Aerodynamic Shape Optimization of Rotor Blades in Hover Using Unstructured Meshes

An aerodynamic shape optimization technique has been developed for helicopter rotor blades in hover based on a continuous adjoint method on unstructured meshes. The Euler flow solver and the continuous adjoint sensitivity analysis were formulated on the rotating frame of reference for the hovering rotor blades. In order to handle the repeated evaluation of design cycles efficiently, the flow and adjoint solvers were parallelized using a domain decomposition strategy. A solution-adaptive mesh refinement technique was adopted for the accurate capturing of the tip vortex. Applications were made for the aerodynamic shape optimization of the Caradonna-Tung rotor blade and the UH60 rotor blade. The results showed that the present method is an effective tool to determine the optimum aerodynamic shape of rotor blades requiring less torque while maintaining the desired thrust level.