The objective of this research is to analyze the hypersonic boundary layer transition process where surface ablation is included using direct numerical simulation and linear stability theory. There has been little research into surface ablation effects on hypersonic boundary layer instability and the understanding of real gas effects on hypersonic boundary layer instability still contains uncertainties. In this paper linear stability theory calculations will be performed to analyze hypersonic boundary layer instability with surface ablation effects. A thermochemical nonequilibrium linear stability theory code with a gas phase model that includes multiple carbon species as well as a linearized surface ablation model is developed and validated. As there are strong near wall gradients in ablative flows a high-order method for discretizing the linear stability equations is given which can easily include high-order boundary conditions. The developed linear stability code along with a high-order shock-fitting method for hypersonic flows with thermochemical nonequilibrium and surface chemistry boundary conditions for graphite ablation are used to study hypersonic boundary layer stability for a 7° half angle blunt cone at Mach 15.99. Five separate meanflow simulations were run with the same geometry and freestream conditions to help separate real gas effects, blowing effects, and carbon species effects on hypersonic boundary layer instability. An N factor comparison shows that real gas effects significantly destabilize the flow when compared to an ideal gas. Carbon species resulting from ablation slightly destabilize the flow by increasing the amplification rate of linear disturbances. Blowing is destabilizing for the real gas simulation and has a negligible effect for the ideal gas simulation due to the different locations of instability onset.
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