Study Of Second Order Response And Couple Analysis Of Tension Leg Platform

The ocean is rich in minerals,oil and natural gas.Along with the depleting of land resources and the developments of economic and social,people to put their sights of the ocean.As effective carrier operations at sea,offshore platforms have been paid more attention to.At the same time,with the increasing water depth of marine operations,people now focus on the research and innovation of deep-water and floating platform structures.Tension Leg Platform(TLP)has the semi-rigid and semi-compliant characteristics.It has an excellent motion response performance;easy handling and low-cost economy which make them get much of the attention and favor from marine engineering.In order to get better understanding on the hydrodynamic performance of tension leg platforms and improvement on independent research of new reserves TLP platform technology,this paper makes a numerical analysis of the TLP platform in first order,second order in frequency domain and couple in time domain.This paper is under the background of the hydrodynamic analysis on deep-water TLP platform also refers to the characteristics of the South China Sea marine environment.First of all,based on the potential flow theory principles,under the different algorithms,this paper makes some numerical analysis of TLP platform's hydrodynamic coefficients(added mass and damping)and wave loads in regular waves.Then discusses and determines the distributions of hydrodynamic coefficients and wave loads.At the same time,taking the impact of the tension leg system's additional stiffness into account,calculates and analyzes the six degrees of freedom motion response under the first order wave loads' effect;explores the distributions of TLP platform's motion response amplitude operation(RAO);and describes the effect of bi-symmetric features on first order motion response.And then,based on the result of analysis on the potential flow theory and perturbation method to derive the second order diffraction questions,this paper uses the numerical method to calculate the second-order difference-and sum-frequency wave loads of TLP platform and discusses the distribution of second-order wave loading.Under the effect of second-order difference-and sum-frequency wave loads,calculate the second-order motion responses of TLP platform;discuss the distributions and characteristics of the quadratic transfer functions(QTF)of motion responses in six degrees of freedom of TLP platform.Describe the relationship between bi-symmetric features and second order motion response of TLP platform.Finally,based on the time domain motion control differential equation,considered the interaction effect between TLP platform body,tension leg system,riser system,the coupled motion response's effect on TLP platform are studied numerically on various conditions: different sea conditions and different direction on wind,waves,currents,second-order difference,sum-frequency wave load.From the analysis of the numerical calculation,we can find that the wind and current loads are the dominant factors on the platform's horizontal offset;and wave load is the key of platform's reciprocating movement.