09:40
Distributed propulsion 2
Chair: Vincenzo Vaccaro
09:40
30 mins
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Aeroelastic analysis of distributed electric propulsion flexible wings
Samet Dede, Ali Tatar, Djamel Rezgui, Jonathan Cooper
Abstract: There is much current emphasis on the development of alternative aircraft propulsion technologies to enable much reduced, and eventually, net-zero in-flight commercial aircraft emissions. The success of this goal is not simply dependent upon the advancements in electric or hydrogen-powered propulsion systems, but also on how to integrate them into the aircraft structures. It is likely that distributed electric propulsion (DEP) configurations featuring small engines spaced across the wing will be the most viable solution. However, the adoption of these novel aircraft wing configurations might initiate the early onset of two potential aeroelastic instabilities: wing flutter and whirl flutter, which must be addressed in the early design stages of DEP aircraft wings. The main aim of this study is to create and evaluate a representative low-order aeroelastic coupled wing-propeller model for parametric aeroelastic studies that can be used in the flutter analysis at the early design stages. An aeroelastic numerical model was developed in MATLAB to analyse the aeroelastic behaviour of a coupled flexible cantilever wing with a variable number of flexibly mounted propellers/rotors. Reed’s model is employed to model the propeller dynamics, with the structural model of the wing being derived through the assumed-mode Rayleigh-Ritz method. The aerodynamic model of the wing was obtained from a combination of the modified strip theory and Theodorsen’s unsteady aerodynamic theory. The proposed coupled aeroelastic model can successfully estimate both wing and whirl flutter in DEP wings through validations with results from the literature. The model was then used for several parametric analyses investigating the effects of propeller spanwise position, advance ratio and rotor radius on the stability of the integrated wing-propeller system. The parametric studies demonstrated that advance ratio and rotor radius have a significant effect on the stability of the coupled wing-propeller model. It was found that increasing the advance ratio has a destabilizing effect, whereas increasing the rotor radius has a stabilizing effect.
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10:10
30 mins
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Gust load alleviation of electric aircraft with distributed propulsors using thrust vectoring
Mohammadreza Amoozgar, Grigorios Dimitriadis, Jonathan Cooper, Rafic Ajaj
Abstract: This paper proposes a new concept for gust load alleviation of an electric aircraft with distributed propulsors (DP) using thrust vectoring. Aircraft electrification has received a lot of attention in recent years due to climate change concerns [1]. There are several concepts available in the literature for electric aircraft, but one of the most promising ones is the distributed electric propulsion (DEP) which has several benefits [2-4]. Moreover, it has already been shown that wings with higher aspect ratios have higher aerodynamic performance [5]. So, if both of these two methods are combined (high aspect ratio wings with distributed propulsion), the wing potentially will have higher aerodynamic performance, which can result in a more energy efficient aircraft. To be able to design the wing structure for such an aircraft, it is crucial to calculate all external loads applied on the wing. One of the most extreme dynamic loads that an aircraft wing can experience is the gust load.
In this study, the effectiveness of thrust vectoring of electric propulsors on gust load alleviation of high aspect ratio wings is studied. It is assumed that the rotor disc of the electric motors can be tilted to the left, right, up or down (as shown in Figure 1), using a mechanism similar to helicopter rotors. This concept has already been investigated for aeroelastic stability enhancement [6], and this study aims to further investigate its effectiveness for gust load alleviation of high aspect ratio wings with DEP configuration.
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