TY  - JOUR
A1  - Finger, Felix
A1  - Bil, Cees
A1  - Braun, Carsten
T1  - Initial Sizing Methodology for Hybrid-Electric General Aviation Aircraft
JF  - Journal of Aircraft
Y1  - 2019
U6  - http://dx.doi.org/10.2514/1.C035428
SN  - 1533-3868
VL  - 57
IS  - 2
SP  - 245
EP  - 255
ER  - 
TY  - JOUR
A1  - Böhnisch, Nils
A1  - Braun, Carsten
A1  - Muscarello, Vincenzo
A1  - Marzocca, Pier
T1  - About the wing and whirl flutter of a slender wing–propeller system
JF  - Journal of Aircraft
N2  - Next-generation aircraft designs often incorporate multiple large propellers attached along the wingspan (distributed electric propulsion), leading to highly flexible dynamic systems that can exhibit aeroelastic instabilities. This paper introduces a validated methodology to investigate the aeroelastic instabilities of wing–propeller systems and to understand the dynamic mechanism leading to wing and whirl flutter and transition from one to the other. Factors such as nacelle positions along the wing span and chord and its propulsion system mounting stiffness are considered. Additionally, preliminary design guidelines are proposed for flutter-free wing–propeller systems applicable to novel aircraft designs. The study demonstrates how the critical speed of the wing–propeller systems is influenced by the mounting stiffness and propeller position. Weak mounting stiffnesses result in whirl flutter, while hard mounting stiffnesses lead to wing flutter. For the latter, the position of the propeller along the wing span may change the wing mode shapes and thus the flutter mechanism. Propeller positions closer to the wing tip enhance stability, but pusher configurations are more critical due to the mass distribution behind the elastic axis.
Y1  - 2024
U6  - http://dx.doi.org/10.2514/1.C037542
SN  - 1533-3868
SP  - 1
EP  - 14
PB  - American Institute of Aeronautics and Astronautics
ER  - 
TY  - JOUR
A1  - Bergmann, Ole
A1  - Möhren, Felix
A1  - Braun, Carsten
A1  - Janser, Frank
T1  - On the influence of elasticity on swept propeller noise
JF  - AIAA SCITECH 2023 Forum
N2  - High aerodynamic efficiency requires propellers with high aspect ratios, while propeller sweep potentially reduces noise. Propeller sweep and high aspect ratios increase elasticity and coupling of structural mechanics and aerodynamics, affecting the propeller performance and noise. Therefore, this paper analyzes the influence of elasticity on forward-swept, backward-swept, and unswept propellers in hover conditions. A reduced-order blade element momentum approach is coupled with a one-dimensional Timoshenko beam theory and Farassat's formulation 1A. The results of the aeroelastic simulation are used as input for the aeroacoustic calculation. The analysis shows that elasticity influences noise radiation because thickness and loading noise respond differently to deformations. In the case of the backward-swept propeller, the location of the maximum sound pressure level shifts forward by 0.5 °, while in the case of the forward-swept propeller, it shifts backward by 0.5 °. Therefore, aeroacoustic optimization requires the consideration of propeller deformation.
Y1  - 2023
U6  - http://dx.doi.org/10.2514/6.2023-0210
N1  - Session: Propeller, Open Rotor, and Rotorcraft Noise II

AIAA SCITECH 2023 Forum, 23-27 January 2023, National Harbor, MD & Online
PB  - AIAA
ER  -