| This dissertation is a report of a study of the physics of the generation of shock waves in water. This pressure wave is produced by rapid discharge of electrical energy in the form of an arc between two suitable electrodes within water. An experimental system was developed. More than two thousand tests were conducted. From these tests, a physical model was developed that shows how the electrical energy is converted to a volume of heated and pressurized water. A review of the literature led to the work of other investigators. The most useful information was a report showing measurement of the temperature and size of the arc. The model presented here shows the radial thickness of the highly pressurized and heated water around the arc to be less than ten thousandth of an inch. Further, most of the heat transfer to the water is by radiation.; From the model presented, a simplified analysis indicates that there should be a linear relationship between peak pressure and capacitor voltage. The experimental result is in general agreement with this aspect of the model. Further, a relaxation of pressure occurs as the time of the energy input is increased. If the peak current can occur in about one to two microseconds, the peak pressure can be above the Hugoniot Elastic Limit (HEL), which is the transition between elastic wave propagation and shock wave propagation.; The time to peak current is governed by the square root of the product of inductance and capacitance, and somewhat by the ratio of the resistance of the circuit to the critical resistance. Experimentally, a method was developed with an eight-microsecond period to the discharge cycle. The time to peak current is approximately one quarter of the period.; It is observed, for a given value of stored energy, shorter discharge period results in higher maximum peak pressure, and there appears to be an optimum electrode gap for maximum water pressure. The relationship between capacitor charged voltage and maximum peak pressure at fixed gap is about linear. |
