Numerical simulations of shock propagation under strong nonequilibrium conditions

A computational approach is developed to simulate high-enthalpy shock propagation under strong nonequilibrium conditions, such as reentry experiments at NASA’s Electric Arc Shock Tube (EAST) facility. Two-dimensional axisymmetric simulations of EAST flow are performed for Earth reentry at 10 km∕s. An 11-species weakly ionized air model is used to capture the real-gas behavior with reaction rates from the literature. Species mass-diffusion fluxes are calculated assuming a self-consistent effective binary diffusion in conjunction with Gupta–Yos collision integral data. The unsteady, linearized system of conservation laws is solved in a moving frame of reference with active shock tracking to reduce the computational cost by three orders of magnitude relative to that of fixed-frame calculations on a uniform grid. This approach enables time-accurate yet computationally feasible predictions of gas behavior at the test section. Computational fluid dynamics predictions can be compared with the experimental data to gain an improved understanding of the flow physics. Additionally, useful quantities such as boundary-layer thickness and growth rate, and radial variation of gas properties can be computed, which are difficult to measure in experiments.