Changing lift and drag by jet oscillation: experiments on a circular cylinder with turbulent separation

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 incre...

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Bibliographic Details
Published in:European journal of mechanics, B, Fluids B, Fluids, 2000-09, Vol.19 (5), p.575-595
Main Authors: Béra, Jean-Christophe, Michard, Marc, Sunyach, Michel, Comte-Bellot, Geneviève
Format: Article
Language:English
Subjects:
Actuators
Boundary layers
control
cylinder wake
Cylinders (shapes)
Drag
Exact sciences and technology
Flow control
Fluid dynamics
Fundamental areas of phenomenology (including applications)
Jets
Lift
Oscillations
Physics
PIV
Pressure distribution
pulsed jet
separation
Turbulent flow
Turbulent flows, convection, and heat transfer
Velocity measurement
Wakes
Wind tunnels
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Summary: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.
ISSN:0997-7546
1873-7390
DOI:10.1016/S0997-7546(00)00122-9