Thermochemical Erosion Analysis of Carbon-Carbon Nozzles in Solid-Propellant Rocket Motors

The erosion of rocket-nozzle materials during motor firing is one of the major limits in the advancement of solid-rocket propulsion. A study is conducted to predict carbon-carbon nozzle erosion behavior in solid rocket motors for wide variations of motor operating conditions. The numerical model considers the solution of Reynolds averaged Navier-Stokes equations in the nozzle, heterogeneous chemical reactions at the nozzle surface, variable multi-component transport and thermodynamic properties, and heat conduction in the nozzle material. Two different ablation models are considered: a surface equilibrium approach and a finite-rate approach. The numerical model is used to study the carbon-carbon nozzle throat insert erosion of the European VEGA launcher third stage and second stage solid rocket motors. The effect of variable chamber pressure over the burning time and the effect of nozzle shape change on the erosion rate are taken into account in the numerical analysis. The obtained results show a very good agreement with the measured final eroded profile along the entire carbon-carbon nozzle throat insert for both motors.