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  • 1
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    Transition on swept leading edges at Mach 3.5 (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 24; 710-717
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Boundary-layer transition on a cone and flat plate at Mach 3.5 (1989)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 27; 687-693
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Effects of cone surface waviness and freestream noise on transition in supersonic flow (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A comparison of transition on wavy-wall and smooth-wall cones in a Mach 3.5 wind tunnel is made under conditions of either low freestream noise (quiet flow) or high freestream noise (noisy flow). The noisy flow compares to that found in conventional wind tunnels while the quiet flow gives transitional Reynolds numbers on smooth sharp cones comparable to those found in flight. The waves were found to have a much smaller effect on transition than similar sized trip wires. A satisfatory correlating parameter for the effect of waves on transition was simply the wave height-to-length ratio. A given value of this ratio was found to cause the same percentage change in transition location in quiet and noisy flows.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 86-1086
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Effects of wind-tunnel noise on swept-cylinder transition at Mach 3.5 (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Transition data are reported for circular cylinders at swept angles of 45 and 60 degrees in the Mach 3.5 pilot-low-disturbance tunnel where free-stream noise levels are varied from approximately .05-0.5 percent in terms of the rms fluctuating pressure normalized by the mean static pressure. Results indicate that end plate or boundary layer trip disturbances at the upstream end of the cylinders cause turbulent flow along the entire test Reynolds number range of 10-170 thousand per inch. With all end plate and trip disturbances removed, transition at the attachment lines occurred at free-stream Reynolds numbers based on diameters of about 70-80 thousand, independent of stream noise levels. The installation of small trips on the attachement lines caused transition at lower Reynolds numbers, depending on both the roughness height and the wind tunnel noise level.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 86-1085
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    Effects of nozzle design parameters on the extent of quiet test flow at Mach 3.5 (1984)
    In:  Other Sources
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    Publication Date: 2018-12-01
    Description: Tests results at the NASA Langley Research Center, involving a Mach 3.5 pilot quiet tunnel, have shown that laminar-layered nozzle walls improve boundary layer stability and reduce stream disturbance levels caused by eddy Mach wave radiation. This type of wall design is required to obtain transition Reynolds numbers on tests models as high as those previously observed in supersonic flight vehicles. The Mach 3.5 pilot nozzle wall boundary layers were tested for Tollmein-Schlichting and Goertler linear amplification, and, in an analysis of Goertler vortices in two axisymmetric Mach 5 nozzles, transition values were found to vary. These values were applied to several nozzles with similar throat heights but different expansion rates. Among the nozzles included in the study, a flat-wall radial flow nozzle and a proposed rod-wall nozzle were tested. For the highest test unit Reynolds number, it was determined that the nozzle wall surface finish should not exceed 0.3 micron. Oil flow studies have indicated that Goertler vortex disturbances were the dominant mechanism causing transition on the walls of the pilot nozzle.
    Keywords: AERODYNAMICS
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    NASA TECHNICAL REPORTS
  • 6
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    Comparison of boundary-layer transition on a cone and flat plate at Mach 3.5 (1988)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: NASA-Langley's Pilot Low-Disturbance Tunnel has been used to obtain boundary layer transition data on a cone and flat plate at Mach 3.5. The transition Reynolds numbers measured under these low noise conditions are higher than those in conventional noisy tunnels by a factor of 3 in the case of the cone and of seven in that of the flat plate. Transition predictions based on compressible linear stability theory and the e exp N method, for N=10, are in excellent agreement with the measured locations with transition onset for both the cone and flat plate under these low noise conditions.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 88-0411
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    NASA TECHNICAL REPORTS
  • 7
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    Effects of streamwise variations in noise levels and spectra on supersonic boundary-layer transition (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Transition data for sharp cones in two quiet wind tunnels at Mach numbers 3.5 and 5.0 have been correlated in terms of noise parameters with data from several conventional wind tunnels and from the flight data for the AEDC transition cone. The noise parameters were developed to account for the large axial variations of the rms stream noise and the high frequency noise spectra that occurred in the quiet tunnels for some test conditions. The correlation results indicated transition in the quiet tunnels was dominated by the local stream noise that was incident on the cone boundary layer upstream of the neutral stability point. The correlation results also suggested that the energy in high frequency components of the quiet tunnel noise spectra had significant adverse effects on transition when the noise was incident on the boundary layer both upstream and downstream of the neutral stability point.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 84-0010
    Format: text
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    NASA TECHNICAL REPORTS
  • 8
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    Instabilities and transition in the wall boundary layers of low-disturbance supersonic nozzles (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Linear stability analysis and experimental nozzles were employed in studying means to control Tollmein-Schlichting (TS) waves and Taylor-Goertler (TG) vortices at transition points along walls in a supersonic wind tunnel. It was hoped that control of the TS waves and TG vortices would cause the wall flows to remain laminar, thereby reducing the turbulence noise in the tunnel. The test nozzles injecting the waves and vertices had Mach numbers from 3 to 5. TG vortices triggered transition, while axisymmetric nozzle flows suppressed it. TS waves were controllable with favorable pressure graients at Mach 3.5. Finally, advances were made in the capability of predicting the locations of the transition points.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 85-1573
    Format: text
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    NASA TECHNICAL REPORTS
  • 9
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    Transition research in low-disturbance high-speed wind tunnels (1990)
    In:  Other Sources
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    Publication Date: 2019-07-27
    Description: The technical requirements and test data from the Mach 3.5 Pilot Low-Disturbance Tunnel are presented. This unique facility provides a test region with essentially zero-acoustic noise and simulates, for the first time, the low-disturbance conditions of atmospheric flight. Applications to the test results of linear stability theory with the e exp N method indicate that transition locations for both simple and complex flows are well predicted by using N of about 9 to 11.
    Keywords: AERODYNAMICS
    Type: IUTAM Symposium on Laminar-Turbulent Transition; Sept. 11-15, 1989; Toulouse; France
    Format: text
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    NASA TECHNICAL REPORTS
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