The Effect of Multi-Component Fuel Evaporation on the Ignition of JP-8

In this work distillation curve (DC) and probability distribution function (PDF) models of multi-component droplet evaporation were investigated in order to determine the feasibility of recovering information about the gas-phase composition from a minimal number of variables associated with the droplet. Both models were assessed against a discrete component model based on the classic B-number formulation using a 63 component model of JP-8. The results indicate that, although the gas-phase fuel composition may undergo large changes during the droplet lifetime, it is possible to recover composition information in terms of the major classes of species present with reasonable accuracy (+/− 5%) using the DC and PDF models. The potential impact of variation in gas-phase fuel composition was investigated by performing ignition delay time (IDT) calculations using two detailed chemical kinetic mechanisms for JP-8. The results indicate that, especially in the low temperature region (700 K – 900 K), variation in gas-phase fuel composition can have a large impact on the ignition delay time. Experimental IDT measurements at 900 and 950 K showed a larger variation in IDT due to composition than that predicted by the models.