Time-Dependent Simulation of Reflected-Shock/Boundary Layer Interaction in Shock Tubes

An initial experimental/numerical investigation has been conducted to gain a better understanding of the multi-dimensional flow phenomena inside pulse facilities and the influence of these phenomena on test conditions and test times. Experimental data from the NASA Ames electric-arc driven shock tube facility (from cold driver shots) is compared to time-dependent ax-isymmetric numerical simulations of the complete facility. These comparisons help establish the numerical modelling requirements for simulating shock tube flow and help validate the computations. The numerical simulations are used to study the interaction between the reflected shock wave and the side wall boundary layer and the resulting shock bifurcation. Of particular interest is the effect of the bifurcated shock structure on the driver/driven gas interface. The computations demonstrate how this shock structure introduces a mechanism for the driver gas to contaminate the stagnation region thereby reducing the duration of the test time. The simulations incorporate finite-rate chemistry, a moving mesh and laminar viscosity.