Coupled fluid, thermal and structural analysis of nozzle inserts in solid rocket motors

In order to accurately predict the thermal and structural behavior of throat inserts in solid rocket-motor environments, a fluid-thermal-structural coupling model was established based on CFD code FLUENT and FEM code ANSYS. Fully coupled fluid-solid analysis was performed first to simulate the heat transfer and material erosion process, using the method of whole-field discretization and solution in FLUENT. Subsequently, the structural analysis was carried out in ANSYS based on the resulting pressure and thermal loading. In such a procedure, two-way coupling was considered between flow and heat transfer while one-way coupling method was employed in structural analysis. Numerical results show that the convective heat transfer coefficient gradually decreases with increase of wall temperature during the motor firing. The wall temperature and erosion rate follow the trend exhibited by the heat flux distribution, and attain peak at upstream of the throat. The stress is most severe in the throat region due to the steep temperature gradient.