caa a22 4500 606199020 CHVBK 20210128100936.0 cr unu---uuuuu 210128e20150201xx s 000 0 eng 10.1007/s00348-015-1915-9 doi (NATIONALLICENCE)springer-10.1007/s00348-015-1915-9 Three-dimensional flow structures and unsteady forces on pitching and surging revolving flat plates [Elektronische Daten] [M. Percin, B. van Oudheusden] Tomographic particle image velocimetry was used to explore the evolution of three-dimensional flow structures of revolving low-aspect-ratio flat plates in combination with force measurements at a Reynolds number of 10,000. Two motion kinematics are compared that result in the same terminal condition (revolution with constant angular velocity and $$45^{\circ }$$ 45 ∘ angle of attack) but differ in the motion during the buildup phase: pitching while revolving at a constant angular velocity; or surging with a constant acceleration at a fixed angle of attack. Comparison of force histories shows that the pitching wing generates considerably higher forces during the buildup phase which is also predicted by a quasi-steady model quite accurately. The difference in the buildup phases affects the force histories until six chords of travel after the end of buildup phase. In both cases, a vortex system that is comprised of a leading-edge vortex (LEV), a tip vortex and a trailing edge vortex is formed during the initial period of the motion. The LEV lifts off, forms an arch-shaped structure and bursts into substructures, which occur at slightly different phases of the motions, such that the revolving-surging wing flow evolution precedes that of the revolving-pitching wing. The delay is shown to be in accordance with the behavior of the spanwise flow which is affected by the interaction between the tip vortex and revolving dynamics. Further analysis shows that the enhanced force generation of the revolving-pitching wing during the pitch-up phase originates from: (1) increased magnitude and growth rate of the LEV circulation; (2) relatively favorable position and trajectory of the LEV and the starting vortex; and (3) generation of bound circulation during the pitching motion, whereas that of the revolving-surging wing is negligible in the acceleration phase. The Author(s), 2015 Percin M. Department of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS, Delft, The Netherlands aut van Oudheusden B. Department of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS, Delft, The Netherlands aut Experiments in Fluids Springer Berlin Heidelberg 56/2(2015-02-01), 1-19 0723-4864 56:2<1 2015 56 348 https://doi.org/10.1007/s00348-015-1915-9 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00348-015-1915-9 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Percin M. Department of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS, Delft, The Netherlands aut NATIONALLICENCE 700 1- van Oudheusden B. Department of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS, Delft, The Netherlands aut NATIONALLICENCE 773 0- Experiments in Fluids Springer Berlin Heidelberg 56/2(2015-02-01), 1-19 0723-4864 56:2<1 2015 56 348