Boundary-Layer Stability and Transition

Reshotko, Eli

doi:10.1146/annurev.fl.08.010176.001523

Cited by 363 publications

(110 citation statements)

References 17 publications

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“…Not that it helps with the boundarv-layer transition prediction problems, but there is some small gratification in knowing that design uncertainties are Reshocko, 2 ' 3 Arnal, 4 and Morkovin and Reshotko 5 are also recommended reading.…”

Section: Wrd-tr-90--3057mentioning

confidence: 99%

Comments on Hypersonic Boundary-Layer Transition

Stetson¹

1990

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OTIC FLIGHT DYNAIMICS LABORATORY WRIGHT RESEARCH AND DEVELOPMENT CENTER AIR FORCE SYSPThS COW~hANDThis is a survey paper on the subject of hypersonic boundary-layer transition. Part 1 discusses boundary-layer stability theory, hypersonic boundary-layer stability experiments, and a comparison between theory and experiment. Part 2 contains comments on how many configuration and flow parameters influence transition. Part 3 discusses some additional general aspects of transition. Part 4 discusses problems of predicting transition and comments on three prediction methods. Part 5 contains some general guidelines for prediction methodology. Thus, much hvpersonic transition guidance must be speculated from subsonic and supersonic results and old hypersonic data must be retrieved and re-evaluated. E-1 S4AE AS RPTNot that it helps with the boundarv-layer transition prediction problems, but there is some small gratification in knowing that design uncertainties are been a considerable number of hypersonic transition experiments; however, these data generally provide only parametric trends (e.g. , the effects of nosetip bluntness on transition location). When the only information obtalned is the location of transition it is impossible to determine details of the boundary-layer disturbance mechanisms which caused the transition. In order to obtain fundamental information about hypersonic boundary-layer instability phenomena it is necessary to perform stability experiments which describe the disturbances in the laminar boundary layer prior to transition. It is unfor-tunate that such an important topic as hypersonic stability has received so little attention. -n understanding of hypersonic instability phenomena is __ortant for obtaining a better understanding of hypersonic transition and is esserclal for analytical prediction methods. The following discus.'ion will briefly discuss our current understanding of hypersonic boundary-layer instabilities. (I.b) STABILITY THEORYIt is now generally believed that the onset of boundary-layer turbulence is the result of instability waves in the laminar boundary layer; however, the direct relationship between instability and transition is unknown. Stability theory provides a means of understanding the characteristics of instability waves and, consequently, a better understanding of transition. Numerical solutions of the stability equations can provide important details of boundarylayer instability; such as, the identity of those disturbance frequencies which are stable and those which are unstable, the minimum critical ReynoldR number at which disturbances scart to grow, their growth rates, their return to a stable condition, the particular disturbance frequency which will cbtain the maximum distuibance amplitude, and the effect of various parameters (e.g., Mach number, pressure gradient, wall temperature, etc.) Stability theory can povIde much valuable information about boundary-layer disturbances, but it cannot predict transition. This Is an inportant point.There is no transition 3 t...

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Section: Wrd-tr-90--3057mentioning

confidence: 99%

Comments on Hypersonic Boundary-Layer Transition

Stetson¹

1990

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“…When the proceedings of transition deviate from this description, the breakdown mechanism is termed bypass transition (Morkovin 1969). This terminology is general, and encompasses a variety of scenarios where T-S waves are absent or play a less prominent role (Morkovin, Reshotko & Herbert 1994), for example due to surface roughness or free-stream vortical or acoustic forcing † Email address for correspondence: t.zaki@imperial.ac.uk (Reshotko 1976;Saric, Reed & Kerschen 2002). The term bypass has, however, often been used in reference to transition in boundary layers exposed to free-stream vortical disturbances.…”

Section: Introductionmentioning

confidence: 99%

Stability of zero-pressure-gradient boundary layer distorted by unsteady Klebanoff streaks

2011

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The secondary instability of a zero-pressure-gradient boundary layer, distorted by unsteady Klebanoff streaks, is investigated. The base profiles for the analysis are computed using direct numerical simulation (DNS) of the boundary-layer response to forcing by individual free-stream modes, which are low frequency and dominated by streamwise vorticity. Therefore, the base profiles take into account the nonlinear development of the streaks and mean flow distortion, upstream of the location chosen for the stability analyses. The two most unstable modes were classified as an inner and an outer instability, with reference to the position of their respective critical layers inside the boundary layer. Their growth rates were reported for a range of frequencies and amplitudes of the base streaks. The inner mode has a connection to the TollmienSchlichting (T-S) wave in the limit of vanishing streak amplitude. It is stabilized by the mean flow distortion, but its growth rate is enhanced with increasing amplitude and frequency of the base streaks. The outer mode only exists in the presence of finite amplitude streaks. The analysis of the outer instability extends the results of Andersson et al. (J. Fluid Mech. vol. 428, 2001, p. 29) to unsteady base streaks. It is shown that base-flow unsteadiness promotes instability and, as a result, leads to a lower critical streak amplitude. The results of linear theory are complemented by DNS of the evolution of the inner and outer instabilities in a zero-pressure-gradient boundary layer. Both instabilities lead to breakdown to turbulence and, in the case of the inner mode, transition proceeds via the formation of wave packets with similar structure and wave speeds to those reported by Nagarajan, Lele & Ferziger (J. Fluid Mech., vol. 572, 2007, p. 471).

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“…half reaction length and post-shock values of density, pressure and sound speed. There are four dimensionless parameters that characterize the ZND flow summarized here: 2 : overdrive factor measuring the extent by which the detonation speed exceeds the minimally allowed Chapman-Jouguet velocityD CJ . -E = gĒ/c 2 i : activation energy scaled with the quiescent speed of sound squared.…”

Section: Governing Equationsmentioning

confidence: 99%

“…The normal-mode analysis was the pre-eminent feature of conventional hydrodynamic stability theory for a number of years before it was recognized that the receptivity problem is also an important element of the flow response [1,2]. The analysis requires the solution of partial differential equations (PDEs), and a possible formulation is the initial-value problem (IVP) where one specifies the initial profile of the perturbation flow.…”

Section: Introductionmentioning

confidence: 99%

Stability of detonation in a circular pipe with porous walls

Chiquete

Tumin

2012

Phil. Trans. R. Soc. A.

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A stability analysis is carried out taking into account slightly porous walls in an idealized detonation confined to a circular pipe. The analysis is carried out using the normalmode approach and corrections are obtained to the underlying impenetrable wall case results to account for the effect of the slight porosity. The porous walls are modelled by an acoustic boundary condition for the perturbations linking the normal velocity and the pressure components and thus replacing the conventional no-penetration boundary condition at the wall. This new boundary condition necessarily complicates the derivation of the stability problem with respect to the impenetrable wall case. However, exploiting the expressly slight porosity, the modified temporal stability can be determined as a two-point boundary value problem similar to the case of a non-porous wall.

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Boundary-Layer Stability and Transition

Cited by 363 publications

References 17 publications

Comments on Hypersonic Boundary-Layer Transition

Comments on Hypersonic Boundary-Layer Transition

Stability of zero-pressure-gradient boundary layer distorted by unsteady Klebanoff streaks

Stability of detonation in a circular pipe with porous walls

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