Rotor Blade Designs for Quiet Performance

CU Aerospace (CUA) and team partner the University of Illinois at Urbana-Champaign (UIUC) propose to develop a new design methodology for rotor blades, which will offer quieter performance compared to conventional approaches. The proposed approach seeks to mitigate the acoustic impact of vortex-induced noise of lifting rotors and propellers, which currently serves as one of the dominant noise sources for these systems. In this approach, the design methodology for the thrust distribution will be guided to passively attenuate the roll-up process of rotor-tip vortices, leading to reduced interactions between shed vortices and subsequent blade elements or wing/body surfaces, as well as noise associated with turbulent regions outside of coherent vortex cores. The design will leverage lessons learned in previous investigations undertaken at UIUC, which involved research on the impact of wing lift distributions on the roll-up of the wing-wake vortex. This research will be extended to applications in the design of rotating wings, including lifting rotors, propellers, and lift fans. In the proposed work, the CUA-UIUC team will produce a tailored rotor design, in which the span-wise load is configured to produce the same lift as a conventional design, but with delayed roll-up of wake vortices controlled by eliminating strong discontinuities in vortex shedding strength along the span. The impact of such a design on rotor acoustics will be determined.  Feasibility studies and customer discovery activities will be conducted during the Phase I effort.