Evaluation of equilibrium turbulence for a naturally developing hypersonic boundary layer at nonadiabatic wall conditions

Experimental data for defining test conditions necessary for a naturally developing hypersonic equilibrium turbulent boundary layer are presented. The tests were conducted at nominal boundary-layer edge Mach number of 6.2 and 5.0; the adiabatic wall to actual wall temperature ratio was 5.4. The data indicate that a momentum thickness Reynold number of at least 4000 is required for an equilibrium turbulent boundary layer. Based on the above results, a test envelope defining equilibrium flow conditions for an eight-foot high-temperature tunnel in terms of the basic facility operating conditions is given for a Mach-7 nozzle configuration. Representative experimental results for two-dimensional and three-dimensional test articles are assessed, including results of complete and partial adaptation and of residual-interference calculations.