ABSTRACT

The objective of the proposed study is to investigate formation of the high-speed (>1000 m/s) water slugs. In the course of a performed research it was demonstrated that slug velocity is sufficient for deformation of brittle and ductile targets. The feasibility of such deformation was demonstrated experimentally. A launcher for formation of the high speed slugs, termed the water cannon, was designed and constructed. Water was accelerated by the powder combustion. Acceleration occurs in a specially designed barrel and nozzle. The performed experiments demonstrated a brute force developed at the slug-target interface. The impacting slug demolished reinforced concrete and pierced steel plates. Destruction of a target occurred at an extremely high rate. The impacting slug destroyed non-dischargeable explosive devices without an explosion due to the speed of the destruction. The performed experiments demonstrated that a high speed water slug is able to cause plastic deformation or fracturing of the most of engineering materials. However, precise control of the momentum transfer to the slug in the course of acceleration in the cannon barrel. The objective of the performed research is to determine the conditions of the slug formation and the water cannon design.

It was investigated experimentally and numerically the water acceleration which occurs in the course of the slug impact by the moving piston or products of powder combustion. A system of equations describing material flow in the course of slug acceleration was constructed and solved numerically. Two kinds of computational technique concerned with acceleration of a slug with and without of free surface were developed and used for process investigation. The fluid velocity and pressure in the course of slug formation were developed numerically. The validity of numerical results was demonstrated experimentally. The numerical technique includes solving a system of balance and constitutive equations for a flow without a free surface. At the presence of a free surface compression waive generated in the course of slug impact regardless of the nature of impact were converted into rarefaction waves as a free surface. These waves were converted into compression waves at the slug-piston or slug-combustion product interface. The compression waves reflected from the interface and generated during the flow through nozzle were converted into rarefaction waves at the free surface. Superposition of rarefaction waives in the front of the slug resulted in the slug acceleration. In order to evaluate pressure and velocity field in the fluid at the presence of flow discontinuities a finite-difference technique combined with characteristic method was used for numerical process description.

In order to demonstrate result of numerical analysis flow velocity at the exit the different standoff distances was measured. Laser transit anemometer and ballistic pendulum were used for velocity measurement. The result of measurement demonstrated high accuracy of the numerical analysis.

The expected applications of the developed device will include explosion-free neutralization of explosion devices, demolition and fracturing of different engineering materials, material forming. The developed numerical code and experimental technique will be used for other applications, such as design of needleless syringes and devices for eye medicine delivery.