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Optimization of Leading Edge Tubercles Applied to Helicopter Rotor Blades

AIAA 2021-0733
Session: Propeller, Rotorcraft and Distributed Propulsion Aerodynamics II
Published Online:https://doi.org/10.2514/6.2021-0733
Abstract:

View Video Presentation: https://doi.org/10.2514/6.2021-0733.vid

The application of leading edge tubercles to rotor blades, with a constant amplitude and wavelength shape, have been previously explored showing improvements in figure of merit from increased thrust generation and reduced power requirements. This paper investigates a multi-objective optimization of rotor blades for increased figure of merit in hover and reduced power in forward flight by selecting the best tubercle amplitude and wavelength shapes along the rotor span. A blade element theory is employed for fast aerodynamic analysis using a sectional aerodynamic properties database at different radial locations. The database is populated using computational fluid dynamic simulations of rotors with different constant tubercles shapes and flow conditions. Pareto frontier results suggest increase in figure of merit by 45% and reduction in power coefficient of 3.5% can be achieved for optimal rotor tubercle configurations with non-uniform tubercle shape distributions. Post-optimal computational fluid dynamics supports the findings of the multi-objective optimization and elucidates tubercle performance enhancements from the change in flow behaviour.