Numerical Investigation of shock tube flows with tailored driver gases and driver inserts

In shock tube experiments, test times can be extended by tailoring the driver gas and non-ideal effects that lead to pre-ignition pressure rise can be mitigated using profiled driver inserts. The effect of these measures on the post-reflected shock conditions and the test time can only be reasonably quantified through numerical studies. In this study the computational fluid dynamics package, OpenFOAM, is used to investigate these two types of shock tube flows. Because of difficulty in perfectly matching the driver gas composition in tailoring, slight compositional deviations leading to under- and over-tailoring are also investigated. The use of shock tube driver inserts to control non-ideal temporal behavior near the shock tube end wall is also considered. The expansion waves reflected from the driver insert used to control temporal increases in pressure. Investigated is the effect of these weak expansion waves on non-ideal temperature increases in the shock tube end wall, which is typically assumed to be related through isentropic compression. These numerical studies are based on the rhoCentralFoam OpenFoam solver.