Dynamic CFD Modelling of Deploying Fins During Transitional Ballistic

Abstract: The transition from inner to outer ballistics is a crucial part for the stability of the projectile. A projectile is mainly stabilized in two ways, with fins or by rotation. This work is limited to analyze a fin stabilized projectile. The launch of the projectile and the deployment of the fins are a quick process, therefore high forces and high temperatures will act the stability of the projectile. Due to these factors, it is hard to quantify experiments to analyze the stability of the projectile. To gain knowledge about how the forces will affect the path of the projectile during the launch and the deployment of its fins Computational Fluid Dynamics (CFD) can be a useful technique. In this work, a 2D methodology have been developed in Ansys Fluent to analyze the launch of a projectile and the deployment of the fins. A RANS model have been used in combination of dynamic mesh in order to handle the movement of the projectile. The projectile accelerates due to a pressure rise which have been initialized by a mass flow and energy curve as a source term. This work indicates that it is possible to predict the flow behavior and the forces influencing the projectile and the deploying fins. This work used a 2D model throughout the simulations and a 3D model is therefore needed to further compare and validate the simulation methodology.