When the plume of a thruster impinges on spacecraft surfaces and instruments, the ow is either in the transitional or the free-molecular regime. The standard method to simulate the transitional regime is Direct Simulation Monte-Carlo, which simulates free-molecular gases too.
In order to improve Astrium’s capabilities and flexibility for plume-spacecraft interaction analysis, the DSMC code DS3V was interfaced with the Astrium tool for thruster’s plume computation PLUMFLOW and with a commercial 3D modeler. This has allowed Astrium to perform plume impingement analysis in complex configurations such as instrument cavities in the Bepi-Colombo spacecraft.
The Astrium tool SYSTEMA/PLUME uses a simplified and fast approach to perform the same kind of analysis. In order to asses its accuracy, SYSTEMA/PLUME results were compared with DS3V results in a configuration where the ow is in the transitional regime. The SYSTEMA/PLUME approach is based on the assumption that the how is in the free-molecular regime so as the how becomes less rare fed, the results become less accurate. However, both method showed good agreement and the deviation between the predicted plume impingement effects was less than 15%
Author: Wartelski, Matías