Reduced kinetic models for the combustion of jet propulsion fuels.
Reduced chemical kinetic models to predict the combustion characteristics of jet propulsion fuels are produced and tested. The parent detailed kinetic model has been developed on the basis of a surrogate fuel formulation methodology that utilizes combustion property targets measured for a particular real fuel to formulate a chemical mixture of n-alkanes, iso-alkanes and aromatic functionalities to emulate the combustion behavior of specific target jet aviation fuels. Detailed model predictions are compared against reflected shock ignition delays of both pure components and surrogate fuel mixtures. Systematically reduced models for each individual fuel component are produced and used to test the parent model performance against laminar burning velocity. Finally, a range of systematically reduced kinetic models for two, substantially different, validated surrogate fuels for a particular jet aviation fuel are produce and tested to allow the user a choice in computational cost versus reduced model fidelity. A reduced model of 233 species is produced that closely shares the predictability of the detailed model over the tested conditions. Analysis of the models provides a basis for further refinements in describing the chemical kinetic behavior of all conventional and alternative jet fuels. The limitations of the presented approach are discussed and needs for further refinements are identified.
Development of Reduced Kinetic Models for Petroleum-Derived and Alternative Jet Fuels.
The surrogate fuel concept to replicate the detailed gas phase combustion behaviors of conventional and alternative jet aviation fuels in numerical combustion models is extended and tested in specific examples of synthetic jet fuels derived from coal and natural gas, and also to the pressure and equivalence ratio dependences of the combustion responses of conventional Jet–A fuel. The formulation of surrogate fuels for Syntroleum S-8, Shell SPK and Sasol IPK, is described. Assuming these compositions, a detailed chemical kinetic model construction previously elaborated upon is extended and tested against reference data sets of shock tube ignition delay and laminar burning velocity. Calculations with the detailed kinetic model, containing 3147 species correctly represent the experimentally measured reactivity of the target fuels for shock tube ignition delay. The model also captures trends in the ignition delay for a reference Jet-A as a function of pressure and equivalence ratio.