Experimental and numerical study on the hydrodynamic loads on a single floating hydrocarbon storage tank and its dynamic responses. (1st July 2019) - Zhang, Chi
Abstract: An innovative floating hydrocarbon storage facility (FHSF) has recently been proposed. The facility consists of several modular floating hydrocarbon storage tanks (FHSTs) surrounded by floating barges with compliant mooring system. Hydrodynamic loads on the FHST and its dynamic response are important for the global design. To validate the concept of the single FHST, model tests at 1:48.7 scale is performed in the coastal basin in National University of Singapore. Two models of single FHST with different bottom slab shapes are tested, one of which has bottom skirts. The mooring fenders to support the model were mimicked by a flexible beam system. Fresh water is used to fill the tank at different filling ratios. Decay tests, regular wave tests and irregular wave tests under design sea states are performed. The rigid body motions in six degrees of freedom and the sum fender reaction forces were measured. Numerical model of the single FHST is established and analyzed in frequency domain and time domain. The effect of the bottom skirt, internal liquid, and the fender system were considered. Viscous damping is calculated based on the empirical formula and adjusted by comparing with measured results. Numerical results are comparative to the experimental results. This paper shows the motions of the tested FHSTs are mild even in the 100-year storm, and the bottom skirts effectively reduce the hydrodynamic responses. Highlights: Dynamic responses of a single Floating Hydrocarbon Storage Tank (FHST) with supporting fender system are verified small even in 100-year storm. Special designed bottom skirts can effectively reduce motions of the FHST by increasing both added mass and viscous damping. Nonlinear sloshing was found in the regular wave tests, but the influence of the sloshing is not significant in the tested random sea states. Numerical model in hybrid frequency domain and time domain compares well with the experimental results in design sea states.