3D CFD-analysis of conceptual bow wings

• Main Author: Nielsen, Paul
• Format: Others
• Language: English
• Published: KTH, Marina system 2011
• Subjects: TECHNOLOGY; TEKNIKVETENSKAP
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-31072

As a small step towards their long-term vision of one day producing emission free vessels, Wallenius em-ployed, in 2009, Mårten Silvanius to carry out his master thesis for them in which he studied five different concepts to reduce the overall fuel consumption using wind powered systems. The vessel on which his study was performed is the 230 m LCTC vessel M/V Fedora. One of the concepts studied was the bow wing which is thought to generate enough force in the ship direction to profitably reduce the overall wind resistance. His calculations showed that the wing would be the preferred method of the different concepts studied since it was determined cheapest to build, had good payback, had good global drag reducing ef-fects and had a predicted performance of a reduction in fuel cost between 3-5% on a worldwide route.This thesis is conducted mainly to verify the results of Silvanius numerical study. The method chosen is to perform a fully viscous 3-D CFD study on the entire flow around the above water portion of the ship in full scale. A 3-D model is created and the wing is placed using suggestions given by Silvanius.One major limitation in this project was the computational capacity available at the time this thesis was conducted. In order to run some of the viscous grids created the grids had to be severely coarsened. This had a negative impact on the reliability on some of the results.Since it has been difficult to obtain satisfactory solutions, no work has been done to optimize the shape and position of the wing.Nevertheless, one it has been shown that the wing does in fact affect the resistance in a positive way, however nowhere near as much as predicted by Silvanius. This effect needs to be further determined through further calculations, both using CFD and also through experimental wind tunnel testing where alternatives to the wing profile should be tested, e.g. replacing the wing with a vortex generator to further delay the point of separation.