Design and Performance Evaluation of Superstructure Modification for Air Drag Reduction of a Container Ship

Abstract

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License(http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.Reduction of the fuel oil consumption and corresponding greenhouse gas exhausted from ships is an important issue for today's ship design and shipping. Several concepts and devices on the superstructure of a container ship were suggested and tested in the wind tunnel to estimate the air drag reduction. As a preliminary performance evaluation, air drag contributions of each part of the superstructure and containers were estimated based on RANS simulation respectively. Air drag reduction efficiency of shape modification and add-on devices on the superstructure and containers was also estimated. Gap-protectors between containers and a visor in front of upper deck were found to be most effective for drag reduction. Wind tunnel tests had been carried out to confirm the drag reduction performance between the baseline(without any modification) configuration and two modified superstructure configurations which were designed and chosen based on the computation results. The test results with the modified configurations show considerable aerodynamic drag reduction, especially the gap-protectors between containers show the largest reduction for the wide range of heading angles. RANS computations for three configurations were performed and compared with the wind tunnel tests. Computation result shows the similar drag reduction trend with experiment for small heading angles. However, the computation result becomes less accurate as heading angle is increasing where the massively separated flow is spread over the leeward side.

Numerical simulation of container ship in oblique winds to develop a wind resistance model based on statistical data

“…In this section, CFD simulation results of the four scenarios -flat surface, image method, rounded base plate, and turntablefor drag force, side force, and yawing moment coefficients are compared with experimental data from Williams et al (2006), Blendermann (Maciejewski and Osmólski 2002) and Kim et al (2015). As can be observed, simulation results for scenarios 1 and 3 are very close to each other.…”

“…In comparison to the test data from four different sources, it is observed in Figure 16(a-c), that scenarios 1 and 3, where the sea surface was represented by a flat extended plane, overestimate the experimental results, while scenario 2 shows higher conformity to the experimental results. One may question the difference in results from scenario 3 and its experimental counterpart (Kim et al 2015). The reason may stem from surface roughness and turbulence phenomena, which are not identical between the physical and numerical models.…”

“…As can be observed, simulation results for scenarios 1 and 3 are very close to each other. The reason is that both scenarios model the sea surface as a stationary extended plane; the only difference is that scenario 3, which mimicked the wind tunnel test in Kim et al (2015), had a rounded front. Scenario 2 which is the innovative image method shows quiet close similarity with the Andersen's test results.…”

“…A series of experimental tests were performed by Kim et al (2015), a group of researchers in Korea Research…”

“…Institute of Ships and Ocean Engineering, on the container ship with 5000 TEU capacity in the wind tunnel in order to investigate the effect of wind load and possible drag reduction. Subsequently, they compared the test results with CFD (Kim et al 2015).…”