Effect of Dilution on Forced Ignition of Jet-A/Air Mixtures

Abstract

Consistent ignition in environments where combustion products are present is critical for the safety and reliability of some propulsion applications. Prior research has shown that residual can reduce the probability of forced ignition of mixtures by decreasing the concentration of H radicals. However, the applicability of these observations to larger hydrocarbon fuels, such as jet-A, is not known. Ignition probabilities and volumetric kernel growth rates for vaporized jet-A/air/diluent mixtures were determined from radiation intensity measurements collected using an FLIR SC6700 infrared camera. Measurements of ignition probability of jet-A/air mixtures showed no appreciable reduction in ignition probability for mixtures with similar and . Mixtures diluted with showed no statistical change in average growth rates compared to undiluted and diluted mixtures. One-dimensional reacting flow simulations were conducted to help identify why no apparent chemical sensitivity to was observed for the jet-A/air mixtures, in contrast to results reported for . A greater concentration of H radicals was predicted for jet-A/air mixtures when compared to mixtures, even when is present. Further analysis showed that different reaction pathways exist for jet-A when compared to and that these reaction pathways are affected differently in the presence of residual .