Transient observation and numerical simulation study on the flow field of flyer driven by the electric explosion of metal foil

Electrical explosion of metal bridge foil can produce plasma with high temperature and pressure, which would shear and drive the insulation film to form a high-speed flyer. The impact initiation and ignition technology based on this process has been widely used in the initiation and ignition system of weapon. To address the deficiency in existing research regarding the description of the flow field evolution during the motion of flyer and promote the development of this technology towards efficient energy utilization and miniaturization, this paper constructs a double-pulse laser schlieren transient observation system. This system enables the acquisition of density distributions of the flow field and the motion distance of the flyer at different time. Additionally, a two-dimensional axisymmetric fluid dynamics calculation model and calculation method for the motion process of flyer driven by the electric explosion of metal foil are established, and corresponding numerical simulation calculations are performed. The simulation fully consider the evolution laws of the flow field inside and outside the acceleration chamber under the effects of the motion of flyer, the compression of shock wave, and the expansion of high-temperature and high-pressure plasma. The phase transition of bridge foil from solid phase to plasma phase is described by phase transition fraction, the state of plasma with high temperature and pressure is described by the state equation of plasma which consider the changes in particle number and coulomb interaction between particles, and the motion of flyer is described by dynamic grid model. The calculated flow field density distribution closely matches the experimental results, and the maximum errors in flyer motion distance and velocity are 6.1% and 8.1%, respectively, validating the accuracy of the calculation model and calculation method. The research results indicate that when the capacitance is 0.33 μF and the initiation voltage is 2800 V, within the research range, the maximum pressure in the flow field remains approximately at 1×10 7 Pa; the temperature in the flow field gradually decreases from 9950 K at 516 ns to 3100 K at 2310 ns; and the plasma phase distribution in the flow field gradually evolves from a flat shape to a long strip shape, with the maximum diffusion distance of plasma in the direction perpendicular to the motion of the flyer being 0.8 mm. After 1360 ns, due to the flyer breaking through the shock wave front, the front ends of the pressure distribution and temperature distribution in the flow field protrude.