BAUDOT, Manon (2016) Drag reduction of wall friction in turbulent flows PRE - Research Project, ENSTA.
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Abstract
A Taylor-Couette facility with counter-rotating cylinders under perfect counter-rotating conditions (riwi=rowo) was used to study drag friction in turbulent flows. It was used to evaluate the dependency of the shear stress on shear Reynolds number on characteristic smooth surfaces and on a ’known’ modifying riblet surface. Issues with the torque-meter occurred in the end, which prevented the obtention of accurate results for coated surfaces. It was also used to estimate the power loss due to the oscillatory flow as a function of the amplitude and the period time. It was proved that an increase in amplitude or a decrease in period result in an important decrease of the velocity efficiency. Typically, the rowing velocity amplitude is between 20 and 30 %, the resulting efficiency is between 0.88 and 0.95. Reducing the velocity fluctuations by 60 would increase the speed by 1.6. To investigate some details in the results, experiments were carried out to study the coupling and bearings, which showed a spring-damper behavior.
Item Type: | Thesis (PRE - Research Project) |
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Uncontrolled Keywords: | Taylor-Couette, oscillations, efficiency, rowing. |
Subjects: | Fluid Mechanics and Energy |
ID Code: | 6713 |
Deposited By: | Manon Baudot |
Deposited On: | 12 oct. 2016 15:35 |
Dernière modification: | 12 oct. 2016 15:35 |
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