T. Zhang, G.N. Barakos

This paper presents a high-fidelity aerodynamic and acoustic evaluation in hover of a heavy-lift eVTOL design. The design, known as Skybus, has an MTOW of 14,000kg, and six tiltable rotors attached at the tip of three sets of tandem wings with flaps. High-fidelity CFD simulations of the entire Skybus vehicle in hover were conducted using the HMB3 framework with scale-adaptive turbulence modelling. The simulations considered three design variations with revised airframe and blades and resolved complex flow details. The aerodynamic performance, blockage, and interactions were analysed in detail. The baseline airframe caused a blockage force of about 13% of the MTOW. The hovering rotors in compact configurations induced a sinusoidal single-blade loading variation, blended with small local interactions corresponding to blade encounter and rotor-wing interactions. However, the overall loading variations were small and were within 1% of the MTOW. Further, the near-field acoustics was directly extracted from the high-fidelity CFD results, and far-field acoustic propagation was computed using the acoustic analogy. The design modifications caused strong impact on the vehicle acoustics because of different aerodynamic interactions, and of the propeller acoustic characteristics. In the far field and below the hovering vehicle, the acoustic directivity was along the longitudinal direction, especially ahead of the cockpit. Tonal corrections were also performed to compute the effective perceived noise level (EPNL) in certification scenarios. The Skybus design showed about 95 EPNdB assuming a 2-min hover duration, which was below the certification limit of equivalent helicopters

49th European Rotorcraft Forum 2023, Bückeburg, 2023

Conference Paper

englisch

21,0 x 29,7 cm, 24 Seiten

DGLR-Bericht, 2023, 2023-01, 49th European Rotorcraft Forum 2023 - Proceedings; S.1-24; 2023; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

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2023