Study On Seakeeping Performance Of Offshore Wind Turbine Installation Vessel

Self-elevating and self-propulsion wind turbine installation vessel (WTIV) is the main equipment for constructing offshore wind farm. To develop this new ship type, there are many key technologies should be solved such as ship motion response, ship grounding, bottom slamming, etc.This thesis is primarily focused upon motion response and environmental load of WTIV. First, hydrodynamic model of WTIV is built using AQWA software. Comparing the simulation result with WTIV model test data, the accuracy of theoretical method is verified. Then, the influence of some parameters on WTIV's RAO is analyzed by numerical calculations. Finally, based on the method of AQWA software applications, motion response of WTIV in different condition is simulated.Through analysis of motion response in time domain, minimum water depth of ship grounding in field transit condition is obtained. Parameters relevant to bottom impact on legs are calculated by using spectral analysis and extreme prediction method.In order to analyze the bottom slamming problem of offshore WTIV with special shape, this paper presents a computation procedure about slamming load of the vessel. Therein, the motion response in wave of the vessel is computed based on wave potential theory, time history of vertical velocity for 2D cross section during water-entry phase is handled by polynomial fitting method, and then slamming loads of the sections are numerically simulated according to computational fluid dynamic (CFD) method. Furthermore compared with experimental data, the accuracy of numerical algorithms for motion response and water entry is verified. Finally, by the present method the characteristic of bottom slamming for wind turbine installation vessel is studied.