INFLUENCE OF VIBRATIONAL EXCITATION OF THE GAS ON THE POSITION OF THE LAMINAR-TURBULENT TRANSITION REGION ON A FLAT PLATE

The influence of thermal nonequilibrium on the laminar-turbulent transition is studied with the use of the e(N)-method for two widespread flow regimes in a supersonic boundary layer at the Mach number M = 4.5. The set of the actual frequencies of spatial disturbances is determined on the basis of the neutral curves for temporal disturbances. Families of the curves of N-factors are calculated for selected frequencies. Then, based on the envelopes of these curves, the transition Reynolds number Re-delta T for a given transition factor N-T is determined. The calculations show that the transition region in the case with N-T = 8 and vibrational excitation level below the dissociation limit is located 12-14% downstream as compared to the transition region in a perfect gas.