Dynamic Supersonic Base Store Ejection Simulation Using Beggar

Static and dynamic conditions throughout various aft supersonic store separation events are examined using the Beggar Computational Fluid Dynamics (CFD) code from Air Force SEEK Eagle Office at Eglin Air Force Base, FL. An 8.9 deg half angle sphere cone is used for the carrier vehicle with an identically shaped store stowed within a hollow compartment in the aft section of the carrier body. Dynamic store separation simulations are implemented at a free-stream Mach of 2.9 with a Reynolds number of Re = 6.9 x 106/m referenced against carrier base diameter. Analysis covers multiple dynamic separation events along with studies of the carrier/store body at various static conditions and configurations. Dynamic store separation simulations show that a successful store separation is more likely to occur at high angles of attack and high flight angles. When a low angle of attack and low flight angle are combined with inadequate ejection forces, it appears that the carrier and store will eventually impact each other due to the tendency of the store to remain within the low drag wake region of the carrier. For all dynamic separation cases, a suction effect or negative drag forces is observed acting on the store as it separates through the near wake region of the carrier body. The duration of the suction effect is found to be directly related to the initial free stream incidence of the two body system at store deployment. The suction force acting upon the store is not observed for identical static cases at equivalent fixed separation distances. This finding indicates that a static system does not accurately capture the body forces of a dynamic store separation event. When the store is stowed slightly offset of the carrier base prior to deployment, it separates further than when the store is stowed flush to the carrier