Collaborative Research: Fundamental Scaling of Rotating Wakes

Rotary systems, such as spinning blades on helicopters, drones, energy systems, and even artificial heart pumps, play a critical role from mechanical and aerospace engineering to biomedical applications and energy systems. However, testing these spinning devices to ensure they operate efficiently and safely is expensive, especially at full-size. This project tackles that problem by enabling engineers to use small-scale models in lower-cost wind tunnels while still capturing the full-scale behavior of the flow. This advancement will be transferable to a broad range of rotary systems for long-term cost reduction of wind tunnel testing. In addition to addressing a critical knowledge gap in fluid mechanics, the project will help educate the future workforce through a modernized curriculum, hands-on research experiences, and outreach activities. The proposed research seeks to validate the hypothesis that rotor thrust and induced power coefficient, rather than total power coefficient, provide sufficient conditions for replicating vortex wake turbulence and stability across scales. The research integrates advanced computational approaches, including inverse blade design, Large Eddy Simulation (LES) of rotary system wakes using actuator lines, and blade-resolved hybrid Unsteady Reynolds-Averaged Navier-Stokes (URANS)/LES methods, with extensive experimental campaigns. Testing will be conducted in three distinct wind tunnel facilities: a compressed-air tunnel for studying Reynolds-dependent roughness and rotational effects, a boundary-layer wind tunnel for exploring sheared turbulent inflow and platform motion effects, and an aerodynamic wind tunnel for analyzing blade loads and wake stability. This research will generate a publicly accessible database, advancing the fundamental understanding of rotary system wakes and providing critical insights for applications ranging from rotorcraft and propellers to distributed propulsion systems and energy technologies. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.