Numerical simulation of chemical erosion in VEGA launcher solid-propellant rocket motor nozzles

The erosion of nozzle ablative thermal protection materials during solid-rocket-motor burning time needs to be accounted for to get reliable performance predictions, especially for long-duration firings and/or smaller nozzles (i.e. upper stages). This work investigates the erosion behavior as a function of chamber conditions for the nozzles of Vega launcher solid rocket motors, namely Zefiro 9, Zefiro 23, and P80. This study has been performed with a Reynolds-averaged Navier-Stokes equation solver developed in-house with speciffc application to solid rocket motors ablative nozzles. The throat region of the nozzle and speciffcally the carbon/carbon nozzle insert has received special attention during this study as its evolution has a significant impact on the motor performance, both in terms of thrust curve and speciffc impulse. Study of the nozzle throat insert has been performed for the three full-scale nozzles by comparing the predictions to measured data from static firing tests. A sensitivity analysis to the parameters that can in uence the throat erosion process has been performed. A characterization in terms of nozzle throat ablation massux dependency upon motor chamber pressure has been derived for the three nozzles via a power-fitting of the numerical data performed at discrete chamber pressure levels. © 2015 American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.