Research Of Marine Diesel Engine Startup Process Based On The Autonomous Simulation Software

Diesel engines have the characteristics of high thermal efficiency,low fuel consumption,wide power range and strong dynamic performance in the field of internal combustion engines,and are widely used in many fields such as industrial production,shipping,military,and agriculture.Starting performance of marine diesel engine is an important performance index,which has a profound impact on emissions,reliability,and safety of ship maneuvering.This paper completes the development of the workflow,simulation system framework,and interface of the marine diesel engine autonomous simulation software,as well as the corresponding engine model library.Based on the autonomous simulation platform,taking the 6EX340 marine low-speed diesel engine as the research object,the propeller model,the in-cylinder process of the diesel engine,the starting system and the crank connecting rod mechanism and other subsystem models are developed.Connecting the subsystem models,the simulation experiment of the starting process of marine diesel engine with propellers is completed,and the starting performance of the diesel engine is studied.The maximum compression temperature and the starting time of the diesel engine during the starting process of the diesel engine are selected as two important indicators to evaluate the starting performance.Using the diesel engine starting simulation model,the influence of parameters such as starting speed,compression ratio,intake air temperature and starting valve continuation angle on the maximum compression temperature and starting time was analyzed by means of orthogonal experiment.Based on the NSGA2 genetic algorithm,the multi-objective optimization analysis was carried out on the two indicators of starting time and maximum compression temperature.After calculating the Pareto optimal solution set,the TOPSIS method was used to decide and analyze the optimal starting plan of the diesel engine.The simulation results show that with the increase of the starting speed,the maximum compression temperature also increases,but the starting time will be prolonged;increasing the intake air temperature and compression ratio can effectively increase the maximum compression temperature,improve the ignition conditions of diesel engine starting,and reduce emissions;the starting valve continuation angle Increasing it can shorten the start-up time.Orthogonal experiments were used to analyze the influencing factors of the maximum compression temperature and starting time.The primary and secondary factors affecting the compression end temperature during the starting process were compression ratio,intake air temperature and starting speed;the primary and secondary factors affecting starting time were starting speed,compression Ratio and pneumatic valve opening continuation angle.The optimal starting strategy based on NSGA2 genetic algorithm reduces the starting time by 2.778s(about 40.8%)and increases the starting temperature by 16.24K(about 2.1%)compared with the initial strategy.