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| Author | : Gary T. Chapman |
| Publisher | : |
| Total Pages | : 38 |
| Release | : 1961 |
| Genre | : Fluid mechanics |
| ISBN | : |
| Author | : Gary T. Chapman |
| Publisher | : |
| Total Pages | : 1 |
| Release | : 1961 |
| Genre | : |
| ISBN | : |
The effects of crossflow and shock strength on transition of the laminar boundary layer behind a swept leading edge have been investigated analytically and with the aid of available experimental data. An approximate method of determining the crossflow Reynolds number on a leading edge of circular cross section at supersonic speeds is presented. The applicability of the critical crossflow criterion described by Owen and Randall for transition on swept wings in subsonic flow was examined for the case of supersonic flow over swept circular cylinders. A wide range of applicability of the subsonic critical values is indicated. The corresponding magnitude of crossflow velocity necessary to cause instability on the surface of a swept wing at supersonic speeds was also calculated and found to be small. The effects of shock strength on transition caused by Tollmien-Schlichting type of instability are discussed briefly. Changes in local Reynolds number, due to shock strength, were found analytically to have considerably more effect on transition caused by Tollmien-Schlichting instability than on transition caused by crossflow instability. Changes in the mechanism controlling transition from Tollmien-Schlichting instability to crossflow instability were found to be possible as a wing is swept back and to result in large reductions in the length of laminar flow. (Author).
| Author | : Don W. Jillie |
| Publisher | : |
| Total Pages | : 36 |
| Release | : 1961 |
| Genre | : Fluid mechanics |
| ISBN | : |
| Author | : George M. Low |
| Publisher | : |
| Total Pages | : 35 |
| Release | : 1956 |
| Genre | : Boundary layer |
| ISBN | : |
The effects of leading-edge blunting on two-dimensional surfaces and surface cooling can be predicted adequately by existing theories, at least in the moderate Mach number range.
| Author | : William A. Cassels |
| Publisher | : |
| Total Pages | : 76 |
| Release | : 1970 |
| Genre | : Aerodynamics, Supersonic |
| ISBN | : |
Boundary-layer transition by the sublimation and impact-pressure techniques and force tests have been performed on three Haack-Adams bodies of revolution of fineness ratios 7, 10, and 13 at zero angle of attack for free-stream Mach numbers of 2.00, 2.75, and 4.63 and a range of Reynolds numbers based on model length of 6 to 15 X 10(to the 6 power) with and without a roughness strip. The grit method of inducing turbulence was found to provide for a nearly complete turbulent flow over the models at the lower Mach numbers and higher Reynolds numbers considered in this study while the amount of trip drag was less than 8 percent of the model drag with transition fixed. A method of interpreting sublimation data was discussed and used and the results compared well with the impact-pressure results.
| Author | : E. R. Van Driest |
| Publisher | : |
| Total Pages | : 108 |
| Release | : 1961 |
| Genre | : Aerodynamics, Supersonic |
| ISBN | : |
Experiments carried out in the 12-inch supersonic wind tunnel to investigate the effect of three dimensional roughness elements (spheres) on boundary-layer transition on a 10-degree (apex angle) cone without heat transfer are described. The local Mach number for these tests was 2.71. The data show clearly that the minimum (effective) size of trip required to bring transition to its lowest Reynolds number varies power of the distance from the apex of the cone to the trip. Use of available data at other Mach numbers indicates that the Mach number influence for effective tripping is taken into account by a simple expression. Some remarks concerning the roughness variation for transition on a blunt body are made. Finally, a general criterion is introduced which gives insight to the transition phenomenon and anticipates effects of external and internal disturbances, Mach number transfer.
| Author | : |
| Publisher | : |
| Total Pages | : 260 |
| Release | : 1970 |
| Genre | : |
| ISBN | : |
| Author | : Colin Phillip Coleman |
| Publisher | : |
| Total Pages | : 212 |
| Release | : 1998 |
| Genre | : |
| ISBN | : |
| Author | : W. E. Moeckel |
| Publisher | : |
| Total Pages | : 14 |
| Release | : 1957 |
| Genre | : Aerodynamics, Supersonic |
| ISBN | : |
Large downstream movements of transition observed when the leading edge of a hollow cylinder or a flat plate is slightly blunted are explained in terms of the reduction in Reynolds number at the outer edge of the boundary layer due to the detached shock wave. The magnitude of this reduction is computed for cones and wedges for Mach numbers to 20. Concurrent changes in "outer-edge" Mach number and temperature are found to be in the direction that would increase the stability of the laminar boundary layer.
| Author | : K. R. Czarnecki |
| Publisher | : |
| Total Pages | : 22 |
| Release | : 1953 |
| Genre | : Aerodynamics, Supersonic |
| ISBN | : |
This paper surveys the available material and summarizes what is known to date about boundary-layer transition at supersonic speeds. Variables studied include Mach number, Reynolds number, pressure gradients, heat transfer, surface roughness, and angle of attack. The discussion is limited to bodies of revolution because similar reliable data for wings is lacking.
