27 th ICDERS July 28 th – August 2 nd , 2019 Beijing, China Correspondence to: G.Ozel-Erol2@newcastle.ac.uk 1 Statistics of Two-Phase Coupling in Turbulent Spherically Expanding Flames in Mono-sized Fuel-Droplet Mists Gulcan Ozel Erol 1 , Josef Hasslberger 2 , Nilanjan Chakraborty 1 1 School of Engineering, Newcastle University, Newcastle-Upon-Tyne, Tyne and Wear, UK 2 Bundeswehr University, Munich, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany 1 Introduction Turbulent combustion of droplet-laden mixtures involves complex interactions between combustion, heat transfer, droplet evaporation and fluid turbulence. A thorough knowledge of the interaction between liquid droplets and carrier gaseous phase is necessary for the purpose of fundamental understanding and modelling flame-droplet interaction. The experimental observations for spherically expanding spray flames revealed that flame-turbulence interaction is strongly affected by droplet diameter and the overall equivalence ratio [1]. Recent advancements in high-performance computing have enabled carrier phase Direct Numerical Simulations (DNS) to analyse different aspects of turbulent combustion processes in droplet-laden mixtures [2,3]. Previous DNS analyses [2,3] indicated that the gaseous phase combustion takes place predominantly in fuel-lean mode even for the overall (i.e. gaseous and liquid phases) fuel-rich fuel-air mixtures because of the differences in time-scales for evaporation and chemical reactions, which in turn affect the resulting combustion and mixing processes. A thorough understanding of the aforementioned behaviour and its influence on the subsequent combustion processes necessitate a detailed analysis of the interaction between liquid and gaseous phases, which serves as the motivation for the current analysis. To meet this objective, a DNS database of spherically expanding flames propagating into mono-sized fuel-droplet mists for a range of different initial droplet diameters and overall equivalence ratios has been considered here to analyse the statistics of liquid and gaseous phase interactions in turbulent combustion in droplet-laden mixtures. 2 Mathematical Background and Numerical Implementation A modified single-step Arrhenius-type chemical mechanism, where the activation energy and the heat of combustion are taken to be functions of the gaseous equivalence ratio   , is used for this analysis to keep computational demand for a detailed parametric analysis within reasonable limits. This chemical mechanism yields a realistic   dependence of the unstrained laminar burning velocity  (  ) in hydrocarbon-air flames. The Lewis numbers of all species are assumed to be unity and all species in the gaseous phase are taken to be perfect gases. Standard values have been considered for the ratio of specific heats ( =