Cavity Geometric Features and Entrainment Characterization Resulting from a Ballistically Induced Hydrodynamic Ram Event
Technical Report,01 Oct 2013,15 Sep 2016
AFIT WPAFB United States
Pagination or Media Count:
Hydrodynamic Ram can cause damage to industrial and aircraft systems. The resulting transient spray increases the probability of fire. To better understand the driving mechanisms behind transient spray, internal, and external measurements of the cavity geometry, and entrained flow field were accomplished. Research determined cavity contraction and separation are pre-cursors to the initiation of the transient spray phases. The entrained flow measurement required development of a new and novel technique using a continuous wave laser and atomized water particles. The peak mass flow correlated well with cavity geometric features, such as cavity contraction. Using the mass flow, cavity diameter at the orifice, and cavity length, projectile kinetic energy dissipation was related to cavity contraction. A relationship was developed for a range of impact velocities for the expected kinetic energy dissipation to occur prior to cavity contraction. Design of safer systems is possible by relating cavity contraction to the projectiles kinetic energy, and understanding how the transient spray is related to the cavity geometric features and the entrained mass flow.
- Fluid Mechanics