Numerical Simulation Of The Wake Field Of A Merchant Ship With Different Appendages

The reducing of the energy consumption of full ships is a widely concerned issue in theshipbuilding and maritime industry since most of the commercial ships are of this type. Theinstallation of hydrodynamic energy-saving appendages is one of the most effective measuresto improve the energy performance of full ships. In this paper, analysis was conducted on theeffects of different energy saving appendages on the stern wake field; comparisons werecarried out between different numerical models on viscous wake field of the full ships.First of all, the stern wake field of a174,000-ton oil tanker was calculated with the CFDsoftware, FLUENT, with the mesh of the ship generated by ANSYS ICEM. Detaileddiscussion was carried out on the effects of the local mesh refinement and the boundary layermesh; besides, the results of different numerical models were compared to the experimentaldata. On this basis, the most effective and appropriate meshing and turbulence model wereidentified for the calculation of full ship stern wake fields. The meshing and the model werefurther validated in the viscous wake field calculation for a35,000-ton bulk carrier.Second, multiple types of appendages were designed for the two ships mentioned abovebased on the calculated wake field; simulations were conducted on the stern wake fieldaffected by different appendage configurations, i.e. the size and position of the appendage ofthe174,000-ton tanker, and the type of the appendage of the35,000-ton bulk carrier. TheWOF method was adopted in the simulations with appendages. A new type of energy-savingappendage was proposed which enables a more uniform wake field on the ora side and henceincreases the propulsion efficiency.The results obtained in this thesis could offer some useful references for the calculationof the viscous wake filed of full ships and the design of energy-saving appendages.