Papers by Nico van der Kolk
This paper deals with the hydrodynamic sideforce production of a wind-assisted ship. The subject ... more This paper deals with the hydrodynamic sideforce production of a wind-assisted ship. The subject is introduced in physical terms, and the importance of the hydrodynamic sideforce is established, before classical models are reviewed. Finally, the complications arising from diverse appendage topologies are discussed, and a theory for zero-aspect ratio lifting surfaces is discussed. The paper concludes with a short summary of ongoing work.
Published in: SWZ|Maritime, Jaargang 137, Januari 2016, 2016
Experimental results for the sailing performance of ships fitted with bilge keel appendages are p... more Experimental results for the sailing performance of ships fitted with bilge keel appendages are presented. Sailing performance is synonymous with manoeuvring forces for the steady drift condition, i.e. increase in resistance, lateral force production, and yaw moment for leeway (drift) angle. Systematic variations in appendage height, length, and position are tested, including several special cases. The appendage typology is shown to mitigate the strong 'destabilizing' yaw moment that is characteristic for wind assisted commercial vessels and to promote the non-linear sideforce component. The entire data set, including all derived quantities and details for the uncertainty assessment, is made available to support ongoing research and eventual commercial uptake for wind-assist ship propulsion.
Wind-assisted ship propulsion is under study at the Delft University of Technology. This alternat... more Wind-assisted ship propulsion is under study at the Delft University of Technology. This alternative propulsion is gaining attention due to increased concern for the environment. For designers who are considering the potential benefits of this new option, a well-founded performance prediction tool is a key prerequisite. Together with Politecnico Milan, the TU Delft is developing such a tool, which will allow for inexpensive assessment of wind-assist concepts using regression based force models. Reynolds-Averaged Navier Stokes (RANS) simulations will be a primary tool during this study. The advent of the numerical towing tank brings possibilities but also new challenges. The predominance of large, separated flow structures in the wake of the sailing ship, and the particular interest in the lateral force generation of the hull, points to a conscientious grid verification study. Here, it is sufficient to achieve parity among uncertainty contributions within the larger context of the project. Diverse procedures are available for evaluating the numerical uncertainty of a RANS simulation. Principal methods were defined and implemented for verification cases at leeway angles of 0, 9, and 20 degrees. The uncertainty for lateral force at 9 degrees leeway for the base grid (2E6 cells) was estimated to be 8.3%.
SUMMARY This paper deals with the hydrodynamic sideforce production of a wind-assisted ship. The ... more SUMMARY This paper deals with the hydrodynamic sideforce production of a wind-assisted ship. The subject is introduced in physical terms, and the importance of the hydrodynamic sideforce is established, before classical models are reviewed. Finally, the complications arising from diverse appendage topologies are discussed, and a theory for zero-aspect ratio lifting surfaces is discussed. The paper concludes with a short summary of ongoing work.
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Papers by Nico van der Kolk