Changing lift and drag by jet oscillation: experiments on a circular cylinder with turbulent separation |
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| Affiliation: | 1. Ural Federal University, Department of Theoretical and Mathematical Physics, Laboratory of Multi-Scale Mathematical Modeling, 620000 Ekaterinburg, Russian Federation;2. Friedrich-Schiller-Universität Jena, Physikalisch-Astronomische Fakultät, D-07743 Jena, Germany;1. Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China;2. Department of Interventional Radiology and Vascular Surgery, Peking University Third Hospital, North Garden Road 49, Haidian District, Beijing 100191, China;1. Laboratory of Food Process Engineering, Wageningen University & Research, Bornse Weilanden 9, 6708WG Wageningen, The Netherlands;2. Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911MA Leeuwarden, The Netherlands;1. Physical Sciences Department, Embry–Riddle Aeronautical University, Daytona Beach, FL 32114, United States;2. Aerospace Engineering Department, Embry–Riddle Aeronautical University, Daytona Beach, FL 32114, United States;1. Faculty of Energy Systems and Nuclear Sciences, Ontario Tech University, Oshawa, ON, Canada;2. Fuel and Fuel Channel Safety Branch, Canadian Nuclear Laboratories, Chalk River, ON, Canada;3. Computational Sciences International, Los Alamos, NM, USA;4. University of Toronto Institute for Aerospace Studies, University of Toronto, Toronto, ON, Canada;5. Institute of Fluid Mechanics, University of Rostock, Rostock, Germany;6. Institute of Gas Turbines and Aerospace Propulsion, Technische Universität Darmstadt, Darmstadt, Germany;7. Institute of Fluid Mechanics and Aerodynamics, Technische Universität Darmstadt, Darmstadt, Germany |
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| Abstract: | Oscillating jet actuators have been implemented and tested on a circular cylinder. Their action on the separation of turbulent boundary layers is investigated using complementary approaches. Wall pressure distribution shows that a large lift is generated, at the expense, however, of a slightly increased drag. Particle image velocimetry measurements provide the mean and fluctuating velocity fields in the near-wake. The control jet deflects the mean flux lines towards the wall, illustrating that the separation is delayed. This effect appears more and more powerful as the pulsed jet velocity increases. Phase averaging of the PIV fields shows that periodic structures are generated by the control, and how these structures modify the aerodynamic forces by entraining the external flow towards the wall. Finally, a few comparisons are made with laminar boundary layers and some general mechanisms are presented for the lift increase. |
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