This cylindrical device generates pulsed pressures of ~100MPa amplitude at 5cms distance from the exploding wire location in radial direction. At close distances the pressures are still higher in amplitude. For the generation of pressure, the system needs to be loaded with wire between external electrodes and then is submerged in water and then a high voltage is applied into it.
The device is used to electrically explode the conducting wire of up to 11cm length of 250 micron diameter in underwater conditions. A pressure pulse is generated inside the water which decays with empirical law of (distance)-0.7 from the metal wire. The pressures at 5cm are expected to be ~100Mpa. At close distances the pressures are still higher in amplitude.The system is tested to be working in the saline water which has salinity level to that of near sea water. The discharge is done in sub-microsecond duration in order to mitigate any considerable shunting possibility of electrical energy through the water instead of desired path of the energy deposition. The dimensions are restricted to 115mm in radius and 1.6m in length for single shot application. The weight of the pressure wave generator without any external housing is 40 kgs. The wire is presently clamped between the nut-bolted output connections points which are accessible from outside of the system.
|4||Operating voltage||230V single phase|
|5||Input power||< 150 Watt|
|6||Discharge electrical energy||350 Joule maximum|
|7||Discharge time||Sub -µSec. (0.9µSec)|
|8||Wall Pressure (radial@5cm from wire)||> 80Mpa|
|9||Life||> 500 shots tested|
|10||System output diagnostics||
This pulsed plasma based pressure/shock wave generator offers advantages that it is electrically driven and highly efficient in terms of electrical energy. More over the System is compact and portable. The generator is high voltage insulated and can work in saline water also. The pressure generated are controlled which do not exceed the ultimate breakdown strength of steel but still beyond the plastics. The high pressures generated are confined in space near exploding conductor. So basic high voltage and high pressure safety is included in the designing and developing the shock wave generator.
The electrical energy is dissipated in to the metal wire which undergoes transitions from solid to liquid and then to the vapor state. In the vapor state, the resistivity and the rate of rise of resistivity is quite high as further energy is dissipated into the metal wire. This rapid rate of rise of resistivity causes the formation of high temperature high velocity expanding metal plasma which interacts through surrounding media for the generation of strong pressure pulse especially in underwater condition.