CMC-LES Modellierung der Sprayverbrennung

Liquid spray combustion is a widely employed concept in engineering, with a range of applications such as internal combustion engines, aircraft- and rocket propulsion. The process covers the aspects of turbulent transport, liquid jet atomisation, evaporation, mixture preparation, ignition and combustion and accurate numerical models for describing these effects and their mutual interaction are required. In this project we develop a combined large eddy simulation (LES) – conditional moment closure (CMC) approach to model turbulent dilute spray flames. LES is used to accurately model the turbulent flow and to provide the mixture fraction as a conditioning variable for CMC. The Eulerian LES-CMC gas phase model is coupled to a Lagrangian description of the liquid spray droplets. An extendedversion of CMC is developed, with a special focus on the modelling of the conditionally-averaged heat and mass transfer terms and the (unresolved) upper boundary in mixture fraction space. The model is successfully validated against a series of well-defined spray flame experiments. The model is further improved by introducing two conditional moments and by coupling CMC to a tabulated chemistry approach.