Theoretical investigation of the performance of alternative aviation fuels in an aero-engine combustion chamber

Abstract

When considering alternative fuels for aviation, factors such as the overall efficiency of the combustion process and the levels of emissions emitted to the atmosphere need to be critically evaluated. The physical and chemical properties of a fuel influence the combustion efficiency and emissions and therefore need to be considered. The energy content of a biofuel, which is influenced negatively by the presence of oxygen in the molecular structure (i.e. oxygenated chemical compounds), is relatively low when compared with that of conventional jet fuel. This means that the overall efficiency of the process will be different. In this article, two possible scenarios have been investigated in order to assess the potential to directly replace conventional jet fuel – kerosene with methyl buthanoate – MB (a short chain fatty acid methyl ester – representing biofuel) and a synthetic jet fuel (Fischer–Tropsch fuel) using computational fluid dynamics (CFD) modelling in a typical modern air-spray combustor. A detailed comparison of kerosene with alternative fuel performance has been made. In addition, the impact of fuel blending on the combustion performance has been investigated. The CFD results indicate that there are notable differences in the engine performance and emissions when replacing conventional jet fuel with alternative fuels. The effect of alternative fuel chemistry on the combustion characteristics is noticeable both in the flamelet calculation and the CFD main flow field computations. This is particularly the case for MB.

Comparative Numerical Study of Four Biodiesel Surrogates for Application on Diesel 0D Phenomenological Modeling

“…The overall trend observed from the various simulation results is that methyl butanoate gives better predictions of engine parameters compared to other surrogates; this is in accordance with its high rate of usage as a surrogate for biodiesel in 3D and 1D simulation studies [4,5,44]. However, this result is somehow contradictory with comments from Brakora et al [45] and Hakka et al [33] that say that methyl butanoate is not a particular good surrogate for biodiesel.…”

Life cycle greenhouse gas analysis of biojet fuels with a technical investigation into their impact on jet engine performance

“…This data defines the "performance" properties of the given fuel in a numerically modelled and validated engine/aircraft system. Such an analysis aims to provide an insight into their thermodynamic influence on an aero-engine performance and emission characteristics [17,20,21]. The empirical data and key performance properties of each of the 100% Bio-SPKs has been presented in Table 1.…”

Genetic Algorithm optimised Chemical Reactors network: A novel technique for alternative fuels emission prediction

“…With the same surrogate methodology, the GTL and the bio-diesel were mimicked by Heptane C7H16 and Methyl-Butonate (MB) C 5 H 10 O 2 respectively. Note that the MB has less energy content than the rapeseed bio-diesel, which are 26.7MJ/kg and 40MJ/kg respectively [30,31], so the fuel flows in the model had been increased to compensate this difference. The assessment of the technical suitability of alternative fuels however is broader than just focusing attention on combustion performance.…”