Aerothermodynamics and Transition in High-Speed Wind Tunnels at NASA Langley

Beckwith, I. E.; Miller, Charles G.

doi:10.1146/annurev.fl.22.010190.002223

Cited by 114 publications

(73 citation statements)

References 18 publications

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13] The elevated freestream disturbance levels in conventional (i.e., noisy) high-speed wind tunnels usually result in an earlier onset of transition relative to that in a flight environment or in a quiet tunnel. Yet, the conventional facilities continue to be used for transition sensitive measurements because of the size and Reynolds number limitations of existing quiet facilities and the prohibitive cost of flight tests.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of Pressure Fluctuations due to a Mach 6 Turbulent Boundary Layer

Duan

Choudhari

2013

51st AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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Direct numerical simulations (DNS) are used to examine the pressure fluctuations generated by a Mach 6 turbulent boundary layer with nominal freestream Mach number of 6 and Reynolds number of Reτ ≈ 464. The emphasis is on comparing the primarily vortical pressure signal at the wall with the acoustic freestream signal under higher Mach number conditions. Moreover, the Mach-number dependence of pressure signals is demonstrated by comparing the current results with those of a supersonic boundary layer at Mach 2.5 and Reτ ≈ 510. It is found that the freestream pressure intensity exhibits a strong Mach number dependence, irrespective of whether it is normalized by the mean wall shear stress or by the mean pressure, with the normalized fluctuation amplitude being significantly larger for the Mach 6 case. Spectral analysis shows that both the wall and freestream pressure fluctuations of the Mach 6 boundary layer have enhanced energy content at high frequencies, with the peak of the premultiplied frequency spectrum of freestream pressure fluctuations being at a frequency of ωδ/U∞ ≈ 3.1, which is more than twice the corresponding frequency in the Mach 2.5 case. The space-time correlations indicate that the pressure-carrying eddies for the higher Mach number case are of smaller size, less elongated in the spanwise direction, and convect with higher convection speeds relative to the Mach 2.5 case. The demonstrated Mach-number dependence of the pressure field, including radiation intensity, directionality, and convection speed, is consistent with the trend exhibited in experimental data and can be qualitatively explained by the notion of 'eddy Mach wave' radiation. NomenclatureC p heat capacity at constant pressure, J/(K·kg) C pp Space-time correlation coefficient of the pressure field, dimensionless C v heat capacity at constant volume, J/(K·kg)

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Section: Introductionmentioning

confidence: 99%

Numerical Study of Pressure Fluctuations due to a Mach 6 Turbulent Boundary Layer

Duan

Choudhari

2013

51st AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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“…Another drawback to transition correlations is that many are based on isolated roughness data collected in conventional ground-test facilities, where the freestream noise levels are an order of magnitude higher than those observed in flight. 6 Recent measurements in a Mach 6 quiet tunnel indicate that freestream noise has a significant impact on roughness induced boundary-layer transition. [7][8][9] Most significantly, transition correlations do not provide any physical insight to the instability mechanisms that play a role in roughness induced boundary-layer transition.…”

Section: Introductionmentioning

confidence: 99%

High-Speed Boundary-Layer Transition Induced by an Isolated Roughness Element

Kegerise

Owens

King

2010

40th Fluid Dynamics Conference and Exhibit

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Progress on an experimental effort to quantify the instability mechanisms associated with roughness-induced transition in a high-speed boundary layer is reported in this paper. To simulate the low-disturbance environment encountered during high-altitude flight, the experimental study was performed in the NASA-Langley Mach 3.5 Supersonic LowDisturbance Tunnel. A flat plate trip sizing study was performed first to identify the roughness height required to force transition. That study, which included transition onset measurements under both quiet and noisy freestream conditions, confirmed the sensitivity of roughness-induced transition to freestream disturbance levels. Surveys of the laminar boundary layer on a 7• half-angle sharp-tipped cone were performed via hot-wire anemometry and pitot-pressure measurements. The measured mean mass-flux and Mach-number profiles agreed very well with computed mean-flow profiles. Finally, surveys of the boundary layer developing downstream of an isolated roughness element on the cone were performed. The measurements revealed an instability in the far wake of the roughness element that grows exponentially and has peak frequencies in the 150 to 250 kHz range.

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“…Unfortunately, most of the ground-test data are ambiguous, due to operation in high-noise conventional wind tunnels and shock tunnels, with disturbance levels much higher than in flight [20]. The mechanisms of transition operational in smalldisturbance environments can be changed or bypassed altogether in high-noise environments [21].…”

Section: Sponsoring/monitoring Agency Name(s) and Address(es) 10 Spomentioning

confidence: 99%

Hypersonic laminar instability on round cones near zero angle of attack

Schneider

2001

39th Aerospace Sciences Meeting and Exhibit

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Reliable predictions for hypersonic laminarturbulent transition will have to be based on simulation of the transition mechanisms. Accurate simulation of the second-mode instability-wave growth on a round cone at zero angle of attack would be a significant step toward this goal. Hypersonic stability experiments in this geometry are reviewed, and three are selected. Extensive and previously unpublished data from Stetson's sharp and blunt cone experiments are reported. Approximate computations were carried out using inviscid-boundary-layer and e N methods. The experimental results are compared to previous high-accuracy computations and to the present approximate computations. Quantitative agreement is at present insufficient for reliable e N predictions. The difficulties with both experiment and computation are described.

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Aerothermodynamics and Transition in High-Speed Wind Tunnels at NASA Langley

Cited by 114 publications

References 18 publications

Numerical Study of Pressure Fluctuations due to a Mach 6 Turbulent Boundary Layer

Numerical Study of Pressure Fluctuations due to a Mach 6 Turbulent Boundary Layer

High-Speed Boundary-Layer Transition Induced by an Isolated Roughness Element

Hypersonic laminar instability on round cones near zero angle of attack

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