Combustion Theory
Lecturer: Professor Moshe Matalon of the University of Illinois at Urbana-Champaign
Course length: 15 hours
Course Objective:
The aim of this course is to provide students with an understanding of the basic principles associated with combustion processes, how these concepts relate to experimental observations and how they can be used for theoretical and/or numerical modeling. The first four lectures cover the fundamental of chemically reacting flows, general conservation laws and classifications of various combustion processes. The remaining lectures focus on low-speed combustion, or flames. Four lectures are devoted to premixed combustion and include the structure of a premixed flame and the determination of the laminar flame speed, multi-step chemistry, hydrodynamics effects, ignition and extinction phenomena and combustion instabilities. The next four lectures are devoted to non-premixed combustion and include the structure of a diffusion flame, the mixture fraction formulation, the burning of condensed fuels, jet flames, flame lift-off and edge flames. The last three lectures will be on turbulent flames covering the different regimes of turbulent combustion, the various approaches used in modeling turbulent flames, the turbulent burning velocity, and the flamelet concept for nonpremixed flames.
Course Outline:
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Hour 1: |
Conservation Equations for Chemically-Reacting Flows |
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Hour 2: |
Chemical Thermodynamics |
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Hour 3: |
Chemical Kinetics and Reaction Mechanisms |
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Hour 4: |
Deflagrations and Detonations in Premixed Gases |
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Hour 5: |
The Structure of a Premixed flame |
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Hour 6: |
Hydrodynamic Theory of Flame Propagation |
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Hour 7 |
Flame Instabilities |
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Hour 8: |
Ignition/Extinction and Flammability Limits |
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Hour 9: |
The Structure of Diffusion flames |
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Hour 10: |
Droplet Combustion and Spray Modeling |
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Hour 11: |
The Mixture Fraction Formulation |
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Hour 12: |
Edge Flames |
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Hour 13: |
Turbulent Combustion - Various Approaches |
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Hour 14: |
Regimes of Turbulent Combustion |
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Hour 15: |
Turbulent Flames |
Combustion Chemistry
Lecturer: Professor Michael J. Pilling of the University of Leeds, UK
Course length: 15 hours
Course Objective:
The aim of this course is to provide students with an understanding of how rate coefficients and products of elementary reactions, of importance in combustion, are determined experimentally, how they are used in conjunction with theoretical models and how they are incorporated in chemical mechanisms for use in combustion models. Thermodynamic properties are also central to combustion and their determination for radical species will be discussed. The course will be illustrated by a number of detailed examples of relevance to high and low temperature hydrocarbon oxidation and NOx formation and control. The final lectures will examine the impact of combustion emissions, and especially of NOx, on climate change and air quality.
Course Outline:
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1. |
Experimental measurements of rate coefficients and product yields for elementary reactions. (3h) - Techniques – e.g. pulsed photolysis; shock tubes, flow methods, end product analysis. - Detection methods – laser absorption, including cavity ring down / enhanced absorption; laser induced fluorescence; mass spectrometry. - Advantages and disadvantages of different techniques. Ranges of applicability. - Determination of rate coefficients. - Determination of product yields - Examples – largely drawn from framework used by Westbrook, stressing importance of the reactions in combustion. o H2 + O2 system, e.g H + O2, branching and termination reactions o Autoignition chemistry, e.g. C2H5 + O2 o Product studies in autoignition range o Methylene chemistry o Nitrogen chemistry o Others |
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2. |
Links with theory. (3h) - Link back to Klippenstein. - Recap on electronic structure and transition state calculations. - Recap on master equation methods - Examples of reactions analyzed / interpreted using a combination of theory and experiment o CH3 + CH3 o CH3 + H o Dissociation 2-C3H7 o OH + C3OCH3 - Eigenvalues and timescales of multiwell systems. Chemically significant eigenvalues. Methods of determination / interpretation. o C2H5 + O2 o CH3OCH2 + O2 o H+ SO2 |
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3. |
Rate coefficient evaluation (1.5h) - Aims and general approaches. - Representation of temperature and pressure dependences. - Uncertainty assessments. Basis. Problems - Examples o H + O2 o H + O2 + M o H + C2H4 o 3CH2 + O2 o Others - Kinetic databases – NIST - PrIMe - Role of theory |
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4. |
Thermodynamics. (1.5h) - Importance of thermodynamics in combustion – heat release, temperature. - Importance in combustion simulations. CHEMKIN. Rate coefficients and equilibrium constants - Determination of radical enthalpies of formation, e.g. alkyl and peroxy radicals, HOSO2. Significance for combustion. - Entropies from statistical mechanics - Thermodynamic databases – experimental, theoretical. |
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5. |
Mechanism construction and evaluation. (2h+) - Recap on Westbrook discussion. - Building up principle. - Target experimental databases - Comparisons of experiment and simulation. Sensitivity analysis. Feedback between mechanism evaluation and elementary reactions. - Mechanism optimization. GRIMech. - Uncertainty analysis, with examples. |
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6. |
NOx chemistry. (1h) - Prompt and thermal NOx formation. - CH + N2 and NH2 + NO. Experimental and theoretical studies - Reburning, selective catalytic reduction (and non-catalytic reduction) as methods for controlling NOx emissions. |
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7. |
Combustion emissions, climate change and air quality. (3h-) - Global emissions inventories and source apportionment: NOx, CO, CH4, volatile organic compounds, particulate matter (especially soot), CO2, N2O. - Secondary processes in the atmosphere. O3 and secondary aerosol formation. - Radiative forcing – basis. Contributions and uncertainties. IPCC diagram. - Emissions scenarios and projections. Impacts of technology. Global climate model and temperature projections. - Air quality – impacts of atmospheric pollutants, especially particles and O3. Cost benefit analysis and quality of life. |
Combustion Laser Diagnostics
Lecturer: Professor Marcus Aldén of Lund University, Sweden
Course length: 12 hours
Course Objective:
The aim of the course is to provide graduate students in combustion with a fundamental understanding of the use and application of laser techniques for diagnostics of combustion processes. The lectures will be concentrated on spectroscopic techniques for measurements of temperature, species concentration and particle characterization. The course will include fundamental issues on molecular spectroscopy and relevant instrumental equipment and will cover techniques based on linear optics, e.g. laser-induced fluorescence, Rayleigh and Raman scattering as well as techniques based on non-linear optics, e.g. CARS, polarization spectroscopy and DFWM. The techniques will be described in terms of relevant theory and exemplified by numerous applications, ranging from small scale laminar flames to full scale boilers.
Course Outline:
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Hour 1: |
Introduction to combustion laser diagnostics, definitions |
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Hour 2: |
Molecular spectroscopy: Definitions, rotational, vibrational, electronic structures |
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Hour 3: |
Laser diagnostic instrumentation: Lasers, detectors, optical components |
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Hour 4: |
Soot diagnostics: Introduction, laser-induced incandescence |
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Hour 5: |
Laser-induced fluorescence: Introduction/theory, basic definitions |
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Hour 6: |
Laser-induced fluorescence: Applications – engines, gasturbines, furnaces |
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Hour 7 |
Rayleigh scattering: Introduction, potential, limitations, filtered Rayleigh scattering |
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Hour 8: |
Raman scattering: Basic theory, thermometry, species concentration measurements |
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Hour 9: |
Surface thermometry: Thermographic phosphorescence – definitions, applications |
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Hour 10: |
Non-linear techniques I: CARS Spectroscopy – Theory, definitions, applications |
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Hour 11: |
Non-linear techniques II: Polarization spectroscopy and Degenerate four-wave mixing – Theory, potential, applications |
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Hour 12: |
New techniques for future challenges: - “New” species detection - Single ended experiments - ps Lidar, Structured illumination - Measurements in optical dense media (sprays) - Ballistic imaging, SLIPI |