About the Heat Flux and Skin Friction Prediction of the DLR TAU-code for Turbulent Supersonic Flows

Abstract

Surface temperatures of missile configuration at supersonic speeds can easily reach values of 2,000 K depending on Mach number and altitude. Hence, the correct prediction of heat loads is crucial for the choice of materials within the design process of a missile configuration. For many Navier-Stokes-flow solvers it is still a challenging task to correctly predict heat flux and skin friction in turbulent supersonic boundary layers. In the hypersonic regime the flow is laminar in many cases, simplifying the equations and the calculation. In the supersonic speed range the flow along the body is nearly always transitional. The applied turbulence model can have a large influence on the predicted heat load distribution especially in the vicinity of reattachment and divergence zones of the flow. The more complex the flow gets, e.g. due to side-jet-injection, high angles of attack, and the associated flow separation, the more difficult it becomes to predict the heat flux correctly. This is the motivation to assess the heat flux obtained by the TAU-code (Gerhold and Evans, 1999 and Schwamborn et al, 1999), which is an internal development of the German Aerospace Centre (DLR), using an appropriate bench mark experiment which was carried out at DLR. The experiment (Schülein et al, 1996) was performed already a few years ago in the DLR Ludwieg Tube (RWG) at M=5.0 on a flat plate with a transitional boundary layer. It was set up as a 2-dimensional test case in which a shock generator was employed in a way that a shock impinged on the flat plate under different angles. The experiment provides for comparison data including boundary layer velocity profiles, heat flux, skin friction, and surface pressure in the region influenced by the shock and also along the turbulent region upstream of the interaction. First steps of the investigation cover the influence of grid cell resolution as well as the cell stretching within the boundary layer, and the influence of different turbulence models.