Numerical Investigation of Gas Models for Retropropulsion Flows for Future Mars Missions

Supersonic retropropulsion is a key technology for next-generation rockets and necessary to land large payloads for human-scale missions. The recent decade has demonstrated the capability to land rockets on Earth as well as the reuse of said rockets to reduce cost. This capability thus far has relied on flight tests. For future missions to Mars, testing requires many compromises, as flight tests are not possible on Earth. Computational fluid dynamics (CFD) simulations are critical to the design and analysis of extraplanetary retropropulsion configurations. This work investigates a single-engine configuration that was previously tested in a wind tunnel using an air medium. The configuration is scaled to Martian conditions. Various gas modeling approaches are employed, including pure Formula: see text, pseudo-species, and a chemical mechanism to model the afterburning of the engine plumes in the Martian atmosphere. The scale-resolving CFD simulations are compared to the simulation and experimental data of the air configuration. The lower-fidelity gas modeling simulations are also compared against the higher-fidelity chemical mechanism simulations to examine the impact of gas models on plume flowfields and forces and moments that are of interest to vehicle design.