Vortex topology of a pitching and rolling wing in forward flight
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Vortex topology of a pitching and rolling wing in forward flight Kyle C. Johnson1 · Brian S. Thurow1 · Kevin J. Wabick2 · Randall L. Berdon2 · James H. J. Buchholz Jr.2 Received: 25 April 2020 / Revised: 17 August 2020 / Accepted: 5 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Vortex topology is analyzed from measurements of flow over a flat, rectangular plate with an aspect ratio of 2 which was articulated in pitch and roll, individually and simultaneously. The plate was immersed into a Re = 10, 000 flow (based on chord length). Measurements were made using a 3D–3C plenoptic PIV system to allow for the study of complete vortex topology of the entire wing. The prominent focus is the early development of the leading-edge vortex (LEV) and resulting topology. The effect of the wing kinematics on the topology was explored through a parameter space involving multiple values of pitch rate and roll rate at pitch and roll angles up to 50◦ . Characterization and comparisons across the expansive data set are made possible through the use of a newly defined dimensionless parameter, kRg . Termed the effective reduced pitch rate, kRg , is a measure of the pitch rate that takes into account the relative rolling motion of the wing in addition to the pitching motion and freestream velocity. This study has found that for a purely pitching wing, increasing the reduced pitch rate k delays the vortex evolution with respect to 𝛼eff . For a purely rolling wing, as the advance coefficient J is increased, the vortex evolution is advanced with respect to nondimensionalized time and the bifurcation point of the LEV shifts inboard. For a pitching and rolling wing, the addition of roll stabilizes and delays the evolution of the LEV in both nondimensionalized time and effective angle of attack. Graphic abstract
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00348-020-03048-9) contains supplementary material, which is available to authorized users. * Kyle C. Johnson [email protected]
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Department of Aerospace Engineering, Auburn University, Auburn, AL 36849, USA
* Brian S. Thurow [email protected]
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Department of Mechanical and Industrial Engineering/IIHR Hydroscience and Engineering, University of Iowa, Iowa City, IA 52242, USA
James H. J. Buchholz Jr. james‑h‑[email protected]
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1 Introduction The unsteady behavior of vortices present in flows over aerodynamic bodies is known to dramatically impact performance and aerodynamic loads. These flow phenomena are present in various aerospace applications including unsteady wings, aggressive maneuvers of fixed wing aircraft, rotorcraft, gas turbine engines, and wind turbines (Chin and Lentink 2016; Yilmaz and Rockwell 2012; Raghav and Komerath 2015; Limacher et al. 2016; Mulleners et al. 2012; Bridges 2010; Lee and Wu 2014). Additionally, there exists an extensive body of work on the elegant vortex dynamics of nature’s flyers a
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