Investigation Of Aft-End Internal Flows In Solid Rocket Motors With Submerged Nozzle

Submerged nozzles are commonly preferred in large solid rocket motors. The Aft-End internal flows are very complex because of submergence. The flow process and mechanism are not very clear yet. This paper described a numerical simulation of solid rocket motor with submerged nozzle with the fixed tracing model, which can simulate different two-phase flow conditions at three periods after ignition with hot flow or cold flow. The figure of streamline vector particle trajectory turbulence intensity was provided. It is showed that Aft-End internal flows vary obviously with the regression of the burning surface during the operation. At the preliminary stage of burning the gas flows along the back surface of the submerged nozzle and no recirculation forms in the Aft-End cavity. At the medium stage of burning a weak recirculation forms in the rear of Aft-End cavity by the force of injection flow. At the end stage of burning the flow separates at the combustion channel and a strong vortex forms in the Aft-End cavity. Under the influence of the submergence the turbulence intensity are quite high at the end stage of burning. However, the turbulence intensity decreases obviously at the medium stage and the preliminary stage of burning because the flow disturbance is eliminated by the mixture of injection flow and main flow. The effects of back surface of nozzle, Aft-Dome configuration and degree of submergence on Aft-End internal flow were studied. It is showed that the separated flow is sensitive to the change of Reynolds number and Aft-End cavity configuration.