Book contents
- Frontmatter
- Contents
- Preface
- INTRODUCTION
- 1 CHEMICAL THERMODYNAMICS
- 2 CHEMICAL KINETICS
- 3 OXIDATION MECHANISMS OF FUELS
- 4 TRANSPORT PHENOMENA
- 5 CONSERVATION EQUATIONS
- 6 LAMINAR NONPREMIXED FLAMES
- 7 LAMINAR PREMIXED FLAMES
- 8 LIMIT PHENOMENA
- 9 ASYMPTOTIC STRUCTURE OF FLAMES
- 10 AERODYNAMICS OF LAMINAR FLAMES
- 11 COMBUSTION IN TURBULENT FLOWS
- 12 COMBUSTION IN BOUNDARY-LAYER FLOWS
- 13 COMBUSTION IN TWO-PHASE FLOWS
- 14 COMBUSTION IN SUPERSONIC FLOWS
- References
- Author Index
- Subject Index
6 - LAMINAR NONPREMIXED FLAMES
Published online by Cambridge University Press: 06 July 2010
- Frontmatter
- Contents
- Preface
- INTRODUCTION
- 1 CHEMICAL THERMODYNAMICS
- 2 CHEMICAL KINETICS
- 3 OXIDATION MECHANISMS OF FUELS
- 4 TRANSPORT PHENOMENA
- 5 CONSERVATION EQUATIONS
- 6 LAMINAR NONPREMIXED FLAMES
- 7 LAMINAR PREMIXED FLAMES
- 8 LIMIT PHENOMENA
- 9 ASYMPTOTIC STRUCTURE OF FLAMES
- 10 AERODYNAMICS OF LAMINAR FLAMES
- 11 COMBUSTION IN TURBULENT FLOWS
- 12 COMBUSTION IN BOUNDARY-LAYER FLOWS
- 13 COMBUSTION IN TWO-PHASE FLOWS
- 14 COMBUSTION IN SUPERSONIC FLOWS
- References
- Author Index
- Subject Index
Summary
Either by nature or design, in most combustion systems fuel and oxidizer are initially spatially separated. If the subsequent mixing between them is not sufficiently fast before chemical reaction is initiated, then the mixing and reaction will take place only in thin reaction zones that separate them. Examples are a wood panel on fire, an oil spray burning in a furnace, a candle flame, and the sparks (i.e., burning metal particles) generated when a metal surface is abraded.
The structure of a nonpremixed flame therefore consists of three zones, with a reaction zone separating a fuel-rich zone and an oxidizer-rich zone. Figure 6.1.1a shows a typical configuration for the model problem to be studied in the next section. As the fuel and oxidizer are transported toward each other, through diffusion as well as whatever convective motion the system may have, they become heated and eventually meet and mix within the reaction zone. Reaction between them subsequently takes place rapidly. The combustion products together with the heat of combustion are then transported away from the reaction zone in both directions. Since reaction occurs at a finite rate and the reaction zone has a finite thickness, complete reaction cannot be accomplished. Small amounts of fuel and oxidizer invariably leak through the reaction zone, as shown in Figure 6.1.1b.
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- Information
- Combustion Physics , pp. 194 - 233Publisher: Cambridge University PressPrint publication year: 2006