An experimental investigation "was conducted to evaluate the slosh-damping effectiveness of positive-expulsion bags and diaphragms in spherical tanks ranging in size from 9.5 to 32 inches in diameter. The scaling effects for sloshing forces and damping ratios "were determined for the butyl rubber positive-expulsion devices tested. The maximum slosh forces that occur at the first natural mode frequency increased with an increase in excitation amplitude and decreased as the diaphragm material thickness increased. The damping ratio (or logarithmic decrement) was found to he essentially independent of the excitation amplitude and increased with an increase in diaphragm material thickness. The second natural mode force peak and the fluid swirl at the natural mode frequencies, which were observed for the unrestricted liquid sloshing, were completely suppressed.
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