Modeling Nonequilibrium Combustion Chemistry Using Constrained Equilibrium Flamelet Model for Kerosene Spray Flame

Abstract

Numerical simulation employing different models is popularly used to predict spray combustion of liquid fuels. In the present work, we have compared the effects of three different combustion models, viz., eddy dissipation model, laminar flamelet model with detailed chemical reaction mechanism, and constrained equilibrium flamelet model, on the temperature, soot, and NOx distributions in an axisymmetric combustor burning kerosene spray. Experiments have also been performed in a combustor of the same geometry to validate some predictions from the models. The constraint condition for the equilibrium flamelet model has been adopted by suitably accounting the effects of scalar dissipation rate on the prediction of scalar variables in a laminar flamelet and by considering the mixture fraction and scalar dissipation rate distributions in the combustor under test. It is found that the results predicted by the two flamelet models agree closely between them and also with the experiments. On the other hand, the eddy dissipation model predicts a much higher flame temperature, soot, and NOx concentrations in the combustor. The results suggest the importance of chemistry in the prediction of the turbulent spray flame. It also suggests that with a proper choice of the constraint condition, the equilibrium flamelet model can address the nonequilibrium chemistry in the flame due to the high value of scalar dissipation rate.

Influence of Chemical Mechanisms on Spray Combustion Characteristics of Turbulent Flow in a Wall Jet Can Combustor

“…It should be mentioned that at a scalar dissipation rate greater than the last scalar dissipation rate, the flame is extinguished. , …”

Analysis of Relationship between Entropy Generation and Soot Formation in Turbulent Kerosene/Air Jet Diffusion Flames

“…Some supplementary terms, similar to the Reynolds stresses tensors, are appeared by the Favre averaging of the governing equations. On the basis of the previously reported studies, − the realizable k – ε model is employed presently to model the Reynolds viscous stresses in a combustor. The realizable k – ε transport equations are defined, as follows: Here k and ε signify kinetic energy and dissipation rate, successively.…”