Three-dimensional reconstruction of helicopter blade–tip vortices using a multi-camera BOS system
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- 作者：André Bauknecht (1)
Benjamin Ewers (1)
Christian Wolf (1)
Friedrich Leopold (2)
Jianping Yin (3)
Markus Raffel (1) - 刊名：Experiments in Fluids
- 出版年：2015
- 出版时间：January 2015
- 年：2015
- 卷：56
- 期：1
- 全文大小：3,070 KB
- 参考文献：1. Bauknecht A, Merz CB, Raffel M (2014a) Airborne application of the background oriented Schlieren technique to a helicopter in forward flight. In: 17th int. symp. on applications of laser techniques to fluid mechanics, Lisbon, Portugal, 07-0 July, 2014
2. Bauknecht A, Merz CB, Raffel M, Landolt A, Meier AH (2014b) Blade–tip vortex detection in maneuvering flight using the background-oriented schlieren technique. J Aircraft. doi:DOIurl10.2514/1.C032672
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Jianping Yin (3)
Markus Raffel (1)
1. Helicopter Department, Institute of Aerodynamics and Flow Technology, German Aerospace Center (DLR), Bunsenstr. 10, 37073, G?ttingen, Germany
2. French-German Research Institute (ISL), 5 rue du Général Cassagnou, 68300, Saint-Louis, France
3. Helicopter Department, Institute of Aerodynamics and Flow Technology, German Aerospace Center (DLR), Lilienthalplatz 7, 38108, Braunschweig, Germany - ISSN：1432-1114
文摘
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 BO?105 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.