A hydrodynamic optimization design methodology for a ship bulbous bow under multiple operating conditions

Yu Lu,Xin Chang,An-Kang Hu

doi:10.1080/19942060.2016.1159987

Abstract

ABSTRACTThe main objective of this article is to describe an innovative methodology for the hydrodynamic optimization of a ship bulbous bow which considers multiple operating conditions. The proposed method is more practical and effective than the traditional optimization process, which is only based on contractually specified design condition. Parametric form approaches are adopted by employing an F-spline curve in order to generate variants of the hull bulbous bow forms using form design parameters modified, resulting in an optimization system based on improved genetic algorithms. The Rankine source panel method is used for the hydrodynamic evaluation, wherein non-linear free surface conditions and the trim and sinkage of the ship are taken into consideration. The validity and effectiveness of the proposed methodology for a large container ship is investigated by comparing the computational results with experimental data, which demonstrates that the proposed methodology can engage well in the automation process and improve hydrodynamic performance during actual ship design practices.

Highlights

With the increasing pressure of the rising cost of fuel and the strict Energy Efficiency Design Index (EEDI) controls on CO2 emissions, economical and environmentallyfriendly technologies are becoming more vital in the extensive field of ship design
A hydrodynamic optimization design methodology for the ship bulbous bow form taking into account multiple operating conditions including design and off-design conditions across a wide range of speeds has been implemented and applied
The transformation of the hull form is based on the parametric form approach by employing a fairness-optimized B-Spline form parameter curve – namely the F-Spline parametric curve – which results in form design parameters for use in the optimization system based on the non-dominated sorting genetic algorithm II (NSGA-II)

Summary

Introduction

With the increasing pressure of the rising cost of fuel and the strict Energy Efficiency Design Index (EEDI) controls on CO2 emissions, economical and environmentallyfriendly technologies are becoming more vital in the extensive field of ship design. Designers and shipyards are required to produce vessels according to draft and speed specifications which have superior hydrodynamic performance under calm water conditions (the contract condition), and the optimization of ship hull designs is a vital part of achieving this goal. From the perspective of the green economy, it is well worth optimizing ships to offer a superior performance for actual multiple load conditions within a set range of drafts and speeds to achieve reduced fuel consumption and lower CO2 emission simultaneously. A numerical solver and an optimization strategy constitute the integrated implementation of the hydrodynamic optimization design

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Conclusion