| The most significant feature of the Air-light hydrocarbon mixing gas combustion method is the difference in the content of hydrocarbon fuel,nitrogen and oxygen in the combustion atmosphere under different blending atmospheres and different proportions of light hydrocarbons,which makes the flame characteristics of fuels very different.The changing characteristics of the flame characteristics?ignition delay time,flame propagation speed,and adiabatic flame temperature?of the Air-light hydrocarbon mixing gas under different blending atmospheres,different light hydrocarbon ratios,different equivalent ratios,and nitrogen concentrations are currently unclear and need to be researched systematically and thoroughly.This paper first establishes a simplified mechanism for mixed-air light hydrocarbon gas.Using ANSYS Chemkin 17.0 software and its nested software ANSYS Reaction Workbench17.0,the detailed mechanism of JetSurF 2.0 version C1-C12 of n-alkanes was simplified.Using a combination of multiple automatic simplification methods,after 7 steps of simplification,the final simplification mechanism of the Air-light hydrocarbon mixing gas is composed of 37speciess and 209 elementary reactions.Compared with the detailed mechanism of JetSurF2.0,the species types are reduced by 89.4%,and the number of elementary reaction steps is reduced by 90.3%;the maximum molar fraction of acetylene?C2H2?,the maximum molar fraction of carbon monoxide?CO?,and the ignition delay time?ignition time[ms]?and other calculation results are within the error range.Then,the final simplified mechanism of Air-light hydrocarbon mixing gas is combined with ANSYS Chemkin 17.0 software to kinetically calculate the ignition delay time,flame propagation speed and adiabatic flame temperature of Air-light hydrocarbon mixing gas under different mixing atmospheres,different mixing ratios of gaseous light hydrocarbons and mixed gases,and different proportions of light hydrocarbon gases,the effects of mixing atmosphere,different mixing ratio of gaseous light hydrocarbon and mixed gas,different light hydrocarbon ratio,equivalent ratio and N2 concentration on the flame characteristics of Air-light hydrocarbon mixing gas were revealed.The conclusions are as follows:When the equivalence ratio is constant and the mixed gas is air,the flame characteristics of the Air-light hydrocarbon mixing gas are as follows:the ignition delay time is significantly smaller than the nitrogen atmosphere,and the flame propagation speed and the adiabatic flame temperature are greater than the nitrogen atmosphere,It shows that the existence of N2 has a certain hindrance to flame propagation and flame stability.When the initial gas temperature and pressure are constant,the ignition delay time increases with the increase of the equivalent ratio,and the flame propagation speed and the adiabatic flame temperature steadily increase and then decrease as the equivalence ratio increases for the Air-light hydrocarbon mixing gas with different light hydrocarbon ratios,mixed with light hydrocarbons and different blending atmospheres.The effects of different N2concentrations on the flame characteristics?including ignition delay time,flame propagation speed,and adiabatic flame temperature?of Air-light hydrocarbon mixing gas under three light hydrocarbon ratios were systematically analyzed.It was found that the N2 concentration affected the flame characteristics of Air-light hydrocarbon mixing gas.The nature of the effect is the physical effects of N2 gas.Finally,using the reactor model selected in the kinetics study of the Air-light hydrocarbon mixing gas flame characteristics,combined with the kinetic calculation results under the respective models,the effects of single factor changes?equivalent ratio,light hydrocarbon ratio?on the sensitivity of the ignition delay characteristics of Air-light hydrocarbon mixing gas are simulated.The important species and elementary reactions involved in the combustion reaction of Air-light hydrocarbon mixing gas were obtained through forced sensitivity analysis,which further verified the rationality of the simplified mechanism and the study of flame characteristics of Air-light hydrocarbon mixing gas using the simplified mechanism.The results show that the final simplified mechanism of the Air-light hydrocarbon mixing gas can be used to guide the chemical kinetic calculation of the flame characteristics of the mixed-air light hydrocarbon gas,which reduces the size of the mechanism and improves the calculation efficiency.This mechanism can be used as a basic tool in the research and analysis of the chemical kinetics of mixed-air light hydrocarbon gas.The detailed mechanism simplification process of the gas can also be used as a theoretical reference for the simplification of other new fuel or gas technology mechanisms.The completed flame characteristics study can provide a theoretical basis for the research and application of mixed-air light hydrocarbon gas. |
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