Modeling And Performance Optimization For Electronic-controlled Turbocharged 4-stroke Marine Diesel Engine

Faced with the dwindling of oil resources and the strictness of emissions regulations, the electronic control transformation of fuel injection system is one of the most effective ways at present to meet the requirement of low oil consumption and low emission. Therefore, the establishment of mathematical model which can reflect the thermodynamic process of electronically-controlled marine engine power plant accurately means a lot to the control of ship power plant, performance optimization.In this paper, the following researches are carried out based on the 4190ZLC-2 type marine diesel engine:1) The electronically-controlled transformation experiment was the starting point. In accordance with the improvement of electronic unit pump replace the type 4190 diesel engine fuel injection system’s mechanical pump. The simulation model of electronic unit pump (EUP) injection system is established by using AMESirii software. The improvement was carried out from the plunger’s diameter, the working segment of camshaft and the diameter of fuel oil injector. The effects of cam working part for fuel supply, injector protrusion, nozzle hole diameter and fuel injection timing on fuel consumption and emission were found out through engine bench test, to realize the optimization of fuel injection system.2) Based on the Simulink simulation software, the mathematical model of the whole model for diesel engine was established by the average method, which including diesel engine turbocharger model, cold model, ontology model and the model of the fuel system, and the accuracy of model was testified. The mathematical model of 4190ZlC-2 type diesel engine working process has been established by using AVL_BOOST software combined with the transformed 4190 diesel engine physical model. The experimental data was used to calibrate the model and to verify the correctness of the model under the propulsion and load condition.3)The the influences of the intake system, exhaust system and compression ratio on the performance of 4190ZlC-2 type diesel engine with the mean value model of the 4190type medium-speed marine diesel engine, which has been established in the former chapter. With the model, the influences of the compression ratio, the starting of combustion angle, the valve timing on the diesel engine’s combustion performance are studied. The running laws of turbocharger system and diesel engine was studied and the combination operating curve of diesel engine and turbocharger under the load characteristics propulsion characteristics has been obtained respectively at the same time, to provide theoretical reference for the optimization and performance analysis of 4190 series diesel engine.4) The combustion model was established with the FIRE software, the simulation result was compared with the diesel engine experimental data to verify the accuracy of the simulation model. The structural parameters of traditional ω combustion chamber, throat diameter, center-crown height, bowl bottom radius depth, was researched intensively, from the influence of a single combustion chamber structure parameters and system parameters matching on the combustion process and emissions. On this basis, the effects of combustion system parameters to the indicated power, NOx emission of the diesel engine are investigated and analyzed based on the Orthogonal Experiment Method. The individual influence coefficient to the indicate power and NOx emission and overall performance of different combustion system parameters are obtained, and the optimized combustion systems to different evaluation objectives of the engine are acquired.