Physical Characterization of Aerial Screw Aeromechanics in Axial Climb and Forward Flight

Abstract:
This study investigates the aerodynamics and performance of aerial screw rotors in axial climb and off-axis flight for the first time. Additionally, this work highlights comparisons between a hover-efficient aerial screw and a two bladed conventional rotor in various flight states. Using high-fidelity Computational Fluid Dynamics (CFD) analysis, the research identifies the formation of the "da Vinci vortex"—a shape-conforming helical structure to be crucial to thrust generation and performance. Investigations of linear and bilinear variations of the screw pitch and taper reveal nuanced effects on loads on the screw surface and climb efficiency. The effect of the pitch rate is found to dominate over the effect of the taper rate in axial and off-axis climbs. Efficiency in axial flight states is heavily dependent on the pitch rate of the aerial screw. Investigation of all forces on the aerial screw surfaces identifies significant phase differencing in loading between linear and bilinear varying designs, suggesting potential for canceling oscillations in one bladed aerial screws. This study builds on the groundwork for the application of aerial screws in next-generation Vertical Take-Off and Landing (VTOL) vehicles by enhancing the understanding of the unique rotor’s aeromechanics.

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