Rocket nozzle lip flow by direct simulation Monte Carlo method

Analyses of the flowfield properties in the immediate vicinity of the lip of the inertial upper stage solid rocket motor have been used to evaluate the differences in the local properties as predicted by continuum, Method of Characteristics codes, and by discrete particle, Direct Simulation Monte Carlo methods. Divergence of the two solutions is observed as the flow expands and the local conditions proceed from continuum through transition and the breakdown parameter passes through the value 0.05. Flowfield contour plots from the two calculations are presented. From the Monte Carlo results, it can be seen that there is a rapid change in the gas composition as the flow expands around the lip; this change depends primarily on species molecular mass and local flow angle. Divergence of the axial and radial mode temperatures is observed, which indicates a breakdown of translational equilibrium. Neither of these nonequilibrium effects can be predicted by the continuum calculation.