Numerical Analysis of Lifted Spray Flames in Various Coflow Conditions

Mohapatra, Subhankar; Nehe, Prashant; Dash, Sukanta Kumar; Reddy, V. Mahendra

doi:10.1080/00102202.2019.1590824

Cited by 6 publications

(2 citation statements)

References 47 publications

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“…The thermochemical scalers like temperature, density, and species fractions are assumed to be uniquely related to the mixture fraction in the flamelet model. Moreover, the effect of intermediate species and dissociation reactions predicted by this model gives more realistic temperature predictions than the Eddy dissipation model . With the laminar flamelet approach, realistic chemical kinetic effects can be incorporated into the turbulent flames with tremendous computational savings.…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, the effect of intermediate species and dissociation reactions predicted by this model gives more realistic temperature predictions than the Eddy dissipation model. 83 With the laminar flamelet approach, realistic chemical kinetic effects can be incorporated into the turbulent flames with tremendous computational savings. However, this model is limited to flames with relatively fast chemistry and thus it gives poor predictions in capturing nonequilibrium effects like extinction, and slow chemistry.…”

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Development of the Reduced Chemical Kinetic Mechanism for Combustion of H₂/CO/C₁–C₄ Hydrocarbons

et al. 2020

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In this study, a reduced 50 species 373 elementary chemical mechanism is developed for the high-temperature combustion of H2/CO/C1–C4 compounds. The reduced skeletal mechanism, based on the detailed skeletal USC 2.0 mechanism (111 species, 784 reactions), is used to study the ignition and combustion characteristics of the H2/H2–CO and C1–C4 hydrocarbons. It is found that the reduced skeletal mechanism can reproduce the results from the detailed USC 2.0 mechanism with a maximum error of less than 12% in the ignition delay times under a range of operating conditions with P = 1–20 atm, T = 900–2000 K, and ϕ = 0.3–2.0. The applicability of the reduced skeletal mechanism is then demonstrated numerically in an industrial gas swirl burner for a 100% C3H8 + air non-premixed turbulent swirl-stabilized flame. The profiles of radial temperature and mole fraction of CO at various axial distances are validated with existing experimental data and are found to be in good agreement. It is therefore established that the reduced skeletal mechanism can be utilized for rapid implementation in a commercial computational fluid dynamics (CFD) package for combustion analysis. It is found that the central-processing-unit (CPU) time cost of the skeletal mechanism is about one-third of that of the detailed USC Mech 2.0 mechanism for the ignition delay and laminar flame speed simulations and is about half of that of the detailed USC Mech 2.0 for non-premixed CFD simulations using a laminar flamelet approach. The present results demonstrate that the reduced skeletal mechanism can provide better scope for studying the combustion characteristics of C1–C4 hydrocarbons at different pressure conditions and compositions.

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Development of the Reduced Chemical Kinetic Mechanism for Combustion of H₂/CO/C₁–C₄ Hydrocarbons

et al. 2020

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Adaptability of different mechanisms and kinetic study of methane combustion in steam diluted environments

Mohapatra

Mohapatro

Pasha

et al. 2022

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The chemical kinetics of methane oxidation in a steam-diluted environment are studied in the present study. Various well-validated mechanisms for methane combustion are adopted and compared with experimental data. Ignition delay, laminar flame speed, and emissions for CH4 combustion with steam dilution are discussed. Cumulative relative error parameter was determined for all mechanisms considered in this study to evaluate the prediction level in quantifiable terms. Reaction pathways under no and steam-diluted environments are analyzed, and key elementary reactions and species are identified in these conditions. The analysis gives a relative idea of the applicability of some of the reduced mechanisms for the diluted steam conditions. This study aims to guide future computational fluid dynamics simulations to accurately predict combustion characteristics in these conditions. Computations of laminar flame speed from GRI-3.0, Aramco3.0, Curran, and San Diego mechanisms were the most precise under diluted steam conditions. Similarly, for the calculation of ignition delay of methane under the steam dilution, the Aramco mechanism and the Curran’s mechanism were able to predict the experimentally observed values most closely. Sensitivity study for the OH concentrations shows that the H-abstraction of methane from OH radicals has an opposing trend with dilution for Aramco and GRI-3.0 mechanism. On the other hand, CO and NO emissions were reduced significantly, with the dilution increased from 0 to 20%. The third-body effect of steam is observed to dominate the deviation observed between the detailed and reduced mechanism. For low operating pressure conditions, the GRI-3.0 mechanism gives an excellent prediction, whereas, for applications like gas turbines and furnaces, Aramco-3.0 and Curran mechanisms can be adopted to give good results. The San Diego mechanism can be chosen for low computational facility purposes as it shows very good predictions for ignition delay and laminar flame speed computations.

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Influence of jet velocity and heat recuperation on the flame stabilization in a non-premixed mesoscale combustor: An exergetic approach

et al. 2023

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An experimental and numerical model to determine the exergy balance based on flow availability and availability transfer in the process of liquefied petroleum gas (LPG)/air combustion in mesoscale gas turbine combustor is developed to elucidate the second law efficiency and total thermodynamic irreversibility. In terms of developing an energy and exergy-efficient combustor design, the present work highlights the influence of vortex shedding and recirculation in the volumetric entropy production and the exergy efficiency. It is performed in a heat recuperative high-intensity LPG-fueled mesoscale combustor for mini-gas turbine applications. The combustor is operated at different thermal inputs ranging from 0.2 to 1.0 kW under range of equivalence ratios of ϕ = 0.4–1.23. The Favre-averaged governing equations are solved by using finite volume-based approach. The standard k–ε turbulence model with modified empirical constant, [Formula: see text], is considered to model the turbulence quantities. The volumetric reaction-based eddy-dissipation concept model and a reduced skeletal model (50 species and 373 reactions) are used for turbulence–chemistry interaction. The design methodology, total volumetric entropy generation, destructive exergy due to thermodynamic irreversibility, exergy efficiency, flow recirculation, and mixing characteristics (reacting and non-reacting) are reported. The entropy generation rate due to thermal conduction is approximately 50% of the total entropy generation, while its contribution percentage due to chemical reaction is the smallest. The exergy efficiency reaches its peak with [Formula: see text] = 79.41% at 1.0 kW under fuel-rich condition, while its minimum value of 41.49% is obtained at 0.2 kW under fuel-lean (ϕ = 0.8) condition.

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Numerical Analysis of Lifted Spray Flames in Various Coflow Conditions

Cited by 6 publications

References 47 publications

Development of the Reduced Chemical Kinetic Mechanism for Combustion of H₂/CO/C₁–C₄ Hydrocarbons

Development of the Reduced Chemical Kinetic Mechanism for Combustion of H₂/CO/C₁–C₄ Hydrocarbons

Adaptability of different mechanisms and kinetic study of methane combustion in steam diluted environments

Influence of jet velocity and heat recuperation on the flame stabilization in a non-premixed mesoscale combustor: An exergetic approach

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Numerical Analysis of Lifted Spray Flames in Various Coflow Conditions

Cited by 6 publications

References 47 publications

Development of the Reduced Chemical Kinetic Mechanism for Combustion of H2/CO/C1–C4 Hydrocarbons

Development of the Reduced Chemical Kinetic Mechanism for Combustion of H2/CO/C1–C4 Hydrocarbons

Adaptability of different mechanisms and kinetic study of methane combustion in steam diluted environments

Influence of jet velocity and heat recuperation on the flame stabilization in a non-premixed mesoscale combustor: An exergetic approach

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Product

Resources

About

Development of the Reduced Chemical Kinetic Mechanism for Combustion of H₂/CO/C₁–C₄ Hydrocarbons

Development of the Reduced Chemical Kinetic Mechanism for Combustion of H₂/CO/C₁–C₄ Hydrocarbons