Study On The Change Of Hull Resistance Based On Oil Consumption Model Of Ship's Main Engine

Since the requirements for the emission of ships have been constantly improved.Nowadays,the control strategy of vessel exhaust emission and cost becomes crucially important,particularly under the background of weak shipping economy.It is of significance to consider two factors affecting total oil consumption in control strategy research.One is main engine fuel consumption,which is the major component of total fuel consumption.The other is the additional resistance caused by fouling.Both elements have a great impact on the total fuel consumption.The current study focuses on the ship's previous_navigation data.With the purpose of optimizing the accuracy of fuel consumption model and establishing the hull fouling degradation model,both particle swarm optimization algorithm and Wiener process are applied in the research.The study is hoped to provide reference for the setting time of dock repair.Firstly,the study analyzed the force of the sailing ship and defined the friction increment coefficient,which represented the influence of the friction subsidy coefficient,the hull roughness and the fouling on the ship.Combined with the power transfer mode of the ship's main propulsion device,the study also established the general expression of the main engine fuel consumption model;Through access to relevant information,the value of each parameter in the expression were determined,in which the unknown parameter was set as the parameter that can not be measured or the results of empirical formula were great different.Secondly,the study attempted to process the data of historical voyage,set friction increment coefficient,appendage coefficient,wake fraction,thrust reduction as the variable of particle swarm optimization,using the average relative error between the calculated value and the actual value of the fuel consumption of main engine as the objective function.The calculation results of each parameter were:1.085x10-4,2.959x10-2,3.928X10-1 5.405X10-1.The relative error of the test calculation of oil consumption model is less than 8%.Finally,the data were divided into several segments at different distances,and the degradation law of the friction increment coefficient was studied by Wiener process.The results showed that the mode of 30 days distance has the best effect,the average relative error is 7.11%.In order to make degradation model more intuitive,the friction increment coefficients were converted to the form of estimated power increment according to the law of the ship sailing history.Meanwhile,the probability density function of the residual life of the hull is also given.The results of the study are believed to provide useful reference for the periodic maintenance plan of ship.