Development of a Combinator Curve Generator

Abstract

Often, vessels have multiple operation modes that are specialised for a certain task. If a vessel is employed with a controllable pitch propeller(CPP), the blade pitch can be adjusted, adding a degree of freedom to the system. This advantage creates the possibility to increase the diversity of operation modes of the vessel and allows for flexibility, precision and specialisation for a certain task. Additionally, CPPs can be controlled such, that operational limits of the driving machinery are not exceeded.

As vessels have become increasingly diverse with respect to their functional abilities, and complex with respect to their propulsion configurations, design of combinator curves becomes increasingly labour intensive. Earlier developed software applications, that aim to support the matching process or combinator settings, lack clear insight of important performance indicators and their impact on the combinator curve design.

In this thesis, a Combinator Curve Generator(CCG) is developed to support the design of combinator curves for vessels that employ CPPs, in order to decrease the labour intensity of the combinator design process. Further, approaches are developed to optimise combinator curves for operation modes of a vessel in terms of four performance indicators; propeller efficiency, cavitation inception, engine efficiency and fuel consumption. The approaches are implemented in the CCG such that a combinator curve can be designed, optimised and evaluated. Additionally, a trip simulation tool is developed and added to the CCG, in order to determine and evaluate the total fuel consumption of a trip for different cruise speeds and a certain time duration, whilst taking into account the distance, the operational profile of the vessel, the combinator settings and the hotel load.

Important recommendations for further development include extension of the database of inception diagrams for propellers with different blade area ratios, and the broadening of the propulsion configuration scope, such that different main engines and power supply systems can be considered. Finally, it is recommended to research the possibility to calibrate the effective angle of attack method on the basis of the optimisation approach proposed in this thesis.