ABS and DSME Offer New Sloshing Analysis Methodology for FLNG

Monday, March 21, 2011

(Houston, TX---)   Class society ABS and Korea’s Daewoo Shipbuilding & Marine Engineering (DSME) are concluding a one-year joint development program (JDP) examining critical wave conditions for sloshing model tests and computational fluid dynamics (CFD) in the cargo tanks of floating liquefied natural gas (FLNG) vessels.

The results will offer  the industry a new methodology to determine critical sloshing conditions more efficiently than in the past and the methodology promises to be valuable in reducing the cost and time duration for sloshing test campaigns.  

Designing for sloshing impact loads is a key concern in tank containment system design.  As the cargo tanks have increased in size along with various filling conditions for offshore FLNG operations, the possibility of severe sloshing becomes more likely as well as the probability of structural damage to the containment system.  The new ABS-DSME methodology is being proposed as a pre-screening procedure for selecting the most severe critical sea states before the start of a sloshing model test or sloshing flow simulation.  

“Model tests can not cover all possible wave height, period, heading and filling levels since there are just too many combinations to determine the life time maximum sloshing loads,” observes Yung Sup Shin, Head of the Containment System Group, ABS Corporate Technology.  “However, we have developed a robust way to determine a finite number of critical sloshing conditions consistently and efficiently compared to other existing methods.”
 
The methodology, explains Shin, consists of two main steps.  A sloshing pseudo-response amplitude operator (RAO) is defined based on the total sloshing wave energy and, secondly, the concept of sloshing severity is introduced based on the area under the sloshing energy response spectrum curve.  This highly advanced theoretical formulation represents ship motion and sloshing interaction calculating the energy of the liquid cargo in the tank.  

The numerical analysis of the fluid motion from this theoretical methodology has been validated by comparing the results to those from conventional sloshing tests for an FLNG cargo tank.

Shin points out that the validation is based on extensive sloshing model test data developed from a joint industry project (JIP) by DSME using Gas Transport & Technigaz (GTT NO 96) membrane containment system for an FLNG with a two-row cargo tank with centerline cofferdam arrangement.  ABS was a participant in this two-row JIP along with other class societies and energy majors.  

It is important to include any critical sea state in a sloshing test matrix, however, current state-of-the-art CFD codes have a limited value for evaluating the life time design sloshing pressures due mainly to the lack of computational efficiency.  Shin says the total sloshing wave energy and severity computation developed jointly by ABS and DSME provides an alternative to selecting relevant sea states in sloshing model testing and analysis.    

This new advanced numerical approach will join other methods of sloshing assessment developed over the past decade such as sloshing flow simulation techniques, scaling laws, fluid-structure interaction, corrugation effects on sloshing and partial filling operation.  

Shin says associated software to carry out the sloshing methodology for site specific offshore FLNG application is expected to be available in May.   

Founded in 1862, ABS is a leading international classification society devoted to promoting the security of life, property and the marine environment through the development and verification of standards for the design, construction and operational maintenance of marine-related facilities.   
 

Source: Eagle.org

Maritime Reporter March 2014 Digital Edition
FREE Maritime Reporter Subscription
Latest Maritime News    rss feeds

Shipbuilding

Newport News, ODU Partner for Bachelor's Degree Program

Huntington Ingalls Industries (HII) announced today that apprentices at Newport News Shipbuilding will now have the opportunity to earn a bachelor of science degree

Azeri Shipyard, BP Sign Vessel Construction Contract

Azeri state energy company SOCAR's shipyard and British oil major BP have signed a $378 million deal to design and build a subsea construction vessel for the Shah Deniz II gas project,

Fishing Vessels Fit with Wärtsilä’s NOx Reducer

Wärtsilä said its new NOx Reducer will be fitted to two new fishing vessels under construction at the Celiktrans yard in Turkey. The ships are owned by HB Grandi,

Maritime Security

Global Shipping Exposed to Cyber Threats

The next hacker playground: the open seas - and the oil tankers and container vessels that ship 90 percent of the goods moved around the planet. In this internet age,

CNR: Innovation Maintains US Naval Advantages

An interview with Rear Adm. Matt Klunder, U.S. Navy Chief of Naval Research What are your near term, mid-term and long term science and technology (S&T) objectives?

USS Taylor to Enter Black Sea

The U.S. Navy reported that the Oliver Hazard Perry-class frigate USS Taylor (FFG 50), homeported in Mayport, Fla., will enter the Black Sea April 22 to promote peace and stability in the region.

 
 
Maritime Contracts Maritime Security Naval Architecture Offshore Oil Pipelines Port Authority Salvage Ship Repair Shipbuilding / Vessel Construction Sonar
rss | archive | history | articles | privacy | contributors | top maritime news | about us | copyright | maritime magazines
maritime security news | shipbuilding news | maritime industry | shipping news | maritime reporting | workboats news | ship design | maritime business

Time taken: 0.1138 sec (9 req/sec)