Influence of the Control Temperature of Park's Two-temperature Model on the Mars Pathfinder Reactive Hypersonic Flow

TL;DR

This study evaluates how Park's two-temperature model weight factors influence thermodynamic and chemical non-equilibrium effects in reactive hypersonic flow around the Mars Pathfinder capsule. Using the LeMANS axisymmetric Navier–Stokes solver with an 8-species Martian atmosphere and two gas compositions (CO2 and CO2+N2), the authors analyze the impact of weight factors on $T_{tr}$ and $T_{ve}$ through the control temperature $T_c = T_{tr}^{a} T_{ve}^{b}$ with $a+b=1$. The results show that varying the weight factors yields negligible changes in the shock position and stagnation point convective heat flux, while maximum temperature modes can vary by up to about $1000$ K for $T_{tr}$ and $600$ K for $T_{ve}$, aligning with experimental data where available. The findings suggest that Park's weight factors can be varied within literature-recommended values without strongly affecting macroscopic flow features, though differences in temperature modes could influence reaction rates and radiative behavior not addressed in this work.

Abstract

Numerical simulations of reactive hypersonic flow under thermodynamic and chemical non-equilibrium conditions are presented for the Mars Pathfinder capsule. An 8-species chemical model is employed to simulate Mars' atmosphere. Park's two-temperature model is used to account for the thermal non-equilibrium phenomena. The present work analyzes the impact of different values of the weight factors used in Park's model, aiming to broaden the understanding of the weight factors influence. The code used to simulate the flows solves the Navier-Stokes equations modified to account for reacting gas mixtures. The findings are depicted in terms of the Mach number and temperature modes along the stagnation streamline in a region close to the shock wave. The present analysis also includes results regarding the stagnation point convective heat flux. The results indicate that varying the weight factors yields negligible differences in the shock wave position and stagnation point convective heat flux. The changes in the weight factors cause variations in the maximum temperature mode values in the non-equilibrium region. The results presented are in good agreement with experimental data present in the literature. The present work indicates that Park's two-temperature model weight factors can substantially affect the temperature mode distributions in the flow non-equilibrium region.

Figures (4)

• Figure 1: Mars Pathfinder computational domains.
• Figure 2: Mach number distribution along the stagnation streamline indicating the shock wave position.
• Figure 3: Temperature mode distributions along the stagnation streamline.
• Figure 4: Stagnation point convective heat flux values.