Numerical investigation of laminar burning velocity for methane-hydrogen-air mixtures at wider boundary conditions

Abstract

To extend the study related to laminar burning velocity (LBV) of methane mixed with hydrogen under different boundary conditions, the FFCM-MECH was selected for chemical kinetic analysis. The influencing mechanisms of LBV of methane mixed with hydrogen were investigated under similar operating conditions for the internal combustion engine, e.g., higher temperatures, higher pressures, CO2 dilution ratios and larger extent of equivalence ratios. The impact of boundary conditions on the concentration of important reactive radicals and the flame structure was also discussed. The results and findings are summarized as follows. The LBV increases as the hydrogen addition ratio and initial temperature increase, but showing opposite trends when the initial pressure and CO2 dilution ratio rise. Moreover, it shows an increasing trend followed by a decreasing trend as equivalence ratio increases. LBV is highly dependent on the concentration of some important radicals in the system, the higher the concentration of radicals, the faster the LBV. Methane mixed with hydrogen has a small rise in adiabatic temperature and an outstanding reduction in carbon dioxide and carbon monoxide content, which can significantly reduce the emission of harmful gases and greenhouse gases. This study not only gives a reference for the design on power machinery, but also is conducive to promoting the development of natural gas engines.