Ablation of pierced C/C composite nozzles in an oxygen/ethanol combustion gas generator

The ablation of pierced C/C composite nozzles was investigated via hot-fire testing by an oxygen/ethanol combustion gas generator simulating combustion environments of the liquid rocket engine. Ablation microstructures and mechanisms of the composite nozzle were discussed. The results showed that both linear ablation rate and mass ablation rate increased with increasing mass ratio of oxygen/ethanol. The ablation of the pierced C/C composite was attributed to the heterogeneous reactions between carbon and oxidizing species and could be interpreted by the thermochemical ablation model. The ablation rate of the composite was determined by both chemical kinetics and diffusion. The ablation of the composite resulted in cone-shape carbon fibers and shell-shape matrix with pits and grooves left on the surfaces.