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

该提案的主要目的是开发、验证和评估一种先进的欧拉-欧拉方法，该方法使用LES描述气相中的流动和混合场，而基于直接求积的截面矩量法（DQbS）用于跟踪欧拉框架中的蒸发液滴相。最近，申请人在RANS背景下引入了DQbS，并成功地应用于描述令人满意的复杂反应多分散喷雾系统。 该建议的第一个问题包括在LES框架中对DQbSourcing的适当描述。新兴的LES为基础的欧拉-欧拉模型，然后将扩展到包括燃料雾化过程。因此，将适当考虑所谓的艾尔莎（欧拉-拉格朗日片状雾化）液体雾化模型，以完成已经集成的聚结（液滴-液滴相互作用）模型。在这种方式下，基本现象，包括初级破碎，液滴-液滴相互作用，湍流分散，蒸发和燃烧过程将首次纳入。最后一个问题将解决的耦合所产生的LES为基础的欧拉-欧拉模型与列表化学描述的燃烧。后者依赖于最近在文献中提出的喷雾小火焰的方法。它将适应LES的上下文中沿着小火焰产生的流形（FGM）制表和进一步发展为喷雾FGM技术。该方法不仅考虑了化学/蒸发液滴的相互作用和非绝热性，而且考虑了刘易斯数效应。这样，在化学成分列表过程中，层流火焰结构中的蒸发过程和部分蒸发将被考虑在内。由此产生的整体模型将在不同几何形状的配置中得到验证和示例性评估。将考虑两种配置的复杂性增加，即乙醇的喷雾射流（马斯里配置）和复杂的正庚烷喷雾配置（CORIA配置）表现出密集的喷雾区域。两者都代表了“湍流喷雾燃烧（TCS）”国际研讨会的两个目标喷雾火焰。

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)“.