Hybrid Finite Element/Molecular Dynamics Simulations of Shock-Induced Particle/Wall Collisions

Contaminant metal particles of the order of 100-500 microns in diameter in the liquid propellant feed systems of rocket engines are a significant hazard and safety concern. These particles may originate from within the propellant tanks, valves, feed lines, pumps, or the propellant itself. Ignition and combustion of the particles when located within a supercritical oxygen-rich environment, such as would be found in an oxidizer-rich rocket engine system, could release a significant amount of energy. In addition, particle impacts with the walls of the propellant feed systems could sufficiently heat the particles to ignite them or to fracture them into smaller particles that are easier to subsequently ignite. Experiments are currently underway at The Aerospace Corporation to improve the knowledge base for particle-impact ignition. Oxygen pressure, particle size and kinetic energy, and the occurrence of fragmentation upon impact are among the parameters to be studied where impacting particle velocity is induced by the passing of a shock wave [1]. A simulation capability, validated by the experiments, would be of value to predict the risk of possible particle contamination.