Coupling of a direct quadrature based sectional method of moments with Large Eddy Simulation (LES) for describing polydisperse reacting spray systems

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The main objective of this proposal is to develop, validate and evaluate an advanced Eulerian-Eulerian method in which the flow and mixing field in the gas phase is described using LES, while the Direct Quadrature based Sectional Method of Moments (DQbSMOM) is used to track the evaporating droplet phase in an Eulerian framework. The DQbSMOM has recently been introduced by the applicant in the RANS context and successfully applied to describe satisfactorily complex reacting polydisperse spray systems. The first issue of this proposal consists of an appropriate description of DQbSMOM in the LES framework. The emerging LES based Eulerian-Eulerian model will be then extended to include fuel atomization processes. Thereby, the so-called ELSA (Eulerian-Lagrangian Sheet Atomization) liquid atomization model will be appropriately considered in order to complete the already integrated coalescence (droplet-droplet interaction) model. In this way, the essential phenomena comprising primary breakup, droplet-droplet interactions, turbulent dispersion, evaporation and combustion processes will be incorporated for the first time. The final issue will address the coupling of the resulting LES-based Eulerian-Eulerian model with a tabulated Chemistry description of the combustion. The latter relies on a spray flamelet approach recently proposed in the literature. It will be adapted in the LES context along the Flamelet Generated Manifold (FGM) tabulation and further developed as Spray-FGM technique. The suggested Spray-FGM method accounts not only for the interaction chemistry/evaporating droplet and the non-adiabaticity but also for the Lewis number effects. With this the evaporation process and partial evaporation will be accounted for within the laminar flame structure during the chemistry tabulation.The resulting overall model will be validated and exemplarily assessed in configurations of different geometries. Two configurations of increasing complexity will be considered, namely a spray jet of ethanol (Masri configuration) and a complex n-heptane spray configuration (CORIA configuration) exhibiting a dense spray region. Both represent two target spray flames of the international workshop on „Turbulent Spray Combustion (TCS)“.