Interactions between a shock and turbulent features in a Mach 2 compressible boundary layer

Baidya, Rio; Scharnowski, Sven; Bross, Matthew; Kähler, Christian J.

doi:10.1017/jfm.2020.208

Cited by 14 publications

(17 citation statements)

References 42 publications

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“…Similar phenomena were also observed in transonic SBLI flows (Pirozzoli et al 2010), where the near-wall low-speed streaks are suppressed near the interaction zone and regenerated downstream at approximately five interaction length scales. Among the few research works that provided the spanwise spectra, a recent experimental study by Baidya et al (2020) found that the two energetic motions are prominent at large spanwise scales, which persist for a long streamwise extent.…”

Section: Turbulence Amplification and Coherent Structuresmentioning

confidence: 99%

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A spectral inspection for turbulence amplification in oblique shock wave/turbulent boundary layer interaction

Zhao

Tang

et al. 2022

J. Fluid Mech.

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Turbulence amplification and the large-scale coherent structures in shock wave/turbulent boundary layer interaction flows have been studied at length in previous research, while the direct association between these two flow features is still lacking. In the present study, the transport equation of turbulent kinetic energy spectra is derived and utilized to analyse the scale-by-scale energy budget across the interaction zone, enabling us to reveal the association between the genesis of the large-scale motions and the turbulence amplification. For the presently considered flow with incipient shock-induced separation, we identified in turbulent kinetic energy spectra distribution that the most energetic motions are converted from the near-wall small-scale motions to large-scale motions consisting of velocity streaks and cross-stream circulations as they go through the interaction zone. The amplification of streamwise velocity fluctuation is triggered first, resulting in the emergence of large-scale velocity streaks, which is attributed to the adverse pressure gradient, as indicated by the spectra of the production term. The energy carried by large-scale velocity streaks is transferred to other velocity components by the pressure-strain term, producing large-scale cross-stream circulations. When large-scale motions are convected downstream, their energy is transferred via turbulent cascade to smaller scales and dissipated by viscosity. The spanwise uniform fluctuations, reminiscent of the unsteadiness of the separation bubble, are contributed primarily by the inter-scale energy transfer from the finite spanwise scale motions.

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Section: Turbulence Amplification and Coherent Structuresmentioning

confidence: 99%

“…Among the few research works that provided the spanwise spectra, a recent experimental study by Baidya et al. (2020) found that the two energetic motions are prominent at large spanwise scales, which persist for a long streamwise extent.…”

Section: Introductionmentioning

confidence: 99%

A spectral inspection for turbulence amplification in oblique shock wave/turbulent boundary layer interaction

Zhao

Tang

et al. 2022

J. Fluid Mech.

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“…Furthermore, an interaction between superstructures and the near-wall dynamics has been demonstrated (Hutchins & Marusic 2007b;Ganapathisubramani et al 2012;Bross, Fuchs & Kähler 2019). Superstructures have also been associated with the low-frequency unsteadiness of the separation bubble downstream of certain shock wave boundary layer interactions (Beresh, Clemens & Dolling 2002;Ganapathisubramani, Clemens & Dolling 2007;Baidya et al 2020), making their impact important for perturbed flows as well. Therefore, the investigation of these superstructures is essential for understanding the overall dynamics of turbulent boundary layers.…”

Section: Introductionmentioning

confidence: 99%

Large-scale coherent structures in compressible turbulent boundary layers

2021

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“…These findings are consistent with previous studies from Refs. [13,[30][31][32]. A movie displaying the temporal variation of the suction side separation bubble in terms of instantaneous friction coefficient, as well as the response of the bubble to the passage of low and high-speed streaks near the wall is provided as supplemental material (movie 3).…”

Section: B Spatio-temporal Analysis Of the Separation Bubblesmentioning

confidence: 99%

Shock-Boundary Layer Interactions in Supersonic Turbine Cascades

Lui,

Ricciardi,

Wolf

et al. 2022

Preprint

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The physics of shock-boundary layer interactions in a supersonic turbine cascade is investigated through a wall-resolved large eddy simulation. Special attention is given to the characterization of the low-frequency dynamics of the separation bubbles using flow visualization, spectral analysis, space-time cross correlations, and flow modal decomposition. The mean flowfield shows different shock structures formed on both sides of the airfoil. On the suction side, an oblique shock impinges on the turbulent boundary layer, whereas a Mach reflection interacts with the pressure side boundary layer. Instantaneous flow visualizations illustrate elongated streamwise structures on the incoming boundary layers and their interactions with the shocks and separation bubbles. The passage of high-speed (low-speed) streaks through the recirculation bubbles leads to the downstream (upstream) motion of the separation point on both suction and pressure sides, resulting in spanwise modulation of the bubbles. Space-time cross-correlations reveal that the near-wall streaks drive the suction side separation bubble motion, which in turn promotes the oscillations of the reattachment shock and shear layer flapping. Space-time correlations also indicate the existence of a π phase jump in the pressure fluctuations along the separation bubble on the suction side.After this phase jump, a downstream propagating pressure disturbance is observed, while prior to this point, the pressure disturbances dominantly propagate in the upstream direction. Finally, the organized motions in the shock-boundary layer interactions and their corresponding characteristic frequencies are identified using proper orthogonal decomposition. I. INTRODUCTIONSupersonic fluid machinery offers size and cost reduction in high-speed propulsion and power generation systems [1, 2] and for compact hydrocarbon cracking [3]. The detailed analysis of supersonic turbines is challenging predominantly due to the shock-boundary layer interactions (SBLIs) which arise when the detached oblique shock waves forming at the stator/rotor leading edges impinge on the boundary layers of the neighboring airfoils. The shocks impose intense adverse pressure gradients on the boundary layers that may cause flow separation. This, in turn, leads to the formation of separation and reattachment shocks that *

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Interactions between a shock and turbulent features in a Mach 2 compressible boundary layer

Cited by 14 publications

References 42 publications

A spectral inspection for turbulence amplification in oblique shock wave/turbulent boundary layer interaction

A spectral inspection for turbulence amplification in oblique shock wave/turbulent boundary layer interaction

Large-scale coherent structures in compressible turbulent boundary layers

Shock-Boundary Layer Interactions in Supersonic Turbine Cascades

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