NUMERICAL MODELING OF PLASMA WIND-TUNNEL FLOWS

In the frame of the Sonderforschungsbereich 259 plasma wind tunnel fac ilities are employed to test candidate materials for thermal protectio n systems. To obtain the necessary understanding of the flow phenomena within these facilities, a variety of experimental diagnostic tools i s used and a CFD code system is developed. First investigations were m ade using nitrogen as flow medium in the plasma wind tunnel. The opera tion parameters were chosen to represent the stagnation region paramet ers as encountered at the wing leading edge of a HERMES type reentry v ehicle at the peak heating trajectory point. Using these experimental results for a free jet in the facility, the code system was validated. Therefore, finite rate chemistry, thermal non-equilibrium effects and turbulence effects were investigated, all of these being implemented in the code system. The results were compared to a straightforward the ory for turbulent free jets with good agreement. Thus, a simple and fa st prediction procedure and a more accurate CFD code system to compute the fine structure of the plasma wind tunnel flow-field were develope d. The basic features of these methods, the results obtained for a nit rogen jet and the comparison to experimental data are presented here.