/1.20723

An adjoint-based error estimation and grid adaptation study is conducted for three-dimensional inviscid flows with unstructured meshes. The error in an integral output functional of interest is estimated by a dot product of the residual error and adjoint variable vector. To suppress excessive mesh refinement in unnecessary regions due to high-frequency noise contained in the residual vector, the flow residual is smoothed using a volume-weighted averaging process. Regions to be adapted are selected based on the error contribution of a local node to the global error. The adaptive regions are refined by the bisection refinement algorithm. The present procedure is applied to three-dimensional transonic inviscid flows around ONERA M6 wing and ONERA M5 airplane models. The same level of prediction accuracy for drag is achieved with much less mesh points than uniformly refined fine meshes. It is found that the residual smoothing strategy remarkably improves the accuracy of error estimation, and there exists an optimum number of smoothing for accurate error estimation.

A new geometry modification method for aerodynamic design optimization is developed using surface mesh coordinates as design variables. Surface meshes are modeled as a spring system with tension and bending springs, and a negative gradient vector of a design objective function is imposed on the spring system as fictitious external forces. Corresponding deformation of the surface spring system is considered as a smoothed vector of the objective function gradient and used for a line search to find an optimum solution along the smoothed vector. This provides a rich design space, which is limited only by the surface mesh density. It also enables smooth variation of design surfaces even for singular gradient vectors. As design examples, sample aerodynamic optimization problems are conducted utilizing two- and three-dimensional computational-fluid-dynamics codes for flow analyses and discrete adjoint codes for sensitivity analyses. A recommendation on the selection of a required parametric value is made based on the design results.

The inverse design method is applied to a design problem of transonic wing planform and section shape design.

A new study investigates the use of a response surface method for transonic airfoil design.

An inverse design method for a new dual-point design procedure for transonic wings is presented. Weighted averages of the residuals were minimized and target pressure distributions were optimized using a genetic algorithm. The characteristics of single-point design wingers were transferred to dual-point design wings in proportion to weighting factors.

A target pressure optimization code with a genetic algorithm has been developed for the inverse design of transonic wings. Minimum wave drag was achieved by minimizing shock strength and maximizing the isobar line sweep angles on the upper wing surface. The inverse design, based on the target pressure optimization approach was found to be efficient in achieving a wing of high performance.

A new dual-point design method for enhancing the aerodynamic performance of transonic airfoils has been researched, with a genetic algorithm used to maximize the design points' target pressure distribution. A hybrid inverse optimization procedure was used to produce a number of intermediate airfoils, with the intermediate airfoil shapes' weighted average used to locate the dual-point design airfoil. An off-design condition's performance can be enhanced using the dual-point design.

An aerodynamic design method has been developed by using a three-dimensional Euler code and an adjoint code with a discrete approach. The method is applied to wing design problems of supersonic transports with wing-body-nacelle and wing-body configurations. Hicks--Henne shape functions are adopted for the surface geometry perturbation, and the elliptic equation method is employed for the interior grid modification during the design process. Interior grid sensitivities are neglected except those for design parameters associated with a body translation such as nacelles. The sequential quadratic programming method is used to minimize the drag with constraints on the lift and airfoil thickness. Successful design results confirm validity and efficiency of the present design method.