Hypersonic attachment-line instabilities with large sweep Mach numbers

Xi, Youcheng; Ren, Jie; Fu, Song

doi:10.1017/jfm.2021.66

Cited by 7 publications

(20 citation statements)

References 63 publications

(96 reference statements)

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“…Moreover, we found that the N-S mean flow solutions, which were used by Xi et al. (2021) in their stability analyses, do not agree with our N-S solutions and the compressible Hiemenz solution, which casts doubt on the correctness of the results reported.…”

Section: Introductioncontrasting

confidence: 80%

“…In addition to reconsidering the cases reported by Xi et al. (2021) and correcting their results, this paper suggests a theoretical model, which captures the attachment-line modes and allows us to determine regions of their dominance in the space. This model helps to perform quick parametric studies of the compressible attachment-line instability, shed light on the mechanisms of instability and extrapolate the knowledge gained on the supersonic boundary layer stability to the attachment-line flow.…”

Section: Introductionmentioning

confidence: 90%

“…Xi, Ren & Fu (2021) recently performed a numerical study of the attachment-line instability for the conditions relevant to the experiments of Gaillard et al. (1999).…”

Section: Introductionmentioning

confidence: 99%

“…However, Xi et al. (2021) did not show detailed point-by-point comparisons with the transition data. It is not clear under what conditions the Mack-like modes compete with the TS-like modes and become dominant.…”

Section: Introductionmentioning

confidence: 99%

“…To clarify this situation, we conduct a broadband parametric study, which is difficult to perform using the computationally expensive 2-D PDE approach of Xi et al. (2021). We put together and employed the following theoretical model: (1) the mean-flow parameters at the upper boundary-layer edge are calculated using the inviscid theory of Rechotko & Beckwith (1958); (2) the boundary-layer profiles are computed using the compressible Hiemenz solution (Pfenninger 1965, Gaster 1967); (3) the stability problem, which describes discrete modes propagating in the laminar attachment-line boundary layer, is solved using the theoretical model of Theofilis, Fedorov & Collis (2006), see also Semisynov et al.…”

Section: Introductionmentioning

confidence: 99%

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Instability of the attachment line boundary layer in a supersonic swept flow

Федоров

Егоров

2021

J. Fluid Mech.

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Theoretical analysis of attachment-line instabilities is performed for supersonic swept flows using the compressible Hiemenz approximation for the mean flow and the successive approximation procedures for disturbances. The theoretical model captures the dominant attachment-line modes in wide ranges of the sweep Mach number ${M_e}$ and the wall temperature ratio. It is shown that these modes behave similar to the first and second Mack modes in the boundary layer flow. This similarity allows us to extrapolate the knowledge gained for Mack modes to the attachment-line instabilities. In particular, we find that at sufficiently large ${M_e}$ , the dominant attachment-line instability is associated with the synchronisation of slow and fast modes of acoustic nature. Point-by-point comparisons of the theoretical predictions with the experiments of Gaillard et al. (Exp. Fluids, vol. 26, 1999, pp. 169–176) demonstrate that at ${M_e} > 4$ , the theory captures a significant drop of the transition onset Reynolds number, which is below the contamination criterion of Poll $({R_\mathrm{\ast }} = 250)$ at ${M_e} > 6$ . This contradicts the generally accepted assumption that the attachment-line flow is stable for ${R_\mathrm{\ast }} \le 250$ . The theoretical critical Reynolds numbers lie well below the experimental transition-onset Reynolds numbers. Stability computations using the Navier–Stokes mean flow and accounting for the leading-edge curvature effect do not eliminate this discrepancy. Most likely, in the experiments of Gaillard et al., we face with an unknown effect that does not fit to the concept of transition arising from linear instability.

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Section: Introductioncontrasting

confidence: 80%

Section: Introductionmentioning

confidence: 90%

“…Xi, Ren & Fu (2021) recently performed a numerical study of the attachment-line instability for the conditions relevant to the experiments of Gaillard et al. (1999).…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Instability of the attachment line boundary layer in a supersonic swept flow

Федоров

Егоров

2021

J. Fluid Mech.

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Receptivity and stability of hypersonic leading-edge sweep flows around a blunt body

Ren

Wang

et al. 2021

J. Fluid Mech.

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Propagation of stationary and traveling waves in a leading-edge boundary layer of a swept wing

Yakeno

Obayashi

2021

Physics of Fluids

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The transition characteristics around the leading edge of a swept-back wing shape were numerically investigated. We conducted direct numerical simulations (DNSs) of a swept-wing shape with a high Reynolds number Re=Rec/cos Λ=5.85×106 based on the chord length with a sweep angle Λ=70°. In the study, a randomly distributed impulsive local body force was applied at the wall to encourage a transition. Through impulsive local forcing, two coherent waves formed in both an attachment line and a three-dimensional boundary layer: A stationary elongated streak structure in the external flow direction and a traveling wave in the sweep direction. These characteristics in the attachment line were slightly different from those in the three-dimensional boundary layer. We computed the nonmodal transient energy growth for the present leading-edge boundary layer and compared the coherent waves observed in the DNSs. The stationary and traveling modes in the DNSs are found to be in a transient growth group; these modes temporally grow to the maximum in the short target time (τ<0.02). One of our conclusions is that both waves occurring in the present attachment line are strongly related to the short-term transient energy growth phenomena of the nonorthogonality of the flow field. When the roughness forcing was gradually increased, the traveling wave was not generated, whereas the stationary wave was. This was considered because the present attachment-line boundary layer was receptive to a small disturbance and more likely to generate a stationary wave than a traveling wave.

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Hypersonic attachment-line instabilities with large sweep Mach numbers

Abstract: Abstract

Cited by 7 publications

References 63 publications

Instability of the attachment line boundary layer in a supersonic swept flow

Instability of the attachment line boundary layer in a supersonic swept flow

Receptivity and stability of hypersonic leading-edge sweep flows around a blunt body

Propagation of stationary and traveling waves in a leading-edge boundary layer of a swept wing

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