Theoretical and empirical investigations on the combustion of conventional and alternative jet fuels; combustion properties modelling and quantitative species measurement

Due to the increasing growth of jet fuels usage in air transportation during the recent decades and the related problems of this growth, such as the issue of greenhouse gases (GHG), and the depletion of fossil fuel resources, the development of new ways to increase the efficiency of combustion, and application of non-oil alternative fuels are necessary to be considered to address these issues. In this regard, this study aims to conduct a series of simulations by the construction of jet fuel surrogate chemical kinetic mechanisms and the laser-based experimental work by the flame investigation to deliver useful data for the combustion process of jet fuels. The construction of the proposed surrogates includes simplified chemical kinetic mechanisms delivering a good prediction ability for all key combustion parameters of aviation kerosene and alcohol to jet fuel (ATJ) in gas phase, covering a wide range of temperatures, pressures and equivalence ratio conditions. Three parameters, including ignition delay time, laminar flame speed, and species concentration are simulated by use of ANSYS Chemkin-Pro using models for zero dimensional homogeneous closed reactors, one dimensional freely-propagating laminar flames, and zero dimensional perfectly-stirred reactors, respectively. The simulation results for these parameters are validated against the available data in the literature and via a series of experiments with liquid fuel burners, incorporating planar laser induced fluorescence (PLIF). A quantitative concentration profile of OH radicals is provided for the jet fuels and is compared to the models developed for the fuels. Due to the scarcity of the dedicated works for the PLIF flame investigations on the OH distribution and the temperature profiles of the heavy liquid fuels, the results of the present study can deliver useful data for the target research community. Sensitivity analysis, optimization tools, and reduction methods in Chemkin-pro are utilized to develop a reduced well-validated reaction mechanism for the components of the fuels and the proposed surrogates for jet A and ATJ fuels, with the aid of a decoupling methodology. The developed chemical kinetic mechanisms for the single components and the fuels can simultaneously fulfil the requirement for a small size mechanism, and more important, the need for a model producing results that accurately agree with the experimental data.