TY  - JOUR
A1  - Hoeveler, B.
A1  - Bauknecht, André
A1  - Wolf, C. Christian
A1  - Janser, Frank
T1  - Wind-Tunnel Study of a Wing-Embedded Lifting Fan Remaining Open in Cruise Flight
JF  - Journal of Aircraft
N2  - It is investigated whether a nonrotating lifting fan remaining uncovered during cruise flight, as opposed to being covered by a shutter system, can be realized with limited additional drag and loss of lift during cruise flight. A wind-tunnel study of a wing-embedded lifting fan has been conducted at the Side Wind Test Facility Göttingen of DLR, German Aerospace Center in Göttingen using force, pressure, and stereoscopic particle image velocimetry techniques. The study showed that a step on the lower side of the wing in front of the lifting fan duct increases the lift-to-drag ratio of the whole model by up to 25% for all positive angles of attack. Different sizes and inclinations of the step had limited influence on the surface pressure distribution. The data indicate that these parameters can be optimized to maximize the lift-to-drag ratio. A doubling of the curvature radius of the lifting fan duct inlet lip on the upper side of the wing affected the lift-to-drag ratio by less than 1%. The lifting fan duct inlet curvature can therefore be optimized to maximize the vertical fan thrust of the rotating lifting fan during hovering without affecting the cruise flight performance with a nonrotating fan.
Y1  - 2020
U6  - http://dx.doi.org/10.2514/1.C035422
SN  - 1533-3868
VL  - 57
IS  - 4
PB  - AIAA
CY  - Reston, Va.
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  -