JP-5 and HRJ-5 autoignition characteristics and surrogate modeling

Abstract

A heated rapid compression machine has been used to investigate the autoignition behavior of JP-5 and camelina-based hydrotreated renewable jet (HRJ-5) fuels. Testing was conducted at low temperatures (T-c = 627-733 K), low-to-moderate pressures (p(c) = 5, 10, and 20 bar), and lean (phi = 0.25 and 0.50) and stoichiometric mixtures in air. The HRJ-5 fuel, which is 99% paraffinic, exhibited greater reactivity than the JP-5 fuel in the form of shorter ignition delays. The HRJ-5 fuel also exhibited transition into the negative temperature coefficient region at a lower compressed temperature (T-c = 675 K) than the JP-5 fuel (T-c = 700 K). Two surrogate fuel blends and kinetic models intended for Jet-A and kerosene-type fuels are evaluated for their ability to predict JP-5. ignition delay tunes because JP-5 and Jet-A ignition delay times showed close resemblance. The models reproduced the-qualitative trend in the data, including an accurate representation of when the negative temperature coefficient behavior appears. The best agreement between the data and predictions was obtained at p(c) = 5 bar and phi = 1.0, but outside of this region, the disparity was often 2-fold or greater.