Electromagnetic simulation and optimization of an electromagnetic launcher

Ceylan, Doğa
Electromagnetic launcher (EML) is an electromagnetic accelerator which uses electrical pulse power instead of conventional gunpowder. A large amount of electric current in the pulse waveform flows in the rails and armature. This current creates large magnetic field between rails. As a result of Lorentz force, armature and projectile accelerate. In this study, finite element (FE) model of an EML which includes both pulsed power supply (PPS) circuits with 2~MJ total electrical energy and barrel with 3~m length is developed. In the barrel side of the model, armature movement is simulated with stationary mesh elements using external variable resistances and inductances depending on the armature velocity, position, frequency of the excitation current and inductance gradient. In addition to the current density and magnetic field distribution in the barrel, alternating current (AC), contact, velocity skin effect and back electromotive force (EMF) resistances are investigated for the described switching scenario of the PPS creating pulsed shaped excitation current with 1~MA peak. Muzzle velocity of projectile and armature with 0.125~kg total mass is found to be 2040~m/s. Total muzzle kinetic energy and system efficiency are calculated as 260~kJ and 13%, respectively. Outputs of the electromagnetic simulations of the designed EML are verified with experimental results. Moreover, the effect of lamination thickness of the containment which supports the rails mechanically is observed. Although using containment in the barrel side is a requirement in order not to lose the contact between the rails and armature, it decreases the efficiency of the launcher because of the eddy currents in the conducting containment. It is concluded that using laminations thicker than 10~mm in the containment is not reliable from the electromagnetic point of view. Finally, armature shape optimization study is presented in the last chapter. The objective function of the optimization study is the muzzle kinetic energy of the projectile. Genetic algorithm (GA) is used as the optimization method. Maximum contact current density and electromagnetic deflection pressure on the armature are chosen as constraints. Since the contact resistance affects the distribution of the contact current density, it is also modeled as thin layers between the rails and armature with variable resistivities depending on the contact pressure values acting on each thin layer.


Smart sensing system for enhanceing reliability of power electronic devices used in wind turbines
Teay, S. H.; Batunlu, C.; Albarbar, A. (2017-06-01)
Reliability of modern power systems, in particular those use wind and solar energies, is affected by the relatively short lifetime of the associated power electronic converters (PECs). Thermal stress has been identified as one of the commonest causes for failures in PECs. However, existing thermal monitoring systems are expensive, bulky and with no intelligent capabilities, which limit their full acceptance as monitoring and control tools in operational power plants. This work presents autonomous and inexpe...
Electromagnetic Launcher Speed Control with a Multilevel Fast Triggering Time Algorithm (MFTTA)
Tosun, Nail; Polat, Hakan; Keysan, Ozan (2021-01-01)
Electromagnetic launchers (EMLs) can provide accurate speed control of a projectile compared to gun-powder based alternatives. However large-caliber launchers have several pulse power supply (PPS) modules connected in parallel to reach the required current levels. Determination of the triggering instants of these parallel PPS modules is a crucial part of the launch mechanism. The triggering instants does not only affect the exit velocity but also the forces on the armature which can lead to transition i.e. ...
Beam modulation in double gap virtual cathode oscillator
Küçük, İbrahim Semih; Demir, Şimşek; Department of Electrical and Electronics Engineering (2018)
Vircator is a promising high power microwave device when its simplicity, frequency tunability, lack of external magnetic field source are considered. Vircator gains importance especially susceptibility testing to electromagnetic pulses of electronic equipments with its tunability. Apart from advantages, main bottleneck of the vircator is its low efficiency. Tunability and efficiency enhancement studies are still continued in literature. Double gap vircator draws attention due to its tunability, generation f...
Energy scavenging from low-frequency vibrations by using frequency up-conversion for wireless sensor applications
Külah, Haluk (2008-03-01)
This paper presents an electromagnetic (EM) vibration-to-electrical power generator for wireless sensors, which can scavenge energy from low-frequency external vibrations. For most wireless applications, the ambient vibration is generally at very low frequencies (1-100 Hz), and traditional scavenging techniques cannot generate enough energy for proper operation. The reported generator up-converts low-frequency environmental vibrations to a higher frequency through a mechanical frequency up-converter using a...
Transient Modeling Techniques for the Analysis of Electromagnetic Launchers
Tosun, Nail; Keysan, Ozan; Department of Electrical and Electronics Engineering (2021-9-7)
Although electromagnetic launchers (EMLs) are better than gun-powder-based launchers, they have to endure severe electrical and mechanical conditions. Therefore, the optimal design and accurate simulations of these devices are essential. The inductance and electromotive force (EMF) variations in the transient, which significantly impact the launch process, are modeled. Moreover, velocity skin effect (VSE) is added to the EML calculations in an effective way. Commercial finite element software cannot solve t...
Citation Formats
D. Ceylan, “Electromagnetic simulation and optimization of an electromagnetic launcher,” M.S. - Master of Science, Middle East Technical University, 2018.