Effects of variation in flow field on store separation

This paper focuses on the effects of variation in Mach number and angle of attack on store separation trajectories of external stores for typical combat aircraft. Multiple cases of variable flight parameters were analyzed to simulate various flight attitudes and velocities of the aircraft. A generic test case of a cropped delta wing with a standard air to ground store was taken as reference and the time dependent Euler and Navier Stokes equations were employed to solve the 6 DoF equations of motion in ANSYS Fluent®. A User Defined Function was used to incorporate the influence of thrusters in the computational analyses. Motion of the store was realized by integrating dynamic meshes in the computational domain. This arrangement enables to accommodate the displacement of store in the flow field. A standard test case was taken as reference to compare with the available literature, while several other test cases were developed to analyze the variation in trajectories due to flow field alteration. The result of the baseline test case was in complete agreement the literature data. Subsequent test cases depicted a complete profile of store behavior in altering flight regimes. The unrestricted movement of a store, coupled with the ejector and gravitational forces, is in complete coherence with the basic aerodynamic fundamentals of a free falling body in the flow field. Moreover, the variation in flight parameters also depicts a consistency in the variation in store release trajectories. The current research can prove beneficial for the prediction of release trajectories on any platform carrying a similar store.