Numerical Investigation of Propulsion Efficiency Depending on Propeller Position

Abstract

Increasingly tight schedules in ship building projects as well as the opportunity of reliable RANS CFD codes including fast and flexible meshing methods lead to the application of numerical propulsion tests as standard procedures in the propeller design process. Due to the benefits of numerical self-propulsion simulations, the investigation of the ship propulsion characteristics and the analysis of fluid flow around the hull, propeller and rudder can be easily done with the relevant computational time consumptions. In this thesis, the propulsion efficiency of the ship is mainly investigated when the axial position of the propeller behind hull is varied. Furthermore, the flow field around the ship hull and operating propeller is presented and analyzed according to the changes of propeller position behind hull. The pressure quantities exerted on the hull at certain points are determined when the positions of propeller operating behind the ship hull are relocated. These numerical investigations are made for the self-propulsion simulations with and without rudder condition to observe the influence of rudder. With a view to fulfill the objectives of this thesis, the numerical propulsion simulations of the ship for different propeller positions with&without rudder conditions and reverse open water simulation of that propeller are performed by using commercial code RANSE solver, ANSYS CFX. All of the simulations are carried out in model scale of research vessel’s hull, its corresponding propeller and rudder. With the results of these simulations, the powering prediction results and propulsion characteristics data in full-scale operating conditions are extrapolated from model scale results by using the ITTC 1978 service performance prediction procedure. The results of propeller hydrodynamic performance and self-propulsion characteristics are analyzed to compare and investigate the propulsion efficiency between the different positions of propeller operating behind the hull with&without rudder conditions. Finally, the distribution of pressure and velocity contour are executed to study the flow effects on the hull-propeller-rudder interaction