Research On Load Characteristics Of Floating Platform In Polar Ice-water Mixed Environment

In recent years,with continuous global warming,the ice-snow cover area in the polar region has decreased sharply,which makes the development and utilization of various natural resources in the polar region possible.The offshore platform engaged in oil and gas development has increased in the polar region.However,ice load is an inevitable important factor when operation in such a harsh environment.Ice load is harmful to the offshore platform structure.Therefore,reasonable analysis of ice load is the key to structural design of polar offshore platforms.Floating platform,a typical offshore platform,has been widely used in oil and gas development due to its wide application range and strong drilling ability.The offshore platform will be subjected to wave attack and sea ice impact at the same time,when the floating platform operates in the ice edge area.Based on the secondary development of the fluid simulation software STAR-CCM+,this thesis studies the load characteristics of the floating platform when it operates in the typical environment of fully open water,broken ice and large ice sheet.The specific research contents are as follows:(1)Based on CFD technology,the VOF method is used to capture the free surface,and the finite volume method was used to solve the control equation to construct a three-dimensional numerical wave tank.In order to prevent the reflection of the incident wave,the damping term is added to the control equation.The floating platform is taken as the research object.The wave climbing effect around the platform is studied in detail.The influence of different wave length and wave steepness parameters on the wave climbing effect of floating platform is mainly analyzed.Moreover,the formation reason of edge wave and the distribution law of fluid velocity around the platform are also explained.(2)Due to the particularity of its working environment,the floating platform will suffer both ice load and fluid load during the whole service period,which poses a serious threat to its structural safety and overall performance.Therefore,the numerical calculation method of CFD-DEM coupling is adopted,without considering the crushing characteristics of ice,and the cylindrical discrete element is used to simulate the lotus leaf-shaped broken ice,so as to study the coupling response between floating platform,fluid and broken ice.In addition,the variation laws of ice breaking resistance and water resistance of floating platform with flow velocity and ice breaking density are discussed in detail.(3)Floating platforms will encounter different types of sea ice when operating in the ice region in different seasons.Therefore,the CFD-DEM coupling numerical calculation method is used to construct the extended polyhedral broken ice and flat ice model based on the discrete element model with bonding-breaking characteristics.The variation law of ice load on floating platform under the different flow velocity and the movement posture of polyhedral ice are analyzed.the influence law of sea ice bending fracture on load characteristics of floating platform is summarized...