Spectral analysis of localized disturbances in boundary layer at subcritical Reynolds numbers

Бойко, А. В.; Grek, G. R.; Sboev, D. S.

doi:10.1063/1.1619138

Cited by 10 publications

(1 citation statement)

References 29 publications

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“…Model experiments have shown that generation of these disturbances by external turbulence can be implemented by means of both localized [2] and distributed [3,4] susceptibilities.…”

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confidence: 99%

Controlling the Development of Stationary Longitudinal Structures in the Boundary Layer on a Flat Plate using Riblets

Lokhov

Бойко

Sboev

2005

J Appl Mech Tech Phys

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This paper reports results of experiments on controlling longitudinal structures in the boundary layer on a flat plate. The longitudinal structures were generated by a controlled vortical disturbance of the external flow by means of a distributed susceptibility mechanism. It is shown that riblets reduce the intensity of both stationary and traveling disturbances. The linear and weakly linear stages in the development of disturbances in the boundary layer are the most favorable for the use of riblets.Introduction. It is known that in many cases, laminar-turbulent transitions are dominated by longitudinal structures. An example is a transition under conditions of elevated free-stream turbulence. Subsequently, the longitudinal structures that arise in this case undergo secondary instability, resulting in turbulent spots [1].At present, the mechanisms of occurrence of longitudinal structures in boundary layers as primary instability under natural conditions have not been clarified. Model experiments have shown that generation of these disturbances by external turbulence can be implemented by means of both localized [2] and distributed [3,4] susceptibilities.There have been few experiments on controlling the development of longitudinal structures in boundary layers. Katasonov and Kozlov [5] employed a method of active control of longitudinal structures localized in space and time (so-called puffs) using localized injection-suction through a hole in the wall. In [6], the growth of these disturbances was suppressed by wall oscillations in the transverse direction, and in [7] by means of riblets. Studies have been performed of the effect of riblets on longitudinal vortices generated using roughness elements in the boundary layer on a flat plate [8] and on an oblique wing [9]. These studies were successful in the sense that a decrease in disturbance energy was achieved using control. It should be noted that all these experiments dealt with controlling disturbances generated by localized susceptibility mechanisms.The distributed generation of a stationary longitudinal structure in a laminar boundary layer on a flat plate was is studied in detail in [3,4]. The data of these experiments are in good agreement with the results of theoretical papers [10][11][12]. In contrast to localized generation, distributed susceptibility ensures a continuous energy flow from external disturbances to disturbances inside the boundary layer [13], which can reduce the control effectiveness. Research on the control of the disturbances resulting from distributed susceptibility has not yet been performed and is therefore very important.Riblets, as is known, are a longitudinal ribbing of a body surface and are an effective passive means for controlling the boundary layer in both turbulent flows [14] and in the early nonlinear stages of laminar-turbulent transitions [15]. Their advantages are ease in manufacturing and stability against external action. Laminarturbulent transitions under high free-stream turbulence conditions are frequently encounte...

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“…Model experiments have shown that generation of these disturbances by external turbulence can be implemented by means of both localized [2] and distributed [3,4] susceptibilities.…”

mentioning

confidence: 99%