Alleviation of Propeller-Slipstream-Induced Unsteady Pylon Loading by a Flow-Permeable Leading Edge

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Alleviation of Propeller-Slipstream-Induced Unsteady Pylon Loading by a Flow-Permeable Leading Edge

Sinnige, Tomas / Corte, Biagio Della / De Vries, Reynard / Avallone, Francesco / Merino-Martínez, Roberto / Ragni, Daniele / Eitelberg, Georg / Veldhuis, Leo L. M.

Abstract

The impingement of a propeller slipstream on a downstream surface causes unsteady loading, which may lead to vibrations responsible for structure-borne noise. A low-speed wind-tunnel experiment was performed to quantify the potential of a flow-permeable leading edge to alleviate the slipstream-induced unsteady loading. For this purpose, a tractor propeller was installed at the tip of a pylon featuring a replaceable leading-edge insert in the region of slipstream impingement. Tests were carried out with four flow-permeable inserts, with different hole diameters and cavity depths, and a baseline solid insert. Particle-image-velocimetry measurements showed that the flow through the permeable surface caused an increase in boundary-layer thickness on the pylon’s suction side. This led to a local drag increase and reduced lift, especially for angles of attack above 6 deg. Furthermore, it amplified the viscous interaction with the propeller tip-vortex cores, reducing the velocity fluctuations near the pylon surface by up to 35%. Consequently, lower tonal noise emissions from the pylon were measured in the far field. This suggests that the desired reduction in surface pressure fluctuations was achieved by application of the flow-permeable leading edge.

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Document information

Title :

Alleviation of Propeller-Slipstream-Induced Unsteady Pylon Loading by a Flow-Permeable Leading Edge

Contributors:

Sinnige, Tomas (author) / Corte, Biagio Della (author) / De Vries, Reynard (author) / Avallone, Francesco (author) / Merino-Martínez, Roberto (author) / Ragni, Daniele (author) / Eitelberg, Georg (author) / Veldhuis, Leo L. M. (author)

Published in:

Journal of Aircraft ; 56 , 3 ; 1214-1230

Publication date :

2019-04-10

Size :

17 pages

ISSN :

0021-8669 , 1533-3868

DOI :

https://doi.org/10.2514/1.C035250

Type of media :

Article (Journal)