Characterization of nozzle thermal and ablation response in dual-pulse solid rocket motors

In order to investigate the nozzle thermal and ablation characteristics in dual-pulse solid rocket motors,the transient value of the throat diameter was obtained from the pressure and thrust measurements.Furthermore,the in-depth thermal response,pyrolysis/char profiles and surface recession of the nozzle assembly were predicted through fully coupled fluid-solid analysis using the commercial code FLUENT.Results show that during pulse operation,the insulation material pyrolysis/char profiles expand and the nozzle insert erosion rate increases.During pulse separation,heat conduction in the material leads to the decrease in the material temperature difference.The heat transfer and ablation processes of pulse 1 and pulse separation make the nozzle insert exhibit small heat sink,high surface temperature and large surface roughness,which would result in higher throat erosion rate when pulse 2 operates.