Numerical study on the non-equilibrium flow properties of CO2 plasma around the catalytic wall of Mars Pathfinder spacecraft

In this study, a multi-physics numerical model is developed to study the thermochemical non-equilibrium flow properties of the carbon dioxide (CO2) plasmas around the catalytic wall of the Mars Pathfinder spacecraft. The multi-physics model incorporates the NavierStokes equations, an 11-species, 59-reaction carbon dioxide (CO2) chemical kinetics model, a four-temperature non-equilibrium model, and a catalytic model of the wall surface. Primarily, the influence of different wall-catalytic conditions on the flow field is studied. It is found that the catalytic effect significantly affects the mole fractions of dominant chemical species around the spacecraft's wall. As altitude decreases, the maximum values of the four temperatures decrease. The degree of CO2 dissociation and overall chemical reaction rates also decrease. Under the fully catalytic wall conditions, fast recombination reactions of CO and O lead to increment of CO2. In addition, the simulations with medium- and high-catalytic coefficients show similar results to those of the fully catalytic case. However, the different catalytic conditions seem to have little effect on the pressure, Mach number, and the four temperatures near the wall. The research findings presented in this study might be helpful for better understanding the spacecraft's flight environment for future Mars exploration missions.