DYNAMICS OF OBLIQUE DETONATIONS IN RAM ACCELERATORS

Time-accurate numerical simulations are used to study the dynamic deve lopment of oblique detonations on accelerating projectiles in ram acce lerators. These simulations show that the oblique detonation can be st abilized on the projectile. The high pressure generated behind the det onation can result in accelerations up to 10(6)G and propel the projec tile to velocities higher than 4.0 km/s. The detonation structure on t he projectile is sensitive to the projectile geometry. A small change in the projectile shape is sufficient to alter the overall detonation structure and significantly affect the pressure distribution on the pr ojectile. In order to maximize the thrust, an appropriate projectile s hape has to be chosen to generate the detonation structure just behind the widest part of the projectile body. The projectile acceleration a lso has strong effects on the flow field and the detonation structure. During the acceleration, the location of the oblique detonation moves upstream from one reflected shock to another. However, once the deton ation is stabilized behind the upstream shock, it remains at the new l ocation until the transition to the next upstream shock occurs. In the simulations, the Non-Inertial-Source (NIS) technique was used to accu rately represent of the projectile acceleration. Also, the Virtual-Cel l-Embedding (VCE) method was employed to efficiently treat the complex projectile geometry on cartesian grids.