In the thesis study, the actual scientific and applied problem concerning improving of fuel saving of combined propulsive plant with kite by the rational adaptation of low-speed engine (LSE) in the best way to the expected ship conditions of its exploitation, has been solved. The information and methodological base has been created for system studies of propulsion plants of transport vessels with moderate speeds at the design stage. According to the developed methodology, the rational value of the “internal combustion engine – turbocharger” (ICE-TC) matching parameter for the main LSE is determined by calculation. Thus, it provides a reduction in the total fuel consumption over the service life of the transport vessel. The matching parameter predetermines, according to the regulations of MAN Diesel & Turbo, a specific turbocharger with the corresponding dimensions of flow sections, which ensures the adaptation of the low-speed engine to the expected spectrum of its load.
The kite has a variable useful thrust that allows, at a favorable wind, to significantly reduce the ship engine load with moderate speeds. This leads to an expansion of the load range of the main engine at the full speed modes of the vessel. In the traditional version of the propulsion plant, the range of load distribution on the engine at the full speed mode is relatively narrow and basically varies from 80 to 93% of the specified engine power. For the combined PP ‒ with the LSE and the kite ‒ this range is much wider, mainly, from 55 to 93%.
In the thesis, a simulation mathematical model and a corresponding software product with a generator of random evenly distributed numbers were developed, representing the original toolkit for the study of ship propulsion plant. The model
and product allow calculating arrays of possible values of target functions and their expected values. Some of the arguments of these functions are random variables with certain distribution laws of their values in the form of inverse integral functions. In this study, the target function is the total fuel consumption of the main low-speed engine for the normative service life of a medium-tonnage tanker with or without a kite. The main random variables are wind speed, wave height and their direction on round voyages in the North Atlantic with a favorable wind potential for the kite. The organization of the vessel motion corresponds to linear navigation.
It has been established that the rational value of the matching parameter is significantly different from the generally accepted one and provides the savings of the total fuel consumption for the medium tonnage vessel with a kite of 640 m2 at an order of 4% if: a) the commercial speed is moderate, that is 13…14 knots; b) operation corresponds to linear navigation with a constant average speed; c) the wind potential of the voyage line is favorable for the kite operation taking place on the transatlantic and trans-Pacific voyage lines.
The significant impact of the given commercial vessel speed on the rational value of the ICE-TC matching parameter was revealed. For a “Dmitriy Medvedev” type tanker with a MAN Diesel & Turbo 6S50ME-C7 engine (specification power is 9006 kW and rotation speed is 124,7 min-1) and SkySails kite with an area of 640 m2, making round voyages in the North Atlantic, the power matching point is: at a speed of 13 knots ‒ 58%, at 13.7 knots ‒ 61% and at 14.7 knots ‒ 85%. The area of the used kite has a significant impact on the rational value of the ICE-TC matching parameter. According to this value, the turbocharger with specific dimensions of the flow sections is being determined, which ensures the adaptation of the low-speed engine to upcoming operating conditions. The rational coordinate of the matching point on the field for selecting the parameters on the loaded screw performance of the engine, as the kite area increases from 160 to 640 m2 to an area of lower power values from 80 to 61%. At the same time, fuel consumption per unit of distance/mileage decreases from 72,8 to 55.6 kg / mile, or by 23.6%.
At the linear navigation with an average voyage speed of 13.7 knots, effect of determining the rational value of the ICE-TC matching parameter and the application of the corresponding turbocharger is positive. The weighted average decrease in fuel consumption of the engine with a capacity of ~ 9000 kW for a tanker with a deadweight of 26470 tons with a kite of 640 m2 is 4.3%; the expected savings for a fuel price of 322 dollars per ton are 2 million dollars over a 25-year operation period, or an average of 81 thousand dollars per year.
The created simulation mathematical model after adjusting the output data, mainly on the ship hull, the main engine, the kite and the voyages line, becomes acceptable for solving the practical problems of adapting the main low-speed engine to the operating conditions of various tankers and bulk carriers.
