Boundary-layer-transitionexperiments on a 5-deg half-angle cone at 0-deg angle of attack were performed in the T5 hypervelocity shock tunnel. The test gases investigated included air, nitrogen, and carbon dioxide. Reservoir enthalpies were varied from 3 to 27 MJ/kg and reservoir pressures from 10 to 95 MPa, depending on the gas and tunnel settings. No clear relationship is found to exist between the transition Reynolds number based on the boundary-layer-edge conditions and the reservoir enthalpy. However, when the reference temperature conditions are used instead, the different test gases are distinguishable and ordered according to their dissociation energy. Data from a free-ight experiment are also compared with the shock tunnel experiments. When the transition Reynolds numbers are evaluated at the boundary-layer-edge conditions, they are an order of magnitude higher than the tunnel results. However, when the reference conditions are used, the ight data fall within the same range as the experiments, although the trend with reservoir enthalpy is reversed. Nomenclatureh = enthalpy, MJ/kg M = Mach number P = pressure, Pa P q = heat transfer rate, MW/m 2 Re = Reynolds number r = recovery factor St = Stanton number T = temperature, K u = velocity, m/s x = axial distance, m ¹ = viscosity, kg/m-s ½ = density, kg/m 3 Subscripts a = adiabatic e = boundary-layer edge tr = transition w = wall 0 = reservoir 1 = freestream Superscript ¤ = reference condition

No abstract

No abstract

No abstract