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BOUNDARY LAYER TRANSITION AT SUPERSONIC SPEEDS THREE DIMENSIONAL ROUGHNESS EFFECTS (SPHERES)
NORTH AMERICAN AVIATION INC DOWNEY CA
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.
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