A CFD/DSMC analysis of plumes and plume impingement during Shuttle /Mir docking

CFD analyses of the plumes from the Shuttle Orbiter Primary Reaction Control System are performed. The effects of dual jet firings and nozzle scarfing are investigated. The physical range for the CFD analyses extend from inside the nozzle out into free space beyond the point where, because of the rapid gas expansion, continuum theory is considered valid. A DSMC analysis of an axisymmetric plume is performed for the flow region far downstream of the nozzle exit where the flow is no longer described by continuum theory. The DSMC analysis obtains boundary condition information from the corresponding CFD analysis at a surface where continuum theory is still applicable. DSMC analyses of plume impingement are performed to predict the anticipated plume forces on the Mir station during Orbiter docking on the STS71 mission. Incoming flow boundary conditions for impingement analyses are based on a semiempirical fit of vaccuum chamber, flight test, and CFD/DSMC estimates of the plume flow field.