This final report describes the research progress made possible with the equipment purchased under this grant, and the manpower supplied by Princeton University as part of cost sharing.

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.

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.

As a prerequisite for relevant model development and improvement of design methodologies for supersonic vehicles, this study aims at investigating the influence of wall heat-transfer and shock interaction on the turbulence structure of supersonic boundary layers. Incipient separation conditions and two different wall thermal boundary conditions (adiabatic and cold) are considered. The analysis focuses on the evolution of mean and turbulent flow properties along the interaction region and in the relaxation region downstream of the shock-system. The strong influence of the mean pressure gradient is quantified through the analysis of mean flow profiles and boundary layer integral parameters. The anisotropic amplification of turbulent quantities through the interaction region is characterized and the turbulent events associated with the modification of the turbulence structure of the perturbed boundary layer are identified. The mean and turbulent thermal fields are shown to be strongly modified by the wall cooling which significantly dampens more particularly the turbulent thermal quantities levels across the boundary layer.

This report presents mean flow profiles across a two-dimensional, flat plate, compressible turbulent boundary layer. The mean flow properties were determined from pitot pressure and total temperature surveys carried out at three streamwise locations for wall to freestream total temperature ratios of 0.94 (adiabatic case), 0.714 and 0.54. All tests were conducted for a freestream Mach number of 3.0 with Reynolds number, based on momentum thickness, varying from 3200 to 4200. Although the outer two thirds of the viscous sublayer was probed, no evidence was found of a linear velocity gradient near the wall. However, the skin friction calculated using two conventional correlations were in good agreement with the trend of data. Furthermore, comparison of the velocity profile with Coles Law-of-the-Wake correlation indicated that the boundary is characteristic of a fully developed zero pressure gradient, flat plate flow. Results were in accord with those of other investigators for supersonic flows. In particular, the calculated eddy viscosity was in excellent agreement with the correlation derived by Maise and McDonald.