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Hybrid propulsion and using liquefied natural gas (LNG) as the alternative fuel have been applied on automobiles and some small ships, but research investigating the fuel consumption and emissions over the total voyage of ocean-going cargo ships with a hybrid propulsion and different fuels is limited. This paper tries to fill the knowledge gap by investigating the influence of the ship mission profile, propulsion modes and effects of different fuels on the fuel consumption and emissions of the ship over the whole voyage, including transit in open sea and manoeuvring in close-to-port areas. Results show that propulsion control and electric power generation modes have a notable influence on the ship’s fuel consumption and emissions during the voyage. During close-to-port manoeuvres, propelling the ship in power-take-in (PTI) mode and generating the electric power by auxiliary engines rather than the main engine will reduce the local NOx and HC (hydrocarbons) emissions significantly. Sailing the ship on LNG will reduce the fuel consumption, CO2 and NOx emissions notably while producing higher HC emissions than traditional fuels. The hybridisation of the ship propulsion and using LNG together with ship voyage optimisation, considering the ship mission, ship operations and sea conditions, will improve the ship’s fuel consumption and emissions over the whole voyage significantly.

This paper focuses on the forces acting in a controllable pitch propeller (CPP) mechanism and the manifestation of unwilling, small amplitude, vibrating motion (fretting) in a blade bearing caused by seaway. If this happens, fretting can result in fretting fatigue of components, fretting wear, and increase of friction in bearings. An attempt has been made to define the circumstances leading to fretting in a CPP and to describe the influence of sea state on fretting behaviour. Using hydrodynamic tools it is possible to determine the theoretical conditions for fretting. A combination of theoretical and experimental results provides a better understanding of the fretting phenomenon in a CPP. The first part of the paper gives an introduction to the working regimes and forces acting on a CPP. In the second part the presence of fretting is defined based on the calculation of forces and moments during one revolution of a blade in the non-actuating regime for the design condition of a specific propeller. The third part investigates self-propulsion tests in irregular seas and hydrodynamic forces acting on a CPP in those conditions. The results indicate a decrease of fretting in higher waves and higher speeds. It has been shown that it is not wise to look only at the load mean value as design criteria.

Mean value modelling of diesel engine combustion based on parameterized finite stage cylinder process Highlights 18 1. Mean Value First Principle (MVFP) model has been built based on Seiliger process, i.e. the 19 in-cylinder process of the engine is characterized by using parameterized finite stages. 20 2. The expressions to calculate the combustion parameters have been obtained. 21 3. MVFP diesel engine model built in this paper has been applied to the simulation of a ship 22 propulsion system. 23 4. The simulation results have shown the adaptability of the MVFP model to variable working 24 conditions and the capability of being integrated into a large system. Abstract: Mean value diesel engine models are widely used since they focus on the main engine performance and 32 can operate on a time scale that is longer than one revolution, and as a consequence use time steps that are much longer 33 than crank-angle models. Mean Value First Principle (MVFP) models are not primarily intended for engine development 34 but are used for systems studies that are become more important for engine users. In this paper two new variants of 35 Seiliger processes, which characterize the engine in-cylinder process with finite stages are investigated, in particular 36 their ability to correctly model the heat release by a finite number of combustion parameters. MAN 4L20/27 engine 37 measurements are used and conclusions were drawn which Seiliger variant should be used and how to model the 38 combustion shape for more engines. Then expressions to calculate the combustion parameters have been obtained by 39 using a multivariable regression fitting method. The mean value diesel engine model has been corrected and applied to 40 the simulation of a ship propulsion system which contains a modern MAN 18V32/40 diesel engine in its preliminary 41 design stage and the simulation results have shown the capability of the integration of MVFP model into a larger 42 system. 43

Off-design conditions can have a severe impact on ship propulsion system behaviour. Resistance increase, for instance, leads to higher engine loading, and can also easily lead to a decrease of cavitation inception speed with respect to calm water conditions. Wakefield variations due to ship motions, waves and manoeuvres also have an effect on engine loading and on propeller cavitation. This paper discusses the model-based development of a propulsion control system aiming at increased cavitation free time in operational conditions, while preventing engine overloading and keeping manoeuvring characteristics acceptable. The developed propulsion control system was tested extensively in a simulation environment before full-scale trials took place in February 2008, onboard a Royal Netherlands Navy frigate. Results in terms of full-scale propulsion system behaviour are presented, including photos showing the propeller cavitation behaviour in operational conditions. Control of propeller cavitation in operational conditions AUTHORS' BIOGRAPHIES Arthur Vrijdag graduated from the Royal Netherlands Naval College in 2004 and in the same year obtained his masters degree in ship hydromechanics at Delft University of Technology. He recently finished his PhD thesis titled 'Control of propeller cavitation in operational conditions. 2 ' The