Erosion in Solid-Propellant Rocket Motor Nozzles with Unsteady Nonuniform Inlet Conditions

Abstract

A computational framework is developed to investigate nozzle erosion in solid-propellant rocket motors. The calculations have several novel features. Among these is an accounting of three-dimensional effects, most strikingly for a vectorednozzle but also in thedescription of the turbulentflow.Also, instead of the hitherto universal strategy of merely solving the nozzle flow with uniform inlet conditions, strategies by which the chamber flow with its nonuniform efflux can be coupled to the nozzle flowwhile still resolving the nozzle boundary layer are discussed. The chamber flow is approximated by either full motor simulations, which do not resolve the boundary layer, or by an asymptotic strategy valid for slender chambers: one first used in turbulent boundary-layer studies. The manner in which the chamber efflux conditions are used as nozzle inlet conditions is part of the discussion. The results suggest that specifying turbulent rather than uniform inlet conditions can have a significant effect on nozzle erosion.