Shock Tube Study of Ignition Delay Characteristics of n-Nonane and n-Undecane in Argon

Ignition delay times of n-nonane and n-undecane in 4% oxygen/argon have been measured behind reflected shock waves in a heated shock tube at temperatures of 1168–1600 K, pressures of 2, 10, and 20 atm, and equivalence ratios of 0.5, 1.0, and 2.0. Ignition delay times are determined by using CH* emission and pressure signals monitored at the sidewall. Results show that ignition delay times of two fuels decrease as the temperature or pressure increases, and a decrease in equivalence ratio results in a shorter ignition delay time. For fuel-lean and stoichiometric mixtures, n-nonane has ∼25%–35% longer ignition delay times than n-undecane. For fuel-rich mixtures, ignition delay times of two fuels are very close. Correlations for ignition delay times of two fuels as a function of temperature, pressure, and equivalence ratio are formulated through regression analysis. The experimental data are in good agreement with shock tube data available, and the trends of experimental data were captured well by the predict...