Unsteady Characteristics of a Swept-Shock/Boundary-Layer Interaction at Mach 2

Arora, Nishul; Mears, Lee; Alvi, Farrukh S.

doi:10.2514/1.j058233

Cited by 31 publications

(11 citation statements)

References 29 publications

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“…We classify this unsteadiness as mid-frequency unsteadiness rather than low-frequency unsteadiness, because it is largely associated with convective coherent structures formed in the separated shear layer (see § 4.2), not stationary large-scale ('breathing') unsteadiness of the separated region as a whole; necessarily, its mechanism is more similar to mid-frequency unsteadiness in comparable spanwise-homogeneous interactions, rather than the low-frequency unsteadiness in such interactions. Recent experiments also confirm this observation that the prominence of the mid-frequency fluctuation band is increased relative to the that of the low-frequency fluctuation band in swept interactions (Arora, Mears & Alvi 2019;Vanstone & Clemens 2019). We note that, by an absolute measure, the mid-frequency content in swept interactions may comprise lower or FIGURE 9.…”

Section: Differences Between 2-d and 3-d Interactionssupporting

confidence: 76%

Dynamics of strong swept-shock/turbulent-boundary-layer interactions

Adler

Gaitonde

2020

J. Fluid Mech.

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Section: Differences Between 2-d and 3-d Interactionssupporting

confidence: 76%

Dynamics of strong swept-shock/turbulent-boundary-layer interactions

Adler

Gaitonde

2020

J. Fluid Mech.

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“…These parameters are chosen to facilitate comparisons, documented in previous work, with concurrent or archival experiments, depending on availability. Specifically, impinging shock simulations [3] were performed in coordination with experiments by Webb et al [84], swept-compression-ramp interactions [2,7] with experiments by Vanstone et al [81,82], Vanstone and Clemens [80], and sharp-fin interactions [4,7] with experiments by Arora et al [11], Baldwin et al [15], Mears et al [49], Arora et al [12], Mears et al [50], Jones et al [42]. Since recent double-fin interactions are not available, these are performed based on conditions of archival experiments by Garrison et al [36], Garrison and Settles [35] and archival RANS calculations by Gaitonde and Shang [27].…”

Section: Stbli Configurationsmentioning

confidence: 99%

“…Some previous results from these campaigns have been described in a variety of forms, including experimental measurements of the swept-compression-ramp (SCR) [80][81][82] and sharp-fin (SF) [11,12,15,42,49,50] interactions, along with high-fidelity large-eddy simulations [2,[4][5][6][7] of both configurations. The double-fin flowfield fosters a better understanding of the separation structure-unsteadiness connection, since it combines elements of swept 3-D interactions with those of 2-D interactions-the symmetry plane, for example, shows the influence of both-and thus aids in the establishment of a more comprehensive perspective.…”

Section: Introductionmentioning

confidence: 99%

Influence of separation structure on the dynamics of shock/turbulent-boundary-layer interactions

Adler

Gaitonde

2021

Theor. Comput. Fluid Dyn.

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Shock/turbulent-boundary-layer interactions (STBLIs) are ubiquitous in high-speed flight and propulsion applications. Experimental and computational investigations of swept, three-dimensional (3-D) interactions, which exhibit quasi-conical mean-flow symmetry in the limit of infinite span, have demonstrated key differences in unsteadiness from their analogous, two-dimensional (2-D), spanwise-homogeneous counterparts. For swept interactions, represented by the swept–fin-on-plate and swept–compression–ramp-on-plate configurations, differences associated with the separated shear layers may be traced to the intermixing of 2-D (spanwise independent) and 3-D (spanwise dependent) scaling laws for the separated mean flow. This results in a broader spectrum of unsteadiness that includes relatively lower frequencies associated with the separated shear layers in 3-D interactions. However, lower frequency ranges associated with the global “breathing” of strongly separated 2-D interactions are significantly less prominent in these simple, swept 3-D interactions. A logical extension of 3-D interaction complexity is the compound interaction formed by the merging of two simple interactions. The first objective of this work is therefore to analyze the more complex picture of the dynamics of such interactions, by considering as an exemplar, wall-resolved simulations of the double-fin-on-plate configuration. We show that in the region of interaction merging, new flow scales, changes in separation topology, and the emergence of lower-frequency phenomena are observed, whereas the dynamics of the interaction near the fin leading edges are similar to those of the simple, swept interactions. The second objective is to evolve a unified understanding of the dynamics of STBLIs associated with complex configurations relevant to actual propulsion systems, which involve the coupling between multiple shock systems and multiple flow separation and attachment events. For this, we revisit the salient aspects of scaling phenomena in a manner that aids in assimilating the double-fin flow with simpler swept interactions. The emphasis is on the influence of the underlying structure of the separated flow on the dynamics. The distinct features of the compound interactions manifest in a centerline symmetry pattern that replaces the quasi-conical symmetry of simple interactions. The primary separation displays topological closure to reveal new length scales, associated unsteadiness bands, and secondary flow separation.

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“…2017; Adler & Gaitonde 2018, 2020), around sharp fins (Schmisseur & Dolling 1994; Gaitonde et al. 1999; Arora, Mears & Alvi 2019) and for swept impinging oblique SBLIs (Doehrmann et al. 2018; Padmanabhan et al.…”

Section: Introductionmentioning

confidence: 99%

“…Depending on the shock strength and the sweep angle, the interaction is characterized by either parallel or diverging separation/reattachment lines along the spanwise direction, which correspond to cylindrical or conical symmetry conditions, respectively (Settles, Perkins & Bogdonoff 1980). This is the case for flows over swept compression ramps (Settles et al 1980;Erengil & Dolling 1993;Vanstone et al 2017;Adler & Gaitonde 2018, 2020, around sharp fins (Schmisseur & Dolling 1994;Gaitonde et al 1999;Arora, Mears & Alvi 2019) and for swept impinging oblique SBLIs (Doehrmann et al 2018;Padmanabhan et al 2021). All the above studies of swept SBLIs agree about the importance of three-dimensional effects on low-frequency unsteadiness, with consensus on an increase of the typical frequencies with the sweep angle.…”

Section: Introductionmentioning

confidence: 99%

On low-frequency unsteadiness in swept shock wave–boundary layer interactions

et al. 2023

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We derive a scaling law for the characteristic frequencies of wall pressure fluctuations in swept shock wave/turbulent boundary layer interactions in the presence of cylindrical symmetry, based on analysis of a direct numerical simulations database. Direct numerical simulations in large domains show evidence of spanwise rippling of the separation line, with typical wavelength proportional to separation bubble size. Pressure disturbances around the separation line are shown to be convected at a phase speed proportional to the cross-flow velocity. This information is leveraged to derive a simple model for low-frequency unsteadiness, which extends previous two-dimensional models (Piponniau et al., J. Fluid Mech., vol. 629, 2009, pp. 87–108), and which correctly predicts growth of the typical frequency with the sweep angle. Inferences regarding the typical frequencies in more general swept shock wave/turbulent boundary layer interactions are also discussed.

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Unsteady Characteristics of a Swept-Shock/Boundary-Layer Interaction at Mach 2

Cited by 31 publications

References 29 publications

Dynamics of strong swept-shock/turbulent-boundary-layer interactions

Dynamics of strong swept-shock/turbulent-boundary-layer interactions

Influence of separation structure on the dynamics of shock/turbulent-boundary-layer interactions

On low-frequency unsteadiness in swept shock wave–boundary layer interactions

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