Study on premixed laminar combustion characteristics of ethanol-air-diluted mixtures at elevated pressures and temperatures

Several fundamental parameters characterizing the ethanol-air premixed mixtures at different equivalence ratios, initial pressures and temperatures, and dilution ratios, like the adiabatic flame temperature, the laminar burning velocity, the laminar burning flux, the laminar flame thickness and the burnt-gas Markstein length, were studied by using a constant volume combustion bomb and high-speed schlieren photography system. The results show that, for ethanol-air premixed mixture at given initial condition, adiabatic flame temperature, laminar burning velocity and laminar burning flux get their maximum values at the equivalence ratios between 1.0 and 1.1, while laminar flame thickness gets its minimum value at the equivalence ratio of 1.1. Markstein length decreases with the increase of equivalence ratio. For ethanol-air premixed mixture at given equivalence ratio, adiabatic flame temperature increases with the increase in initial pressure and temperature, and it decreases with the increase in dilution ratio. Laminar burning velocity decreases with the increase in initial pressure and dilution ratio, and it increases with the increase in initial temperature. Laminar burning flux increases with the increase in initial pressure and temperature, and it decreases with the increase in dilution ratio. Laminar flame thickness and Markstein length decrease with the increase in initial pressure and temperature, and they increase with an increase in dilution ratio.