Advanced Combustion Science

Non-uniform combustion, as encountered in diesel and gas turbine engines, furnaces, and boilers, is responsible for the conversion of fossil fuel to energy and also for the corresponding formation of pollutants. In spite of great research efforts in the past, the mechanism of non-uniform combustion has remained less explored than that of other combustion types, since it consists of many, mostly transient processes which influence each other. In view of this background, a group research project, "Exploration of Combustion Mechanism", was established to explore the mechanism of combustion, especially that of diffusive combustion, and also to find efficient ways to control the combustion process for better utilization of fuel and the reduction of pollutant emission. The group research was started, after preparatory activity of 2 years, in April 1988, for a period of 3 years, as a project with a Grant-in-Aid for Scientific Research of Priority Area subsidized by the Ministry of Education, Science and Culture of Japan. The entire group of 43 members was set up as an organizing committee of 13 members, and five research groups, consisting of 36 members. The research groups were: (1) Steady combustion, (2) Unsteady spray combustion, (3) Control of combustion, (4) Chemistry of combustion, and (5) Effects of fuels. At the beginning of the project it was agreed that we should pursue the mechanism of combustion from a scientific viewpoint, namely, the target of the project was to obtain the fundamentals, or "know why", rather than "know how" of combustion.

1. Structure of Turbulent Diffusion Flames.- 1.1 Introduction of Turbulent Diffusion Flame Structures.- 1.1.1 Importance of turbulent diffusion flames.- 1.1.2 History of measuring methods.- 1.1.3 Laser diagnostics.- 1.1.4 Two-dimensional or sheet-cut imaging of turbulent diffusion flames.- 1.1.5 Turbulent diffusion flame structure and how to attain high combustion efficiency and control pollutants formation.- 1.2 Optical Measurement of Flame Structure Analysis.- 1.2.1 Introduction.- 1.2.2 Experimental Apparatus and Procedures.- 1.2.3 Results and Discussions.- 1.3 Effect of Surrounding Gas Motion on Turbulent Diffusion Flames.- 1.3.1 Introduction.- 1.3.2 Experimental apparatus and procedures.- 1.3.3 Numerical analysis.- 1.3.4 Results and discussions.- 1.4 Visualization of Turbulent Diffusion Flame Surface.- 1.4.1 Introduction.- 1.4.2 Experimental apparatus and procedures.- 1.4.3 Numerical calculation.- 1.4.4 Visualization of turbulent diffusion flame surface.- 1.5 Colorimetric Analysis of Turbulent Flames.- 1.5.1 Introduction.- 1.5.2 Principle of flame color utilization.- 1.5.3 Factors affecting the flame color.- 1.5.4 Application to practical flames.- 2. Modeling of Turbulent Diffusion Flames.- 2.1 Introduction.- 2.2 Modelling of Turbulent Diffusion Flames.- 2.2.1 The mixture fraction variable.- 2.2.2 The flamelet concept of diffusion flames.- 2.2.3 Comparison of time scales.- 2.2.4 Applications of the flamelet concept.- 2.2.5 Conclusions.- 2.3 A Lagrangian Stochastic Model for Non-Premixed Reacting Flows.- 2.3.1 A Lagrangian stochastic model.- 2.3.2 Model computations.- 2.4 Estimation of Combustion Models.- 2.4.1 Local reaction rate.- 2.4.2 Modeling.- 2.4.3 Results and discussion.- 2.5 Simulation of the Vortex Generation and Mixing Process in Gas Jets.- 2.5.1 Method of numerical analysis.- 2.5.2 Numerical simulation.- 2.5.3 Conclusions.- 2.6 Laminarization Due to Combustion and Its Modeling.- 2.6.1 Laminarization due to combustion.- 2.6.2 A triple jet diffusion flames[42].- 2.6.3 Modeling of the laminarization.- 2.7 Simulation of Mixing and Combustion in Swirling Flames.- 2.7.1 Formulation.- 2.7.2 Analysis and discussions.- 2.7.3 Conclusions.- 2.8 Modeling of Spray Combustion of Slurry Fuels.- 2.8.1 Numerical analysis.- 2.8.2 Experimental apparatus and conditions.- 2.8.3 Simulation of combustion characteristics for PWM and CWM.- 2.8.4 Conclusions.- 3. Spray Formation and Combustion.- 3.1 Diagnostics.- 3.1.1 Reviews.- 3.1.2 Phase-doppler anemometry and spray measurements.- 3.1.3 The polarization properties of the scattered light to study the condensed phases in combustion systems.- 3.1.4 2-D soot imaging.- 3.2 Spray and Ignition.- 3.2.1 Reviews.- 3.2.2 Atomization and spray formation.- 3.2.3 Evaporation and impingement.- 3.2.4 Turbulent mixing process in unsteady gas jets.- 3.2.5 Application of the Stochastic Ignition Theory.- 3.3 Spray Combustion.- 3.3.1 Review.- 3.3.2 Combustion with high injection pressure.- 3.3.3 Numerical Simulation of Transient Spray Combustion.- 3.3.4 Flame Structure of Steady Spray Flames.- 4. Kinetics.- 4.1 Chemical Kinetics and Modeling of Combustion.- 4.1.1 Recent development of reaction kinetics and modeling study.- 4.1.2 Kinetic models of individual fuels.- 4.2 The Rate Constants of Elementary Combustion Reactions and Empirical Rate Laws.- 4.2.1 Measurement of rate constant.- 4.2.2 Empirical rate laws.- 4.3 Combustion and Oxidation Mechanism of Aromatic Compounds.- 4.3.1 Kinetic study of benzene oxidation and some problems.- 4.3.2 A Study of reaction mechanism of benzene oxidation at high temperature by means of shock tube method.- 4.4 Applications of Simulation Work to Some Combustion Problems.- 4.4.1 Introduction.- 4.4.2 Zero-dimensional modeling with kinetics.- 4.4.3 Spatially-dependent models with kinetics.- 4.5 Applications of Modeling Study to Combustible Gas Flow.- 4.5.1 Introduction.- 4.5.2 Numerical algorithm of chemically reactive flows.- 4.5.3 Numerical calculation of flame ignition.- 5. Soot Formation Fundamentals.- 5.1 Overview and Characterization of Soot.- 5.1.1 Introduction.- 5.1.2 Overview.- 5.1.3 Outline of nucleation theories.- 5.1.4 Characterization of soot particle.- 5.2 Detailed Mechanism and Modeling of Soot Formation.- 5.2.1 PAH formation and growth.- 5.2.2 Soot particle inception in flames.- 5.3 Nucleation and Carbon Clustering.- 5.3.1 Chemical inception.- 5.3.2 Species in flames.- 5.3.3 Mechanistic study of carbon clusters.- 5.4 Prediction of Soot and Soot Precursors.- 5.4.1 Predictions based on PAH model.- 5.4.2 Soot prediction based on homogeneous nucleation.- 5.5 Growth and Destruction of Soot Particles.- 5.5.1 Growth of soot particles.- 5.5.2 Soot oxidation.- 5.5.3 The Effect of Oxygen Addition on Sooting in Diffusion Flames.- 6. Emissions and Heat Transfer in Combustion Systems.- 6.1 General.- 6.1.1 Emissions in Combustion Systems.- 6.1.2 The role of heat transfer in combustion systems.- 6.2 Fuel Pyrolysis and Fuel-Air Mixing in the Diesel Combustion Process..- 6.2.1 Introduction.- 6.2.2 Fuel pyrolysis.- 6.2.3 Diesel combustion process.- 6.2.4 Conclusions.- 6.3 Particulate Formation in Compression-Ignited Mixtures.- 6.3.1 Introduction.- 6.3.2 Experimental apparatus.- 6.3.3 Results and discussion.- 6.3.4 Conclusions.- 6.4 Surrounding Gas Effects on Soot Formation and Oxidation Process in Spray Combustion.- 6.4.1 Introduction.- 6.4.2 Experimental procedures and results.- 6.4.3 Summary.- 6.5 Characteristics of Opposed Spray Combustion.- 6.5.1 Introduction.- 6.5.2 Experimental apparatus and procedure.- 6.5.3 Experimental results and discussion.- 6.5.4 Concluding remarks.- 6.6 Heat Transfer in Exothermic Turbulent Thermal Boundary Layers.- 6.6.1 Introduction.- 6.6.2 Wall temperature dependance of heat transfer in a steady turbulent diffusion flame — Experimental study.- 6.6.3 Wall temperature dependance of heat transfer in an unsteady turbulent flame in a piston-cylinder apparatus — Computational study in one dimension.- 6.7 Heat Transfer Measurements in Combustion Systems.- 6.7.1 Thin-film thermocouple for measuring the instantaneous temperature on surface of combustion chamber wall.- 6.7.2 Heat transfer in a cycle to the combustion chamber wall surface...- 6.7.3 Real rate of heat release under high-temperature combustion.- 6.8 Simulation of Radiative Heat Transfer in Flames.- 6.8.1 Introduction.- 6.8.2 Heat ray tracing method.- 6.8.3 Results.- 7. Effects of Fuel Properties in Combustion Systems...- 7.1 Introduction.- 7.2 Basic Studies of Fuel Effects on Combustion.- 7.2.1 Fuel effects on the turbulent diffusion flame structure.- 7.2.2 Liquid fuel properties and combustion characteristics.- 7.3 Application of Extremely Light and Heavy Fuels for Engines.- 7.3.1 Hydrogen-injected engines.- 7.3.2 Spray combustion of heavy oil fuels.- 8. New Approaches to Controlling Combustion.- 8.1 Combustion Control Based on Electrical Aspects.- 8.1.1 Introduction.- 8.1.2 Plasma jet ignition fundamentals.- 8.1.3 Plasma jet effect on steady diffusion flames.- 8.1.4 Plasma jet effects on unsteady diffusion flames.- 8.1.5 Effect of electric fields on diffusion flames.- 8.2 Magnetic Field Effect on Combustion Reactions.- 8.2.1 Introduction.- 8.2.2 Review of MFEs on the gas phase reactions.- 8.2.3 MFEs in low pressure diffusion flames.- 8.2.4 SO2 afterglow and LIF intensity of SO2 C state.- 8.2.5 Concluding remarks.- 8.3 Catalytic Combustion — Roles of Catalyst.- 8.3.1 Introduction.- 8.3.2 Mechanism of catalytic combustion.- 8.3.3 Catalytic combustion of methane.- List of Authors.