High Speed and Highly Efficient Rotor Blade Design

Aerodynamic design of the high speed, highly efficient rotor (HSHER) blade is presented. The main objective was to design a medium-lift utility scale blade with improved high-speed performance and no penalty in hover, suitable for a single-main rotor operating at speeds between 180 and 200 knots. To accomplish this, a design concept was chosen consisting of an advanced passive blade shape along with an adjustable trailing-edge device. Initial studies using a blade-element solver combined with a genetic algorithm were used to quickly survey large portions of the design space. Next, a CFD-based process was established whereby CREATETM-AV HELIOS was used for high-speed forward-flight simulations while hover performance was addressed using a combination of Star-CCM+ for rapid iterations and HELIOS for more detailed evaluation. While fully-automated optimization was not performed, automation was introduced wherever possible to minimize manual effort and keep the engineering effort focused on high-level strategic decisions that are still somewhat difficult to automate. The final result was a new blade design which showed significant improvements in both high-speed performance (?L/D ~1) and hover efficiency (?FM ~0.03) with increased thrust capability.