Numerical Analysis of the Pendulous Installation Method in Deep Water

2018 ◽  
Author(s):  
Zhicheng Hou ◽  
Liping Sun ◽  
Xiaomeng Zhu
Keyword(s):  
Numerical Analysis ◽  
Dynamic Response ◽  
Deep Water ◽  
Time Domain ◽  
Free Fall ◽  
Entire System ◽  
Environmental Loads ◽  
Wave Heights ◽  
Significant Wave Heights ◽  
Optimum Direction

This paper mainly studies the numerical analysis of the Pendulous Installation Method of a pump module in 1,500 meter water. A nonlinear time-domain coupled vessel and the pump installation system is established using ORCAFLEX riser program to simulate the pendulous free-fall motion of the pump module. The analysis studies the effect of environmental loads and vessel’s dynamic response on the entire installation system. Different directions of environmental loads and a series of sea-states defined using significant wave heights are taken into consideration. The results show that the optimum direction of the environmental loads is taken as 180 degrees (aganist vessel length), and the dynamic response of the vessel has a great impact on the entire system and should not be neglected.

An Idealization of Wave Scatter Diagram for Spectral Fatigue Analysis

2009 ◽  
Author(s):  
Min Han Oh ◽  
Ki Myung Lee ◽  
Young Sik Jang
Keyword(s):  
Fatigue Analysis ◽  
Scatter Diagram ◽  
Analysis Method ◽  
Sea State ◽  
Environmental Loads ◽  
Wave Data ◽  
Wave Measurements ◽  
Spectral Models ◽  
Wave Heights ◽  
Significant Wave Heights

A spectral fatigue analysis method is most popularly applied for the detailed design of FPSOs. As the environmental loads at the installation site are directly calculated in the spectral analysis, this method gives the most reliable results although it needs much time-consuming works to fully reflect the environmental loads. As the technology of wave measurements advances, the measured wave data increase. Also their spectral models are very complicated because these include many wave components such as swells and wind seas. Since much time and effort are needed to treat these enormous and complicated wave data for the spectral fatigue analysis, a rational idealization of wave data is definitely required. In this paper, wave scatter diagram at Offshore Nigeria was reviewed and their idealization method was proposed. The influence level of each sea state of the wave scatter diagram was identified considering the fatigue damage levels estimated from the significant wave heights and dominant fatigue load RAOs. The sea states giving small fatigue damages were lumped symmetrically by merging or disregarding while those giving large fatigue damages were kept as original. For the validation of this method, the comparisons of dominant fatigue loads and representative fatigue damages were presented for the idealized wave scatter diagram and the original one. From these comparison works, it was confirmed that the idealized wave scatter diagram gives reliable results with reduced amount of calculation work.

SIMULATION OF NEARSHORE WAVES AND CURRENTS ALONG SALALAH COAST (OMAN) DURING THE TROPICAL CYCLONE ARB01

2017 ◽  
Author(s):  
AbdAlla M. AbdAlla ◽  
AbdAlla M. AbdAlla ◽  
Abkar A. Iraqi ◽  
Abkar A. Iraqi ◽  
Magdy M. Farag ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
Domain Boundary ◽  
Circulation Model ◽  
Shielding Effect ◽  
Strong Current ◽  
Waves And Currents ◽  
Wave Heights ◽  
Nearshore Waves ◽  
Flood Period ◽  
Significant Wave Heights

Sea level and wave data at Salalah coast (Oman) were used to simulate nearshore waves and current during the tropical cyclone ARB01 (9 May2002). STWAVE model (Steady State Spectral Wave) was applied for nearshore wave simulation, while M2D model ((Two-Dimensional Depth Averaged circulation model) was used to simulate nearshore current. The results of simulations (taking into account the mutual effects of both current and waves) showed that: The significant wave heights generally decrease from about 6m at the domain boundary to about 1 m close to the coast. The wave heights during the ebb period were higher than that during the flood period by about 1.5m. Along Salalah coast, higher waves were found along the eastern side of the domain. This is because the shielding effect of breakwater, which protect the western part of the coast from high waves. Relatively Strong current with values up to 1.5 ms-1 were found in the nearshore region during both ebb and flood periods. The M2D model results also showed cyclonic circulations during these periods which help in the renewal of harbor waters. Generally, the model results showed good agreements with observations in the investigated area.

scholarly journals Sensitivity with Respect to the Path Parameters and Nonlinear Stiffness of Vibration Transfer Path Systems

2010 ◽  
Vol 2010 ◽  
pp. 1-11
Author(s):  
Yimin Zhang ◽  
Xianzhen Huang
Keyword(s):  
Dynamic Response ◽  
Time Domain ◽  
Evaluation Criteria ◽  
Nonlinear Stiffness ◽  
Vibration System ◽  
Transfer Path ◽  
Dynamic Sensitivity ◽  
The Time Domain

Generally speaking, a vibration system consists of three parts: vibration resource, vibration transfer path, and vibration receiver. Based on the dynamic sensitivity technique, this paper proposes a method for evaluating the contribution of each vibration transfer path to the dynamic response of the vibration receiver. Nonlinear stiffness is an important factor in causing the nonlinearity of vibration systems. Taking sensitivity as the evaluation criteria, we present an effective approach for estimating the influence of nonlinear stiffness in vibration transfer paths on the dynamic response of the vibration receiver. Using the proposed method, the sensitivity of the vibration system with multiple and/or multidimensional transfer paths could be determined in the time domain.

High Holding Power Torpedo Pile: Results for the First Long Term Application

2004 ◽  
Author(s):  
Jairo Bastos de Araujo ◽  
Roge´rio Diniz Machado ◽  
Cipriano Jose de Medeiros Junior
Keyword(s):  
Water Depth ◽  
Deep Water ◽  
Field Tests ◽  
Free Fall ◽  
Mooring System ◽  
Holding Power ◽  
Campos Basin ◽  
Anchoring System ◽  
Very High

Petrobras developed a new kind of anchoring device known as Torpedo. This is a steel pile of appropriate weight and shape that is launched in a free fall procedure to be used as fixed anchoring point by any type of floating unit. There are two Torpedoes, T-43 and T-98 weighing 43 and 98 metric tons respectively. On October 2002 T-43 was tested offshore Brazil in Campos Basin. The successful results approved and certified by Bureau Veritas, and the need for a feasible anchoring system for new Petrobras Units in deep water fields of Campos Basin led to the development of a Torpedo with High Holding Power. Petrobras FPSO P-50, a VLCC that is being converted with a spread-mooring configuration will be installed in Albacora Leste field in the second semester of 2004. Its mooring analysis showed that the required holding power for the mooring system would be very high. Drag embedment anchors option would require four big Anchor Handling Vessels for anchor tensioning operations at 1400 m water depth. For this purpose T-98 was designed and its field tests were completed in April 2003. This paper discusses T-98 design, building, tests and ABS certification for FPSO P-50.

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