Effect of scavenge port angle and swirl ratio on performance of a marine diesel engine
LIU Mengyu
LU Zhen
ZHU Feng
LU Tianlong
Abstract：A three-dimensional numerical simulation model is established on the Converge software for a large-bore low-speed two-stroke marine diesel engine.The influence of the horizontal inclination angle of scavenging ports was studied,and the separate influence mechanism of swirl ratio was decoupled.The results show that scavenge ports angle affects the swirl ratio and scavenging efficiency.Excessive or insufficient horizontal inclination of scavenging ports create counterflow zones and lead to premature overflow of fresh air,which reduces the scavenging efficiency.When the angle of scavenging ports is 10°,the BSFC and NOxemissions are both reduced compared with the original machine with scavenging ports angle of 15°.Increasing the swirl ratio within a reasonable range can effectively improve the uniformity of oil-gas mixing and combustion process.Compared with the original engine with a swirl ratio of 4.5,when the swirl ratio is 20.5,the brake specific fuel consumption(BSFC)can reduce by 5.09%and the fuel economy has significantly improved.However,the excessive swirl ratio is relatively small for improvement of BSFC,and it is accompanied by a large amount of wall heat transfer loss,so the swirl ratio should be controlled below 20.5.
Keywords：two-stroke marine diesel enginescavenge port angleswirl ratiocombustionemission
Publication Date：2023-12-28
Online Publishing Date：2026-05-22(First online date of this platform, not the publication date of the document)
Pages：10( 1-9,51 )