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Modélisation des Effets de Boucles d'Immunisation dans les Navires

Abstract : This thesis présent the computatior.of degaussing coils effects in ships by die finite cléments method. The degaussing System is cornposed of electrical circuit the liull to compensate the magnelic anomaly generated by me vessel in the eanh's magnetic field. The difficuiiy is the shori distance between the coil and die ferromagnetic sheets. The magnetization of thesi sheets is sa localized that it can be correctly caleulated only by using an extrême fine mesh. Without spécial numerical tool, this modelling is expensive, and may be unrealisable in a real case. A new technique, called the reduced scalar potential jump method is proposed to solve die problem. Physically. me coil effecton a sheet générâtes a quasi disconlinuity of die reduced scalar potential which is the mean unknown of the System and represents die reaction of die ferromagnetic material. Taking into lunt die disproportion between die sheet dimensions and die distances coil-sheet, this local effect can be considered as a bidimcnsicnal problem and calculated by a simple analytical or numerical method. The potential jump so computed is imposed in die whole diree-dimensional rnodelling as a constraint on the nodes of die sheet near die coil. The différent numerical validations reveal very satisfying results on simple geometries, and promising resulls on a complex geometry, nearer to a real ship. The gain in terms of computation time and nodes number is significant, compared to the modelling using a very fine mesh. The expérimental results reveal die reliability of die used mathematica! models and the linear behaviour of die ferromagnetic materials under me coils effect So it is useless to take die hystérésis into account in the gênerai rnodelling of degaussing coils, and especially in the calculus of die potential jumps.
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Submitted on : Wednesday, July 18, 2012 - 11:53:20 AM
Last modification on : Thursday, November 19, 2020 - 1:00:08 PM
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  • HAL Id : tel-00718819, version 1



Fabrice Le Dorze. Modélisation des Effets de Boucles d'Immunisation dans les Navires. Energie électrique. Institut National Polytechnique de Grenoble - INPG, 1997. Français. ⟨tel-00718819⟩



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