Numerical Models for Interactions of Ablating-Capillary Plasma With Air and Bulk-Loaded Liquid

The jet expansion behaviors of ablating-capillary plasma used in the liquid propellant electrothermal chemical gun were investigated. A pulsed power system was built up to drive the arc plasma generator by high-voltage discharge in polyethylene capillary. The temporal evolutions of the arc plasma jet in both open air and bulk-loaded liquid were analyzed with high-speed imaging and dynamic pressure measurements. The arc plasma jet exhibited rapid axial expansion and strongly turbulent mixing with the ambient fluids. Experiments conducted with different discharge voltages showed that the voltage had a significant effect on the axial expanding speed of the arc plasma jet. A 2-D magneto-hydrodynamic model, which consisted of several submodels, such as the capillary ablation model, the species ionization model, the high-temperature radiation model, and the turbulent model, was developed to describe the generation and evolution of arc plasma jet. Good agreements between calculations and experiments in the aspects of jet contours and pressure histories indicated that the current model had the capacity to capture the major physical features of the ablating-capillary arc plasma jet.