Shear-layer instability in the Mach reflection of shock waves

Rubidge, S.; Skews, B. W.

doi:10.1007/s00193-014-0515-6

Cited by 9 publications

(4 citation statements)

References 4 publications

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“…The interaction of the oblique shock with perturbed shear layer triggers the unstable growth of the contact surface ripple, which can be seen as a combination of Kelvin-Helmholtz and Richtmyer-Meshkov instabilities (Samtaney 1993;Mikaelian 1994;Rikanati 2006;Rubidge 2014). In this respect, the analysis of the perturbations growth behind the shock impingement cannot be uniquely determined by the free-stream Mach numbers M 2 − M 1 , as the upstream shear (U 2 − U 1 )/δ u and the density ρ 2 − ρ 1 would contribute differently.…”

Section: Induced Vorticity Downstreammentioning

confidence: 99%

“…Therefore, the analysis assumes that the shear layer evolution ahead of the shock impingement is negligible in first approximation. Certainly, this might not be true if the shock is sufficiently far from the streams' contact point, partly due to the Kelvin-Helmholz instability triggered by the velocity shear that may eventually turn the initially-laminar layer into a turbulent mixing layer (Rikanati 2006;Rubidge 2014). However, as the convective Mach number may also be created by more stable configurations, as those involving same-velocity different-temperature streams, the focus is placed here on the large structures that are only dominated by the incident shock angle and the stream Mach numbers.…”

Section: Introductionmentioning

confidence: 99%

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Irregular self-similar configurations of shock-wave impingement on shear layers

et al. 2019

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An oblique shock impinging on a shear layer that separates two uniform supersonic streams, of Mach numbers $M_{1}$ and $M_{2}$, at an incident angle $\unicode[STIX]{x1D70E}_{i}$ can produce regular and irregular interactions with the interface. The region of existence of regular shock refractions with stable flow structures is delineated in the parametric space $(M_{1},M_{2},\unicode[STIX]{x1D70E}_{i})$ considering oblique-shock impingement on a supersonic vortex sheet of infinitesimal thickness. It is found that under supercritical conditions, the oblique shock fails to deflect both streams consistently and to provide balanced flow properties downstream. In this circumstance, the flow renders irregular configurations which, in the absence of characteristic length scales, exhibit self-similar pseudosteady behaviours. These cases involve shocks moving upstream at constant speed and increasing their intensity to comply with equilibrium requirements. Differences in the variation of propagation speed among the flows yield pseudosteady configurations that grow linearly with time. Supercritical conditions are described theoretically and reproduced numerically using highly resolved inviscid simulation.

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Section: Induced Vorticity Downstreammentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Irregular self-similar configurations of shock-wave impingement on shear layers

et al. 2019

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“…The mechanical disquisitions over the equilibrium and dynamics of high-speed flows have long benefited from theoretical approximations of ideal flow [28,29] and small-perturbation methods [30,31]. In addition, further efforts to include real-flow effects have shed light on viscous processes in the related mechanics [32][33][34][35][36]24] as well as thermal and thermochemical non-equilibrium [37]. However, besides few studies on one-dimensional [38][39][40] and two dimensional waves [41], ideal-gas and calorically-perfect assumptions have been adopted in the vast majority of the analyses of compressible continuum-model fluids.…”

Section: Introductionmentioning

confidence: 99%

Specific heat effects in two-dimensional shock refractions

et al. 2021

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Compressible mixtures in supersonic flows are subject to significant temperature changes via shock-waves and expansions, which affect several properties of the flow. Besides the widely-studied variable transport effects such as temperature-dependent viscosity and conductivity, vibrational and rotational molecular energy storage is also modified through the variation of the heat capacity c p and heat capacity ratio γ, specially in hypersonic flows. Changes in the composition of the mixture may also modify its value through the species mass fraction Y α , thereby affecting the compression capacity of the flow. Canonical configurations are studied here to explore their sharply-conditioned mechanical equilibrium under variations of these thermal models. In particular, effects of c p (T, Y α ) and γ(T, Y α ) on the stability of shock-impinged supersonic shear and mixing layers is addressed, on condition that a shock wave is refracted. It is found that the limits defining regular structures are affected (usually broadened out) by the dependence of heat capacities with temperature. Theoretical and high-fidelity numerical simulations exhibit a good agreement in the prediction of regular shock reflections and their post-shock aerothermal properties.

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“…In all experiments, the jets burned through the metal body of the cone and the striker, indicating that one jet was directed towards the moving striker fi lling the cavity, and the other toward the top of the cone. Perhaps this eff ect is associated with irregular refl ection of the shock front from the surface of the conical notch [20,21]. The second eff ect is associated with an anomalously high value of the manganese concentration at the interface between the metal and the cavity formed by the action of the jets.…”

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confidence: 99%

Formation of converging cylindrical detonation front

Soboliev¹,

Skobenko²,

Usyk³

et al. 2021

Nauk. visn. nat. hirn. univ.

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Purpose. To develop a laser method for initiating a converging cylindrical front of a detonation wave and a method for calculating the kinematic parameters of the cylindrical shell walls, accelerated by the pressure of the detonation products of an external explosive charge. Methodology. An experimental technology for the manufacture of a photosensitive explosive composite and an experimental technique for igniting the surface of its layer with an extended laser beam without the use of a fiber-optic cable are used. The results of simulation modeling the Monte Carlo method were used to study the effect of illumination on the process of ignition of explosives by laser pulsed radiation. For the selected type of photosensitive explosive composite, its explosive and optical characteristics, the distance from the surface of the explosive charge to the lens scattering the laser beam, and taking into account the total area of the expanded beam, the regularities of the distribution of the radiation energy density over the vertical and horizontal sections of the laser beam were studied. Findings. The analysis of the scientific and technical level of methods of shock-wave processing of materials in the region of ultrahigh pressures from the point of view of the fundamental value of the cumulation of energy in the waves of a converging cylindrical detonation and shock front is carried out. Physicomathematical modeling was carried out and the regularities of pressure increase in the wave front were established in the process of approaching the shell walls to the axis. The scientific results of modeling converging cylindrical shells under the influence of the pressure of the explosion products have been analyzed. A method for laser initiation of a converging cylindrical front of a detonation wave has been developed, and a method for calculating the kinematic parameters of the converging walls of a cylindrical shell has been proposed. Originality. A technique has been developed for determining the energy characteristics of an expanded laser beam, calculating the laser radiation energy required to initiate detonation simultaneously on the entire lateral cylindrical surface of a photosensitive explosive composite. The idea of technical implementation of the cumulation of converging cylindrical detonation and shock waves was developed further. A technique has been developed for the numerical determination of the change in the internal average compression rate of the shell during the movement of its walls towards the axis for various ratios of its external radius to the wall thickness and taking into account the increase in pressure in the converging detonation front. Practical value. For the first time, a method for laser initiation of a converging cylindrical front of a detonation wave was developed and a device was tested that forms a converging cylindrical front of a detonation wave and a corresponding shock front in the material under study by the impact of a metal shell converging to the axis. The core of the device is a laser explosive initiation system that uses light-sensitive explosive composites to initiate an explosive charge.

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Shear-layer instability in the Mach reflection of shock waves

Cited by 9 publications

References 4 publications

Irregular self-similar configurations of shock-wave impingement on shear layers

Irregular self-similar configurations of shock-wave impingement on shear layers

Specific heat effects in two-dimensional shock refractions

Formation of converging cylindrical detonation front

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