Experimental Characterization of Leading Edge Tubercles on Rotor Blades

This paper presents the first experimental measurements of leading edge tubercles applied to rotor blades. Using the Royal Military College Rotor Rig, the effect of applying uniform SinA03L12.5 and SinA06L25 tubercles was characterized by comparing thrust, power, and acoustic measurements to a baseline NACA 0014 blade. Tubercles showed an improvement in overall sound pressure levels at low to moderate pitch angles attributed to a reduction in blade wake interaction noise. Such improvement appears to come with a reduction in peak Figure of Merit at higher thrust coefficient with larger loss in performance for the SinA06L25 shape than the SinA03L12.5. Non-linear deflections induced via elasticity of the blade affect the performance interpretation of the obtained results and further experimentation will be required. Results indicate that improvements in performance and reduction in noise is possible if proper selection of tubercles shape is done at specific span-wise locations.