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Investigations into the effects of an arc discharge on a high velocity liquid jet

Technical Report ·
DOI:https://doi.org/10.2172/7298517· OSTI ID:7298517
High velocity liquid jets have been shown to be effective in removing rock in drilling and mining. The high pressures needed to accelerate the fluid to the required velocities are difficult to sustain at reasonable costs. The effect of an arc discharge on the stream of liquid is investigated to determine the value of the spark as an enhancement device. The primary effects investigated are the enhancement of the initial shock wave by the stream velocity, the water hammer from the inerrupted stream, the possibility of disruption of the arc by the jet, and the jetting into a collapsing cavitation bubble. All of the experiments are conducted at atmospheric conditions with an analysis of the effects of hydrostatic pressure on the system. The experimental apparatus is a 25 kV capacitive discharge system to develop the arc in a liquid with a jet passing between the electrodes. Pressures up to 20 MP/sub a/ (3 kpsi) that give velocities of 200 m/s (650 fps) are used in the experiments. The primary diagnostic techniques are piezoelectric pressure transducers, framing and streak cameras, and rock specimen damage observations. A definite enhancement in the rock removing capabilities is observed. Steady jets that will not erode a specimen become effective in rock erosion when disrupted by an arc discharge. The energy required by the arc discharge is much less than the amount required to comminute rock with the spark alone. Problems in operating an impulse type jet cutter at atmospheric pressure when the working fluid is not degassed are discussed.
Research Organization:
Sandia Labs., Albuquerque, NM (USA)
DOE Contract Number:
EY-76-C-04-0789
OSTI ID:
7298517
Report Number(s):
SAND-77-1135
Country of Publication:
United States
Language:
English