caa a22 4500 606197516 CHVBK 20210128100929.0 cr unu---uuuuu 210128e20150901xx s 000 0 eng 10.1007/s00348-015-2031-6 doi (NATIONALLICENCE)springer-10.1007/s00348-015-2031-6 Dynamic pitching effect on a laminar separation bubble [Elektronische Daten] [A. Nati, R. de Kat, F. Scarano, B. van Oudheusden] The unsteady effect of a periodic pitching motion on the characteristic of a laminar separation bubble on the suction side of a SD7003 aerofoil is investigated by means of time-resolved planar and tomographic particle image velocimetry. The measurements provide information on the separation, transition and vortex roll-up onset as well as the spanwise distribution of vortical structures, for both the dynamic pitching between 4° and 8° and corresponding cases at a static pitch angle. During pitching, a clear hysteresis behaviour is observed for the vortex roll-up position and shedding frequency, showing a strongly delayed recovery of the shear layer with respect to the steady aerofoil case. The development of the shear layer transition exhibits initially 2D Kelvin-Helmholtz rollers that are interrupted, forming Λ-shaped rollers, which eventually evolve into 3D arch-shaped hairpin structures. The 3D analysis of undulated rollers allowed the determination of the rollers streamwise spatial separation for both static and pitching aerofoil cases . The Author(s), 2015 Nati A. Department of Climatic Wind Tunnels BMW AG, Schleißheimer Straße 424, 80788, Munich, Germany aut de Kat R. Aerodynamics and Flight Mechanics Group, University of Southampton, Tizard (blg 13), Highfield, S017 1EU, Southampton, UK aut Scarano F. 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 56/9(2015-09-01), 1-17 0723-4864 56:9<1 2015 56 348 https://doi.org/10.1007/s00348-015-2031-6 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/s00348-015-2031-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Nati A. Department of Climatic Wind Tunnels BMW AG, Schleißheimer Straße 424, 80788, Munich, Germany aut NATIONALLICENCE 700 1- de Kat R. Aerodynamics and Flight Mechanics Group, University of Southampton, Tizard (blg 13), Highfield, S017 1EU, Southampton, UK aut NATIONALLICENCE 700 1- Scarano F. 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 56/9(2015-09-01), 1-17 0723-4864 56:9<1 2015 56 348