High-fidelity CFD validation and assessment of ducted propellers for aircraft propulsion

Zhang, T. and Barakos, G. N. (2021) High-fidelity CFD validation and assessment of ducted propellers for aircraft propulsion. Journal of the American Helicopter Society, 66(1), pp. 1-28. (doi: 10.4050/JAHS.66.012008)

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Abstract

This paper presents validation and assessment of ducted propellers for aircraft propulsion. Numerical methods and simulation strategies are put forward, including steady/unsteady high-fidelity computational fluid dynamics (CFD) simulations and simpler momentum-based methods. The validation and comparisons of the methods are made using a ducted propeller proposed by NASA. Simulations are also performed and analyzed at extended advance ratios, blade pitch setting, and cross-wind angles. Comparisons are also made with open propeller counterparts. The ducted propeller shows superior performance over its unducted counterpart in hover and at low advance ratios. The major thrust gain is identified from the combination of duct leading-edge suction and the higher pressure at the diffuser exit. The propeller is off-loaded due to the higher inflow velocities. The ducted propeller is also shown to have less intrusive wake features at low axial speeds. However, as the advance ratio increases, the duct thrust contribution becomes negative and the ducted propeller becomes deficient, due to growing high-pressure areas at the leading edge. At cross-wind, high-fidelity CFD simulations offer accurate aerodynamic loads predictions despite the complex flow features. The duct surface separation is found to be delayed due to the propeller suction, while the propeller is shown shielded by the duct, thereby suffering less from the unbalanced inflow velocities. Decomposition of induced velocities by each part is carried out and presented. A large, nonlinear extra induction component, due to mutual interactions of the duct and the propeller, is observed and found favorable for the performance augmentation.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Barakos, Professor George and Zhang, Tao
Authors: Zhang, T., and Barakos, G. N.
College/School:College of Science and Engineering > School of Engineering > Aerospace Sciences
Journal Name:Journal of the American Helicopter Society
Publisher:American Helicopter Society Inc.
ISSN:0002-8711
Published Online:13 October 2020
Copyright Holders:Copyright © 2021 Vertical Flight Society
First Published:First published in Journal of the American Helicopter Society 66(1):1-28
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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