An exploding foil overpressure actuator for multipoint synchronous initiation and mach reflection generation

Abstract

In this paper, two new forms (series-parallel and serial) of exploding foil overpressure actuators (EFOA) have been designed for the Mach reflection pressure studies and initiation of insensitive explosives at a small laboratory scale. These actuators, prepared with microelectromechanical system (MEMS) technique, can be in-situ integrated and mass-produced to reduce manufacturing cost. Electrical characterizations were carried out to obtained some important parameters, such as peak current and voltage, burst time and deposited energy, and the results revealed that the bridge foil of serial-type actuator has an earlier burst time and lower deposited energy than that of series-parallel one. Using an in-house built photon Doppler velocimetry (PDV), each flyer velocity history was measured separately, and the results indicated that the flyer speed of series-parallel actuator is higher, and its exit velocity consistency and time synchronicity are better than that of the serial ones. The flyers of two actuators exhibited a high level of integrity through the ultra-high-speed camera shooting. Based on the Lagrange hydrodynamic equation group, one-dimensional simulation was conducted by introducing the equation of state, discharging circuit equation and Joule heat equation to numerically simulate the whole process of actuator action. The simulation results are well agreed with the experimental ones both in electrical parameters of bridge foil and flyer velocity. Finally, the multipoint synchronous initiation of HNS-IV explosives was successfully achieved with the actuator. All the efforts demonstrated that the actuators are feasible and attractive.