Abstract :

Using surrogate fuels in lieu of real fuels is an appealing concept for combustion studies. A major limitation, however, is the capability to design compact and reliable kinetic models that capture all the specificities of the simpler, but still multi-component surrogates. This task is further complicated by the fairly large nature of the hydrocarbons commonly considered as potential surrogate components, since they typically result in extremely large detailed reaction schemes. The main goal is hence, to propose a compact and reliable scheme for the oxidation of potential Fischer-Tropsch (F-T) and jet fuel surrogates. Such a model could be coupled with engine simulations to gain quantitative understanding of emissions. Previously, a consistent chemical mechanism was developed to describe the oxidation of smaller hydrocarbon species [Blanquart et al., Combust. Flame (2009)] and a few substituted aromatics [Narayanaswamy et al., Combust. Flame (2010)], including iso-octane and m-xylene, that are key components of a potential F-T surrogate and jet fuel surrogate, respectively. In order to extend the well-characterized model above to include oxidation pathways of other key components of F-T and jet fuel surrogates, a short mechanism for low-to-high temperature oxidation of n-dodecane (paran representative) and methylcyclohexane (cyclic alkane representative) are extracted from the detailed schemes of Westbrook et al. [Combust. Flame (2009)], and Pitz et al. [Proc. Combust. Inst. (2007)], respectively. A multi-stage reduction strategy proposed by Pepiot and Pitsch [Combust. Flame. (2008), Combust. Theory. Modell. (2008)] is employed to accomplish the mechanism reduction. The skeletal level mechanisms are integrated in a systematic way into the previous model [Narayanaswamy et al., Combust. Flame (2010)]. A comprehensive validation of the resulting mechanism is performed using a wide range of experimental conditions and data sets. A F-T and jet fuel surrogate is proposed using iso-octane, m-xylene, n-dodecane and methylcyclohexane as components. Using this sample surrogate formulation and the proposed chemical model, preliminary predictions of the ignition delays and me speeds of F-T and jet fuels are made. The talk will focus on the general approach behind chemical kinetic modeling, the methodology adopted in the present work, with specific emphasis on n-dodecane kinetics. About the Speaker : Ms. Krithika Narayanaswamy is an alumna of IIT Madras with a BTech in Mechanical Engineering in 2008, and she is currently pursuing her PhD at Stanford University with Prof. Heinz Pitsch on chemical kinetics of surrogate fuels. She has published her research in Combustion and Flame and has presented several papers in US conferences and posters in international combustion meetings/symposium."