Generation and Propagation of Pressure Wave by Spark Discharge in Liquid

Abstract

This paper deals with the energy conversion processes as the basic phenomena in underliquid electrical discharge forming. Based on precise observation of electrical and mechanical phenomena, a model is proposed for the process in which the electrical energy released in the electrode gap is converted into the internal energy, the radiation energy of the bubble and the energy of the pressure wave in turn. The validity of the model is discussed with both the pressure wave measured by the device of special design and the electrical energy. It is shown that the pressure level, the size and the possible temperature of the bubble and the form of pressure wave in liquid can be reasonably evaluated by the model in the case of a shorter electrode gap. In the typical electrode gap, the maximum value of the pressure, that of temperature and that of expansion velocity are 2.8×10 2 MPa,8.7×10 4 K and 160 m/s, respectively. The size of the bubble at the end of the first wave of discharge power is 2.2 mm in radius. The results present the basis for the analytical design of the system of underliquid electrical discharge forming.