Laminar Boundary-Layer, Sound Receptivity and Control

Kosorygin, V. S.; Radeztsky, Ronald H.; Saric, William S.

doi:10.1007/978-3-642-79765-1_61

Cited by 17 publications

(13 citation statements)

References 9 publications

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“…On the other hand, the irrotational parts of the freestream disturbances (sound) contribute to the initial amplitudes of the 2-D T-S waves (Kosorygin et al 28 ) Thus, freestream sound and turbulence present a different set of problems in the understanding, prediction, and control of boundary transition and, as such, each require unusual experimental and computational techniques. One needs knowledge, being able to separate the amplitudes, frequencies, length scales, and orientations of both the sound and vorticity components present in the freestream.…”

Section: Why Is Receptivity Important?mentioning

confidence: 99%

Receptivity: The Inspiration of Mark Morkovin (Invited)

Reed

Saric

2015

45th AIAA Fluid Dynamics Conference

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This paper provides a review of the current findings in receptivity for subsonic/transonic flows, including a discussion of the origin of the concept via Mark Morkovin, a remarkable aeronautical engineer, educator, and colleague. Disturbances external to the boundary layer -whether freestream sound or vorticity -can interact with surface roughness, the leading edge, or other inhomogeneities and enter the boundary layer as steady and/or unsteady fluctuations of the basic state. This process establishes the initial conditions of disturbance amplitude, frequency, phase, and scales for the breakdown of laminar flow. The past decades have seen considerable progress in the understanding of receptivity mechanisms guided by the roadmap (Morkovin et al. 1 ).

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Section: Why Is Receptivity Important?mentioning

confidence: 99%

Receptivity: The Inspiration of Mark Morkovin (Invited)

Reed

Saric

2015

45th AIAA Fluid Dynamics Conference

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“…It was found that K s = 0.031. After normalization with C r (α r ) (see above) this gives a receptivity coefficient for the experiments by Kosorygin et al (1995) of G ar = 0.212. Taking again the influence of Reynolds number and frequency parameter into account, which requires an interpolation over a wider range than for the experiment of Saric et al (1991), this value reduces to G ar = 0.161 for the present conditions and becomes rather close to (somewhat higher than) the value of G ar = 0.134 reported here.…”

Section: Comparison With Related Receptivity Experimentsmentioning

confidence: 99%

“…It is necessary to note some important experimental papers devoted to this problem. After the famous work by Aizin & Polyakov (1979) the excitation of the two-dimensional instability waves by acoustics on two-dimensional roughness elements was studied experimentally by Kosorygin, Levchenko & Polyakov (1985), Kosorygin (1986), Saric, Hoos & Kohama (1990), Wiegel & Wlezien (1993), Zhou, Liu & Blackwelder (1994), Kosorygin, Radeztsky & Saric (1995) and others. It was found that the acoustics excite the two-dimensional TS-waves even on a microscopically small non-uniformity.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional acoustic-roughness receptivity of a boundary layer on an airfoil: experiment and direct numerical simulations

et al. 2003

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The paper is devoted to an experimental and numerical investigation of the problem of excitation of three-dimensional Tollmien–Schlichting (TS) waves in a boundary layer on an airfoil owing to scattering of an acoustic wave on localized microscopic surface non-uniformities. The experiments were performed at controlled disturbance conditions on a symmetric airfoil section at zero angle of attack. In each set of measurements, the acoustic wave had a fixed frequency fac, in the range of unstable TS-waves. The three-dimensional surface non-uniformity was positioned close to the neutral stability point at branch I for the two-dimensional perturbations. To avoid experimental difficulties in the distinction of the hot-wire signals measured at the same (acoustic) frequency but having a different physical nature, the surface roughness was simulated by a quasi-stationary surface non-uniformity (a vibrator) oscillating with a low frequency fv. This led to the generation of TS-wavetrains at combination frequencies f1,2=fac ∓ fv. The spatial behaviour of these wavetrains has been studied in detail for three different values of the acoustic frequency. The disturbances were decomposed into normal oblique TS-modes. The initial amplitudes and phases of these modes (i.e. at the position of the vibrator) were determined by means of an upstream extrapolation of the experimental data. The shape of the vibrator oscillations was measured by means of a laser triangulation device and mapped onto the Fourier space.

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“…It is believed that the acoustic disturbances contribute to the initial amplitudes of the two-dimensional Tollmien-Schlichting (T-S) waves [1], whereas the vorticity waves contribute to the three-dimensional behavior of the breakdown process [2,3]. It is believed that the acoustic disturbances contribute to the initial amplitudes of the two-dimensional Tollmien-Schlichting (T-S) waves [1], whereas the vorticity waves contribute to the three-dimensional behavior of the breakdown process [2,3].…”

Section: Introductionmentioning

confidence: 99%

“…Boundary layer receptivity is the process by which disturbances in the external free-stream flow or at the wall surface interact with the boundary layer and generate internal waves. It is believed that the acoustic disturbances contribute to the initial amplitudes of the two-dimensional Tollmien-Schlichting (T-S) waves [1], whereas the vorticity waves contribute to the three-dimensional behavior of the breakdown process [2,3]. It is now known that the receptivity of boundary layers to free-stream turbulence or to surface imperfections plays an important role in the prediction of the transition onset.…”

Section: Introductionmentioning

confidence: 99%

A study of the effect of step excrescences and free‐stream disturbances on boundary layer stability

Sescu

Visbal

Rizzetta

2015

Numerical Methods in Fluids

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SummaryIn this work, a study of the mechanism by which free‐stream acoustic and vorticity disturbances interact with a boundary layer flow developing over a flat plate featuring a step excrescence located at a certain distance from a blunt leading edge is included. The numerical tool is a high‐fidelity implicit numerical algorithm solving for the unsteady, compressible form of the Navier–Stokes equations in a body‐fitted curvilinear coordinates and employing high‐accurate compact differencing schemes with Pade‐type filters. Acoustic and vorticity waves are generated using a source term in the momentum and energy equations, as opposed to using inflow boundary conditions, to avoid spurious waves that may propagate from boundaries. The results show that the receptivity to surface step excrescences is largely the result of an overall adverse pressure gradient posed by the step, and that the free‐stream disturbances accelerate the generation of instabilities in the downstream. As expected, it is found that the acoustic disturbance interacting with the surface imperfection is more efficient in exciting the Tollmien–Schlichting waves than the vorticity disturbance. The latter generates Tollmien–Schlichting waves that are grouped in wave packets consistent with the wavelength of the free‐stream disturbance. Copyright © 2015 John Wiley & Sons, Ltd.

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Laminar Boundary-Layer, Sound Receptivity and Control

Cited by 17 publications

References 9 publications

Receptivity: The Inspiration of Mark Morkovin (Invited)

Receptivity: The Inspiration of Mark Morkovin (Invited)

Three-dimensional acoustic-roughness receptivity of a boundary layer on an airfoil: experiment and direct numerical simulations

A study of the effect of step excrescences and free‐stream disturbances on boundary layer stability

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