Modeling and simulation of muzzle flow field of railgun with metal vapor and arc

The blowback caused by the separation of rail and armature at muzzle is an important factor for the degradation of bore insulator. A small caliber launcher was modified by the transparent material of polycarbonate for capturing the process of blowback in inner bore with a high-speed camera. Three groups of experiments with the same peak linear current density and various muzzle currents were carried out. Nesting insulator samples were used to reduce the measurement error in cutting samples after experiments. Insulation performance of postshot samples was conducted from surface morphology, surface flashover voltage, and partial surface conductivity. Results show that the effects of blowback are related to muzzle current. With the increases of muzzle current, the average flashover voltage of samples in the region of 300–600 mm (600–900 mm) decreases from 9.98 kV/cm (5.37 kV/cm) to 3.59 kV/cm (3.01 kV/cm). Moreover, the number of samples that the flashover voltage is less than 9 kV/cm (half value of the original samples) increases from 7 to 12, which indicates that the damage area caused by blowback is gradually expanding with the muzzle current. Correspondingly, the partial surface conductivity of samples in 300–900 mm region increases with muzzle current. The increase of surface conductivity should be the main reason for the sharply decrease of surface flashover voltage.

Muzzle Blowback and Its Effects on Degradation of Bore Insulator

Numerical investigation of a muzzle multiphase flow field using two underwater launch methods

This article has designed a 200-kJ pulsed power system (PPS) for electrothermal-chemical (ETC) guns to be installed in combat vehicle. The PPS consists of a pulse-forming network, a primary power, a high-voltage (HV) charger, and a remote control system. Two independent 100-kJ pulsed power units (PPUs) are integrated in a compact frame to build the pulse-forming network. A charging system consisting of a primary power and a 30-kW charger charges two PPUs simultaneously, and it is also integrated into the PPS. In each PPU, a pulse capacitor, a semiconductor switch stack, an inductor, a dump device, and a data acquisition system are integrated. The PPU is designed to achieve a peak output current up to 30 kA at a maximum charging voltage of 10 kV. After all the subsystems are integrated, the equivalent experiments are carried out with resistive load. The experimental results show that the PPS can flexibly adjust the output current waveform to meet the application requirements. The design ideas and results in this article have engineering application value in improving the performance of a PPS-based ETC launch system.

Development of a 200-kJ Capacitive Pulsed Power System for Vehicular Electrothermal-Chemical Launcher

The electromagnetic railgun is a new concept weapon with the hypersonic launch capability. During the railgun launch process, the armature is accelerated along the rails. A complex and high-speed flow field occurs in the muzzle area when the armature leaves the barrel. Meanwhile, the muzzle temperature will be very high because of the secondary arc and friction. In this paper, an analysis of the railgun muzzle fluid flow field after the armature left the barrel is presented, and a three-dimension numerical model for arc plasma is obtained based on the electromagnetic and hydrodynamic equations. The aerodynamic simulation method with moving boundary is adopted to deduce the boundary conditions of the arc model, where the coupling model and the dynamic meshing method are applied. In addition, the backflow phenomenon is considered in the arc model. The distributions of the temperature and the velocity near the muzzle are computed, especially for the dynamic distribution of the arc plasmas. As we can see from the results, the plasma near the muzzle expands outward when the armature leaves the barrel, and most of the plasma will flow back to the bore in a short time. The existence of muzzle plasma may aggravate the erosion and aluminum deposition, which will lead to negative effects on the launcher’s lifetime.

Simulation and Analysis of the Railgun Muzzle Flow Field Considering the Arc Plasma

Method of ballistic control and projectile rotation in a novel railgun

Preload force is an essential factor to maintain good electrical contact between the power connector and plasma injector in electric thermal chemical (ETC) launch. In order to obtain the minimum preload requirement of the coaxial power connector, a calculation model considering contact resistance and electromagnetic repulsion force was established. Simulation results, such as the contact surface force distribution and the forces on the power connector anode and cathode were obtained and discussed. Results show that the electromagnetic repulsion force is the primary component of preload force. It is accounted for approximately 98.7% of the total preload at 210-kA peak current. Furthermore, the force mainly focuses on the outer range of the contact surface due to skin effect. Moreover, the conclusion was confirmed by a set of comparative experiments.

Yingtao Xu

Papers

Modeling and simulation of muzzle flow field of railgun with metal vapor and arc

Simulation and Analysis of the Railgun Muzzle Flow Field Considering the Arc Plasma

Method of ballistic control and projectile rotation in a novel railgun

Study on the Preload of Coaxial Power Connector in ETC Launch

Research on momentum transfer in simple railgun