Research On Modelling Method Of Low-Speed Main Engine On Intelligent Ship

Intelligent ship industry of China is in a period of vigorous development.Although the relevant technical theories are developing rapidly,they still need to be verified in the real environment.As an important component of the ship,the main engine of intelligent ship is closely related to many intelligent systems.It has become the object to provide data for intelligent systems or to verify the intelligent level of intelligent systems.The model development of main engine on intelligent ships can provide technical support for validating and evaluating the functions of intelligent systems on intelligent ship.According to the functions and relevant specifications of intelligent ships,the modelling requirements for main engine on intelligent ship are summarized in this study.The control volume model of the 7G80ME-C9.5 low-speed engine,which is the main engine of a VLOC intelligent demonstration ship in the R&D special project of "Intelligent Ship 1.0",is developed in the MATLAB/Simulink environment.A closed-loop model of the whole engine is established,including the cylinder working process,the intake and exhaust system,the turbocharger and the air cooler.The steady-state model of the low-speed engine is modified at three operating points of the propulsion characteristics,and the simulation results are compared and analyzed according to the test data.Besides,a dynamic simulation model is developed,including the main engine,the load,the shafting rotation balance and the speed control.The simulation works of the main engine dynamic model under variable operating conditions are carried out,whilst the simulation results in the stable stage of low-speed engine speed under variable operating conditions are analyzed.Based on the functions of intelligent engine room on intelligent ship and its relationship with the main engine,the condition monitoring items of main engine required by intelligent engine room are described in this study.Combining with the main engine thermal parameters for fault diagnosis,the output parameters for condition monitoring provided by the low-speed engine control volume model are summarized.Based on the developed 7G80ME-C9.5 low-speed main engine model on the VLOC intelligent demonstration ship,the above parameters are simulated,which proves that the developed main engine model for intelligent ship is able to provide effective operation parameters of the condition monitoring for intelligent systems.The purpose of using control volume method for the model development of low-speed main engine on intelligent ship is discussed in this study.The method of selecting boundary condition parameters is summarized in order to improve the simulation accuracy on basis of conventional modelling.Besides,a modelling optimization method is proposed to improve the simulation speed of control volume model and realize real-time simulation.The study presented in this paper has certain applicable value for the simulation of low-speed main engine on intelligent ship.