Role of Transverse Baffle Designs on Transient Three-Dimensional Liquid Slosh in a Partly-Filled Circular Tank 2005-01-3594

Transient fluid slosh within a partly-filled tank could impose high stresses on the tank structure and affect the directional performance in an adverse manner. A three-dimensional nonlinear model of a partly filled circular cylindrical tank with and without baffles is formulated and analyzed to derive the pressure distribution over the wetted tank surface. The baffles and end caps are modeled with curved shapes in accordance with the current standard. The analyses are performed for 40% and 60% fill volumes and different types of baffles, including single-nozzle and multiple-orifice baffles, using the FLUENT software under time varying acceleration fields representing simultaneous braking and turning maneuvers. The pressure data are further analyzed to evaluate steady-state and transient slosh forces, load shifts along the longitudinal and lateral axes, and the roll, pitch and yaw moments imposed on the tank structure. The significance of destabilizing forces and moments caused by transient fluid slosh is particularly emphasized. The results attained for the cleanbore tank suggest that the steady-state slosh forces and moments are comparable to those estimated from the widely used kineto-static fluid motion, while the transient forces and moments could approach twice the corresponding steady-state values. The results further show that baffles play an important role in reducing not only the magnitudes of longitudinal slosh force but also the lateral load shift and slosh force, and roll, pitch and yaw moments. The use of multiple-orifice baffles could reduce the roll moment amplification factor to 1.45, while this factor attains the magnitude in the order of 1.85 for the cleanbore tank under similar conditions. The fundamental frequencies of fluid slosh within cleanbore and baffled tanks are further investigated as functions of the fill volume and intensity of the acceleration fields.