Abstract
The thrust production of an oscillating wing in the low Reynolds number regime (75 ≤ Re ≤ 1000) was investigated via threedimensional numerical simulations, primarily focusing on exploring the effects of aspect ratio AR (3 ≤ AR ≤ 10) and heave-pitch phase difference φ (0° ≤ φ ≤ 360°) on thrust production and propulsion efficiency ηp by tracing the tip vortices. The propulsion characteristics were observed to be strongly dependent on φ and Re but weakly dependent on AR. The oscillating wing produces positive thrust + C̅x for 67.5° ≤ φ ≤ 135°. The maximum + C̅x is produced at φ = 112° due to the flow features namely ‘constructive wake deflection’ and ‘mild flow separation during stroke reversal’. The coherent vortex structures reveal that the horseshoe ring HSR formed in each stroke aids in producing positive thrust via momentum change. The shape and size of the HSR are affected by the AR of wing. The shape of HSR is nearly circular at low AR, whereas it is a rounded rectangle at high AR. The HSR is noticed to transport the flow of high magnitude in uvelocity when Re = 450 and 1000, that will increase the positive thrust.
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This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education [NRF-2017R1D1A1B03032472].
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Arun Raj Shanmugam received his M. Tech. (Eng) from IIT Bombay in 2012. He is currently pursuing a Ph.D. in Mechanical Engineering, Kyungpook National University, Daegu. His research interests include turbo machines, CFD, and fluid-structure interactions.
Chang Hyun Sohn received his M.Sc. (Eng) and Ph.D. from KAIST in 1985 and 1991, respectively. Dr. Sohn is currently a Professor at the School of Mechanical Engineering, Kyungpook National University, Daegu. His research interests include CFD, PIV, flowinduced vibration, thermal-hydraulics, and fluid-structure interactions.
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Shanmugam, A.R., Sohn, C.H. Numerical investigation on thrust production and unsteady mechanisms of three-dimensional oscillating wing. J Mech Sci Technol 33, 5889–5900 (2019). https://doi.org/10.1007/s12206-019-1134-z
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DOI: https://doi.org/10.1007/s12206-019-1134-z