Global instability of the interaction between an oblique shock and a laminar boundary layer

Song, Ziming; Hao, Jiaao

doi:10.1063/5.0160648

Cited by 6 publications

(1 citation statement)

References 44 publications

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“…Laminar-turbulent transition has attracted increased attention in designing supersonic aircraft as it significantly influences the friction drag and heat transfer. [1][2][3][4][5] Thus, understanding the physical mechanisms of transition is essential in fluid dynamics. In actual flight environments, the natural transition is a common path to turbulence.…”

Section: Introductionmentioning

confidence: 99%

Direct numerical simulation of mechanism and control of secondary instability induced transition in a supersonic boundary layer

Liu,

Huang,

Liu

2024

Physics of Fluids

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Mechanisms and control of secondary-instability-induced-transition in a supersonic boundary layer are studied numerically via direct numerical simulation. The aim is to investigate and compare the transition mechanisms of fundamental, subharmonic, asymmetric subharmonic, and detuned resonances, and to control these secondary instabilities using a local wall cooling strip. The results indicate that the nonlinear interaction between the high-amplitude primary mode and low-amplitude secondary modes is the main contributor to transition. The mutual- and self-interactions of the primary and secondary modes generate other harmonic modes with laminar breakdown soon appearing. The asymmetric subharmonic resonance induces the earliest transition, while the fundamental subharmonic has the latest. Wall cooling effects are also studied. The results show that a lower wall temperature significantly suppresses the secondary instabilities, and steady modes become dominant and lead to obvious streamwise vortexes. Numerical data demonstrate that all secondary-instability-induced transitions result in fully developed turbulent boundary layers, as supported by the skin friction and scaled velocity profiles. The transition control cases indicate that the local wall cooling strip can significantly delay the transition by suppressing the growth of the primary mode. An upstream control strip is found to have a more obvious suppression effect. The fundamental and asymmetric subharmonic resonances are sensitive to the location of the local wall cooling strip and show a stronger transition delaying effect.

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Section: Introductionmentioning

confidence: 99%

Direct numerical simulation of mechanism and control of secondary instability induced transition in a supersonic boundary layer

Liu,

Huang,

Liu

2024

Physics of Fluids

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Experimental study on the heat flux of transitional shock wave–boundary layer interaction at Mach 6

Jiao,

Ma,

Xue

et al. 2024

Acta Astronautica

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Bi-global stability of supersonic backward-facing step flow

Yu,

Hao,

Wen

et al. 2024

J. Fluid Mech.

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Supersonic backward-facing step (BFS) flow is numerically studied using direct numerical simulation (DNS) and global stability analysis (GSA) with a free stream Mach number of 2.16 and a Reynolds number of 7.938 × 105 based on the flat-plate length L and free stream conditions. Two-dimensional BFS flow becomes unstable to three-dimensional perturbations as the step height h exceeds a certain value, while no two-dimensionally unstable mode is found. Global instability occurs with the fragmentation of the primary separation vortex downstream of the step. Two stationary modes and one oscillatory unstable mode are obtained at a supercritical ratio of L/h = 32.14, among which the two stationary modes originate from the coalescence of a pair of conjugate modes. The most unstable mode manifests itself as streamwise streaks in the reattached boundary layer, which is similar to that in shock-induced separated flow, although the flow separation mechanisms are different. Without introducing any external disturbances, the DNS captures the preferred perturbations and produces a growth rate in agreement with the GSA prediction in the linear growth stage. In the quasi-steady stage, the secondary separation vortex breaks up into several small bubbles, and the number of streamwise streaks is doubled. A low-frequency unsteadiness that may be associated with the oscillatory mode is also present.

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Global instability of the interaction between an oblique shock and a laminar boundary layer

Cited by 6 publications

References 44 publications

Direct numerical simulation of mechanism and control of secondary instability induced transition in a supersonic boundary layer

Direct numerical simulation of mechanism and control of secondary instability induced transition in a supersonic boundary layer

Experimental study on the heat flux of transitional shock wave–boundary layer interaction at Mach 6

Bi-global stability of supersonic backward-facing step flow

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