Experimental Determination of the Aeroacoustic Environment about a Slender Cone

Martellucci, A.; Chaump, L.; Rogers, David A.; Smith, D. L.

doi:10.2514/3.50503

Cited by 32 publications

(19 citation statements)

References 10 publications

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“…The rms overshoots the smooth-wall turbulent value and then decreases farther downstream. This overshoot is typical because maximum rms pressures are often observed within transitional flow [41]. The peak in the rms moves forward with increasing k as expected.…”

Section: B Effect Of Roughness Height On Rms Pressuresupporting

confidence: 52%

“…Again, the initial increase in rms appears to be large. At some distance farther downstream, the rms "overshoots" the smooth-wall turbulent value during the transition process, as is typical [41]. After the overshoot, the rms then decreases to a value near that for a smoothwall turbulent boundary layer.…”

Section: Effect Of Incremental Changes In Roughness Reynolds Numbermentioning

confidence: 85%

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Hypersonic Boundary-Layer Instabilities due to Near-Critical Roughness

Wheaton

Schneider

2014

Journal of Spacecraft and Rockets

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Measurements of instability and transition were obtained in the wake of a cylindrical roughness within the laminar nozzle-wall boundary layer of the Purdue Mach-6 Quiet Tunnel. Using wall-mounted pressure transducers along the wake centerline, the root-mean-square pressure and power spectra were computed to find evidence of instabilities within the roughness wake. The roughness height was adjusted to explore the case of incipient transition on the nozzle wall. It appeared that small variations in the experimental parameters could have a large effect on transition for the near-critical case. Several dominant disturbance frequencies were identified for a selected set of conditions. These disturbances appear to be due to instabilities developing within the wake of the roughness. The streamwise evolution of these disturbances are reported, as well as the spanwise distribution at one streamwise location within the wake. The experimentally observed disturbances can be used as a test case to continue to develop methods for computing the stability of roughness wakes. Nomenclature D = cylindrical roughness diameter, mm k = cylindrical roughness height, mm p 0 = tunnel stagnation pressure, kPa p 0 = fluctuating component of pressure, kPa Re k = roughness Reynolds number, ρ k u k k∕μ k Re k;crit = critical roughness Reynolds number Re ∞ = unit freestream Reynolds number, 1∕m T driver = temperature from a thermocouple at the upstream end of the driver tube, K T nozzle = mean temperature recorded by the thermocouples on the nozzle, K T 0 = tunnel stagnation temperature, K t = time after the diaphragm burst, s x = streamwise distance downstream from the central axis of the roughness, mm z = spanwise arc length from the center of the roughness, mm δ = boundary-layer thickness, defined as the height where the local velocity is 99.5% of the freestream value Subscripts i = initial condition k = roughness height condition ∞ = freestream condition

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Section: B Effect Of Roughness Height On Rms Pressuresupporting

confidence: 52%

Section: Effect Of Incremental Changes In Roughness Reynolds Numbermentioning

confidence: 85%

Hypersonic Boundary-Layer Instabilities due to Near-Critical Roughness

Wheaton

Schneider

2014

Journal of Spacecraft and Rockets

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“…[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%

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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“…e = 10x!0 6 /ft. Martellucci et al 20 have shown that the fluctuating pressure spectra under transitional and turbulent boundary layers have the same shape, although the level of the turbulent spectra is significantly greater. If the lifted boundary layer over a region of separated flow is similarly affected by transition, this could indeed be indicative of transitional separation.…”

Section: Power Spectramentioning

confidence: 96%

Fluctuating Pressures on Mildly Indented Nosetips

Reding¹

1979

Journal of Spacecraft and Rockets

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Fluctuating pressure measurements at M=5.0 are presented for turned (axisymmetric) nose shapes that represent approximations of cross sections (at various meridians) of the recovered graphite nosetip of the Nosetip Recovery Vehicle (NRV). Selected fluctuating pressure measurements are also presented for a replica of the NRV nosetip and a replica of a wind-tunnel-ablated camphor nosetip that roughly resembles the NRV nosetip. The greatest fluctuating pressures occurred under imbedded shock waves and/or the reattachment shock waves of imbedded regions of separated flow. The nondimensionalized power spectra under the reattachment shocks are in good agreement with similar measurements for spiked cones and a drag-reduction spike. Evidence of a Reynolds number sensitive resonant peak was observed in the spectra under reattachment on the NRV nose due to surface irregularities. coef-,psi Nomenclature a = speed of sound, in. /s C p = pressure coefficient = (p-p 00 )/q Q>(rms) = root-mean-square fluctuating pressure ficient = Ap (rms) /0 D = nosetip reference diameter, in. / = frequency, Hz M = Mach number = U/a PSD = power spectral density, (psi) 2 /Hz p = local pressure, psi p w = freestream static pressure, psi p ( t) = time varying pressure, psi I -q = freestream dynamic pressure =pU 2 /2, psi R e = freestream Reynolds number, ft ~ J U = freestream velocity, in./s X -axial coordinate, in. a = angle of attack, deg d m = maximum separated flow height, in. p = freestream density, Ib sec 2 /in. 4

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Experimental Determination of the Aeroacoustic Environment about a Slender Cone

Cited by 32 publications

References 10 publications

Hypersonic Boundary-Layer Instabilities due to Near-Critical Roughness

Hypersonic Boundary-Layer Instabilities due to Near-Critical Roughness

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

Fluctuating Pressures on Mildly Indented Nosetips

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