Abstract:
This study experimentally explores the behavior of an isolated propeller of an electric vertical takeoff and landing (eVTOL) aircraft, a next-generation type of vehicle that combines the operational capabilities of both helicopters and airplanes, in vortex ring state (VRS). VRS is a hazardous aerodynamic phenomenon that occurs when a propeller in vertical descent interacts with its own wake, forming a vortex ring around the propeller disk. Depending on the inflow and operating conditions of the propeller, VRS can lead to a significant loss of thrust, making it a critical flight condition for helicopters, tiltrotors, and eVTOL aircraft. Despite its importance, VRS has not yet been extensively studied in the context of eVTOL systems. This research study, carried out under the collaboration between Archer Aviation and the Department of Aerospace Science and Technology of Politecnico di Milano, focuses on characterizing the performance of a propeller of an eVTOL vehicle during vertical descent and analysing the flow field around the propeller blades in VRS. Experimental tests were conducted at the "S. De Ponte" wind tunnel of Politecnico di Milano using a 1:4 scaled model of one of the tilting propellers of Archer Aviation eVTOL Maker vehicle.