Turbulent hypersonic flow at a wedge-compression corner

Elfstrom, Gary

doi:10.1017/s0022112072000060

Cited by 114 publications

(62 citation statements)

References 3 publications

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“…L sep has also been shown without exception, both experimentally and computationally, to increase with decreasing M 1 . 4,6,8,11,12,18,[21][22][23][24] For purely laminar interactions, L sep increases with increasing Re x 1 . 11,19,21,22,[25][26][27] Experiments with transitional interactions all show L sep decreasing with increasing Re x 1 , due to upstream movement of transition in the shear layer.…”

Section: Perfect-gas Flowsmentioning

confidence: 99%

“…For purely laminar or turbulent interactions, L sep has been shown to increase with increasing T w /T 1 , 4,5,12,19,23,26,[30][31][32][33] the effect being much stronger for laminar interactions. There are conflicting results for transitional flows; experiments by Johnson 25 showed L sep increasing with T w /T 1 , while experiments by Coët and Chanetz 31 show the opposite trend.…”

Section: Perfect-gas Flowsmentioning

confidence: 99%

“…For shear-layer transition, the Reynolds number of importance is based on distance from the origin of the shear layer, denoted here as Re L sep and evaluated for the present experiments using L sep measurements and inviscid triple-wedge computational results in region 2. Transition is shown to occur for a number of shots in the range 2ϫ10 4 ϽRe L sep Ͻ2ϫ10 5 , corresponding to 2ϽM 2 Ͻ5. Compilations of data by Birch and Keyes 126 and by King et al 125 both indicate transition Reynolds number on the order of 10 5 but varying by at least a factor of 4 over this range in Mach number.…”

Section: B Reynolds-number Effectsmentioning

confidence: 99%

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

Davis

Sturtevant

2000

Physics of Fluids

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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.

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Section: Perfect-gas Flowsmentioning

confidence: 99%

Section: Perfect-gas Flowsmentioning

confidence: 99%

Section: B Reynolds-number Effectsmentioning

confidence: 99%

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

Davis

Sturtevant

2000

Physics of Fluids

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“…Assuming that the oil-dot result for the 20 flare case is true, the experimental value of incipient separation is approximately 18 , and the computational value of incipient separation is approximately 13 . This contradicts the findings of Kuehn,8) Coleman 14,16) and Elfstrom 15) who found higher incipient separation angles. This is because the determination of incipient separation is very sensitive to the detection method employed.…”

Section: Turbulent Boundary Layer Studiesmentioning

confidence: 58%

“…This is one of the most significant differences between laminar and turbulent flow. Various researchers 1,8,[14][15][16] have found that very high incipient separation angles (¼ $ 30 ) are possible in hypersonic flow under turbulent conditions. A collection of incipient separation data is shown in Fig.…”

Section: Turbulent Interactionsmentioning

confidence: 99%

Flare-Control Effectiveness at Hypersonic Speeds

Kontis

2004

Trans. Japan Soc. Aero. S Sci.

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The effects of flare control on the aerodynamic characteristics, performance, and stability of a cylindrical body under laminar and turbulent boundary layer conditions have been studied experimentally and computationally. The experimental study has been carried out in a hypersonic gun tunnel at a Mach number of 8.2 and a Reynolds number of 158,100, based on the cylinder diameter, at flare angles 0, 5, 10, 15, 20, 25 and 30 degrees and at pitch angles of À12 to 12 deg for the 10 deg flare case only. The surface flow was studied using the oil-dot technique. Some information regarding the shock layer was obtained from schlieren pictures. The effects of turbulence on onset of separation were also deduced from pressure measurements over the cylinder and the flare. The forces were measured with a three-component balance equipped with semiconductor strain gauges. The effects of centre of gravity (CG) location on the aerodynamic characteristics and in particular on the C M were examined. The results under turbulent conditions and zero-incidence were compared with numerical simulations performed using a 3-D time-marching Navier-Stokes code. The magnitude of the separated region, the minimum flare angle required to induce separation, and the effects of small-scale separation are detailed.

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External flows

Fernholz¹

1976

Topics in Applied Physics

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Turbulent hypersonic flow at a wedge-compression corner

Abstract: A hypersonic gun tunnel has been used to investigate turbulent shock-boundary-layer interaction at a wedge-compression corner. The results extent the Mach number range of existing data, in particular of incipient separation.

Cited by 114 publications

References 3 publications

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

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

Flare-Control Effectiveness at Hypersonic Speeds

External flows

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