Hydrodynamic analysis of a marine propeller in open water conditions using the computational code OpenFoam

Abstract

The constant growth of computing power the last years, has rendered the use of Computational Fluid Dynamics (CFD) extensive in the marine industry. For the purpose of meeting the greater requirements in efficient ship propulsion with low emissions and noise level as the International Maritime Organization (IMO) regulations demand, optimal propeller designs are expected. The open water test is performed as a means of obtaining characteristics important for the propeller design, and it is traditionally conducted using model tests in towing tanks. According to MEPC. 351(78) – 2022, numerical simulations (CFD) can be used complementary to model tests, of fully replace them. The aim of the present thesis is the investigation and evaluation of the opensource CFD code OpenFOAM, that is suitable for the propeller’s open water characteristics calculation. Initially, the motivation behind this study is presented which is the reduction of emissions in shipping as well as the assessment of underwater noise caused mainly by the propeller function. Consequently, the main framework of Regulations is outlined, on which the fidelity of the methodology used is based. The thesis continues with a brief historical review of the propeller and a presentation of the most commonly used numerical methods for designing and analyzing propellers. In Chapters 3 and 4, the basic theory behind this study is presented. Chapter 3 includes information about the propeller geometry and the open water characteristics, and Chapter 4 introduces the main hydrodynamic and numerical theory background. The study continues with the numerical simulation process which is analyzed in Chapter 5. Initially, the propeller model is selected, and the CAD model is created. Consequently, the set-up of the simulation and the mesh generation are conducted. The mesh independence study verifies that the calculated values are not dependent on mesh fineness. Afterwards, in terms of validating the methodology, the values are compared with official bibliographic data and with EFD (Experimental Fluid Dynamics) test results. For further validation, visualization figures are also presented, providing a clear sight of the calculated values. The study is coming to an end by discussing the results and some considerations for future work.