Numerical Simulation of Store Separation for Quasi-Steady Flow

The main purpose of the FoT25-project "Studies of weapons bays" project has been to gain knowledge about the impact of unsteady flow around weapons bays on flight performance, on the cavity walls and on store separation trajectories. One of the long terms goals is to be able to predict trajectories for stores from weapons bays usually implying unsteady flow conditions. In this report a method for computations of separation of an external store assuming quasi-steady flow conditions is presented. An integrated system for store separation simulations with the flow solver Edge has been developed. Computations of quasi-steady flow have been directly coupled to a flight mechanics model and the relative movement between the aircraft and the store are mapped by a sequence of deformed and remeshed grids. The flight mechanics model consists of the equations for rigid body motion solved by a fifth order Runge-Kutta scheme. The flight mechanics model was verified against analytical test cases demonstrating that the accuracy is more than sufficient to compute typical store separation trajectories. In order to validate the implementation of the system for store separation computations, an AGARD-test case for external store separation was computed. A finned missile is separated from a generic wing-sting-pylon configuration with use of an ERU (Eject Release Unit). The computed trajectories and attitudes agree well with experiment.