A. Hosseinzadeh

Thermoacoustics of a turbulent premixed flame

Quantitative analyses of noise induced by turbulent combustion processes are essential for the design of efficient combustors. To understand the noise generating mechanisms detailed thermoacoustic source mechanisms for the acoustic perturbation equations are deduced from the governing equations of compressible reactive fluids. A generic burner configuration operated with a turbulent premixed flame is experimentally and numerically investigated to identify relevant source mechanisms and to show the dependence of the noise radiation on the operating conditions. Besides direct combustion noise mechanisms by heat release fluctuations indirect mechanisms by acceleration of entropy inhomogenities and non-isentropic mixing processes are identified as major noise sources.

Effects of subgrid scale and combustion modelling on flame structure of a turbulent premixed flame within LES and tabulated chemistry framework

The effects of combustion and SubGrid Scale (SGS) modelling on the overall flame characteristics of a turbulent premixed flame are investigated. This is achieved in terms of mean flow statistics, variances and flame surfaces. In particular, the chemical flame structure is analysed and compared. The Artificially Thickened Flame (ATF) approach coupled with the Flamelet Generated Manifolds (FGMs) and Filtered TAbulated Chemistry for LES (F-TACLES) approaches are used for this investigation. A Germano like procedure for dynamical calculation of SGS wrinkling is used which ensures the conservation of the total flame surface for both models. It turns out that using the dynamic SGS wrinkling model improves the results. Although the results of both combustion models in terms of statistics, mean and variances show very good agreement, the resolved flame surfaces hide different dynamic behaviour.