Low temperature autoignition of conventional jet fuels and surrogate jet fuels with targeted properties in a rapid compression machine

The autoignition characteristics of conventional jet fuels (category A) and alternative fuels with targeted properties (category C) are investigated using a rapid compression machine and the direct test chamber charge preparation approach. The category C fuels were purposefully built to anticipate special property variations that generally occur in alternative fuels. Ignition delay measurements were made to examine the effects of these unique fuels at low compressed temperatures (625 K <= T-c <= 735 K), a compressed pressure of P-c = 20 bar and equivalence ratios of phi = 0.25, 0.5 and 1.0 in synthetic dry air. Chemical makeup of the fuel shows insight into the effect of the amount of branching in isoalkanes and aromatic influences on autoignition. The results show noteworthy variability in the ignition properties at these low temperature and lean conditions. This variability may impact combustion performance when the engine is running outside the normal operational map or for new engine architectures in the future. (C) 2016 by The Combustion Institute. Published by Elsevier Inc.