Flow behind the boundary layer separation point in a supersonic stream

Neiland, V. Ya.

doi:10.1007/bf01013988

Cited by 14 publications

(8 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A five-deck asymptotic structure describing flow downstream of separation was later introduced by Stewartson and Williams 107 and independently by Neiland. 108 For large scaled distance x downstream of separation, a form was found for the flow near * that asymptotically matches the flow near separation; the leading-order term in the series for scaled velocity is…”

Section: Application Of Asymptotic Theorymentioning

confidence: 99%

Separation length in high-enthalpy shock/boundary-layer interaction

Davis

Sturtevant

2000

Physics of Fluids

View full text Add to dashboard Cite

Experiments were performed in the T5 Hypervelocity Shock Tunnel to investigate nonequilibrium real-gas effects on separation length using a double-wedge geometry and nitrogen test gas. Local external flow conditions were estimated by computing the inviscid nonequilibrium flow field. A new scaling parameter was developed to approximately account for wall temperature effects on separation length for a laminar nonreacting boundary layer and arbitrary viscosity law. A classification was introduced to divide mechanisms for real-gas effects into those acting internal and external to viscous regions of the flow. Internal mechanisms were further subdivided into those arising upstream and downstream of separation. Analysis based on the ideal dissociating gas model and a scaling law for separation length of a nonreacting boundary layer showed that external mechanisms due to dissociation may decrease separation length at low incidence but depend on the free-stream dissociation at high incidence. A limited numerical study of reacting boundary layers showed that internal mechanisms due to recombination occurring in the boundary layer upstream of separation cause a slight decrease in separation length relative to a nonreacting boundary layer with the same external conditions. Correlations were obtained of experimentally measured separation length using local external flow parameters computed for reacting flow, which scales out external mechanisms but not internal mechanisms. These showed the importance of the new scaling parameter in high-enthalpy flows, a linear relationship between separation length and reattachment pressure ratio, and a Reynolds-number effect for transitional interactions. A significant increase in scaled separation length was observed in the experimental data at high enthalpy. The increase was attributed to an internal mechanism arising from recombination in the free-shear layer downstream of separation, perhaps altering its velocity profile. This real-gas effect depends on the combined presence of free-stream dissociation and a cold wall.

show abstract

Section: Application Of Asymptotic Theorymentioning

confidence: 99%

Separation length in high-enthalpy shock/boundary-layer interaction

Davis

Sturtevant

2000

Physics of Fluids

View full text Add to dashboard Cite

show abstract

“…Burggraf (1975) estimated the lengthscales for this case. His analysis is based on the asymptotic structure of the reverse-flow region presented by Neiland (1971) and Stewartson & Williams (1973). Brown & Williams (1975) extended the triple-deck analysis and included a higher-order term of the expansion.…”

Section: Introductionmentioning

confidence: 99%

On the lengthscales of laminar shock/boundary-layer interaction

Katzer

1989

J. Fluid Mech.

115

View full text Add to dashboard Cite

The interaction of an oblique shock with a laminar boundary layer on an adiabatic flat plate is analysed by solving the Navier-Stokes equations numerically. Mach numbers range from 1.4 to 3.4 and Reynolds numbers range from 105 to 6 × 105. The numerical results agree well with experiments. The pressure distribution at the edge of the boundary layer is proposed as a sensitive indicator of the numerical resolution. Local and global properties of the interaction region are discussed. In the vicinity of the separation point, local scaling laws of the free interaction are confirmed. For the length of the separation bubble a new similarity law reveals a linear influence of the shock strength. A comparison with the triple-deck theory shows that, for finite Reynolds numbers, the triple deck tends to overestimate the lengthscale substantially and that this discrepancy increases with increasing Mach number. The triple-deck model of displacing the main part of the boundary layer is substantiated by the numerical results. An asymmetrical structure within the separation bubble causes a characteristic distribution of the wall shear stress.

show abstract

“…However, the solutionF is unique when written in the formF (η −η S ), withF (−∞) = −ā . = − 1.2539 (Neiland 1971;Stewartson & Williams 1973;Diesperov 1984). Accordingly, forȲ = O(A), we expect backflow that is governed by the inviscid form of (5.3a).…”

Section: Lower Deck and Near-wall Flow Reversalmentioning

confidence: 99%

Break-away separation for high turbulence intensity and large Reynolds number

2011

View full text Add to dashboard Cite

Massive flow separation from the surface of a plane bluff obstacle in an incompressible uniform stream is addressed theoretically for large values of the global Reynolds numberRe. The analysis is motivated by a conclusion drawn from recent theoretical results which is corroborated by experimental findings but apparently contrasts with common reasoning: the attached boundary layer extending from the front stagnation point to the position of separation never attains a fully developed turbulent state, even for arbitrarily largeRe. Consequently, the boundary layer exhibits a certain level of turbulence intensity that is linked with the separation process, governed by local viscous–inviscid interaction. Eventually, the latter mechanism is expected to be associated with rapid change of the separating shear layer towards a fully developed turbulent one. A self-consistent flow description in the vicinity of separation is derived, where the present study includes the predominantly turbulent region. We establish a criterion that acts to select the position of separation. The basic analysis here, which appears physically feasible and rational, is carried out without needing to resort to a specific turbulence closure.

show abstract

Flow behind the boundary layer separation point in a supersonic stream

Cited by 14 publications

References 3 publications

Separation length in high-enthalpy shock/boundary-layer interaction

Separation length in high-enthalpy shock/boundary-layer interaction

On the lengthscales of laminar shock/boundary-layer interaction

Break-away separation for high turbulence intensity and large Reynolds number

Contact Info

Product

Resources

About