Propeller clock thesis

The propeller was designed for the ship by the Danish Maritime Institute, DMI. In the design the highest possible efficiency was emphasized, but in the same time a certain amount of tip unloading was applied to limit the extent of possible noise and vibration.

To evaluate the design, open-water, self-propulsion and cavitation model tests have been carried out. The tests are done for the conventional propeller originally designed for the ship and for a tip-fin propeller designed for the same ship under the same operating conditions.

Although the propellers of the small series tested were designed for open water conditions, experiments with a propeller in behind condition and cavitation experiments gave promising results in form of predicted power savings of 5 to 6 per cent for a 225 m, 22 knot container ship.

The efficiency of the full scale tip-fin propeller is 0.025 better than the conventional propeller (3.8 per cent relative). This increase is due to the fact that the tip-fin propeller has relatively more area at the outer sections of the blade where the velocities are higher.