Development and Full-Scale Evaluation of a New Marine Propeller Type

The KAPPEL propeller has blades curved towards the suction side at the tips. A similar application of non-planar lifting surfaces is known from modern aircraft wings having pronounced fins or winglets at the wing tips to obtain better lift-to-drag ratios. For the propeller the task is to optimise the geometry with respect to efficiency and maintain good cavitation performance and low noise and vibration levels.

The development work has been concentrated on propellers for a medium-sized container ship and a product tanker. In total nine KAPPEL and two conventional, comparator propellers have been designed and models of all propellers examined with respect to efficiency in open-water and behind conditions. Cavitation tests were carried out for all propellers in the HYKAT cavitation tunnel at HSVA.

In full scale, for the product carrier comparative sea trials were made with the conventional and the KAPPEL propeller. The propulsive efficiency and vibration levels were measured, and furthermore the full-scale cavitation performance was observed through observation windows. The sea trials show higher propulsive efficiency with the KAPPEL propeller and lower levels of noise and vibration excitation relative to the conventional propeller.