n-Dodecane oxidation at high-pressures: Measurements of ignition delay times and OH concentration time-histories

Ignition delay times and OH concentration time-histories were measured during n-dodecane oxidation behind reflected shocks waves using a heated, high-pressure shock tube. Measurements were made over temperatures of 727-1422 K, pressures of 15-34 atm, and equivalence ratios of 0.5 and 1.0. Ignition delay times were measured using side-wall pressure and OH^∗ emission diagnostics, and OH concentration time-histories were measured using narrow-linewidth ring-dye laser absorption near the R-branchhead of the OH A-X (0, 0) system at 306.47 nm. Shock tube measurements were compared to model predictions of four current n-dodecane oxidation detailed mechanisms, and the differences, particularly in the low-temperature negative-temperature-coefficient (NTC) region where the influence of non-ideal facility effects can be significant, are discussed. To our knowledge, the current measurements provide the first gas-phase shock tube ignition delay times (at pressures above 13 atm) and quantitative OH concentration time-histories for n-dodecane oxidation under practical engine conditions, and hence provide benchmark validation targets for refinement of jet fuel detailed kinetic modeling, since n-dodecane is widely used as the principal representative for n-alkanes in jet fuel surrogates.