INVESTIGATION OF JP-8 AUTOIGNITION UNDER VITIATED COMBUSTION CONDITIONS

Abstract

Limited data on jet fuel ignition and oxidation at low-O2, vitiated conditions has hindered the validation of kinetic models for combustion under such conditions. In this study, ignition delay time experiments of JP-8 have been performed with vitiated air at low pressures. Initially, the effects of temperature, equivalence ratio, and mole fractions of vitiated components on JP-8 ignition at 1 atm were screened to discover that temperature, O2 and NO have the largest significance. A following detailed investigation examined the effect on JP-8 ignition of larger concentrations of NO (0 - 1000 ppm) at lower temperatures (700 - 900 K), pressure (0.5 - 1.0 atm) and O2 mole fractions (12 - 20%). Results show that even trace amounts of NO dramatically enhance the oxidation of JP-8 with reduction in ignition delay time of up to 80%. Significant coupling exists between NO and the other design variables (temperature, oxygen level and pressure) as related to the effect of NO on ignition. An empirical model relating temperature, O2 and NO to ignition delay time of JP-8 has also been developed.