Bėgių tipo atvirojo kanalo elektromagnetinės svaidyklės magnetomechaninio efekto tyrimas

The dissertation investigates the electromagnetic launcher electromagnetic properties and their influence on mechanical construction. The main object of research is open bore two rail construction electromagnetic launcher. The dissertation aims to investigate the distribution of electromagnetic forces and their influence over the electromagnetic launcher construction volume. The work presents five tasks such as the electromagnetic and mechanical model application of the numerical model. The first task is formulated to rewiev the literature. The next two tasks are formulated to calculate the distribution of electromagnetic forces throughout the electromagnetic launcher construction volume. The last two tasks investigate the effect of the forces distribution differences over the electromagnetic launcher construction. The dissertation work consists of an introduction, four chapters, general conclusion, references, a list of publications by the author on the topic of the dissertation, a summary in Lithuanian and five annexes. The introductory chapter discusses the research problem, relevance of the work, introduces the object of the research, formulates the aim and the tasks of the work, describes the research methodology, scientific novelty of the work, considers the practical significance of the work results and defensive statements. At the end of the introduction, the publications and reports published by the author of the dissertation and the structure of the dissertation are presented. Chapter 1 is devoted to review the electromagnetic launcher analyses methods in literature. A brief overview of the adaptation and development history of electromagnetic launchers are provided. At the end of the chapter, conclusions are formulated, and the tasks of the dissertation are refined. Chapter 2 presents the structure and parameters of the electromagnetic launcher. According to this type of launcher, the electromagnetic and mechanical models were developed. The mathematical model of each modeling and boundary conditions are described, and the conclusions are presented. Chapter 3 and 4 provide the results of electromagnetic and mechanical modeling. The dependence between electromagnetic and mechanical problems are described. Conclusions are presented at the end of both sections. 4 articles have been published on the topic of the dissertation in the scientific journals included in the Clarivate Analytics Web of Science list, one article is in conference materials in the Clarivate Analytics Web of Science Proceedings database, and two is in peer-reviewed international conferencing materials. 4 presentations on the subject of the dissertation have been given in conferences at national and international levels

Feasibility of intercalated graphite railgun armatures

Graphite intercalation compounds may provide an excellent material for the fabrication of electro-magnetic railgun armatures. As a pulse of power is fed into the armature the intercalate could be excited into the plasma state around the edges of the armature, while the bulk of the current would be carried through the graphite block. Such an armature would have the desirable characteristics of both diffuse plasma armatures and bulk conduction armatures. In addition, the highly anisotropic nature of these materials could enable the electrical and thermal conductivity to be tailored to meet the specific requirements of electromagnetic railgun armatures. Preliminary investigations were performed in an attempt to determine the feasibility of using graphite intercalation compounds as railgun armatures. Issues of fabrication, resistivity, stability, and electrical current spreading are addressed for the case of highly oriented pyrolytic graphite

The LeRC rail accelerators: Test designs and diagnostic techniques

The feasibility of using rail accelerators for various in-space and to-space propulsion applications was investigated. A 1 meter, 24 sq mm bore accelerator was designed with the goal of demonstrating projectile velocities of 15 km/sec using a peak current of 200 kA. A second rail accelerator, 1 meter long with a 156.25 sq mm bore, was designed with clear polycarbonate sidewalls to permit visual observation of the plasma arc. A study of available diagnostic techniques and their application to the rail accelerator is presented. Specific topics of discussion include the use of interferometry and spectroscopy to examine the plasma armature as well as the use of optical sensors to measure rail displacement during acceleration. Standard diagnostics such as current and voltage measurements are also discussed

Modeling of the armature-rail interface in an electromagnetic launcher with lubricant injection

In electromagnetic launcher (EML) systems, the behavior of the materials and forces at the armature-rail interface involves fluid mechanics, electromagnetics, thermal effects, contact mechanics and deformation mechanics. These factors must interact successfully in order for a launch to be successful. A lubricant film either deposited on the rails prior to launch or injected from the armature during launch has been suggested as a means of improving the electrical conductivity of the rail-armature interface and of avoiding the occurrence of arcing. The fluid pressure generated by such film, together with the magnetic force, the contact force and the uneven temperature field in the armature, deforms the armature and changes the interface gap shape. An analytical model to study the interfacial behavior under these influences is necessary in order to predict the performance of a potential EML design and to provide optimization information. Studies of this interfacial behavior have been done by a number of researchers. However, many critical factors were not included, such as surface roughness, cavitation, injection, magnetic lateral force, interface deformation and thermal effects. The three models presented in this study investigate the influence of those factors on the EML interface problem. The magneto-hydrodynamic (MHD) model establishes a description of the lubrication process under electromagnetic stress but neglects interface deformation. The magneto-elastohydrodynamic (MEHD) model extends the MHD model by considering the lateral magnetic force, interface contact force and elastic deformation. Finally, the magneto-elastothermohydrodynamic (METHD) model adds the thermal effects to the deformation analysis. A coupled analysis of the interface behavior with the METHD model is developed and the history of a typical launch is studied. Detailed injection, lubrication and launch processes are revealed and the performance is predicted. A failed launch is simulated and the cause of failure is identified to be debris left on the rails. Several operation and design parameters, such as rail surface profile, electric current pattern, reservoir load, lubrication length, pocket size and geometry, injection conduit diameter, are analyzed and a recommended injection design procedure is developed. A scaling study is performed by doubling the dimensions to predict the scaling effects. In the end, the base case configuration and scaled configuration are optimized using the technique developed in this study.Ph.D.Committee Chair: Salant, Richard F.; Committee Member: Bair, Scott; Committee Member: Cowan, Richard S; Committee Member: Danyluk, Steven; Committee Member: Scott, Waymond