Date of Award

Fall 2006

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Mechanical Engineering - (Ph.D.)

Department

Mechanical Engineering

First Advisor

E. S. Geskin

Second Advisor

Denis L. Blackmore

Third Advisor

Bernard Koplik

Fourth Advisor

Pushpendra Singh

Fifth Advisor

R. S. Sodhi

Abstract

The work comprises experimental and numerical studies of generation and application of high-speed liquid projectiles. Numerical models were created for a projectile formation by two kinds of launchers, water extruder and water cannon. In the water extruder the kinetic energy of a fast moving piston is transferred to the water load and extrudes the load at a high speed. By contrast in the water cannon the water load itself accumulates the kinetic energy from the expanding combustion gasses. Then, in the course of water motion through the converging nozzle the energy is redistributed between head and tail of the projectile. This enables us to accelerate the front part of the water load to extremely high velocity which may exceed the speed of sound in the water. Inviscid, quasi-stationary model of water flow in the extruder was applied for investigation of the projectile generation in the water extruder. Unsteady 1 -D compressible and incompressible models of water flow in the water cannon were applied for the process investigation. Comparison of the result of application of compressible and incompressible models demonstrated that fluid compressibility and subsequently wave processes in the fluid do not contribute for the fluid acceleration. Thus, the acceleration is due to redistribution of the fluid momentum between different parts of a projectile. The numerical study also demonstrated the feasibility to attain the supersonic velocity in the course of acceleration in a converging nozzle. Of course this phenomenon is possible only for unsteady processes.

An experimental technique was developed and applied for online measurement of the projectile head velocity. The acquired experimental data validated the developed numerical technique. Because the attainment the velocity of 1750m/s was shown experimentally, while the sound speed in the water is 1500m/s, the possibility to reach the supersonic velocity in a converging nozzle was demonstrated experimentally.

The constructed numerical model was integrated into the Nelder-Mead simplex search optimization procedure provided by Matlab and used for evaluation of an optimal parameter of a launcher. Particularly, the possibility of the improvement of the nozzle design was shown.

Feasibility of material processing and explosive setups neutralization with high-speed liquid projectiles was studied experimentally using a water extruder and a water cannon. The series of experiments were carried out to evaluate peculiarities of deformation of ductile and brittle materials in the course of high-speed liquid impact. It was shown that while the depth of penetration into a ductile material is monotonously decreasing with increase of stand-off distance, the effect of stand-off distance onto penetration of brittle material has an extremal character. A series of experiments were carried out in order to investigate the demolition of brittle, deformation of ductile and neutralization of explosive material by the use of high-speed liquid projectile. The feasibility of the development of novel impact-based construction, manufacturing and demining technology based on the use of high-speed liquid projectiles was demonstrated.

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