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

Abstract

The objective of present paper is to assess the influence of different chemical mechanisms on nonpremixed combustion of kerosene liquid fuel in a gas turbine model combustor. Simulation of two-phase reacting flow is performed employing realizable k − ε turbulence, laminar flamelet combustion, and discrete ordinates radiation models in a structured finite volume grid. An Eulerian−Lagrangian approach is applied to model spray of liquid fuel. Distributions of mean axial velocity, temperature, scalar dissipation rate, mixture fraction, mass fraction, and rate of formation of carbon dioxide, water vapor, and nitrogen monoxide are compared for three different cases (three different chemical reaction mechanisms). Results depict that minimum deviations concerning the mean axial velocity and mean temperature are observed for case A, which consists of 17 species and 26 reaction steps. The maximum scalar dissipation rate is shown for case B, comprising 21 species and 30 reactions steps due to a higher mixture fraction variance. By enhancing the laminar scalar dissipation rate, mean temperature is reduced against mixture fraction. The reaction development and energy release rates are slower for case C, including 16 species and 26 reactions steps. The concentrations of predicted NO and CO 2 for the three cases are different due to the predicted temperature differences. The thermal NO formation rate is higher for case A, then C, and last of all B.

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.…”

“…The chemical reactions in the combustor are modeled employing the laminar flamelet model, which is also applied recently by the authors , and some other researchers. ,, The nonpremixed combustion and turbulent flows are correlated via the β PDF . The flamelet equations are formulated as where ω̇ i , S i , H i , C p, i , C p , Y i , and χ are the production rate from chemical reaction, the source term of reaction rate, the specific enthalpy of species i , the specific heat of species i , the mixture mean specific heat, the mass ratio of species i , and the scalar dissipation rate, respectively.…”

“…The flamelet database is produced on the basis of the JetSurf 1.0 reaction mechanism which includes 194 species and 1459 reduced chemical reactions of kerosene. Further descriptions of the flamelet model are available in references. ,,, …”

“…In the present work, the discrete ordinates model (DOM) is applied for modeling the radiation heat transfer. The weighted sum of gray gases model (WSGGM) is implemented for gaining the nonconstant absorption coefficient of combustion gases due to the continuous variations of the combustion characteristics (i.e., temperature and species concentration) during the combustion process. , More information about the WSGGM and DOM is available in the literature. ,− …”

“…C 1 is not a constant, and it depends on the ratio of turbulence characteristic time to flow field characteristic time. The chemical reactions in the combustor are modeled employing the laminar flamelet model, 30 which is also applied recently by the authors 28,31 and some other researchers. 6,15,32 The nonpremixed combustion and turbulent flows are correlated via the βPDF.…”