Hypersonic boundary-layer separation on a cold wall

Kerimbekov, Ruslan M.; Ruban, Anatoly I.; Walker, James D.

doi:10.1017/s0022112094002089

Cited by 17 publications

(41 citation statements)

References 16 publications

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“…In addition, for stable flows, wall cooling was found to limit either the upstream or the downstream propagation of disturbances and thereby have a dramatic effect on both the location and size of the recirculation zone. Finally, the present numerical results were found to blend smoothly with those in regime 3 predicted by the analytic theory of Kerimbekov et al (1994) for strong wall cooling.…”

Section: Introductionsupporting

confidence: 73%

“…The third regime is characterized by very low wall temperatures where the displacement-thickness contribution due to the main deck is dominant. This situation has been considered recently by Kerimbekov et al (1994) for subcritical and supercritical boundary layers that encounter a compression ramp. For the limiting case of strong supercritical wall cooling, it was found that there are no disturbances upstream of the corner, and separation can only occur on the inclined portion of the ramp; furthermore, the boundary layer on the ramp exhibits marginal separation behaviour similar to that which is known to occur near the leading edge of thin airfoils at a critical angle of attack (Ruban 1981and Stewartson, Smith & Kaups 1982.…”

Section: Introductionmentioning

confidence: 98%

“…The thickness of the upstream wall layer (region a') is much greater than that of the viscous sublayer in the interaction region (region I), and this necessitates an intermediate layer (region I,) between the conventional viscous sublayer (region I) and the main deck (region 11). The intermediate layer is essentially a continuation of the upstream inner wall layer into the interaction region and communicates changes between the viscous sublayer and the main and upper decks; however, it does not contribute to leading order to the displacement effect of the boundary layer (Kerimbekov, Ruban & Walker 1994). The third and most significant effect of wall cooling consists of a reduction in both the longitudinal extent of the interaction region and the displacement thickness of the viscous sublayer; the former change may come into play even when the mainstream Mach number M , is finite.…”

Section: Introductionmentioning

confidence: 99%

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The influence of wall cooling on hypersonic boundary-layer separation and stability

1996

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The effect of wall cooling on hypersonic boundary-layer separation near a compression ramp is considered. Two cases are identified corresponding to the value of the average Mach number $\overline{M}$ across the upstream boundary layer approaching the compression ramp. The flow is referred to as supercritical for $\overline > 1$ and subcritical for $\overline{M} < 1$. The interaction is described by triple-deck theory, and numerical results are given for both cases for various ramp angles and levels of wall cooling. The effect of wall cooling on the absolute instability described recently by Cassel, Ruban & Walker (1995) for an uncooled wall is of particular interest; a stabilizing effect is observed for supercritical boundary layers, but a strong destabilizing influence occurs in the subcritical case. Wall cooling also influences the location and size of the separated region. For supercritical flow, progressive wall cooling reduces the size of the recirculating-flow region, the separation point moves downstream, and upstream influence is diminished. In contrast for the subcritical case downstream influence is reduced with increased cooling. In either situation, a sufficient level of wall cooling eliminates separation altogether for the ramp angles considered. The present numerical results closely confirm the strong wall cooling theory of Kerimbekov, Ruban & Walker (1994).

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Section: Introductionsupporting

confidence: 73%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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The influence of wall cooling on hypersonic boundary-layer separation and stability

1996

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“…The first, near the wall, is a rotational viscous subsonic region which is most sensitive to disturbances, the second is a main inviscid rotational region and the third is an inviscid irrotational outer region, which is most resistive to disturbances. Interaction between these decks (Stewartson 1974) has been shown to be dependent on wall temperature by a number of authors such as Brown, Cheng & Lee (1990), Seddougui, Bowles & Smith (1991), Kerimbekov, Ruban & Walker (1994), Cassel, Ruban & Walker (1995), Cassel, Ruban & Walker (1996), Neiland, Sokolov & Shvedchenko (2009) and Shvedchenko (2009).…”

Section: Introductionmentioning

confidence: 99%

Numerical study of bluntness effects on laminar leading edge separation in hypersonic flow

Khraibut¹,

Gai²,

Neely³

2019

J. Fluid Mech.

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Bluntness effects on laminar hypersonic leading edge separation are investigated numerically at Mach number $M\approx 10$, unit Reynolds number $Re=1.3\times 10^{6}~\text{m}^{-1}$, specific enthalpy $h_{o}=3.1~\text{MJ}~\text{kg}^{-1}$ and wall-to-stagnation temperature ratio $T_{w}/T_{o}=0.1$. Such effects are important from an experimental point of view and because bluntness can affect a separated flow favourably or adversely. In this study, two blunt leading edge cases of small radius ($15~\unicode[STIX]{x03BC}\text{m}$) and large radius ($100~\unicode[STIX]{x03BC}\text{m}$) are investigated. A comparison with the idealised sharp leading edge case is also given. General flow features and surface parameters such as the shear stress, pressure and heat flux are presented and analysed. The results have also been interpreted in terms of Cheng’s displacement-bluntness similitude parameter affecting the size of separation. Previous experiments by Holden delineated small and large bluntness effects based on Cheng’s parameter and considering small to moderate separated regions. In this study, leading edge separation was found to suppress the favourable effect of bluntness in delaying separation. Bluntness, furthermore, seemed to promote the appearance of secondary vortices within a main separated region. Analysis of reverse flow boundary layer profiles such as velocity, pressure and temperature is also given. It is shown that bluntness accentuates large transverse gradients. This in turn adversely effects the reverse flow boundary layer leading to the appearance of secondary vortices.

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“…The only circumstance when the assumption T w 1 is no longer valid arises when strong cooling is applied to the cone surface. Studies of the effects of severe cooling include those by Seddougui, Bowles & Smith (1991) for general compressible flows and investigations by Brown, Cheng & Lee (1990) and Kerimbekov, Ruban & Walker (1994) for hypersonic flows. Hereafter we shall suppose that T w = T b T r where T r is the adiabatic wall temperature given by…”

Section: Formulationmentioning

confidence: 99%

Instability of hypersonic flow over a cone

Seddougui

Bassom

1997

J. Fluid Mech.

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The linear stability analysis of hypersonic flow over a sharp slender cone with an attached shock is described. Attention is focused on the viscous modes of instability which may be described by a triple-deck structure. The situation in which both the effect of the shock and the influence of curvature are important is considered in the weak-interaction region. Both neutral and non-neutral solutions are presented for both axisymmetric and non-axisymmetric disturbances. The results obtained suggest that the effect of curvature on the stability of hypersonic flow is significant when the attached shock is taken into account.

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Hypersonic boundary-layer separation on a cold wall

Cited by 17 publications

References 16 publications

The influence of wall cooling on hypersonic boundary-layer separation and stability

The influence of wall cooling on hypersonic boundary-layer separation and stability

Numerical study of bluntness effects on laminar leading edge separation in hypersonic flow

Instability of hypersonic flow over a cone

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