Investigation On The Hydrodynamic Analysis Of 27000 Cube Meter' LNG-FSRU

In this paper,the hydrodynamic analysis is studied on a 27000 cube meter' LNG-FSRU(liquefied natural gas floating storage and regasification unit).The hydrodynamic analysis is carried out on typical loading conditions by the software “HYDROSTAR”.The RAOs including ship motion,the relative elevation and internal load was carried out.Short term analysis corresponding to 100 year return period was also performed with the expected wave spectra and environmental conditions in order to provide extreme responses for structural strength analysis.The hydrodynamic analysis with sloshing effect is studied through the method of dynamic coupling of seakeeping and sloshing.The RAOs of ship motion is also obtained after considering the effect of sloshing of cargo tanks.Comparison and analysis is performed on the ship's motion with and without considering sloshing effects of tank liquid.The analysis on the effect of sloshing shows that apparently differently from the main response in roll for the single row arrangement of cargo tanks,two rows arrangement of cargo tanks result in less effect in roll,but mainly in surge and sway.The shifting between the response frequencies and the natural frequencies of cargo tanks increases with the increasing of the filling level of cargo tanks.Short term analysis on dynamic pressure in tank is also performed with the expected wave spectra and environmental conditions in order to get the extreme responses.Distribution of dynamic pressure in tank is finally worked out for further analysis of structural strength of the cargo tanks.The analysis shows that the distribution of dynamic pressure in tank has much to do with the filling level of the cargo tanks.The order ranked on typical loading conditions as per the maximum dynamic pressure at free surface is not completely consistent with which ranked in accordance with the response of the ship motion with considering sloshing effects of tank liquid.Sloshing effect is most onerous at the low filling level about 10%.