Study On Hydrodynamic Characteristics And Optimization Of Heave Plates Of Deep Sea Truss Spar Platform

With the improvement of technology and human society,the demand for energy is becoming more and more prominent..However,as the resource of land gradually drains away,the development of oil and gradually move to the deep sea, the hydrodynamic problems faced in the design and production process are more complex than in shallow water. The petroleum has a huge storage in the South China Sea, but at present, the petroleum development the deep waters of the South China Sea has not yet form a large scale and lack of independent key technology. Spar platform is such a floating platform suitable to the development of the deep sea of the south China sea in economy.and the study of Spar platform has become a hot issue.This study adopts a Truss from Spar platform serving in the gulf of Mexico as the numerical simulation model and the Marine environment parameters adopt the South China sea condition,the numerical simulation and theoretical analysis to analyze the hydrodynamic performance of the platform in the frequency domain and time domain and the changing structure of heaving plate movement characteristics are studied.The classification,development, performance,and structural characteristic of Spar platform are introduced firstly in this essay,emphasizing the advancement of Spar platform at home and abroad.Geometry parameters of the platform in the essay are shown and inputted into FEM software ANSYS to setup its three dimensional model which is imported into hydrodynamic analysis software AQWA. Center of gravity and rotational inertia is defined in AQWA-LINE module to obtain the added mass, added dampness, wave excitation force and response amplitude operator (RAO) of the platform under different frequency waves. The analysis shows that the platform is healthy under working conditions.Then respectively to simulate the time-domain motion characteristic of the platform under extreme environmental conditions, as well as the mooring line tension with a single cable breakage under extreme environmental condition, the results show that the platform motion responses and mooring tension are within the scope of the safety, and the structure is security.Finally,the study explores the influence of the heave plate structure on the platform movement.Firstly,comparing the hydrodynamic characteristics of the heave plate and the solid borad plate,the result shows that the openings of the heave plate can reduce platform heave response.Then selected six different platform opening ratios to do the frequency-domain and time-domain hydrodynamic comparison, summes up the hydrodynamic parameters with the variation of the opening ratios, the optimal opening ratio was about 5%.Based on this, the influence of the number of the opening holes on the motion of the platform is further considered.Selected the pening ratio at 5%,law indicated that the trend of the platform movement response changes little.In order to simplify the construction process,a hole heave plate can be considered.This provides a reference for the design of Truss Spar platform in the future.