Unsteady lifting-line theory and the influence of wake vorticity on aerodynamic loads

Bird, H. J.A. and Ramesh, K. (2021) Unsteady lifting-line theory and the influence of wake vorticity on aerodynamic loads. Theoretical and Computational Fluid Dynamics, 35(5), pp. 609-631. (doi: 10.1007/s00162-021-00578-8)

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Frequency-domain unsteady lifting-line theory (ULLT) provides a means by which the aerodynamics of oscillating wings may be studied at low computational cost without neglecting the interacting effects of aspect ratio and oscillation frequency. Renewed interest in the method has drawn attention to several uncertainties however. Firstly, to what extent is ULLT practically useful for rectangular wings, despite theoretical limitations? And secondly, to what extent is a complicated wake model needed in the outer solution for good accuracy? This paper aims to answer these questions by presenting a complete ULLT based on the work of Sclavounos, along with a novel ULLT that considers only the streamwise vorticity and a Prandtl-like pseudosteady ULLT. These are compared to Euler CFD for cases of rectangular wings at multiple aspect ratios and oscillation frequencies. The results of this work establish ULLT as a low computational cost model capable of accounting for interacting finite-wing and oscillation frequency effects and identify the aspect ratio and frequency regimes where the three ULLTs are most accurate. This research paves the way towards the construction of time-domain or numerical ULLTs which may be augmented to account for nonlinearities such as flow separation.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Ramesh, Dr Kiran and Bird, Hugh
Authors: Bird, H. J.A., and Ramesh, K.
College/School:College of Science and Engineering > School of Engineering > Autonomous Systems and Connectivity
Journal Name:Theoretical and Computational Fluid Dynamics
ISSN (Online):1432-2250
Published Online:31 July 2021
Copyright Holders:Copyright © 2021 The Authors
First Published:First published in Theoretical and Computational Fluid Dynamics 35(5): 609-631
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
301531UNSflow: A low-order, open-source solver for problems that involve unsteady and nonlinear fluid dynamicsKiran RameshEngineering and Physical Sciences Research Council (EPSRC)EP/R008035/1ENG - Aerospace Sciences