Aerodynamic Shape Optimization of a Helicopter Main Rotor Hub Beanie Using Advanced Multi-Objective Evolutionary Algorithms

The main rotor hub cap beanie is an aerodynamic component involved in the reduction of helicopter tail shake phenomenon. Recently, an extensive CFD test campaign concerning the AgustaWestland AW101 beanie has been carried out in order to assess its aerodynamic performance at specific operating conditions. These numerical analyses were essential for the beanie aerodynamic multi-objective optimization which is described in the present work. Specifically, the original beanie model was first modified and then, the new geometry was parameterized and the variables describing the main beanie geometrical characteristics were defined. Finally, the aerodynamic optimization was carried out using a specific procedure based on the advanced multi-objective evolutionary algorithm GeDEA developed by the University of Padova. The objectives were the beanie drag reduction and increase of its wake deflection capabilities. Amongst the different optimal solutions belonging to the final Pareto front, three new beanie geometries were finally selected and analyzed via CFD to evaluate the margins of improvement with respect to the baseline configuration.