Experimental Investigation of Aerodynamic and Aeroacoustic Performance of Porous Tip Designs for Drone Blades

Unmanned aerial vehicles (UAVs) have emerged as a prominent technology across diverse fields, including industrial, military, and agricultural applications. Among various propulsion types, rotary-wing UAVs (drones) are particularly favored for civilian use due to their compact design, hovering capability, and vertical take-off and landing (VTOL) features. However, substantial noise from rotating blades remains a major challenge, highlighting the need for low-noise blade designs. In rotary-wing configurations, maximum velocity occurs at the blade tip, where strong pressure gradients generate tip vortices. These vortical structures primarily contribute to aerodynamic noise through broadband self-noise production and blade-wake interactions. This study experimentally investigates the aerodynamic and aeroacoustic characteristics of a two-blade rotor, focusing on tip vortex formation. A NACA0012 airfoil with a square lattice porous tip is evaluated against a solid tip baseline design. Measurements include time-resolved particle image velocimetry (PIV) flow fields, thrust measurements, and acoustic spectra in an anechoic chamber at a tip Reynolds number of 60,000. Results demonstrate the potential application of porous designs for rotary-wing blades, suggesting low-noise UAV blade designs can be achieved through enhanced understanding of wake dynamics.