Hypersonic transition in flat-plate boundary layers with chemical and thermal non-equilibrium

Investigations on laminar-turbulent transition for highspeed flows at hypersonic Mach-numbers will be presented. Dissociation takes place above a temperature of T>2000K within the boundary layer, a temperature which is reached easily at hypersonic Mach-numbers above M approximate to 5. Additional degrees of freedom for the energy must be taken into account by employing a vibrational energy equation. Chemical reactions take place which are modeled by a 5-species model proposed by Park (1989, 1990). Further details on the chemical modeling can be found in Stemmer (2002, 2003). Controlled disturbances are introduced by means of a disturbance strip (Besteck & Ei ss ler 1996) at the wall which is also capable of modeling point source disturbances. Results will be shown for free-flight conditions at an altitude of H=50Km and at a speed of M=20. Experiments for qualitative validation of the results are available in Mironov & Maslov (2000).