LES of a swirl-stabilized kerosene spray flame with a multi-component vaporization model and detailed chemistry

摘要

Due to the introduction of alternative aviation fuels, new methods and models are necessary which have the capability to predict the performance of combustors dependent on the fuel composition. Towards this target, a multi-component vaporization model is coupled to a direct, detailed chemistry solver in the context of Eulerian-Lagrangian LES. By means of the computational platform, a lab-scale, swirl-stabilized spray flame is computed. The burner exhibits some of the key features of current aero-engine combustors. Global features like the measured spray distribution and the position of the reaction zone are well reproduced by the LES. The comparison of droplet size, droplet velocity and liquid volume flux profiles with experimental data also show a good agreement. However, discrepancies in the temperature profiles in the central mixing zone exist. The computational results show that evaporation and mixing are the rate controlling steps in the flame zone. In this zone, chemistry can be assumed to be infinitely fast. However, other zones exist where finite rate chemistry effects prevail. For these states, the direct computation of the elementary reactions by means of Arrhenius equations and the transport of all individual species are beneficial. Furthermore, the finite rate chemistry approach demonstrates a great potential with respect to pollutant formation, as precursors can be directly computed. Additionally, the example of benzene forming from one specific chemical class in the fuel suggests that a multi-component description of the liquid phase and the evaporation process is required to correctly predict soot emissions. (C) 2019 Deutsches Zentrum fur Luft- und Raumfahrt e.V. (DLR). Published by Elsevier Inc. on behalf of The Combustion Institute.