Transonic wing aerodynamic design based on continuous adjoint method and free form deform technique

The approach of transonic wing aerodynamic design based on the combination of continuous adjoint method with free form deform (FFD) technique has been presented. Bernstein basis function has been chosen to establish the FFD parameterization of arbitrary spatial property to overcome the disadvantages of discontinuity or unsmoothness by the bump function method or the B-spline approach. Besides, the scheme to compute the sensitivity of aerodynamic objective function respecting to geometrical shape has been established using the continuous adjoint method based on control theory, in which the sensitivity computation of all the design variables would cost one flow field computation and one adjoint field computation. Combined with torsional spring mesh deformation technique, FFD geometric parameterization, continuous adjoint method and computational fluid dynamics have been integrated to establish a design system for transonic wing aerodynamic configuration aimmed at drag reduction, which is good at both efficiency and robustness. This system has been testified with optimization design cases of ONERA M6 wing and a typical large civil jet wing, the results of which have shown that this method is of good feasibility and efficiency in aerodynamic optimization design for drag reduction. Moreover, the results have shown that this method is of good capability of conserving the geometry continuity and smoothness.