Unsteady pylon loading caused by propeller-slipstream impingement for tip-mounted propellers

Unsteady pylon loading caused by propeller-slipstream impingement for tip-mounted propellers

Sinnige, T. (TU Delft Flight Performance and Propulsion)
de Vries, R. (TU Delft Flight Performance and Propulsion)
della Corte, B. (Università degli Studi di Napoli Federico II)
Avallone, F. (TU Delft Wind Energy)
Ragni, D. (TU Delft Wind Energy)
Eitelberg, G. (TU Delft Flight Performance and Propulsion)
Veldhuis, L.L.M. (TU Delft Flight Performance and Propulsion)

2018

An experimental analysis was performed of the unsteady aerodynamic loading caused by the impingement of a propeller slipstream on a downstream lifting surface. When installed on an aircraft, this unsteady loading results in vibrations that are transmitted to the fuselage and are perceived inside the cabin as structure-borne noise. A pylon-mounted tractor-propeller configuration was installed in a low-speed wind tunnel at Delft University of Technology. Surface-microphone and particle-image-velocimetry measurements were taken to quantify the pressure fluctuations on the pylon and visualize the impingement phenomena. It was confirmed that the propeller tip vortex is the dominant source of pressure fluctuations on the pylon. Along the path of the tip vortex on the pylon, a periodic pressure response occurs with strong harmonics. The amplitude of the pressure fluctuations increases with increasing thrust setting, whereas the unsteady lift coefficient displays a nonmonotonic dependency on the propeller thrust. The lowest integral unsteady loads were obtained for cases with approximately integer ratios between the pylon chord and the wavelength of the perturbation associated with the propeller tip vortices. This implies that structure-borne-noise reductions might be obtained by matching the pylon chord with an integer multiple of the axial separation between the propeller tip vortices.

http://resolver.tudelft.nl/uuid:84ea6587-829d-4d25-9ae0-3671d3e14a6b

https://doi.org/10.2514/1.C034696

2019-02-01

0021-8669

Journal of Aircraft: devoted to aeronautical science and technology, 55 (4), 1605-1618

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© 2018 T. Sinnige, R. de Vries, B. della Corte, F. Avallone, D. Ragni, G. Eitelberg, L.L.M. Veldhuis