正十二烷-甲烷双燃料非线性着火特性及稀释气体效应研究

This study systematically investigates the ignition characteristics of n-dodecane-methane dual-fuel mixtures in low-to-intermediate temperature conditions using experimental and numerical simulation methods. The ignition delay times of the dual-fuel mixtures, obtained from rapid compression machine experiments, reveal a nonlinear promoting effect of n-dodecane addition on ignition. Furthermore, the type of diluent gas significantly affects the ignition characteristics of the dual-fuel mixture. Combined with the newly developed reaction kinetic mechanism (Mai2024), the experimental data were numerically simulated and analyzed to reveal the mechanism of action of n-dodecane addition and the type of dilution gas on the dual fuel ignition. The experimental data align well with the model predictions, verifying the accuracy of the Mai2024 model in predicting the ignition characteristics of n-dodecane-methane dual-fuel mixtures. The results indicate that adding n-dodecane promotes ignition in a nonlinear manner, consistent with a nonlinear increase in the ·OH radical production rate. The nonlinear promoting effect of n-dodecane addition on ignition is partly due to its low-temperature oxidation process, which enhances the generation and accumulation of the radical pool, and partly from the heat release of its low-temperature oxidation, which raises the system temperature. Additionally, the type of diluent gas has little impact on the first-stage ignition of the fuel, but for total ignition delay time, differences in the thermal properties of the diluent gas play a decisive role in the low-temperature region, while chemical effects primarily influence ignition characteristics at higher temperatures.