caa a22 4500 606196994 CHVBK 20210128100927.0 cr unu---uuuuu 210128e20150101xx s 000 0 eng 10.1007/s00348-014-1866-6 doi (NATIONALLICENCE)springer-10.1007/s00348-014-1866-6 Three-dimensional reconstruction of helicopter blade-tip vortices using a multi-camera BOS system [Elektronische Daten] [André Bauknecht, Benjamin Ewers, Christian Wolf, Friedrich Leopold, Jianping Yin, Markus Raffel] Noise and structural vibrations in rotorcraft are strongly influenced by interactions between blade-tip vortices and the structural components of a helicopter. As a result, knowing the three-dimensional location of vortices is highly desirable, especially for the case of full-scale helicopters under realistic flight conditions. In the current study, we present results from a flight test with a full-scale BO105 in an open-pit mine. A background-oriented schlieren measurement system consisting of ten cameras with a natural background was used to visualize the vortices of the helicopter during maneuvering flight. Vortex filaments could be visualized and extracted up to a vortex age of 360°. Vortex instability effects were found for several flight conditions. For the camera calibration, an iterative approach using points on the helicopter fuselage was applied. Point correspondence between vortex curves in the evaluated images was established by means of epipolar geometry. A three-dimensional reconstruction of the main part of the vortex system was carried out for the first time using stereophotogrammetry. The reconstructed vortex system had good qualitative agreement with the result of an unsteady free-wake panel method simulation. A quantitative evaluation of the 3D vortex system was carried out, demonstrating the potential of the multi-camera background-oriented schlieren measurement technique for the analysis of blade-vortex interaction effects on rotorcraft. Springer-Verlag Berlin Heidelberg, 2014 Bauknecht André Helicopter Department, Institute of Aerodynamics and Flow Technology, German Aerospace Center (DLR), Bunsenstr. 10, 37073, Göttingen, Germany aut Ewers Benjamin Helicopter Department, Institute of Aerodynamics and Flow Technology, German Aerospace Center (DLR), Bunsenstr. 10, 37073, Göttingen, Germany aut Wolf Christian Helicopter Department, Institute of Aerodynamics and Flow Technology, German Aerospace Center (DLR), Bunsenstr. 10, 37073, Göttingen, Germany aut Leopold Friedrich French-German Research Institute (ISL), 5 rue du Général Cassagnou, 68300, Saint-Louis, France aut Yin Jianping Helicopter Department, Institute of Aerodynamics and Flow Technology, German Aerospace Center (DLR), Lilienthalplatz 7, 38108, Braunschweig, Germany aut Raffel Markus Helicopter Department, Institute of Aerodynamics and Flow Technology, German Aerospace Center (DLR), Bunsenstr. 10, 37073, Göttingen, Germany aut Experiments in Fluids Springer Berlin Heidelberg 56/1(2015-01-01), 1-13 0723-4864 56:1<1 2015 56 348 https://doi.org/10.1007/s00348-014-1866-6 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/s00348-014-1866-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Bauknecht André Helicopter Department, Institute of Aerodynamics and Flow Technology, German Aerospace Center (DLR), Bunsenstr. 10, 37073, Göttingen, Germany aut NATIONALLICENCE 700 1- Ewers Benjamin Helicopter Department, Institute of Aerodynamics and Flow Technology, German Aerospace Center (DLR), Bunsenstr. 10, 37073, Göttingen, Germany aut NATIONALLICENCE 700 1- Wolf Christian Helicopter Department, Institute of Aerodynamics and Flow Technology, German Aerospace Center (DLR), Bunsenstr. 10, 37073, Göttingen, Germany aut NATIONALLICENCE 700 1- Leopold Friedrich French-German Research Institute (ISL), 5 rue du Général Cassagnou, 68300, Saint-Louis, France aut NATIONALLICENCE 700 1- Yin Jianping Helicopter Department, Institute of Aerodynamics and Flow Technology, German Aerospace Center (DLR), Lilienthalplatz 7, 38108, Braunschweig, Germany aut NATIONALLICENCE 700 1- Raffel Markus Helicopter Department, Institute of Aerodynamics and Flow Technology, German Aerospace Center (DLR), Bunsenstr. 10, 37073, Göttingen, Germany aut NATIONALLICENCE 773 0- Experiments in Fluids Springer Berlin Heidelberg 56/1(2015-01-01), 1-13 0723-4864 56:1<1 2015 56 348