Influence of the entropy layer on the stability of a supersonic shock layer and transition of the laminar boundary layer to turbulence

Lysenko, V. I.

doi:10.1007/bf00854199

Cited by 14 publications

(8 citation statements)

References 13 publications

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“…[21][22][23] A similar transition reversal due to bluntness was shown by Lysenko to occur on flat plates. 24 Numerical studies have also investigated entropy-layer instabilities and their role in transition reversal 25 . 26 A study by Reshotko and Khan predicted separate instabilities in the boundary layer and the entropy layer.…”

Section: A Introductionmentioning

confidence: 99%

“…He also tried to measure the pressure fluctuations using surface pressure transducers but was unsuccessful due to the low signal levels. 24 Previous experimental measurements were made in the BAM6QT with a 30-degree cone-ogive-cylinder model using Kulite pressure transducers on the surface and in a pitot configuration off the surface. The data from these preliminary measurements showed evidence of an entropy-layer instability outside the predicted boundary layer that appears to approach the model as it proceeds axially.…”

Section: A Introductionmentioning

confidence: 99%

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Transition and Instability Measurements in a Mach 6 Quiet Wind Tunnel

Henderson

Chynoweth

Abney

et al. 2014

52nd Aerospace Sciences Meeting

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This paper details five different projects in the Boeing/AFOSR Mach 6 Quiet Tunnel (BAM6QT) at Purdue University. In the first project, a highly swept fin on a 7 • half-angle cone was examined. Temperature sensitive paint and pressure fluctuation measurements showed the presence of an instability near 200 kHz. In the second, the effect of roughness on the stationary and travelling crossflow instabilities was investigated on a cone at an angle of attack. It was found that when the roughness generated larger stationary waves, the travelling waves were damped. In the third, discrete roughness elements made of epoxy were applied to a flared cone. The roughness elements were sized to interact with the second-mode waves without becoming a trip. Using this technique, the spacing of streaks of increased heating was controlled. The fourth project involves improving the current pulsed jet perturber used to study nozzle-wall boundary-layer perturbations. Two improvements have been designed and have undergone preliminary testing. Finally, a new model was designed to measure what appears to be an entropy-layer instability at Mach 6. Surface pressure measurements and hot-wire data are used to investigate the entropy layer.

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Section: A Introductionmentioning

confidence: 99%

Section: A Introductionmentioning

confidence: 99%

Transition and Instability Measurements in a Mach 6 Quiet Wind Tunnel

Henderson

Chynoweth

Abney

et al. 2014

52nd Aerospace Sciences Meeting

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“…The detached curved bow shock upstream of a blunt body at supersonic speeds induces an entropy layer that is swallowed downstream by the growing boundary layer. Experiments with different shapes of blunt bodies [I, 2,3,4,5] have shown that the final point of laminar/turbulent boundary-layer transition is displaced downstream with increasing nose radius up to a certain critical value; further increase of the radius leads to an upstream movement of the transition location. This so-called blunting transition reversal phenomenon is currently not fully understood.…”

Section: Introductionmentioning

confidence: 99%

“…In particular, the reduction of the local Reynolds number based on the boundary-layer edge quantities due to the entropy layer can explain the delay of the transition [6]. But the reason for the upstream movement is currently not fully understood, although it is assumed in the literature [7] that entropy-layer instabilities [5,7,8,9] may partially explain this phenomenon. Entropy-layer instabilities were first observed in experiments over blunt cones [I].…”

Section: Introductionmentioning

confidence: 99%

Entropy-Layer Instabilities in Plane Supersonic Flow

Dietz

Mählmann

Hein³

1999

Notes on Numerical Fluid Mechanics (NNFM)

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SummaryEntropy-layer instabilities in the supersonic flow over a blunt flat plate are investigated. Two types of entropy-layer instabilities are identified with the linear, local, parallel stability theory. The most amplified mode is a two-dimensional one. In order to validate the numerical findings experiments were carried out: The computed steady, laminar mean-flow data agree with experimentally obtained mass-flow and Pitot-pressure distributions. The wall-normal distribution of the mass-flow eigenfunction of the most amplified entropy-layer instability is found in hot-wire data. The streamwise wave number and the wall-normal phase distribution of the numerically obtained density eigenfunctions agree with a Schlieren picture.

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“…This approach simplifies the upper boundary conditions and allows one to focus on the flow stability due to the viscous boundary layer. However, for supersonic flows over bodies with blunt leading edges, where the inviscid entropy layer between the boundary layer and the shock wave has a significant impact on the global stability behaviour of the flow [1], the free-stream conditions should be replaced by appropriate shock conditions.…”

Section: Introductionmentioning

confidence: 99%

Stability analysis of supersonic entropy layers including shock effects

Mählmann

2002

Proc. Appl. Math. Mech.

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The prediction of the laminar/turbulent transition location in supersonic boundary layers plays an important role to accurately compute aerodynamic forces and heating rates for the aerodynamic design and control of hypersonic vehicles. The stability characteristics of supersonic boundary layers depend e.g. on nose bluntness, transverse curvature, wall temperature, shock waves, etc. Most parameters can be theoretically investigated by performing conventional stability calculations with vanishing or asymptotic perturbation conditions at the far field. In this approach the formation of a shock in front of the leading edge of a blunt body is ignored. However, to improve the understanding of the interaction between instability waves originating inside supersonic boundary layer with those coming from the inviscid entropy layer, the presence of the shock has to be taken into account.This paper presents a method, how shock effects can be physically consistently included in stability calculations. The outer free-stream boundary conditions are replaced by appropriate shock conditions. The required perturbation equations can be derived from the linearized unsteady Rankine-Hugoniot equations, accounting for the effect of shock oscillations due to perturbated waves which originate from the flow field windward of the shock.

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Influence of the entropy layer on the stability of a supersonic shock layer and transition of the laminar boundary layer to turbulence

Cited by 14 publications

References 13 publications

Transition and Instability Measurements in a Mach 6 Quiet Wind Tunnel

Transition and Instability Measurements in a Mach 6 Quiet Wind Tunnel

Entropy-Layer Instabilities in Plane Supersonic Flow

Stability analysis of supersonic entropy layers including shock effects

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