(2009a)) and conferences proceedings, with only few journal papers on this specific subject being referenced. (1998)) and/or experimental (see list of references), proves to be very limited, except for US technical reports (see Varas et al. The scientific literature on HRAM effects in liquid tanks, be it numerical (see Anderson et al. Both loads can possibly rupture the entire tank structure. When the penetrating projectile transfers its residual energy and momentum to the fluid, it creates first a primary shock wave, then a secondary load when a cavity develops in the liquid as described in Ankeney (1977). Indeed, when hit by a high speed/high energy projectile, such a tank might suffer from a special failure mode (called Hydrodynamic Ram). the Concorde accident), and Defence (cheap kill of military aircraft, or unmanned vehicle systems) aircraft industries. The design of fuel tanks with a reduced vulnerability with respect to hydrodynamic ram pressure (HRAM) effects is an episodic need in the Civil (e.g. The originality of the work consists in the fact that – compared with other published works – the phenomenon is studied up to tens of milliseconds in a very large pool for theoretical analysis of the bullet/liquid interactions only, and in a realistic fuel tank specimen to consider influence of boundary conditions onto the cavity characteristics (geometry, dynamics). The authors concentrate on two topics: on the one hand, digital image analysis to measure the cavity geometry during its growth and collapse phases and, on the other hand, pressure measurements that catch the transient shock wave. They concern two types of firing tests that were performed at ONERA using the NATO 7.62 mm projectile, respectively in the frame of ONERA (pool) and EUCLID (caisson) funded research projects. For that purpose, test configurations and experimental results are described, documented and discussed. The presented work concerns experimental research which aims at observing two hydraulic ram events – both induced by a 7.62 mm bullet shot in very different containers – throughout their various steps until the final collapse of the generated cavity, in order to study the nature of HRAM, the influence of the containers geometry, and to measure original dynamic data for numerical modelling developments and validation. the Concorde accident), and Defence (military aircraft, unmanned vehicle systems) aircraft industries. The design of fuel tanks with a reduced vulnerability with respect to hydrodynamic ram pressure (HRAM) effects is of an increasing need in the Civil (e.g.

Hydrodynamic ram pressure explained