A localized heating or cooling effect on stability of the boundary-layer flow on a sharp cone at zero angle of attack and freestream Mach number 6 is analyzed. Experiments were carried out in the Transit-M wind tunnel of the Institute of Theoretical and Applied Mechanics (Novosibirsk, Russia) for different heating/cooling intensities and freestream Reynolds numbers. The mean flows with localized heating/cooling are calculated using axisymmetric Navier-Stokes equations. These solutions are used for the spatial linear stability analysis to estimate the transition onset points using the e N method. Direct numerical simulations of two-dimensional disturbances propagating in the boundary layer through the cooled/heated region are performed. The experiment and computations showed similar qualitative trends. The localized cooling decreases the second-mode amplitude and delays transition. The heating produced an opposite effect, which is less pronounced.

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Experimental results of the influence of local heating/cooling on the development of hypersonic boundary layer disturbances are reported. Local heating/cooling is applied at the cone nose tip. The experiments are carried out at the Mach number M = 5.95, stagnation temperature T0 = 360–418 K, and stagnation pressure P0 = 3.7–45 atm. The unit Reynolds number is varied in the interval Re1 = (4.5–63) × 106 m−1. The investigations are conducted in the boundary layer on a cone with an apex half-angle of 7° and varied bluntness radius of the nose tip [R = 0.03 (sharp nose), 0.75, and 1.5 mm] for different values of the local temperature factor. The nose tip is heated by an ohmic heater. Cooling is performed by supplying liquid nitrogen into the internal cavity of the model nose. A comparative analysis of pressure pulsation spectra on the cone surface is performed. It is demonstrated that heating/cooling in the case of a sharp cone leads to flow destabilization/stabilization. The opposite effect is observed for blunted cones: heating/cooling stabilizes/destabilizes the second-mode disturbances. This effect is enhanced by increasing the nose tip bluntness. All the observed effects vanish with distance downstream from the nose tip.

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Hypersonic boundary layer stability and transition were studied experimentally and numerically for the test case of 7 degree half-angle cone equipped with local wall heating and cooling. The experiments were performed for M = 6. Heat §ux distributions and wall pressure pulsations were measured. It was obtained that variation of the wall temperature signi¦cantly a¨ects the transition location. It was found that development of the second mode depends on the upstream wall temperature. The results of numerical simulation con¦rmed the general trends of the second mode evolution obtained in the experiment.