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.