Effect of Manufacturing Tolerances on Performance of Marine Propellers

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Propeller cavitation is of major concern for ships since it is the predominant source of propeller-generatednoise and vibration. Very limited efforts have been made to understand the impact of propeller manufacturingtolerances on the propeller performance. The majority of propellers manufactured today are hand-finished fromcastings which are roughly machined using Computer Numerical Control (CNC). Manual grinding of propellersurfaces introduces inaccuracies and deviations from design, which could lead to degradation of propellerperformance in terms of efficiency, cavitation and noise. Ship screw propellers are typically manufactured tomeet the ISO 484 Standard, which specifies the manufacturing tolerances.As the key propeller manufacturer in Canada, Dominis Engineering needs the evidence that the high precisionof hydrodynamic surfaces, which can be achieved by the technology of CNC machining to final form andfinish, improves propeller performance. The investigation into propeller manufacturing tolerances will becarried out using computational fluid dynamics (CFD) simulations. The proposed research will focus on 2-DCFD simulations of a full-scale modified NACA 66 section, considering the variations in geometry (chordlength, camber and thickness) due to manufacturing tolerances.The outcomes of the project will enable Dominis to develop improved processes of propeller manufacturing interms of efficiency of production and high precision for reduced noises and vibrations as well as increased fuelefficiency. It will also enable Dominis to further support the Canadian Shipbuilding Strategy and Canada'sglobal competiveness in marine propeller manufacturing, which will ultimately benefit the Canadian economy.