Design and performances of intake for atmosphere-breathing electric propulsion systems with the direct simulation Monte Carlo method

The design of an effective intake is a critical aspect of atmosphere-breathing electric propulsion development. Using the Direct Simulation Monte Carlo method, the intake collection efficiency, compression ratio, and drag were evaluated and compared across different geometries, including a scaled-down version. Key performance parameters were analyzed over a wide range of Very Low Earth Orbit altitudes (160–240 km), focusing on gas–surface interactions and the impact of inter-particle collisions at lower altitudes. The results derived from the Maxwellian and Cercignani–Lampis–Lord models were compared under various reflection scenarios: fully specular, partially diffuse, and diffuse. The study first examined intake geometries, highlighting how surface curvature affects performance. Further analysis of the best-performing geometry at different altitudes (160–240 km) revealed that neglecting inter-particle collisions at lower altitudes can lead to discrepancies in capture efficiency of up to 40%. This difference diminishes with increasing altitude, becoming negligible. The intake is sized down to a 1:5 ratio to match the dimensions of a CubeSat with no significant effect on compression ratio or capture efficiency, opening up the possibility for nanosatellite applications. Finally, the different gas–surface interaction models provided a range of performance predictions for each analyzed altitude, potentially reflecting the behavior of a real intake operating in the atmosphere. Variations in the mass flow rate supplied to the electric thruster across models offer valuable insights for thruster design.