Pressure Fields Repeatability at Electrohydraulic Pulse Loading in Discharge Chamber with Single Electrode Pair

Abstract

The paper is devoted to improvements in technology of electrohydraulic impact forming (EHF) via investigation of stability of high-voltage underwater discharges and pressure fields they generate along surface of a sheet blank. The experimental research is held with use of conical discharge chamber equipped with one pair of electrodes. Measurements of pressure fields along round flat area are based on application of multi-point membrane pressure gauge (MPG). The tests conditions include wide range of spark gaps with four levels of charge voltage and energy. The investigation results showed strong influence of geometric parameters of discharge work volume and electric parameters of discharge circuit on repeatability of pressure fields. The spark gap value should be in severe correlation with distance to a sheet blank and dimensions of a loaded area. Parameter “normalised spark gap” is proposed for determination of geometric characteristics of discharge volume. The results confirm the validity of charge voltage-to-spark gap ratio of 1 kV/mm recommended for approximate setting the gap in order to ensure high pressure generation. This ratio is also good for repeatability of pressure fields and can be also expended. The factors that influence the stability of discharge parameters, shock wave generation and pressure fields are analysed.