| In today’s context,countries are increasingly investing in the exploration and development of oil and gas in deep sea areas.As a result,there are more than 1,000 old platforms with more than 4,000 tons of oil and gas in the global waters that need to be dismantled.Therefore,it is necessary to develop professional platform dismantling equipment.The object of this thesis is a new type of semi-submersible crane dismantling platform,whose main feature is the non-transverse brace asymmetric main hull structure.These platforms are capable of operating in relatively difficult sea conditions.In complex and changeable sea conditions,the platform is prone to be hit by violent waves,which often leads to the destruction of the platform structure and even endangers the life safety of the operators.Therefore,it is of great significance to explore the characteristics of the wave bang load of this type of platform and to study the intensity,distribution,characteristics and causes of the wave bang load under the ultimate sea conditions.In this thesis,STAR CCM+ Computational Fluid Dynamics(CFD)software is used to simulate the thud load of the platform under the condition of wave parameters under multiple working conditions.The influence of various factors on the platform wave thud load is explored,and the distribution of the ultimate thud load under various typical working conditions is determined.On this basis,the sensitivity factors affecting the platform column wave climb and their influence on the thud load effect are studied with the theory of wave climb effect.Specific research is as follows:Firstly,in recent years,the research status of platform bang load and wave climb related at home and abroad is summarized,and the research focus of the current calculation and three-dimensional numerical simulation of offshore platform bang load is understood.Secondly,the calculation conditions were selected and the mesh parameters used in the three-dimensional numerical simulation were verified.The results show that the mesh selected in this thesis reduces the number of grids by 76.76% on the premise of ensuring the accuracy,thus effectively reducing the load of the computer.Due to the asymmetry of the platform column,the air gap response of the platform under various operating conditions was analyzed,and the location of the negative air gap was found to be on the side of the hull.In this case,the bang location and load would be different from that of the traditional semi-submersible platform.Thirdly,under the action of different sensitivity factors(wave angle,wave height,wave steepness parameters,cross-section size of the column facing the wave,etc.),the slam load effect of the platform in regular and irregular waves is considered.It is found that the connection between the downstream column and the upper deck is prone to strong wave breaking bang.There is a positive correlation between the peak bang pressure and the span of the column on the wave side.It is worth noting that only when the wave steepness parameter is about 0.57 to 0.08,the bang load shows a linear increasing trend.Finally,based on the phenomenon of double wave peak and negative pressure intensity found in the study of the platform thud load effect,this thesis combines the change of water body around the platform column and the wave climbing effect with the study of the platform thud load effect to explore the relationship between the wave climbing effect of the platform column and the thud load.It is found that the column wave climb is most obvious at the position of the wave-facing surface: wave climb is positively correlated with wave steepness parameter KA and wave scattering parameter KR,and the area where the peak pressure of the upper deck bang occurs is usually accompanied by the mutual superposition of the nonlinear effects of water bodies such as side wave,wave breakage and vortex.In litigation,this article from the multiple perspectives analysis the research object on the basis of special shape,slamming load effect related features,the machine adopts horizontal brace asymmetric slamming load of the main hull structure platform on a more in-depth study of the distribution type platform considering the effect of slamming load influence during the design and practical use has a certain reference value and guiding significance. |
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