The flamelet/progress variable (FPV) combustion model [30] tabulates thermochemical state information depending on the mixture fraction Z and the reaction progress variable PV in a pre-processing step using one-dimensional laminar flamelets. These flamelets can be based on premixed or counterflow diffusion (non-premixed) computations. In this context, progress of combustion reactions is often described using the sum of mass fractions of main combustion products. However, Hansinger et al. [20] performed LES simulations based on a progress variable definition which includes the species mass fractions of carbon dioxide, water and carbon monoxide. This PV defintion generated unsatisfying results in the context of partially premixed Sandia flame configurations. Hence, the investigations in this thesis comprise two alternative definitions of the reaction progress. In particular, these approaches are based on entropy on the one hand and the chemical potential on the other hand. Entropy is monotonically increasing during reaction in selfcontained, adiabatic thermodynamic systems. On the contrary, the chemical potential is applied to open thermodynamic systems and is steadily declining while chemical reactions occur. The monotonic behaviour of these thermodynamic quantities is an important property considering their application to the FPV model. Thus, this thesis introduces the thermodynamic fundamentals of both of these state variables and outlines necessary assumptions in order to use these parameters in the FPV model. Further, these concepts are applied to premixed and non-premixed flamelets and the according thermochemical state allocations are compared to the approach of Hansinger et al. [20]. Based on the obtained flamelet libraries, large-eddy simulations of two partially premixed Sandia flames are carried out. These flame configurations differ in their level of homogeneity of methane and air at the exit plane of the burner. With regard to the non-premixed flamelets, the numerical results of the entropy based progress variable definition show good accordance with the experimental data in case of both Sandia flame configurations. However, the chemical potential concept indicates significant deviation from experimental measurements. Referring to the premixed flamelets, the overall accuracy of the progress variable definition investigated by Hansinger et al. [20] is higher compared to both approaches introduced in this thesis.     «

The flamelet/progress variable (FPV) combustion model [30] tabulates thermochemical state information depending on the mixture fraction Z and the reaction progress variable PV in a pre-processing step using one-dimensional laminar flamelets. These flamelets can be based on premixed or counterflow diffusion (non-premixed) computations. In this context, progress of combustion reactions is often described using the sum of mass fractions of main combustion products. However, Hansinger et al. [20] pe...     »

The flamelet/progress variable (FPV) combustion model [30] tabulates thermochemical state information depending on the mixture fraction Z and the reaction progress variable PV in a pre-processing step using one-dimensional laminar flamelets. These flamelets can be based on premixed or counterflow diffusion (non-premixed) computations. In this context, progress of combustion reactions is often described using the sum of mass fractions of main combustion products. However, Hansinger et al. [20] performed LES simulations based on a progress variable definition which includes the species mass fractions of carbon dioxide, water and carbon monoxide. This PV defintion generated unsatisfying results in the context of partially premixed Sandia flame configurations. Hence, the investigations in this thesis comprise two alternative definitions of the reaction progress. In particular, these approaches are based on entropy on the one hand and the chemical potential on the other hand. Entropy is monotonically increasing during reaction in selfcontained, adiabatic thermodynamic systems. On the contrary, the chemical potential is applied to open thermodynamic systems and is steadily declining while chemical reactions occur. The monotonic behaviour of these thermodynamic quantities is an important property considering their application to the FPV model. Thus, this thesis introduces the thermodynamic fundamentals of both of these state variables and outlines necessary assumptions in order to use these parameters in the FPV model. Further, these concepts are applied to premixed and non-premixed flamelets and the according thermochemical state allocations are compared to the approach of Hansinger et al. [20]. Based on the obtained flamelet libraries, large-eddy simulations of two partially premixed Sandia flames are carried out. These flame configurations differ in their level of homogeneity of methane and air at the exit plane of the burner. With regard to the non-premixed flamelets, the numerical results of the entropy based progress variable definition show good accordance with the experimental data in case of both Sandia flame configurations. However, the chemical potential concept indicates significant deviation from experimental measurements. Referring to the premixed flamelets, the overall accuracy of the progress variable definition investigated by Hansinger et al. [20] is higher compared to both approaches introduced in this thesis.     «

The flamelet/progress variable (FPV) combustion model [30] tabulates thermochemical state information depending on the mixture fraction Z and the reaction progress variable PV in a pre-processing step using one-dimensional laminar flamelets. These flamelets can be based on premixed or counterflow diffusion (non-premixed) computations. In this context, progress of combustion reactions is often described using the sum of mass fractions of main combustion products. However, Hansinger et al. [20] pe...     »