Influence of erosion-induced geometry changes on the flow vented vessel experiments

In the development of new, more powerful propellant charges the erosion of the gun barrel must be considered. During the combustion process high pressure is produced and hot gases cause erosive material removal within the barrel. Vented vessel tests are regularly performed to evaluate the erosivity of gun propellants. In these tests, a gun propellant is burned and the resulting combustion gases flow out of the combustion chamber through a metal nozzle. While giving a relative measure for the erosivitiy of gun propellants the transferability of the results to the conditions in a real gun and the dominant erosion mechanisms are still under investigation. The gas flow causes material removal of the nozzle, which is measured by weighing and is used to evaluate the erosion. In this work computed tomography (CT) scans are utilized to further quantify the erosion during the experiment. The removal of the material alters the geometry of the nozzle drastically, hence the flow conditions during the test change as well. This phenomenon has not been sufficiently investigated. The aim of this work is to investigate the influence of the geometry change on the resulting flow during vented vessel tests to better understand the mechanisms that lead to erosion. For this the CT scans were transferred to a 2D CFD grid and numerical fluid dynamic simulations are performed within the OpenFOAM framework.