| Submarine booster system(S.B.S), an important oil and gas transportation device, has been found an increasingly wide utilization in deep-water oil and gas engineering. Offshore installation of S.B.S always encounters many problems, considering its large scale, heavy weight, ultra deep-water, etc. So it's extremely significant to carry out researches on marine operation of S.B.S. Based on the research named "Offshore Installation Technology of Submarine Mixed Transportation Booster System", this paper investigates engineering projects and academic achievements of offshore installation in the domestic and overseas.Aiming to install S.B.S successfully, Pendulous Installation Method(PIM) is selected for the solution. According to relevant numerical methods, time-domain simulation is performed for the entire marine operation.In the paper,hull wetted surface element model is established in AWQA, and parameters such as added mass, damping, wave forces can be obtained through frequency-domain hydrodynamic analysis. Based on the Fast Fourier Transform Algorithm(FFT), former results are transferred into the time-domain results,which is prepared for the following time-domain analysis. C++ program is written combining with PID control theory and Kalman filtering principle. Then, the program is packaged as a dynamic link library model and embedded into the interface of OrcaFlex, which is called to simulate the Dynamic Positioning System of the ship. The CFD theory is applied to establish a numerical tank model, upon which steady flow is simulated to calculate the drag coefficients of booster system. Besides, added mass coefficients are computed through forcing the facility oscillating in the tank model.Pendulous installation process is divided into two independent stages, lifting through the water surface and lowing to the seabed. By considering the shipping maneuvering equation,the cable equilibrium equation and the S.B.S's motion equation, the time domain multi-body coupling method is adopted to solve the problem. OrcaFlex is used to calculate S.B.S's motion response and cable tension of each stage, as well as make prediction of dangerous conditions during the offshore operation. Furthermore, the sensitivity to parameters of wave direction, wave height, current direction and speed is analyzed in details. The paper discusses the influence of environmental loads in the two stages respectively, and also makes helpful advices to the marine operation. In the end, some improvement measures such as adding a restraining cable or increasing diameter of the floaters are proposed, whose effects to offshore installation are verified in OrcaFlex. |
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