Study On Work Process And Fault Simulation For Marine Low-speed Two-stroke Diesel Engine

Research on work process simulation for marine diesel engine is significant for fault diagnosis and performance optimization of diesel engine. A Mathematical and Physical model of diesel engine is established and simulation computation of work process is carried out, according to the MAN B&W 6S5050MC-C two-stroke low-speed diesel engine, which was made by DALIAN MARINE DIESEL WORKS.Based on one-dimensional simulation computation software of engine work process-AVL BOOST and low-speed two-stroke diesel engine-MAN B&W 6S5050MC-C, this paper analyzed the Mathematical model of diesel engine work process and finally the method to accurate simulation was developed. The Mathematical model includes cylinder model, combustion model, scavenging model, piston motion model, heat transfer model, turbine charger model and air cooler model. With the help of the software-BOOST, the Physical model of MAN B&W 6S5050MC-C diesel engine was established. Comparison with test report, the Physical computation model was simulated and according to repeatedly debugging, gains the accurate simulation computation model of diesel engine.Finally, on the basis of the validated model, many simulation calculations were made about usual faults of marine diesel engine, which includes combustion duration extension, one cylinder misfiring, fuel injector nozzle holes wearing, turbocharger efficiency decreasing, the cooler dirty and cooling capacity worsen and exhaust valve timing fault. According to fault simulation theory, three levels (slight, medium and heavy) were set about every fault, which simulated the cause, development and deterioration. Through fault simulation, main factors which influence the performance of Two-stroke diesel engine were analyzed. And when faults gradually deepen, main performance factors of diesel engine including effective power, fuel consumption rate, IMEP, maximum combustion pressure was also analyzed. At last, through the change of main performance parameter of diesel engine, fault grade was recognized. It also provide criterion for fault diagnosis.