Aerodynamic Shape Optimization of a NACA0018 Airfoil Using Adjoint Method and Gradient-Based Optimizer

The purpose of this study is to demonstrate the suitability and efficacy of the adjoint method on the aerodynamic shape optimization on a simple symmetrical airfoil NACA0018 at low Reynolds number for wind turbine application. The adjoint method has been used in many pressure-based numerical simulations with various degrees of success leading to optimized geometries in their respective uses. ANSYS Fluent code was used in this simulation. Lift to drag ratio was defined as the observables for which adjoint sensitivities were formulated. The objective function of the optimization was set to maximize the lift to drag ratio of the airfoil by 20%. The optimization regime showed significant increase in lift and drag ratio from the initial baseline NACA0018 value of 0.0211 up to 3.66 for the optimal NACAOpt. The results demonstrate the potential of the adjoint solver paired together with the gradient-based optimizer to improve the geometry for shape optimization in many CFD applications.