O EDP Sciences, Les Ulis

Abstract: A ram accelerator experiment which was done in ISL's RAMAC 30, was numerically simulated in this study. The case of shot 225 was considered and the initial projectile launching speed was 1.8 km/s which corresponded to the superdetonative speed of the stoichiometric W O, mixture diluted with 5C0,. CFD code had some enhanced features suitable for the high-pressure gaseous combustion. In this study, it was found that neither shock heating nor viscous heating was sufficient to ignite the mixture at the low speed of 1.8 kmls, as was found in the experiments using a steel-covered projectile. However, we could succeed in igniting the mixtures by imposing an amount of additional heat to the combustor section and simulate the positive acceleration of the shot 225 with an aluminum-covered projectile in reasonable agreement. Some additional studies were preformed concerning the location of the forced ignition and the conical angle of the projectile. The results gave some insights into the combustion mechanism and the condition of positive acceleration in a scram accelerator. 1