The Effect of Controlled Three-Dimensional Roughness on Boundary-Layer Transition at Supersonic Speeds

Driest, E. R. Van; Mccauley, William D

doi:10.2514/8.8501

Cited by 43 publications

(13 citation statements)

References 2 publications

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“…The effect of the experimental parameters on the repeatability of these cases will be explained in this section. The effect of small changes in experimental conditions on transition is consistent with historical data showing that, for critical roughness, the transition location moves quickly forward for small changes in conditions [43,44].…”

Section: Repeatability Of Transition For Small Roughness Heightssupporting

confidence: 88%

“…These conditions include roughness shape, freestream Mach number, and wind-tunnel test geometry, all of which could affect Re k;crit . For example, Van Driest et al [43,44] calculate Re k using the boundary-layer edge conditions instead of the local conditions. Smith and Clutter [42] show observations of critical roughness at supersonic speeds, but for two-dimensional roughness, using conditions behind a normal shock to calculate Re k .…”

Section: B Effect Of Roughness Height On Rms Pressurementioning

confidence: 99%

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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: Repeatability Of Transition For Small Roughness Heightssupporting

confidence: 88%

Section: B Effect Of Roughness Height On Rms Pressurementioning

confidence: 99%

Hypersonic Boundary-Layer Instabilities due to Near-Critical Roughness

Wheaton

Schneider

2014

Journal of Spacecraft and Rockets

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“…The figure is redrawn from Fig. 12 in [11], and the Mach number at the boundary-layer edge was M e 1:9. Van Driest and McCauley measured transition due to an azimuthal row of spherical roughness elements, on a 5-deg half-angle sharp cone at zero angle of attack, in the 12-in.…”

Section: Typical Effects Of Roughnessmentioning

confidence: 99%

“…Van Driest and McCauley measured transition due to an azimuthal row of spherical roughness elements, on a 5-deg half-angle sharp cone at zero angle of attack, in the 12-in. (305-mm) supersonic wind tunnel at the Jet Propulsion Laboratory [11]. The freestream Mach number was varied from 1.97 to 3.84 by varying the flexibleplate nozzle.…”

Section: Typical Effects Of Roughnessmentioning

confidence: 99%

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Effects of Roughness on Hypersonic Boundary-Layer Transition

Schneider

2008

Journal of Spacecraft and Rockets

287

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The effect of roughness on hypersonic boundary-layer transition has been studied for three primary purposes: to trip a laminar layer to turbulence, to determine whether naturally occurring roughness is expected to cause early transition, and to determine the largest allowable roughness that will not affect the location of transition. Roughness is often divided into two classes: isolated roughness, in which each protuberance can be considered separately, and distributed roughness similar to sandpaper, in which the roughness elements are many and are not considered separately. The effects of roughness on hypersonic transition are reviewed, considering the physics of the process, known parametric effects, some of the common correlations, and a few case studies. The three or more modes by which roughness can affect transition are outlined. At hypersonic edge Mach nunbers, it requires very large roughness heights to affect transition. Various correlations are often used to estimate the effect of roughness; several of these are described, although none provide good agreement with all the data.

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