Coupled numerical simulation for the later period of the stage separation of a multi-stage rocket

Telemetry data of flight showed that there was a heat flux peak value of 50kW/m2 on the midpoint of aft-dome of upper-stage during the later period of the stage separation of a multi-stage rocket. In order to investigate the flow mechanism of the stage separation and the cause and effect of the heat flux, coupled CFD and rigid body dynamics simulation by means of chimera/overset method is performed to study the dynamic and aerodynamic characteristics of the later period of the stage separation of a multi-stage rocket. Both an axisymmetric case without the third stage nozzle rotation and a three-dimensional case with the third stage nozzle rotation have been studied. The results show that flow field of the axisymmetric case shows significant oscillation while stage separation of the three-dimensional case is relatively smooth. The reason for this difference is investigated. The difference of thermal effect on the aft-dome of the upper-stage between the two cases has also been studied.