Simulation And Optimization Research Of 390 Marine Diesel Engine Combustion System

Combustion system design and optimization play important roles in a diesel engine performance research and development.Reasonable optimization of engine combustion system parameters helps to improve engine thermal efficiency and reduce emissions.With the development of computer technology,CFD and optimization technology have become the important means of IC engine performance development,which contributes to effectively shorten the development cycle and reduce the development costs.In this paper,chamber geometry parameters,swirl ratio and injection parameters design optimization study has been performed on a medium–speed diesel engine at a full-load operating condition using AVL FIRE and optimization software.First of all,based on the 1D simulation and experimental data,an accurate 3D combustion chamber calculation model has been built by using AVL FIRE ESE diesel module.The calculation result was used to analyze the base engine combustion and emissions.Then,AVL Design Explorer software was adopted to establish the automatic optimization platform.In the platform,Genetic Algorithm was utilized to optimize five chamber geometric parameters automatically,with the aim to reduce NOx,soot emissions,and improve the engine power.A total of 215 computational results were obtained.The results showed that the chamber with large throat diameter and shallow piston bowl was beneficial to reduce the diesel engine emissions.The two best chambers selected from the 215 optimization results,had different degree of decline on the NOx and soot emissions.Finally,based on the two best chambers,Isight software with multi-islands GA and NLPQL algorithm was utilized to optimize swirl ratio,two nozzle parameters and two injection parameters.This paper analyzed the influence of every optimization parameters on the diesel engine performance.The study finally got three optimization schemes.