Academic Journal
Opposition flow control for reducing skin-friction drag of a turbulent boundary layer
| العنوان: | Opposition flow control for reducing skin-friction drag of a turbulent boundary layer |
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| المؤلفون: | Dacome, G. (author), Mörsch, R. (author), Kotsonis, M. (author), Baars, W.J. (author) |
| سنة النشر: | 2024 |
| المجموعة: | Delft University of Technology: Institutional Repository |
| الوصف: | This work explores the dynamic response of a turbulent boundary layer to large-scale reactive opposition control, at a friction Reynolds number of Reτ≈2240. A surface-mounted hot-film is employed as the input sensor, capturing large-scale fluctuations in the wall-shear stress, and actuation is performed with a single on/off wall-normal blowing jet positioned 2.4δ downstream of the input sensor, operating with an exit velocity of vj=0.4U∞. Our study builds upon the work of Abbassi et al. [Int. J. Heat Fluid Flow 67, 30 (2017)0142727X10.1016/j.ijheatfluidflow.2017.05.003] and includes a control-calibration experiment and a performance assessment using PIV- and PTV-based flow field analyses. With the control-off calibration-experiment conducted a priori, a transfer kernel is identified so that the velocity fluctuations that are to-be-controlled can be estimated. The controller targets large-scale high-speed zones in an "opposing"mode and low-speed zones in a "reinforcing"mode. A desynchronized mode was tested for reference and consisted of a statistically similar control mode, but without synchronization to the incoming velocity fluctuations. An energy-attenuation of about 40 % is observed for the opposing control mode in the frequency band corresponding to the passage of large-scale motions. This proves the effectiveness of the control in targeting large-scale motions: an energy-intensification of roughly 45% occurs for the reinforcing control mode instead, while no change in energy, within the wall-normal range targeted, appears with the desynchronized control mode. Moreover, direct measures of the skin-friction drag are inferred from PTV data. Results indicate that the opposing control logic yields the lowest wall-shear stress (3% lower than the desynchronized control, and 10% lower than the uncontrolled flow). Finally, a FIK-decomposition of the skin-friction coefficient revealed that the off-the-wall turbulence follows a consistent trend with the PTV-based wall-shear stress measurements, although biased by an ... |
| نوع الوثيقة: | article in journal/newspaper |
| اللغة: | English |
| Relation: | http://www.scopus.com/inward/record.url?scp=85195266806&partnerID=8YFLogxK; Physical Review Fluids--2469-990X--9cf3574b-6304-4546-a8df-9b618ea4d5d3; http://resolver.tudelft.nl/uuid:1f3b4143-deda-4387-8350-03e56c380e85; https://doi.org/10.1103/PhysRevFluids.9.064602 |
| DOI: | 10.1103/PhysRevFluids.9.064602 |
| الاتاحة: | http://resolver.tudelft.nl/uuid:1f3b4143-deda-4387-8350-03e56c380e85 https://doi.org/10.1103/PhysRevFluids.9.064602 |
| Rights: | © 2024 G. Dacome, R. Mörsch, M. Kotsonis, W.J. Baars |
| رقم الانضمام: | edsbas.D3A10B23 |
| قاعدة البيانات: | BASE |
| DOI: | 10.1103/PhysRevFluids.9.064602 |
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