Shock-vortex shear-layer interaction in the transonic flow around a supercritical airfoil at high Reynolds number in buffet conditions

Szubert, Damien; Grossi, Fernando; García, Antonio Jiménez; Hoarau, Yannick; Hunt, J. C. R.; Braza, Marianna

doi:10.1016/j.jfluidstructs.2015.03.005

Cited by 51 publications

(74 citation statements)

References 56 publications

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“…The peak at Strouhal St = 11.5 observed in the PSD confirms shedding phenomena typical of Kelvin-Helmholtz instabilities. The shear layer instability frequency is consistent with the estimation provided in Section 4, as well as with the findings of Szubert et al (2015) for numerical simulations in transonic conditions. With this regard it is worth remarking that the flow beside the wake in Szubert et al (2015) features local Reynolds number comparable to that of the experiments carried out in the present work.…”

Section: Proper Orthogonal Decomposition Of the Wake Flowsupporting

confidence: 90%

“…Thanks to this effect, the shear layers are thinned and the distance between them is reduced. By activating higher-range POD modes where energy is concentrated in the TNT, an effect of loss of coherence on the low-range most energetic POD modes is achieved, as demonstrated by Szubert et al (2015). Regarding the present experiment, the eddy blocking effect can be achieved by means of morphing: by the vibrations of the trailing edge, energy is introduced in the wake.…”

Section: Control Strategy: From Eddy Blocking Effect To the Vortex Brmentioning

confidence: 55%

“…the expansion or contraction of the turbulent wake. It has been shown (Hunt et al, 2008;Szubert et al, 2015)[p] that by activating smaller-scale structures of the inertial range in the turbulence energy spectrum in between the two shear layers, an upscale energy transfer is achieved towards the larger scale coherent eddies and a shear-sheltering mechanism leads to constriction of the turbulent-non-turbulent interfaces. This mechanism has been depicted in free shear layer flows (Hunt et al, 2008).…”

Section: Control Strategy: From Eddy Blocking Effect To the Vortex Brmentioning

confidence: 99%

“…Yarusevych et al (2006) investigates the dynamics of the coherent vortices on the wake of a NACA 0025 at Re up to 150 000. More details on the dynamics of vortex shedding past an airfoil can be found in Huang and Linf (1995), Hoarau et al (2003), Bourguet et al (2008), Szubert et al (2015Szubert et al ( , 2016. These experimental or numerical analyses characterize the size and the frequencies of coherent vortices from low to high Reynolds numbers, including also compressibility effects.…”

Section: Introductionmentioning

confidence: 99%

“…Hence at a given controlled camber, the vibrating trailing edge adds kinetic energy in the wake that fosters the suppression of coherent turbulent structures. This concept was first studied theoretically numerically by Szubert et al in Szubert et al (2015) for a transonic flow around a supercritical airfoil. Introducing a small amount of kinetic energy by means of Proper Orthogonal Decomposition (POD) provides an eddy blocking effect that reduces significantly the wake thickness.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Dynamics of a hybrid morphing wing with active open loop vibrating trailing edge by time-resolved PIV and force measures

Jodin

Motta

Scheller

et al. 2017

Journal of Fluids and Structures

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et al.. Dynamics of a hybrid morphing wing with active open loop vibrating trailing edge by Time-Resolved PIV and force measures.This is an author-deposited version published in: http://oatao.univ-toulouse.fr/ Eprints ID: 16095Open Archive Toulouse Archive Ouverte (OATAO)OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. Keywords:Morphing Smart materials Wind tunnel experiments Vortex breakdown Harmonic forcing a b s t r a c t A quantitative characterization of the effects obtained by high frequency-low amplitude trailing edge actuation is presented. Particle image velocimetry, pressure and aerodynamic forces measurements are carried out on a wing prototype equipped with shape memory alloys and trailing edge piezoelectric-actuators, allowing simultaneously high deformations (bending) in low frequency and higher-frequency vibrations. The effects of this hybrid morphing on the forces have been quantified and an optimal actuation range has been identified, able to increase lift and decrease drag. The present study focuses more specifically on the effects of the higher-frequency vibrations of the trailing edge region. This actuation allows manipulation of the wake turbulent structures. It has been shown that specific frequency and amplitude ranges achieved by the piezoelectric actuators are able to produce a breakdown of larger coherent eddies by means of upscale energy transfer from smaller-scale eddies in the near wake. It results a thinning of the shear layers and the wake's width, associated to reduction of the form drag, as well as a reduction of predominant frequency peaks of the shear-layer instability. These effects have been shown by means of frequency domain analysis and Proper Orthogonal Decomposition.

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Section: Proper Orthogonal Decomposition Of the Wake Flowsupporting

confidence: 90%

Section: Control Strategy: From Eddy Blocking Effect To the Vortex Brmentioning

confidence: 55%

Section: Control Strategy: From Eddy Blocking Effect To the Vortex Brmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Dynamics of a hybrid morphing wing with active open loop vibrating trailing edge by time-resolved PIV and force measures

Jodin

Motta

Scheller

et al. 2017

Journal of Fluids and Structures

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The eddy, wave, and interface structure of turbulent shear layers below/above stably stratified regions

2015

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High resolution three‐dimensional simulations are presented of the interactions between turbulent shear flows moving with mean relative velocity ΔU below a stably stratified region with buoyancy frequency (N+). An artificial forcing in the simulation, with a similar effect as a small negative eddy viscosity, leads to a steady state flow which models thin interfaces. Characteristic eddies of the turbulence have length scale L. If the bulk Richardson number Rib=(LN+/ΔU)2 lies between lower and upper critical values denoted as Ri∗(<1/5) and trueR~i(∼0.3em0.3em0.3em1), a “detached” layer is formed in the stable region with thickness L+ greater than L, in which rotational fluctuations and inhomogeneous turbulence are induced above an interface with large gradients of density/temperature. Comparisons are made with shear turbulent interfaces with no stratification. When Rib>trueR~i, vertical propagating waves are generated, with shear stresses carrying significant momentum flux and progressively less as Rib increases. Simulations for a jet and a turbulent mixing layer show similar results. A perturbation analysis, using inhomogeneous Rapid Distortion Theory, models the transition zone between shear eddies below the interface and the fluctuations in the stratified region, consistent with the simulations. It demonstrates how the wave‐momentum‐flux has a maximum when Rib∼2 and then decreases as Rib increases. This coupling mechanism between eddies and waves, which is neglected in eddy viscosity models for shear layers, can drive flows in the stratosphere and the deeper ocean, with significant consequences for short‐ and long‐term flow phenomena. The “detached layer” is a mechanism that contributes to the formation of stratus clouds and polluted layers above the atmospheric boundary layer.

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Numerical Simulation and Modelling of a Morphing Supercritical Airfoil in a Transonic Flow at High Reynolds Numbers

Tô

Zilli

Simiriotis

et al. 2021

Notes on Numerical Fluid Mechanics and Multidisciplinary Design

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The flow dynamics and their morphing modification concerning the transonic flow around an Airbus A320 airfoil have been investigated via 2D simulations at a high Reynolds number. A distinctive flow topology, organised and chaotic occurs in this regime driven by appearance of coherent structures such as the Von-Kármán instability as well as the Kelvin-Helmholtz instability. When the Mach number and angle of attack both belong to a certain range of values, the shock wave develops a low-frequency motion along a specific distance on the suction side, issued from the development of transonic buffet instability. This phenomenon is crucial for the design because it leads to a high rise of drag and can trigger in extreme conditions dangerous dip-flutter modes. Electroactive morphing of the trailing edge region achieved by optimal vibration of piezo-actuators has proved capable to create vortex breakdown of the coherent structures and to act through an eddy-blocking mechanism to a considerable thinning of the shear layers and of the wake as has been proven in subsonic regime as shown by Scheller et al. (2015). The eddy-blocking effect in the transonic regime has been studied in the present article in cruise-speed the conditions, following the studies by Szubert et al. (2015) and Hunt, Eames, and Westerweel (2008). Accordingly, computations have been made to determine which type of actuation offers the best performance in terms of buffet dampening and aerodynamic efficiency as a whole. Lastly, it is shown that a flapping motion of the trailing edge can lock-in the frequency of the buffet phenomenon at the flapping frequency, which has potentially useful applications in terms of controlling and reducing shock oscillations.

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Shock-vortex shear-layer interaction in the transonic flow around a supercritical airfoil at high Reynolds number in buffet conditions

Abstract: OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.

Cited by 51 publications

References 56 publications

Dynamics of a hybrid morphing wing with active open loop vibrating trailing edge by time-resolved PIV and force measures

Dynamics of a hybrid morphing wing with active open loop vibrating trailing edge by time-resolved PIV and force measures

The eddy, wave, and interface structure of turbulent shear layers below/above stably stratified regions

Numerical Simulation and Modelling of a Morphing Supercritical Airfoil in a Transonic Flow at High Reynolds Numbers

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