The delay of turbulent boundary layer separation by oscillatory active control

Katz, Y.; Nishri, B.; Wygnanski, I.

doi:10.2514/6.1989-975

Cited by 23 publications

(6 citation statements)

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“…2.1. Apparatus and data acquisition The experiment was carried out in a cascade wind tunnel described by Oster & Wygnanski (1982), Katz, Nishri & Wygnanski (1989) and NW. A straight Plexiglas flap of chord L f = 240 mm was hinged to the test-section sidewalls at the edge of a much longer horizontal flat plate.…”

Section: The Experimentsmentioning

confidence: 99%

Active management of naturally separated flow over a solid surface. Part 1. The forced reattachment process

2004

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The forced reattachment of flow to an inclined flat surface, simulating a simple flap, was investigated experimentally. The transition from a separated to an attached state of the flow was initiated by an abrupt change in the frequency and the amplitude of periodic perturbations emanating from a slot at the flap shoulder. The excitation parameters determined the total duration of the reattachment process. Minimum reattachment time occurred at an optimal excitation frequency of $F_{\hbox{\scriptsize{\it opt}}}^{+} \approx 1.5$, which was independent of amplitude and flap inclination. The control over the process was achieved by enhancing large spanwise vortices in the flow. Spatial amplification of consecutive vortices induces mean transport of fluid away from the flap surface which causes the main stream to reattach. The time scales of the excitation are at least an order of magnitude smaller than the typical reattachment times.

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Section: The Experimentsmentioning

confidence: 99%

Active management of naturally separated flow over a solid surface. Part 1. The forced reattachment process

2004

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“…Some early fundamental work was by Katz et al (1989), and an extensive review of open-loop separation control has been given by Greenblatt and Wygnanski (2000). The majority of experiments were open-loop-controlled; that is, no feedback signal was used.…”

Section: B Modern Afc In Canonical Flowsmentioning

confidence: 99%

“…Oscillating-fl ap actuators were used by Katz et al (1989) to reattach a separated shear layer to a defl ected plate. Delay of separation from a wing's fl ap was demonstrated by Nishri and Wygnanski (1998) using periodic excitation with a pulsed-blowing actuator.…”

Section: Afc For Aerodynamic Applicationsmentioning

confidence: 99%

Fundamentals and Applications of Modern Flow Control

Joslin¹,

Miller²,

Miller³

2009

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“…Flow reattachment of an otherwise separated flow field was also achieved using a small vibrating flaperon located at the apex of a divergence in a wind tunnel wall (Katz, Nishiri and Wygnanski, 1989). The frequency of the excitation was noted to have a large impact on the effectiveness of reattachment.…”

Section: Literature Reviewmentioning

confidence: 99%

Dynamic-Active Flow Control - Phase I

Soria¹

2006

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The delay of turbulent boundary layer separation by oscillatory active control

Cited by 23 publications

References 0 publications

Active management of naturally separated flow over a solid surface. Part 1. The forced reattachment process

Active management of naturally separated flow over a solid surface. Part 1. The forced reattachment process

Fundamentals and Applications of Modern Flow Control

Dynamic-Active Flow Control - Phase I

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