Aerodynamic shape optimization of a modern transport wing using only planform variations

Generic aerodynamic shape optimization technology is presented, based on a domain element approach linked with global interpolation functions. This allows an efficient shape parameterization from which both the design surface geometry and corresponding computational fluid dynamics volume mesh can be deformed directly, in a high quality and robust fashion. The technique also provides a method that allows geometries to be parameterized at various levels, ranging from general planform alterations to detailed local surface changes. The global interpolation developed is totally independent of mesh type (structured or unstructured), and optimization independence from the flow solver is achieved by obtaining sensitivity information for an advanced gradient-based optimizer (feasible sequential quadratic programming) by finite differences. Results have been presented recently for two-dimensional aerofoil cases, and drag reductions of up to 45 per cent were demonstrated. Hence, this article presents initial extension of the method to three dimensions. Results are presented for highly constrained optimization of a modern aircraft wing in transonic cruise, using only planform parameters (design variables), i.e. wing sections can move but may not deform locally. This is done to test and validate the method before moving on to higher fidelity optimizations, and more computationally expensive applications. Even with this fidelity of parameterization, only 30 parameters are used, optimization produces an 8 per cent reduction in drag.