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Keywords
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Diesel Engine, Very Large Crude Oil Carrier, Fuel Consumption
Emissions, Sea Wave and Wind, Mean Value Engine Model
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Abstract
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The behavior of ship engine encountering stormy waters with different sea wavelengths has been
investigated. In this study, a mathematical model is developed using governing equations for
various parts of the ship, that is the hull, engine, power transmission shafts from the engine to the
propeller also the propeller of the ship itself were implemented in MATLAB/ Simulink software
environment. The model consists of the torsional vibrations of the transmission shafts; this enables
a more accurate analysis of the engine behavior which is the source of power generation in the
ship's propulsion system. The simulation results showed that the wavelength of sea waves has a
significant effect on the dynamic performance of the engine. In this research, the effect of different
ratios of wavelength to ship length (λ/LPP) including 0.5, 1, 1.5 and 2 in violent stormy sea
conditions with a wave height of 11.5 m and wind speed of 28.5 m/s has been investigated. The
results showed that with the exception of λ/LPP of 1.5, at another ratios of λ/LPP, changes in engine
performance parameters such as torque, fuel and air consumption, CO2 emission and power are
decreasing with increasing wavelength. Most variations in engine speed are related to λ/L PP of 2.
The results showed that by reducing the wavelength, the period of oscillations is reduced. As the
ratio of wavelength to ship length increases, the number of oscillating points in the engine
behavior increases and the lowest number of oscillating points can be seen at λ/LPP of 1.5. This
study highlights the importance of effects of sea wavelengths as one of the most important physical
parameters of the sea which should not be ignored in the design phase of the ship propulsion
system and engine selection.
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