DSMC and Navier-Stokes Study of Backflow for Nozzle Plumes Expanding into Vacuum

摘要

An important problem for space vehicles is contamination of the spacecraft surface by combustion products and unburned fuel exhausting from control thruster nozzles. The objective of the present work is a detailed simulation of the backflow in the case of gas exhaustion from the nozzle into vacuum. A specific feature of this problem is the drastic expansion of the initially dense flow at the nozzle exit, which makes necessary simulations of the near-continuum flow inside the nozzle, the transitional flow near the nozzle exit, and the free-molecular flow outside the nozzle. The simulations are performed by a combined Navier-Stokes/DSMC approach.