Numerical assessment of plume heat and mechanical loads and contamination on multi-layer insulation in hard vacuum

The paper presents a numerical analysis of plume exhausted from the 10 N bipropellant thruster. The computations have been performed for steady state and pulse mode firing of the thruster. The plume impinges a multi-layer insulation (MLI) that covers a satellite surface, where plume effects have been computed for ideal and bulged shapes of the MLI. The ideal shape is a circular cylinder surface, where the bulge is a deflection of the MLI due to satellite spin. Plume effects, pressure and heat flux, are almost doubled for the bulged MLI. An engineering model based on experimental data has been applied. It was shown that it is conservative against the numerical modeling in the plume backflow. An application of the pulse mode leads to a formation of droplets. One of the sources of the droplets is a rupture of liquid film at the nozzle lip. A parametric study with different droplet sizes and initial velocities has been performed for thrusters firing along and against the satellite spin. The thruster that fires against the satellite spin contaminates the MLI more than the other thruster. Droplets with an initial velocity smaller than 6 m/s cannot contaminate the MLI. (C) 2011 Elsevier Ltd. All rights reserved.