Numerical simulations of pilot fuel spray and compressing ignition forpre-mixed natural gas ignited by pilot diesel are described. By means of these modeling, the dualfuel and diesel fuel ignition mechanism of some ph...Numerical simulations of pilot fuel spray and compressing ignition forpre-mixed natural gas ignited by pilot diesel are described. By means of these modeling, the dualfuel and diesel fuel ignition mechanism of some phenomena investigated on an optional engine bytechnology of high-speed CCD is analyzed. It is demonstrated that the longer delay of ignition indual fuel engine is not mainly caused by change of the mixture thermodynamics parameters. Theanalysis results illustrate that the ignition of pre-mixed nataral gas ignited by pilot dieseltaking place in dual fuel engine is a process of homogenous charge compression ignition.展开更多
Natural gas/diesel dual-fuel combustion strategy has a great potential to reduce emissions for marine engines while the high fuel consumption is the major problem.Pre-chamber system is commonly employed as the ignitio...Natural gas/diesel dual-fuel combustion strategy has a great potential to reduce emissions for marine engines while the high fuel consumption is the major problem.Pre-chamber system is commonly employed as the ignition system on large-bore dual-fuel marine engines especially under lean-burn condition,due to its advanced ignition stability and engine efficiency.However,the ignition and combustion mechanism in such dual-fuel pre-chamber engine is still unclear and the effects of in-cylinder swirl flow and mixture stratification on combustion require further investigation specifically.This paper numerically studied the detailed ignition mechanism and combustion process in a marine engine equipped with a pre-chamber ignition system,and revealed the flame development process in main chamber.Moreover,the effects of mixture stratification and swirl ratio on the combustion rate and further engine thermal efficiency are investigated under decoupled condition.The results mainly show that the jet flame develops along the pre-chamber orifice centerline at the initial stage and premixed combustion play an important role,while after that,heat release zone only exist at flame surface,and premixed flame propagation controls the combustion process.In addition,with higher swirl ratio the combustion rate increases significantly due to the wider ignition area.Mixture stratification degree plays a role in accelerating the combustion,either too high or too low stratification degree reduce the combustion rate,while a moderate stratification increases the combustion rate.And appropriate stratification degree by verifying the gas injection parameters can reduce fuel consumption in 0.3%.展开更多
基金This project is supported by National Natural Science Foundation of China (No.50076031).
文摘Numerical simulations of pilot fuel spray and compressing ignition forpre-mixed natural gas ignited by pilot diesel are described. By means of these modeling, the dualfuel and diesel fuel ignition mechanism of some phenomena investigated on an optional engine bytechnology of high-speed CCD is analyzed. It is demonstrated that the longer delay of ignition indual fuel engine is not mainly caused by change of the mixture thermodynamics parameters. Theanalysis results illustrate that the ignition of pre-mixed nataral gas ignited by pilot dieseltaking place in dual fuel engine is a process of homogenous charge compression ignition.
基金the financial supports provided by the Low-speed Marine Diesel Project(Project No.CDGC01-KT0308)National Natural Science Foundation of China(Grant No.91941102)。
文摘Natural gas/diesel dual-fuel combustion strategy has a great potential to reduce emissions for marine engines while the high fuel consumption is the major problem.Pre-chamber system is commonly employed as the ignition system on large-bore dual-fuel marine engines especially under lean-burn condition,due to its advanced ignition stability and engine efficiency.However,the ignition and combustion mechanism in such dual-fuel pre-chamber engine is still unclear and the effects of in-cylinder swirl flow and mixture stratification on combustion require further investigation specifically.This paper numerically studied the detailed ignition mechanism and combustion process in a marine engine equipped with a pre-chamber ignition system,and revealed the flame development process in main chamber.Moreover,the effects of mixture stratification and swirl ratio on the combustion rate and further engine thermal efficiency are investigated under decoupled condition.The results mainly show that the jet flame develops along the pre-chamber orifice centerline at the initial stage and premixed combustion play an important role,while after that,heat release zone only exist at flame surface,and premixed flame propagation controls the combustion process.In addition,with higher swirl ratio the combustion rate increases significantly due to the wider ignition area.Mixture stratification degree plays a role in accelerating the combustion,either too high or too low stratification degree reduce the combustion rate,while a moderate stratification increases the combustion rate.And appropriate stratification degree by verifying the gas injection parameters can reduce fuel consumption in 0.3%.
