Abstract
It is shown that there are many mathematical models (MM) of ship power plants for various purposes. Such MM are integrated into decision support systems (DSS) and used in the design and power optimization of ship power plants (SPP) of various constructional configurations. Experimental research and scientific literature analysis prove that such integrated MM into DSS are not always adequate to real physical processes in some modes, for example, dynamic ship positioning. That is why integrated MM SPP into DSS need clarification as well as the existing DSS need further development. The approach for the creation of specialized DSS SPP of the ship combined propulsive complexes (CPC) is proposed, which allows predicting the number and type of thrusters (T), pods, power system, and does not require the application of similarity criteria, allows a multiple analysis of the structure at minimal initial data. The designed DSS applies the principles of the construction of DMI-models ships and methods of implementation of characteristic spatial vectors of power processes, gives a possibility to synthesize recommendations to T designers, controllers and power systems for ships operating in the dynamic positioning modes. Created DSS can be used practically for any type of vessels and adapted for the modes of dynamic ship positioning. It is established for a given rotation speed of the pods, traction, torque and stepper ratio with the help of created DSS, that traction coefficient grows with the change in mutual location of T relative to each another and diametrical plane of the vessel. It is proved that the interelation of thrusts coefficients are correlated better with the power coefficients than with the stepping pods coefficients, allowing increasing energy efficiency of SPP CPC in the dynamic positioning modes. The results of the research can be implemented into data bases of similar DSS and provide researchers with verified information needed for creation of new concepts of SPP CPC design for modification of existing systems.
Highlights
In recent decades the growth of capacity, energy-efficiency, increasing prices for fuel and materials, enhanced operational modes, which is associated, first of all, with the development of the offshore fleet, have substantially aggravated the problems of design, construction and operation of the optimal combined propulsion complexes (CPC) and ship power plants (SPP) that provide their power
In addition to the mentioned above, worth noting are: – uncertainty of structures and parameters of the models of studied SPP CPC; – difficulties of system analysis and quality of evaluation of the models parameters; – the absence or unavailability of statistics of the observed systems, which are a part of amount of the data with available omissions, pulse emissions, disturbing influences and errors in measurement; – ambiguity of methodology research from various, sometimes unrecognized data processing techniques or solving problems; – the impossibility of organizing all the possible options of SPP CPC set, which derives from all the types of uncertainties and is essentially caused by them
For the implementation of deep comprehensive analysis of the made decision regarding the projected SPP CPC it should have a set of recognized rules, based on reliable data from decision making in this area, which were collected by decomposition of specific operational problems which would have enabled to implement the developed SPP CPC at the lowest risks for operational inefficiency
Summary
In recent decades the growth of capacity, energy-efficiency, increasing prices for fuel and materials, enhanced operational modes, which is associated, first of all, with the development of the offshore fleet, have substantially aggravated the problems of design, construction and operation of the optimal combined propulsion complexes (CPC) and ship power plants (SPP) that provide their power. Before the 70-ies of the last century, the results of serial testing were processed by the accepted in a certain organization methods and were used to construct their own empirical methods of calculation of towing resistance of ships with bypasses of installed capacity of SPP, dynamic characteristics of CPC, etc., built according to the rules in this series or slightly different from them [2]. We can state that the development of DSS in the design and research of SPP CPC, with the introduction of its components in energy processes in order to increase the effectiveness of the decisions is a relevant issue, especially when choosing one or another CPC structure, setting up various regulators, contributing to the improvement of operational modes of a ship
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