Numerical Simulation of Diesel Combustion Chamber Optimization to Improve Emission Performance
Taking a four cylinder diesel engine used in a certain vehicle as the research object,the combustion chamber shape was changed through joint simulation using CAESES and CONVERGE software,and a dual objective optimization was carried out to reduce NOx and SOOT.The best case of improving diesel engine emission performance under rated power and constant compression ratio was obtained.The emission related schemes were analyzed,and the influence of combustion chamber related parameters on NOx and SOOT emission performance was explored.The results show that for this diesel engine,the dual objective optimal optimiza-tion scheme obtained through joint simulation and optimization using two software programs,without changing the compression ratio,reduces NOx and SOOT emissions by 8%and 11.7%respectively compared to the original engine,while ensuring power and economy.Analysis of three key parameters reveals that in this state,the depth of the throat and the radius of the lip have a greater impact on NOx and SOOT emissions,while the radius of the concave arc at the bottom has a smaller impact.