Modeling And Simulation Of Large-Scale Low-Speed Marine Diesel Engine

Modern merchant ship is usually equipped with a large-scale low-speed two-stroke marine diesel engine as its main propulsion system. Dynamic capability of the whole ship relies on the engine's dynamic capability. The construction of an accurately dynamic model for diesel engine propulsion system is important to control, simulation and performance analysis.Filling and emptying model, mean value engine model (MVEM) and others are models that are used to system simulation. These models are valuable in various application fields. Filling and emptying model can precisely predict pressure fluctuation in cylinders, but it is time consuming. Accordingly, it's traditionally used to steady simulation. MEVM is moderately simple. Therefore, the model is widely used to nonlinear control and state observation of diesel engine. But the excess air ratio is calculated without full considering all factors that affect the computation precision. Moreover, these two models can't be directly applied to control system design. Therefore, further studies on existent models become an important research field. These models are to be amended and optimized with the objective of satisfying the need of idustry.The MAN B&W 6S60MC large-scale low-speed two-stroke marine diesel engine being taken as an example, filling and emptying model, MVEM and linear paratmeter varying model are developed respectively. The MATLAB/SIMULINK software is selected as the simulation tool. Simulation results are compared with experimental data.Scavenging model, which deeply affects the precision and calculating speed, is an important component of "filling and emptying" model. The widely used "thick exhaust gas" scavenging model is amended. By introducing exhaust gas efficiency, a new formula is presents in the model. The formula unites the calculation of exhaust gas temperature. Then linear interpolation is applied to simplify parameters' computation for the combustion heat release rule in dynamic process. At last, by making use of the dynamic turbocharger model, "filling and emptying" diesel engine model is established.Based on the working process model, a marine power plant kinetics model is established by means of introducing crank-connecting rod kinetics model. Thus, characteristics of "filling and emptying" model are applied to simulation of marine power plant. Furthermore, it is presented that the "filling and emptying" dynamic model...