A Direct Numerical Simulation-Based Analysis of Entropy Generation in Turbulent Premixed Flames

Farran, Richard; Chakraborty, Nilanjan

doi:10.3390/e15051540

Cited by 31 publications

(53 citation statements)

References 55 publications

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“…In the differential approach, the local exergy destruction rate per unit volume of the fluid is determined at every point of the flow field. The total exergy destruction rate is then determined by integrating the local exergy destruction rate over the given volume [16,17]. In the control volume approach, the exergy balance is carried out over a finite control volume and the exergy destruction rate is determined for the whole control volume.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

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Exergy Destruction in Pipeline Flow of Surfactant-Stabilized Oil-in-Water Emulsions

Pal

2014

Energies

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Exergy destruction in adiabatic pipeline flow of surfactant-stabilized oil-in-water emulsions is investigated in five different diameter pipes. The dispersed-phase (oil droplets) concentration of the emulsions is varied from 0% to 55.14% vol. The emulsions are Newtonian in that the viscosity is independent of the shear rate. For a given emulsion and pipe diameter, the exergy destruction rate per unit pipe length increases linearly with the increase in the Reynolds number on a log-log scale in both laminar and turbulent regimes. However the slope in the turbulent regime is higher. The exergy destruction rate increases with the increase in the dispersed-phase concentration of emulsion and decreases with the increase in the pipe diameter. New models are developed for the prediction of exergy destruction rate in pipeline flow of surfactant-stabilized oil-in-water emulsions. The models are based on the single-phase flow equations. The experimental data on exergy destruction in pipeline flow of emulsions shows excellent agreement with the predictions of the proposed models.

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Section: Theoretical Backgroundmentioning

confidence: 99%

“…Substitution of the friction factor expressions from Equations (18) and (19) into Equation (17) leads to the following relations for exergy destruction in pipe flows:…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Exergy Destruction in Pipeline Flow of Surfactant-Stabilized Oil-in-Water Emulsions

Pal

2014

Energies

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“…McEligot et al [36] studied the entropy generation in the near wall region of a turbulent channel flow. Farran and Chakraborty [37] conducted DNS prediction of entropy generation in a turbulent premixed flame. Ghasemi et al [38,39] used DNS and Reynolds averaged Navier-Stokes (RANS) to study the entropy generation and energy dissipation in transitional regions in wall shear flows.…”

Section: Introductionmentioning

confidence: 99%

Progress in the Prediction of Entropy Generation in Turbulent Reacting Flows Using Large Eddy Simulation

Safari

Hadi

Sheikhi

2014

Entropy

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An overview is presented of the recent developments in the application of large eddy simulation (LES) for prediction and analysis of local entropy generation in turbulent reacting flows. A challenging issue in such LES is subgrid-scale (SGS) modeling of filtered entropy generation terms. An effective closure strategy, recently developed, is based on the filtered density function (FDF) methodology with inclusion of entropy variations. This methodology, titled entropy FDF (En-FDF), is the main focus of this article. The En-FDF has been introduced as the joint velocity-scalar-turbulent frequency-entropy FDF and the marginal scalar-entropy FDF. Both formulations contain the chemical reaction and its entropy generation effects in closed forms. The former constitutes the most comprehensive form of the En-FDF and provides closure for all of the unclosed terms in LES transport equations. The latter is the marginal En-FDF and accounts for entropy generation effects, as well as scalar-entropy statistics. The En-FDF methodologies are described, and some of their recent predictions of entropy statistics and entropy generation in turbulent shear flows are presented.

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“…For the study reported here, the flowing gas is made up of the products of the combustion of methane with 300 per cent theoretical air at various chamber pressures. The products of the combustion process consist of 3.38 per cent CO 2 [17], including the Wilke approximation for mixtures of polyatomic gaseous species. The primary parameter required for the computation of the given set of equations is the kinematic viscosity, with the specific values determined by the applied pressure levels.…”

Section: Combustion Chamber Environmentmentioning

confidence: 99%

“…Understanding these sources of irreversibility in the combustion process should lead to improvements in thermal and combustion efficiencies of future energy conversion systems. Application of large eddy simulation (LES) techniques for the exergy analysis of turbulent combustion systems by Safari et al [1] and the use of the direct numerical simulation (DNS) procedure in the analysis of entropy generation in turbulent premixed flames by Farron and Chakraborty [2] have clearly identified that turbulent flow conditions significantly enhance the entropy production of various physical processes within the flame structure. These studies, of necessity, assumed homogeneous turbulence environments, both upstream and downstream of the combustion process, as the bases for their studies.…”

Section: Introductionmentioning

confidence: 99%

Spectral Entropy, Empirical Entropy and Empirical Exergy for Deterministic Boundary-Layer Structures

Isaacson

2013

Entropy

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A modified form of the Townsend equations for the fluctuating velocity wave vectors is applied to a laminar three-dimensional boundary-layer flow in a methane fired combustion channel flow environment. The objective of this study is to explore the applicability of a set of low dimensional, coupled, nonlinear differential equations for the prediction of possible deterministic ordered structures within a specific boundary-layer environment. Four increasing channel pressures are considered. The equations are cast into a Lorenz-type system of equations, which yields the low-dimensional set of equations. The solutions indicate the presence of several organized flow structures. Singular value decomposition of the nonlinear time series solutions indicate that nearly ninety-eight percent of the fluctuating directed kinetic energy is contained within the first four empirical modes of the decomposition. The empirical entropy computed from these results indicates that these four lowest modes are largely coherent structures with lower entropy rates. Four regions are observed: low-entropy structures over the first four modes; steep increase in entropy over three modes; steady, high entropy over seven modes; and an increase to maximum entropy over the last two modes. A measure, called the empirical exergy, characterizes the extent of directed kinetic energy produced in the nonlinear solution of the deterministic equations used to model the flow environment. The effect of increasing pressure is to produce more distinct ordered structures within the nonlinear time series solutions.

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A Direct Numerical Simulation-Based Analysis of Entropy Generation in Turbulent Premixed Flames

Cited by 31 publications

References 55 publications

Exergy Destruction in Pipeline Flow of Surfactant-Stabilized Oil-in-Water Emulsions

Exergy Destruction in Pipeline Flow of Surfactant-Stabilized Oil-in-Water Emulsions

Progress in the Prediction of Entropy Generation in Turbulent Reacting Flows Using Large Eddy Simulation

Spectral Entropy, Empirical Entropy and Empirical Exergy for Deterministic Boundary-Layer Structures

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