Development of a fluid structure interaction tool for the study and prevention of transformer tank explosions

Oil filled transformers explosions and their prevention is a complex industrial issue. Experimental tests showed that when an electrical fault occurs in a transformer, it generates dynamic pressure waves that propagate in the oil. Reflections of these waves on the walls build up high static pressure which transformer tanks cannot withstand. The tank´s ability to withstand this pressure is thus one of the key parameters of transformer explosion prevention, and a numerical tool was developed to simulate the phenomena highlighted during the tests, especially the pressure wave propagation. The present paper´s aim is thus to complete this numerical tool so that the mechanical behavior of the tank can be accurately studied. The hydrodynamic numerical tool was subsequently coupled with a dynamic structure analysis package: the open source software Code_ASTER. A weak coupling strategy was first developed by applying the simulated pressures to the structure geometry in order to evaluate stresses and deformations. This strategy has evolved with the development of a strong coupling strategy which required establishing a moving mesh technique for the hydrodynamic code to accept displacement data from the structure code and complete the exchange between hydrodynamic and structure codes. First encouraging results are shown.