Hydrodynamic Ram Effects

Numerical Simulations of Ram Gun

BlazeTech has been producing numerical simulations of hydrodynamic ram using LS-DYNA software. Click on the image below for a video of the deformation produced by the impact of a projectile (in red) against the front section of a ram gun.

Click the image below to watch a video of the stress contours in the entire ram gun (projectile, impact plate, tube, and support plate.)

Results with Aircraft Structures

Hydrodynamic ram can occur in aircraft structures when sufficiently-energetic debris impact and penetrate a tank below the fuel level, resulting in an increase in pressure that can tear the tank apart. The subsequent fuel release can have catastrophic consequences.

The study on hydrodynamic ram in commercial aviation was basically ignored until the Concorde disaster. Since then, it has received a lot of attention, particularly in Europe.

BlazeTech analyzed the response and failure of metal aircraft structural panels subjected to hydrodynamic ram pressure loading. Transient in-plane and out-of-plane displacements of the panels were calculated using COSMOS/M and simplified engineering models. Furthermore, we developed a new method to protect tanks from hydrodynamic ram (link to page). Based on our design, a bread-board system was built and proof of concept tests were carried out. The measured reduction of the hydrodynamic ram effect was very significant.

Description: After penetration of fuel tank, fragment motion produces additional loading on the tank wall This phenomenon has been observed in tests of fuel tank panels in military applications Potential Hazards: Strong ram: Catastrophic rupture of tank Loss of fuel and loss of aircraft Weak ram: Increase in size of penetration hole Fuel leakage with potential for a fire

Damage to fuel tank from hydrodynamic ram effect.

We recently developed a novel system (FuelShield^TM) to protect fuel tanks against ballistically-induced fire and explosions. Preliminary tests demonstrated that the system fully protected a tank that would otherwise rupture catastrophically under identical test conditions.  Based on our design, a bread-board system was built and proof of concept tests were carried out. The measured reduction of the hydrodynamic ram effect was very significant.

The system can be used in all types of fixed- and rotary-wing military aircraft as well as certain ground vehicles.  Thus, it is of critical value to the Air Force, Navy, Army and their contractors.  Also, it has potential safety applications in the chemical and oil/gas industries.