Aerodynamic shape optimization using the adjoint Euler equations

Purpose - An aerodynamic shape optimization algorithm is presented, which includes all aspects of the design process: parameterization, flow computation and optimization. The purpose of this paper is to show that the Class-Shape-Refinement-Transformation method in combination with an Euler/adjoint solver provides an efficient and intuitive way of optimizing aircraft shapes. Design/methodology/approach - The Class-Shape-Transformation method was used to parameterize the aircraft shape and the flow was computed using an in-house Euler code. An adjoint solver implemented into the Euler code was used to compute the required gradients and a trust-region reflective algorithm was employed to perform the actual optimization. Findings - The results of two aerodynamic shape optimization test cases are presented. Both cases used a blended-wing-body reference geometry as their initial input. It was shown that using a two-step approach, a considerable improvement of the lift-to-drag ratio in the order of 20-30 per cent could be achieved. The work presented in this paper proves that the C,SRT method is a very intuitive and effective way of parameterizating aircraft shapes. It was also shown that using an adjoint algorithm provides the computational efficiency necessary to perform true three-dimensional shape optimization. Originality/value - The novelty of the algorithm lies in the use of the Class-Shape-Refinement-Transformation method for parameterization and its coupling to the Euler and adjoint codes.