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Deflected wake interaction of tandem flapping foils

Published online by Cambridge University Press:  18 September 2020

N. S. Lagopoulos Open the ORCID record for N. S. Lagopoulos [Opens in a new window] ,
G. D. Weymouth Open the ORCID record for G. D. Weymouth [Opens in a new window]  and
B. Ganapathisubramani Open the ORCID record for B. Ganapathisubramani [Opens in a new window]
N. S. Lagopoulos*
Affiliation:
Aerodynamics and Flight Mechanics Group, University of Southampton, Southampton, UK
G. D. Weymouth*
Affiliation:
Southampton Marine and Maritime Institute, University of Southampton and Alan Turing Institute, London, UK
B. Ganapathisubramani
Affiliation:
Aerodynamics and Flight Mechanics Group, University of Southampton, Southampton, UK
*
†Email addresses for correspondence: n.lagopoulos@soton.ac.uk, g.d.weymouth@soton.ac.uk
†Email addresses for correspondence: n.lagopoulos@soton.ac.uk, g.d.weymouth@soton.ac.uk
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Abstract

Symmetric flapping foils are known to produce deflected jets at high frequency–amplitude combinations even at a zero mean angle of attack. This reduces the frequency range of useful propulsive configurations without side force. In this study, we numerically analyse the interaction of these deflected jets for tandem flapping foils undergoing coupled heave-to-pitch motion in a two-dimensional domain. The impact of the flapping Strouhal number, foil spacing and phasing on wake interaction is investigated. Our primary finding is that the back foil is capable of cancelling the wake deflection and mean side force of the front foil, even when located up to five chord lengths downstream. This is achieved by attracting the incoming dipoles and disturbing their cohesion within the limits of the back foil's range of flapping motion. We also show that the impact on cycle-averaged thrust varies from high augmentation to drag generation depending on the wake patterns downstream of the back foil. These findings provide new insights towards the design of biomimetic tandem propulsors, as they expand their working envelope and ability to rapidly increase or decrease the forward speed by manipulating the size of the shed vortices.

JFM classification

Aerodynamics: Flow-structure interactions Vortex Flows: Vortex interactions Wakes/Jets: Wakes

Information

Type
JFM Papers
Information
Journal of Fluid Mechanics , Volume 903 , 25 November 2020 , A9
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Copyright
© The Author(s), 2020. Published by Cambridge University Press

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References

REFERENCES

Akhtar, I., Mittal, R., Lauder, G. V. & Drucker, E. 2007 Hydrodynamics of a biologically inspired tandem flapping foil configuration. Theor. Comput. Fluid Dyn. 21 (3), 155–170.CrossRefGoogle Scholar
Alexander, D. E. 1984 Unusual phase relationships between the forewings and hindwings in flying dragonflies. J. Expl Biol. 109 (1), 379–383.Google Scholar
Betz, A. 1912 Ein beitrag zur erklaerung segelfluges. Z. Flugtech. Motorluftschiffahrt 3, 269–272.Google Scholar
Bohl, D. G. & Koochesfahani, M. M. 2009 MTV measurements of the vortical field in the wake of an airfoil oscillating at high reduced frequency. J. Fluid Mech. 620, 63–88.CrossRefGoogle Scholar
Broering, T. M. & Lian, Y. -S. 2012 The effect of phase angle and wing spacing on tandem flapping wings. Acta Mechanica Sin. 28 (6), 1557–1571.CrossRefGoogle Scholar
Cleaver, D. J., Wang, Z. & Gursul, I. 2012 Bifurcating flows of plunging aerofoils at high Strouhal numbers. J. Fluid Mech. 708, 349–376.CrossRefGoogle Scholar
Couder, Y. & Basdevant, C. 1986 Experimental and numerical study of vortex couples in two-dimensional flows. J. Fluid Mech. 173, 225–251.CrossRefGoogle Scholar
Godoy-Diana, R., Aider, J. L. & Wesfreid, J. E. 2008 Transitions in the wake of a flapping foil. Phys. Rev. E 77 (1), 016308.CrossRefGoogle ScholarPubMed
Godoy-Diana, R., Marais, C., Aider, J. L. & Wesfreid, J. E. 2009 A model for the symmetry breaking of the reverse Bénard–von Kármán vortex street produced by a flapping foil. J. Fluid Mech. 622, 23–32.CrossRefGoogle Scholar
He, G.-Y., Wang, Q., Zhang, X. & Zhang, S.-G. 2012 Numerical analysis on transitions and symmetry-breaking in the wake of a flapping foil. Acta Mechanica Sin. 28 (6), 1551–1556.CrossRefGoogle Scholar
Kim, M. J. & Lee, J. H. 2019 Wake transitions of flexible foils in a viscous uniform flow. Phys. Fluids 31 (11), 111906.Google Scholar
Knoller, R. 1909 Die gesetzedes luftwiderstandes. Flug-und Motortechnik 3 (21), 1–7.Google Scholar
Koochesfahani, M. M. 1989 Vortical patterns in the wake of an oscillating airfoil. AIAA J. 27 (9), 1200–1205.CrossRefGoogle Scholar
Kozłowski, T. & Kudela, H. 2014 Transitions in the vortex wake behind the plunging profile. Fluid Dyn. Res. 46 (6), 061406.CrossRefGoogle Scholar
Lagopoulos, N. S., Weymouth, G. D. & Ganapathisubramani, B. 2019 Universal scaling law for drag-to-thrust wake transition in flapping foils. J. Fluid Mech. 872.CrossRefGoogle Scholar
Maertens, A. P. & Weymouth, G. D. 2015 Accurate cartesian-grid simulations of near-body flows at intermediate Reynolds numbers. Comput. Meth. Appl. Mech. Engng 283, 106–129.CrossRefGoogle Scholar
Marais, C., Thiria, B., Wesfreid, J. E. & Godoy-Diana, R. 2012 Stabilizing effect of flexibility in the wake of a flapping foil. J. Fluid Mech. 710, 659–669.CrossRefGoogle Scholar
Muscutt, L. E., Dyke, G., Weymouth, G.l D., Naish, D., Palmer, C. & Ganapathisubramani, B. 2017 a The four-flipper swimming method of plesiosaurs enabled efficient and effective locomotion. Proc. R. Soc. Lond. B 284 (1861), 20170951.Google ScholarPubMed
Muscutt, L. E., Weymouth, G. D. & Ganapathisubramani, B. 2017 b Performance augmentation mechanism of in-line tandem flapping foils. J. Fluid Mech. 827, 484–505.CrossRefGoogle Scholar
Platzer, M. & Jones, K. 2008 Flapping wing aerodynamics-progress and challenges. AIAA J. 46 (9), 2136–2149.CrossRefGoogle Scholar
Polet, D. T., Rival, D. E. & Weymouth, G. D. 2015 Unsteady dynamics of rapid perching manoeuvres. J. Fluid Mech. 767, 323–341.CrossRefGoogle Scholar
Schlanderer, S. C., Weymouth, G. D. & Sandberg, R. D. 2017 The boundary data immersion method for compressible flows with application to aeroacoustics. J. Comput Phys. 333, 440–461.CrossRefGoogle Scholar
Thomas, A. L. R., Taylor, G. K., Srygley, R. B., Nudds, R. L. & Bomphrey, R. J. 2004 Dragonfly flight: free-flight and tethered flow visualizations reveal a diverse array of unsteady lift-generating mechanisms, controlled primarily via angle of attack. J. Expl Biol. 207 (24), 4299–4323.CrossRefGoogle ScholarPubMed
Triantafyllou, M. S., Triantafyllou, G. S. & Gopalkrishnan, R. 1991 Wake mechanics for thrust generation in oscillating foils. Phys. Fluids A 3 (12), 2835–2837.CrossRefGoogle Scholar
Usherwood, J. R. & Lehmann, F. -O. 2008 Phasing of dragonfly wings can improve aerodynamic efficiency by removing swirl. J. R. Soc. Interface 5 (28), 1303–1307.CrossRefGoogle ScholarPubMed
Von Kármán, T. 1935 General aerodynamic theory-perfect fluids. Aerodyn. Theory 2, 346–349.Google Scholar
Warkentin, J. & DeLaurier, J. 2007 Experimental aerodynamic study of tandem flapping membrane wings. J. Aircraft 44 (5), 1653–1661.CrossRefGoogle Scholar
Zheng, Z. C. & Wei, Z. 2012 Study of mechanisms and factors that influence the formation of vortical wake of a heaving airfoil. Phys. Fluids 24 (10), 103601.CrossRefGoogle Scholar
Zurman-Nasution, A. N., Ganapathisubramani, B. & Weymouth, G. D. 2020 Influence of three-dimensionality on propulsive flapping. J. Fluid Mech. 886.CrossRefGoogle Scholar