Abstract: Dual fuel engine has become an important development trend of marine engines. In order to further understand the influence of scavenging pressure on combustion characteristics of marine natural gas/diesel dual fuel engine, on the basis of experimental verification, the finite volume method was adopted to discrete the equations of the combustion process, and the semi-implicit method was adopted to solve the multivariable coupling numerical analysis. The effect of different scavenging pressure on combustive pressure, temperature, turbulence intensity in a cylinder, and emission of the engine were investigated. The results showed that the increase in the scavenging pressure increased the peak cylinder pressure, but decreased the peak temperature and peak cylinder turbulent kinetic energy. NO and CH4 emission was decreased with the increase in the scavenging pressure in the meantime. It was found that, with increase in scavenging pressure every 0.25 bar, the peak cylinder pressure respectively rose by 5%, while peak temperature, peak cylinder turbulent kinetic energy, NO emissions and CH4 emissions was reduced by 2.5%, 6.9%, 7.8% and 10.9%, respectively. The effect of scavenging pressure on CH4 emission was more pronounced than that on NO emission. Therefore, the marine natural gas/diesel dual fuel engine should be use high scavenging pressure as far as possible, within the allowable range of engine heat load in the work condition, to reduce unburned CH4 and NO emissions, for enhancing the power and economy of an engine.
2018, Vol. 33 
