Effect of the Electrode Immersion Depth on the Development of Pre-Breakdown Flows in Distilled Water

An experimental and numerical study of the velocity field in distilled water occurring at the pre-breakdown stage when a voltage pulse is applied to the electrode-needle at different immersion depths has been carried out. The results obtained are analyzed in terms of the extremum (maximum) of the flow velocity achieved in the observation area in the immediate vicinity of the high-voltage electrode. Satisfactory agreement between the experimental and numerical time dependences of the velocity extremum and the calculation is obtained. It is shown that the maximum velocity in the emerging flow is achieved at later times with increasing immersion depth. A decrease in the immersion depth leads to an electric discharge when the high-voltage electrode loses contact with water because of the flow occurring near it. The studies performed show the further direction of the development of the constructed physical and mathematical model.