Modelling flow induced AOD-converter sloshing by analytical considerations, numerical simulation and cold water experiments

Flow induced sloshing represents a severe problem in operating AOD converters since high dynamic torques are introduced into the foundation via the torque support. In the long run this could lead to unacceptable wear of the support bearings. During this study the phenomenon of flow induced sloshing has been studied by means of (a) analytic considerations, (b) cold water experiments and (c) numerical simulations. The first set of experiments is based on a rectangular tank model that is mounted on a set of load cells. If exited by a collapsing water column characteristic sloshing modes and frequencies can be detected. In this case it could be shown that all three investigation methods lead to very similar results with respect to the sloshing modes and the sloshing frequencies. In a second experiment the bath is excited by gas injection. In that case numerical simulations are not straight forward since they have to cover the gas plume behaviour as well as the unsteadily moving free surface. Thereby, it could be shown that while Reynolds averaged turbulence models fail in picturing sloshing even qualitatively a multi-phase large eddy model is able to resolve this type of gas injection induced sloshing. In a further modified experiment, the water tank is allowed to rotationally oscillate around one axis, in order to model the feedback of the vessel support system and possible resonance effects within the fluid-solid interactions. Based on the previously obtained results the mechanical eigenfrequency of the modified experiment could be adjusted in order to stimulate resonance between the vessel suspension and the fluid behaviour. In the course of ongoing experiments the occurrence of resonance oscillations is evaluated at different water levels and gas flow rates.