Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 23
Book Description
A numerical simulation of entrainment, turbulent advection, molecular import and chemical kinetics in a turbulent diffusion flame is used to investigate effects of molecular transport on turbulence-chemistry interactions. A fun finite-rate chemical mechanism is used to represent the combustion of a hydrogen-argon mixture issuing into air. Results based on incorporation of differential diffusion and variable Lewis number are compared to cases with the former effect, or both-effects, suppressed. Significant impact on radical species production and on NO emission index (based on a reduced mechanism for thermal NO) is found. A reduced mechanism for hydrogen-air combustion, omitting both effects and incorporating other simplifications, performs comparably except that its NO predictions agree well with the case of full chemistry and molecular transport, possibly due to cancellation of errors.
Effects of Molecular Transport on Turbulence-chemistry Interactions in a Hydrogen-argon-air Jet Diffusion Flame
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 23
Book Description
A numerical simulation of entrainment, turbulent advection, molecular import and chemical kinetics in a turbulent diffusion flame is used to investigate effects of molecular transport on turbulence-chemistry interactions. A fun finite-rate chemical mechanism is used to represent the combustion of a hydrogen-argon mixture issuing into air. Results based on incorporation of differential diffusion and variable Lewis number are compared to cases with the former effect, or both-effects, suppressed. Significant impact on radical species production and on NO emission index (based on a reduced mechanism for thermal NO) is found. A reduced mechanism for hydrogen-air combustion, omitting both effects and incorporating other simplifications, performs comparably except that its NO predictions agree well with the case of full chemistry and molecular transport, possibly due to cancellation of errors.
Publisher:
ISBN:
Category :
Languages : en
Pages : 23
Book Description
A numerical simulation of entrainment, turbulent advection, molecular import and chemical kinetics in a turbulent diffusion flame is used to investigate effects of molecular transport on turbulence-chemistry interactions. A fun finite-rate chemical mechanism is used to represent the combustion of a hydrogen-argon mixture issuing into air. Results based on incorporation of differential diffusion and variable Lewis number are compared to cases with the former effect, or both-effects, suppressed. Significant impact on radical species production and on NO emission index (based on a reduced mechanism for thermal NO) is found. A reduced mechanism for hydrogen-air combustion, omitting both effects and incorporating other simplifications, performs comparably except that its NO predictions agree well with the case of full chemistry and molecular transport, possibly due to cancellation of errors.
Scientific and Technical Aerospace Reports
Energy Research Abstracts
Author:
Publisher:
ISBN:
Category : Power resources
Languages : en
Pages : 806
Book Description
Semiannual, with semiannual and annual indexes. References to all scientific and technical literature coming from DOE, its laboratories, energy centers, and contractors. Includes all works deriving from DOE, other related government-sponsored information, and foreign nonnuclear information. Arranged under 39 categories, e.g., Biomedical sciences, basic studies; Biomedical sciences, applied studies; Health and safety; and Fusion energy. Entry gives bibliographical information and abstract. Corporate, author, subject, report number indexes.
Publisher:
ISBN:
Category : Power resources
Languages : en
Pages : 806
Book Description
Semiannual, with semiannual and annual indexes. References to all scientific and technical literature coming from DOE, its laboratories, energy centers, and contractors. Includes all works deriving from DOE, other related government-sponsored information, and foreign nonnuclear information. Arranged under 39 categories, e.g., Biomedical sciences, basic studies; Biomedical sciences, applied studies; Health and safety; and Fusion energy. Entry gives bibliographical information and abstract. Corporate, author, subject, report number indexes.
41st AIAA Aerospace Sciences Meeting & Exhibit
Government Reports Annual Index
Author:
Publisher:
ISBN:
Category : Research
Languages : en
Pages : 1142
Book Description
Sections 1-2. Keyword Index.--Section 3. Personal author index.--Section 4. Corporate author index.-- Section 5. Contract/grant number index, NTIS order/report number index 1-E.--Section 6. NTIS order/report number index F-Z.
Publisher:
ISBN:
Category : Research
Languages : en
Pages : 1142
Book Description
Sections 1-2. Keyword Index.--Section 3. Personal author index.--Section 4. Corporate author index.-- Section 5. Contract/grant number index, NTIS order/report number index 1-E.--Section 6. NTIS order/report number index F-Z.
Study of Finite-Rate Chemistry Effects on Turbulent Jet Diffusion Flames and Non-homogeneous Autoigntion Using the One-Dimensional Turbulence Model
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
In current study Numerical simulation of turbulent combustion process is approached using One Dimensional Turbulence (ODT) model. The ODT model is based on the coupling of molecular processes (reaction and diffusion) with turbulent transport in a spatially- and temporally-resolved fashion over a one-dimensional domain. The domain corresponds to a transverse (or radial) direction; while, the transient evolution of the thermo-chemical scalars on the 1D domain represents the spatial evolution downstream of the jet inlet. The linear-eddy approach for modeling molecular mixing in turbulent flow involves stochastic simulation on a 1D domain with sufficient resolution to predict all relevant physical length scales properly. Firstly ODT is carried out to predict the hydrogen and air jet diffusion flame with helium dilution in the fuel. The comparison with existing experimental data was made for the numerical result of ODT simulation of jet diffusion flames in both conditional means and rms of scalars of measurements and computational results. Another application of ODT was made in present work to verify the capability of prediction of autoignition (self-ignition) of one of free shear layer flow -- jet diffusion flow. Different range of pressure and Reynolds number are set to identify the effects of turbulence intensity and mixture properties on the self-ignition chemistry. Autoignition delay time was studied based on these different conditions. At the same time the ability of the prediction of mixture temperature and species mass fraction profile were tested. A principle numerical result is expected and discussed. Conditional pdf and progress variable were used to analyze the computational result of ODT. Analysis was focus on the temperature growth and the mass fraction distribution of intermediate species and product.
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
In current study Numerical simulation of turbulent combustion process is approached using One Dimensional Turbulence (ODT) model. The ODT model is based on the coupling of molecular processes (reaction and diffusion) with turbulent transport in a spatially- and temporally-resolved fashion over a one-dimensional domain. The domain corresponds to a transverse (or radial) direction; while, the transient evolution of the thermo-chemical scalars on the 1D domain represents the spatial evolution downstream of the jet inlet. The linear-eddy approach for modeling molecular mixing in turbulent flow involves stochastic simulation on a 1D domain with sufficient resolution to predict all relevant physical length scales properly. Firstly ODT is carried out to predict the hydrogen and air jet diffusion flame with helium dilution in the fuel. The comparison with existing experimental data was made for the numerical result of ODT simulation of jet diffusion flames in both conditional means and rms of scalars of measurements and computational results. Another application of ODT was made in present work to verify the capability of prediction of autoignition (self-ignition) of one of free shear layer flow -- jet diffusion flow. Different range of pressure and Reynolds number are set to identify the effects of turbulence intensity and mixture properties on the self-ignition chemistry. Autoignition delay time was studied based on these different conditions. At the same time the ability of the prediction of mixture temperature and species mass fraction profile were tested. A principle numerical result is expected and discussed. Conditional pdf and progress variable were used to analyze the computational result of ODT. Analysis was focus on the temperature growth and the mass fraction distribution of intermediate species and product.
Government Reports Announcements & Index
Theories of Turbulent Combustion in High Speed Flows
Author: Paul A. Libby
Publisher:
ISBN:
Category : Combustion
Languages : en
Pages : 12
Book Description
Publisher:
ISBN:
Category : Combustion
Languages : en
Pages : 12
Book Description
Turbulence and Molecular Processes in Combustion
Author: T. Takeno
Publisher: Elsevier
ISBN: 0444598898
Category : Science
Languages : en
Pages : 462
Book Description
An understanding of the intricacies in the turbulent combustion process may be a key to solving many of the current energy and environmental problems. The essential nature of turbulent combustion can be derived from the interaction between stochastic flow fluctuations and deterministic molecular processes, such as chemical reaction and transport processes. Undoubtedly, this is one of the most challenging fields of engineering science today, requiring as it does the interaction of scientists and engineers in the respective fields of chemical kinetics and fluid mechanics. The 28 papers in this volume review recent advances in these two disciplines providing new insights into the fundamental processes, addressing a great deal of recent progress. This progress ranges from descriptions of elementary chemical kinetics, to working those descriptions into combustion calculations with large numbers of elementary steps, to improved understanding of turbulent reacting flows and advances in simulations of turbulent combustion. The contributions will inspire further research on many fronts, advancing the understanding of combustion processes, as well as fostering a growing interdisciplinary cooperation.
Publisher: Elsevier
ISBN: 0444598898
Category : Science
Languages : en
Pages : 462
Book Description
An understanding of the intricacies in the turbulent combustion process may be a key to solving many of the current energy and environmental problems. The essential nature of turbulent combustion can be derived from the interaction between stochastic flow fluctuations and deterministic molecular processes, such as chemical reaction and transport processes. Undoubtedly, this is one of the most challenging fields of engineering science today, requiring as it does the interaction of scientists and engineers in the respective fields of chemical kinetics and fluid mechanics. The 28 papers in this volume review recent advances in these two disciplines providing new insights into the fundamental processes, addressing a great deal of recent progress. This progress ranges from descriptions of elementary chemical kinetics, to working those descriptions into combustion calculations with large numbers of elementary steps, to improved understanding of turbulent reacting flows and advances in simulations of turbulent combustion. The contributions will inspire further research on many fronts, advancing the understanding of combustion processes, as well as fostering a growing interdisciplinary cooperation.
Molecular Transport Effects in Turbulent Diffusion Flames at Moderate Reynolds Number
Author: R. W. Bilger
Publisher:
ISBN:
Category :
Languages : en
Pages : 38
Book Description
In flames molecular diffusivities are enhanced by the high temperatures and can be of the same order as turbulent diffusivities in flames of moderate Reynolds number. A perturbation analysis is used to quantify effects in a hydrogen/air diffusion flame which arise from differential molecular diffusivities. The analysis uses perturbations about the equal diffusivity, adiabatic, equilibrium theory commonly used and yields solutions for the average and higher moments for the departures in normalized element mass fractions and enthalpy. The results are compared with the laser-Raman measurements of Drake et al. in a relatively low Reynolds number flame. Generally the agreement is excellent. (Author).
Publisher:
ISBN:
Category :
Languages : en
Pages : 38
Book Description
In flames molecular diffusivities are enhanced by the high temperatures and can be of the same order as turbulent diffusivities in flames of moderate Reynolds number. A perturbation analysis is used to quantify effects in a hydrogen/air diffusion flame which arise from differential molecular diffusivities. The analysis uses perturbations about the equal diffusivity, adiabatic, equilibrium theory commonly used and yields solutions for the average and higher moments for the departures in normalized element mass fractions and enthalpy. The results are compared with the laser-Raman measurements of Drake et al. in a relatively low Reynolds number flame. Generally the agreement is excellent. (Author).