Aerodynamic design optimization of a helicopter rotor blade-sleeve fairing

Within the Clean Sky 2 project full fairing rotor head aerodynamic design optimization (FURADO), the aerodynamic design optimization of a full-fairing rotor head by means of CFD simulations is conducted. The rotor head is developed for a novel compound helicopter known as rapid and cost-effective rotorcraft (RACER). The FURADO project deals with three main components, the blade-sleeve fairing, the full-fairing beanie and the pylon fairing. Within the scope of the present publication, the two-dimensional aerodynamic design optimization of the RACER blade-sleeve fairing sections is at focus. The optimized two-dimensional shapes represent the supporting structure for the three-dimensional blade-sleeve fairing. For the optimization purpose, a sophisticated optimization tool chain allowing for automated aerodynamic design optimization is developed and the demonstration of its functionality is presented. The actual tool chain represents a modular software package, which has been developed within the FURADO project. In the first part of the publication, an introduction to the tool chain and the applied methods is given and subsequently, the results concerning the design optimization of a selected rotor blade-sleeve section are illustrated. The modules of the tool chain comprise state of the art software regarding computer aided design, mesh generation and numerical flow simulation. Concerning the optimization approach, a multi-objective genetic algorithm is employed to cover a wide range of the design space and to allow for the independent evaluation of multiple objective functions without weighting. Further, the gradual development of the Pareto-frontier can be observed and the most promising designs are thoroughly investigated.