| A numerical study was undertaken to predict the stability of a variety of high-speed boundary-layer flows. Using a finite-volume code, the Navier-Stokes equations were solved for a series of flows around spherically blunted cones. These solutions were used to perform linear-stability analyses for second-mode disturbances.; Two investigations were undertaken using an ideal-gas model: the Stetson experiment and a recent experiment conducted at the Institute of Theoretical and Applied Mechanics in Russia. Comparisons were made with both basic-state and disturbance state quantities. For both cases, linear-growth regions have been identified. For the Stetson case, using an experimentally determined wall-temperature distribution for the basic-state appeared to give better agreement with the experimentally measured growth than does the classical adiabatic-wall boundary condition. For the Russian experiment, initial comparisons were made in order to continue a careful collaboration.; A third investigation was made which used a chemical non-equilibrium model, considering a Mach 13.5 flow in upper-atmospheric conditions. The goal of this investigation was to evaluate the sensitivity of second-mode growth predictions to changes (within accepted uncertainties) in thermodynamic, reaction-rate; and transport models. The magnitude of change in the stability results correlated strongly with changes in the basic-state thermal boundary-layer profile, consistent with second-mode theory. The largest change in the stability behavior was observed for the case where the transport model was changed.; For high-speed flows, the development of computational techniques is in some ways ahead of the experimental community's ability to verify the results. As these techniques are applied to flows in thermochemical non-equilibrium, the fidelity of the constitutive relationships should be considered. |
