Numerical analysis of the shadow effect of an LNG floating platform on an LNG carrier under wind conditions

FDPSO is a multifunction floating platform, which has the combined function of drilling, production, storage and offloading oil. The moonpool is necessary for drilling operation and the moonpool size effect will play a role on the hydrodynamic performance of FDPSO. A study of the moonpool size effect on such performance of FDPSO hull is presented in this paper, making use of numerical analysis and model tests techniques. The code WADAM is used for the hydrodynamic performance analysis. A model test aiming to validate the accuracy of the numerical analysis results was conducted in the Ocean Engineering basin in the State Key Laboratory of Ocean Engineering in the Shanghai Jiao Tong University. The model test included decaying test and white noise test. The decaying tests are performed in still water for heave, roll and pitch. White noise tests were carried out to obtain the RAO of FDPSO, with the wave incoming direction of 180° and 135°. The numerical results show a good agreement with the model test results, indicating a reliable model. The “piston” motion of the water inside the moonpool is significant, affecting the hydrodynamic performance of the FDPSO. The effect of moonpool size on the hydrodynamic performance of the FDPSO is analyzed through a numerical method. The relationship between the piston natural frequency of the water column inside the moonpool and its diameter and draft, are studied. An empirical formula of the “piston” natural frequency is proposed, and its validity is assessed.

Download Full-text

Drag Analysis of Three Rudder-Shaped Like Bodies

Journal of Advanced Research in Fluid Mechanics and Thermal Sciences ◽

10.37934/arfmts.78.1.1122 ◽

2020 ◽

Vol 78 (1) ◽

pp. 11-22

Author(s):

Mohd Azzeri Md Naiem ◽

Eizul Hanis Omar ◽

Adi Maimun Abdul Malek ◽

Arifah Ali ◽

Faizul Amri Adnan ◽

...

Keyword(s):

Numerical Analysis ◽

Advisory Committee ◽

Body Shape ◽

Concept Design ◽

Floating Platform ◽

Unmanned Surface Vehicle ◽

Resistance Model ◽

Power Operation ◽

Drag Analysis ◽

Naca 0012

This paper presents an investigation of Rudder Shaped-Like (RSL) hull configurations with low-drag characteristic using the resistance model tests and numerical analysis. The new design of the floating platform using three hulls with a self-manoeuvring system as Unmanned Surface Vehicle (USV) and capable of collecting the same data as a hydrography boat is needed. This platform was designed with three hulls placed in a triangle position in the form of rudder shape and vertically placed as a slender body shape using National Advisory Committee for Aeronautics (NACA) 0012 profile. This provides the low-drag characteristic to USV. The results from the experimental and numerical analysis revealed that a larger configuration distance between three hulls leads to a reduction in resistance of the same speed. This result may help to accomplish the required concept design related to low-drag and minimum power operation.

Download Full-text

Installation of a Submerged Buoy for Supporting Risers (BSR) System in Campos Basin Site

Volume 1: Offshore Technology; Polar and Arctic Sciences and Technology ◽

10.1115/omae2011-50167 ◽

2011 ◽

Author(s):

Jairo Bastos de Arau´jo ◽

Jose´ Carlos Lima de Almeida ◽

Antonio Carlos Fernandes

Keyword(s):

Numerical Analysis ◽

Model Test ◽

Water Depth ◽

Water Model ◽

Floating Platform ◽

Mooring Lines ◽

Sea Bottom ◽

Campos Basin ◽

Steel Catenary Risers ◽

Field Location

The BSR (Buoy for Supporting Risers) concept is composed by a submerged buoy anchored to the sea bottom by tethers and intended to support risers coming from the bottom (probably SCRs — Steel Catenary Risers) and going to the floating platform (probably with flexible jumpers). For the case under analysis here, the main dimensions of the BSR prototype are 27.2 m length × 27.2 m width × 5.0 m depth. The paper describes all final full scale installation step so that the BSR may be considered a suitable technology. The installation indeed was the great challenge of this design due the size of the hull. The present work also evaluates numerically and experimentally a specific new manner to install the BSR with the support of auxiliary mooring lines among with the four tethers connected to it. One of the installation premises was to make use of Anchor Handling Supply Vessels instead of Crane Vessels. After this numerical analysis, the work went on by performing model tests that simulates the operation in a deep water model basin using 1:40 scale. The model test anticipated several problems such as the chain stopper weakness in the operation and others as discussed in this paper. As a conclusion the work was devised the most important parameters during the system installation and suggested ways to improve the methodology. In November 2009 the BSR was installed in 500 m of water depth at Congro field location, Campos Basin, offshore Brazil. The tethers were adjusted in January 2010 and in March 2010 two risers were installed. Thenceforward the last edge of this knowledge was considered over passed.

Download Full-text

Analytical and numerical analysis of the dynamics of a marine riser connected to a floating platform

Ocean Engineering ◽

10.1016/0029-8018(96)87670-0 ◽

1997 ◽

Vol 24 (2) ◽

pp. 111-131 ◽

Cited By ~ 26

Author(s):

A.S. Atadan ◽

S.M. Calisal ◽

V.J. Modi ◽

Y. Guo

Keyword(s):

Numerical Analysis ◽

Marine Riser ◽

Floating Platform

Download Full-text

A Shelved Structure for the Support of An Electron Optical Column

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100068825 ◽

1970 ◽

Vol 28 ◽

pp. 366-367

Author(s):

P.H. McLaughlin

Keyword(s):

Electron Source ◽

Floating Platform ◽

Supporting Structure

A shelved structure for the support of an electron optical column affords advantages both to the designer and the user. A lens may be removed for cleaning for example, without demounting the remaining lenses. A custom device for another example, may be placed on a shelf, substituting for the standard lens perhaps so that some specialized research may be undertaken. Especially advantageous is a shelved arrangement if the column assembly is designed to hang from a supporting structure such as a gas borne floating platform, as is the case with the system described below.As shown on the schematic, a floating platform (I) supports the electron source apparatus (2) and a U-shaped column support shelf (3). The column support shelf acts as a key for locating and supporting three struts (4) which with nuts (5) support the condenser shelf (6), the objective shelf (7), the upper projector shelf (8), and the lower projector shelf (9).

Download Full-text