![]() ![]() The cavity formed in the liquid and the resultant complex pressure field may cause the liquid to spurt from the penetration orifices. When a high-velocity penetrator impacts a liquid-filled container, such as a fuel tank, the phenomenon of hydrodynamic ram occurs. The analysis shows that the proposed method is useful for engineers to determine which components are more likely to cause aircraft performance degradations in the combat environment from the standpoint of vulnerability. Two applications, one with eight critical components and one consisting of 84 noncritical components and 28 critical components dealing with aircraft being hit by metallic fragments detonated from a missile, are provided. Component vulnerability importance measures considering performance degradations are proposed. This work aims to investigate how performance-related importance measures in the field of reliability can be modified to rank the vulnerable components. Currently, when comparing the contributions of components to the overall aircraft vulnerability in a military context, existing methods focused on the aircraft kill state without considering the intermediate states that are related to performance degradations. One of the most important tasks of aircraft vulnerability assessment is to rank vulnerable components so that proper actions can be applied to the weaker components to improve survivability. Furthermore, the main spurt maintains its axial momentum for a much longer axial transition that that for a self-preserving single phase jet. The initial radial spreading of the spurt, as it moves downstream, takes on a reduced spread as the residual kinetic energy increases. Of particular interest is the near field velocity profile of the exiting spurt, where a transition in the velocity profile has been observed. It was found that projectile residual kinetic energy levels influenced the shape, magnitude of the velocity profile, and spread of the exiting spurts. The resulting fuel spurt that exits the entrance hole can be highly atomized and flammable and therefore, highly conducive to ignition and fire. This phenomenon is of particular interest to the aircraft survivability community where fuel tank vulnerability and protection is a major concern. This highly transient event is induced by the impact and penetration of a high energy projectile into a liquid filled tank, producing an accelerating liquid “spurt” exiting from the projectile entrance hole. The main phase of a spurt produced by a hydrodynamic ram (HRAM) event has been quantified using Particle Image Velocimetry. ![]()
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