Double Shock Control Bump Design Optimisation Using Hybridised Evolutionary Algorithms

The paper investigates the application of two advanced optimisation methods for solving active flow control device shape design problem and compares their optimisation efficiency in terms of computational cost and design quality. The first optimisation method uses Hierarchical Asynchronous Parallel Multi-Objective Evolutionary Algorithm (HAPMOEA) and the second uses Hybridized EA with Nash-Game strategies (HybridGame). Both optimisation methods are based on a canonical evolution strategy and incorporate the concepts of parallel computing and asynchronous evaluation. One type of active flow control device named Shock Control Bump (SCB) is considered and applied to a Natural Laminar Flow (NLF) aerofoil. The concept of SCB is used to decelerate supersonic flow on upper/lower surface of transonic aerofoil that leads to a delay of shock occurrence. Such active flow technique reduces total drag at transonic speeds which is special interest to commercial aircraft. Numerical results show that the Hybrid-Game helps an EA to accelerate optimisation process. From the practical point of view, applying a SCB on the suction and pressure sides significantly reduces transonic total drag and improves lift on drag (L/D) value when compared to the baseline design. Keywords—Active Flow Control, Shock Control Bump, Shape design optimisation, Hybrid-Game, Nash Equilibrium, Evolutionary Algorithm.