Development Of The Coupled ESF/FGM Turbulent Combustion Model

At present,the mainstream turbulent combustion models are divided into the flamelet-based model and the probability density function based model.The biggest advantage of the flamelet-based model is that it greatly improves the calculation efficiency by taking into accountants the detailed chemical reaction mechanism.But the deficiency is that it is greatly affected by combustion mode.The probability density function model's advantage lies in the high precision feature,which can accurately consider the interaction between turbulence and chemical reaction by using the probability density function of the variable in real-time computing.But the shortage is that the calculation is large.The main goal of this paper is to combine the two types of mainstream models well,and to achieve the perfect combination of computational accuracy and computational efficiency to the greatest extent,to maximize the advantages of the two types of models.In the process of combination,this paper selects Flamelet Generated Manifolds(FGM),which is widely used in the flamelet-based model and has good calculation results.Eulerian Stochastic Field(ESF)which is one of the probability density function models is selected because it is easier to implement into the software.Based on the open source computational fluid dynamics software OpenFOAM,this thesis developed a extendable turbulent combustion numerical simulation solver based on the coupled ESF/FGM method.For the model validation,this paper selects a series of turbulent jet diffusion flames released by Sandia National Laboratory,which is rich in experimental data and simulated by many scholars as the verification development model.Firstly,the Sandia D flame of the Sandia series flame is used to verify the accuracy,advancement and software compatibility of the RANS turbulent combustion model which used the coupled ESF/FGM model.Secondly,the Sandia D,E,F flames of the Sandia series flame are used to verify the accuracy,advancement and software compatibility of the LES turbulent combustion model which used the coupled of ESF and FGM model.This model effectively improves many problems in the RANS version of this method.The LES version of this method not only has a greater improvement in the accuracy,but also has a strong ability to capture combustion phenomena such as local blow-out and re-ignition.To make a step further,the liquid phase models such as atomization,dispersion and evaporation were added to the coupled ESF/FGM model.A numerical simulation solver for turbulent spray combustion based on the coupled ESF/FGM method was developed based on OpenFOAM platform.The model validation was carried out by using the Delft Spray-in-Hot-Coflow(DSHC)flame which is rich in experimental data and issued by the Delft University of Technology,The simulation results verified the accuracy,advancement and expandability of the LES turbulent spray combustion model which used the coupled of ESF and FGM model.Compared with the original FGM model without ESF method,the accuracy of the model has been greatly improved.