Vortex approach for downwash and outwash of tandem rotors in ground effect

Tan, J. F., Sun, Y. M. and Barakos, G. N. (2018) Vortex approach for downwash and outwash of tandem rotors in ground effect. Journal of Aircraft, 55(6), pp. 2491-2509. (doi:10.2514/1.C034740)

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Abstract

A vortex-based approach is employed to predict the downwash and outwash of a tandem rotor in ground effect and provide an understanding of its wake. The aerodynamic loads of the blades are represented through a panel method, and the behavior of the wake is captured by a viscous vortex particle method. The viscous effects of the ground are accounted for by a viscous boundary model satisfying the no-slip and nonpenetration boundary conditions. The method is first validated for an isolated full-scale Lynx tail rotor and a 172-mm-diameter-scale rotor in ground effect. The results show that the predicted trajectories of the tip vortices and the radial velocity profiles compare favorably with experiments and published computational fluid dynamics results. The results for model CH-47D are then compared with experiments for the downwash and outwash of the tandem rotor. As opposed to the isolated single rotor, a radial outward expansion in the overlapping area is observed, and the peak and the corresponding vertical distance of the velocity maximum of the radial outwash flow for the tandem rotor are larger. Moreover, the rotational direction of the tandem rotor leads to a wake with several vortical interactions resulting in different outwashes on the port and starboard sides.

Item Type:Articles
Additional Information:This work was supported by the National Natural Science Foundation of China (Grant No. 11502105), and the support of Natural Science Foundation of Jiangsu Province (Grant No. BK20161537) and the Jiangsu Government Scholarship for Overseas Studies were gratefully acknowledged.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Barakos, Professor George and Tan, Mr Jianfeng
Authors: Tan, J. F., Sun, Y. M., and Barakos, G. N.
College/School:College of Science and Engineering > School of Engineering > Aerospace Sciences
Journal Name:Journal of Aircraft
Publisher:American Institute of Aeronautics and Astronautics
ISSN:0021-8669
ISSN (Online):1533-3868
Published Online:28 June 2018
Copyright Holders:Copyright © 2018 The Authors
First Published:First published in Journal of Aircraft 55(6): 2491-2509
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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