Boundary layer acoustic measurements in transitional and turbulent flow at M infinity equals 4.0

Johnson, Ronald E.; Macourek, Miloš; Saunders, H.

doi:10.2514/6.1969-344

Cited by 7 publications

(7 citation statements)

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“…The low-frequency pressure fluctuations measured by the Kulites peak during transition. [2][3][4][5][6] Transition onset location can also be defined using Kulite measurements.…”

Section: B Model and Instrumentationmentioning

confidence: 99%

“…[2][3][4][5][6] These high pressure fluctuations result from repeated intermittent spatial-temporal switching between laminar and turbulent regions, creating a broad spectrum of disturbances. Unfortunately in flight, natural transition typically occurs over a large portion of the vehicle, 7 making transitional fluctuations of primary interest for this work.…”

Section: Introductionmentioning

confidence: 99%

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High-Speed Schlieren Imaging of Disturbances in a Transitional Hypersonic Boundary Layer

Casper

Beresh

Henfling

et al. 2013

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

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A high-speed schlieren system was developed for the Sandia Hypersonic Wind Tunnel. Schlieren images were captured at 290 kHz and used to study the growth and breakdown of second-mode instabilities into turbulent spots on a 7 • cone. At Mach 5, wave packets would intermittently occur and break down into isolated turbulent spots surrounded by an otherwise smooth, laminar boundary layer. At Mach 8, the boundary layer was dominated by second-mode instabilities which would break down into larger regions of turbulence. Second-mode waves surrounded these turbulent patches as opposed to the smooth laminar flow seen at Mach 5.Detailed pressure and thermocouple measurements were also made along the cone at Mach 5, 8 and 14, in a separate tunnel entry. These measurements give an average picture of the transition behavior that complements the intermittent behavior captured by the schlieren system. At Mach 14, the boundary-layer remained laminar so the transition process could not be studied. However, the first measurements of second-mode waves were made in HWT-14. Nomenclatureδ boundary-layer thickness (mm) φ cone azimuthal angle ( • ) τ w nozzle wall shear stress (Pa) D model base diameter (m) M freestream Mach number M e Mach number at boundary-layer edge P 0 tunnel stagnation pressure (kPa) p root-mean-square pressure fluctuation (Pa) p pressure fluctuation, p − p e (Pa) p e boundary-layer edge pressure (Pa) q e dynamic pressure at boundary-layer edge (Pa) R cone radius (mm) Re freestream unit Reynolds number (1/m) Re D freestream Reynolds number based on model base diameter St Stanton number T 0 tunnel stagnation temperature (K) U c average convection velocity (m/s) U e boundary-layer edge velocity (m/s) x axial model coordinate measured from nose (m)

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“…The low-frequency pressure fluctuations measured by the Kulites peak during transition. [2][3][4][5][6] Transition onset location can also be defined using Kulite measurements.…”

Section: B Model and Instrumentationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High-Speed Schlieren Imaging of Disturbances in a Transitional Hypersonic Boundary Layer

Casper

Beresh

Henfling

et al. 2013

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

View full text Add to dashboard Cite

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“…The low-frequency pressure fluctuations measured by the Kulites peak near the end of transition. [23][24][25][26][27] The location of this peak can be compared to N factor computations from STABL, as well as transition location as measured by thermocouples.…”

Section: Model and Instrumentationmentioning

confidence: 99%

“…These low frequency fluctuations have been shown to peak during boundary layer transition. 18,[24][25][26][27]34 Figure 13a shows unnormalized RMS pressure fluctuations along the cone for increasing freestream unit Reynolds number. The lowest two cases show approximately constant pressure fluctuations along the cone, indicating laminar flow over the cone.…”

Section: Tunnel 9 Kulite Datamentioning

confidence: 99%

Measurements and Computations of Second-Mode Instability Waves in Several Hypersonic Wind Tunnels

Berridge

Casper

Rufer

et al. 2010

40th Fluid Dynamics Conference and Exhibit

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High-frequency pressure-fluctuation measurements were made in AEDC Tunnel 9 at Mach 10 and the NASA Langley 15-Inch Mach 6 and 31-Inch Mach 10 tunnels. Measurements were made on a 7 •-half-angle cone model. Pitot measurements of freestream pressure fluctuations were also made in Tunnel 9 and the Langley Mach-6 tunnel. For the first time, second-mode waves were measured in all of these tunnels, using 1-MHz-response pressure sensors. In Tunnel 9, second-mode waves could be seen in power spectra computed from records as short as 80 µs. The second-mode wave amplitudes were observed to saturate and then begin to decrease in the Langley tunnels, indicating wave breakdown. Breakdown was estimated to occur near N ≈ 5 in the Langley Mach-10 tunnel. The unit-Reynolds-number variations in the data from Tunnel 9 were too large to see the same processes. In Tunnel 9, the measured transition locations were found to be at N = 4.5 using thermocouples, and

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Section: American Institute Of Aeronautics and Astronauticsmentioning

confidence: 99%

Experimental Study of Second-Mode Instabilities on a 7-Degree Cone at Mach 6

Rufer

Berridge

2011

41st AIAA Fluid Dynamics Conference and Exhibit

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Boundary layer acoustic measurements in transitional and turbulent flow at M infinity equals 4.0

Cited by 7 publications

References 0 publications

High-Speed Schlieren Imaging of Disturbances in a Transitional Hypersonic Boundary Layer

High-Speed Schlieren Imaging of Disturbances in a Transitional Hypersonic Boundary Layer

Measurements and Computations of Second-Mode Instability Waves in Several Hypersonic Wind Tunnels

Experimental Study of Second-Mode Instabilities on a 7-Degree Cone at Mach 6

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