AVL. Fire. Version 8. Vol 2: Combustion. CFD Solver v8.3 - Combustion

99 Pages·1.382 MB·English

FIRE
Version 8
Combustion
May 2004

Vol 2: Combustion FIRE Version 8
Address comments concerning this document to:
AVL LIST GmbH
A-8020 Graz Hans-List-Platz 1
Phone: [phone]
Telefax: [phone]
E-Mail: [email protected]
Web Site: http://www.avl.com
Revision Date Description Document No.
A 16-Jan-2002 CFD Solver v8.01 – Combustion 08.0205.0572
B 28-Jun-2002 CFD Solver v8.1 – Combustion 08.0205.0587
C 24-Jan-2003 CFD Solver v8.1.1 – Combustion 08.0205.0606
D 18-Jul-2003 CFD Solver v8.2 – Combustion 08.0205.0656
E 17-May-2004 CFD Solver v8.3 – Combustion 08.0205.0699
Product: FIRE Version 8
Volume: 2
Module: CFD Solver v8.3 – Combustion
Copyright © 2004, AVL
All rights reserved. No part of this publication may be reproduced, transmitted, transcribed, stored
in a retrieval system or translated into any language or computer language, in any form or by any
means, electronic, mechanical, magnetic, optical, chemical, manual or otherwise, without prior
written consent of AVL.
This document describes how to run the FIRE software. It does not attempt to discuss all the
concepts of computational fluid dynamics required to obtain successful solutions. It is the user’s
responsibility to determine if he/she has sufficient knowledge and understanding of fluid dynamics
to apply this software appropriately.
This software and document are distributed solely on an "as is" basis. The entire risk as to their
quality and performance is with the user. Should either the software or this document prove
defective, the user assumes the entire cost of all necessary servicing, repair, or correction. AVL
and its distributors will not be liable for direct, indirect, incidental, or consequential damages
resulting from any defect in the software or this document, even if they have been advised of the
possibility of such damage.
FIRETM is a registered trademark of AVL LIST. FIRETM will be referred as FIRE in this manual.
All mentioned trademarks and registered trademarks are owned by the corresponding owners.

Vol 2: Combustion FIRE Version 8
Table of Contents
1. Introduction_____________________________________________________1-1
1.1. Scope _______________________________________________________________________1-1
1.2. Symbols_____________________________________________________________________1-1
1.3. Configurations_______________________________________________________________1-1
1.4. Documentation ______________________________________________________________1-2
2. Overview ________________________________________________________2-1
2.1. Spray/Combustion Interaction_________________________________________________2-2
2.2. Activation and Handling of the Combustion Module______________________________2-2
3. Theoretical Background _________________________________________3-1
3.1. Nomenclature________________________________________________________________3-1
3.1.1. Roman Characters________________________________________________________3-1
3.1.2. Greek Characters_________________________________________________________3-3
3.1.3. Subscripts _______________________________________________________________3-3
3.1.4. Superscripts _____________________________________________________________3-4
3.2. Combustion Module __________________________________________________________3-5
3.2.1. Multi-Species Chemically Reacting Flows____________________________________3-5
3.2.1.1. Hydrocarbon Auto-Ignition Mechanism__________________________________3-5
3.2.1.2. AnB Knock-Prediction Model___________________________________________3-7
3.2.1.3. Empirical Knock Model________________________________________________3-9
3.2.1.4. High Temperature Oxidation Scheme __________________________________3-10
3.2.2. Turbulence Controlled Combustion Model__________________________________3-10
3.2.3. Turbulent Flame Speed Closure Combustion Model _________________________3-11
3.2.4. Coherent Flame Model___________________________________________________3-13
3.2.4.1. Standard CFM-2A Model______________________________________________3-13
3.2.4.2. MCFM Model________________________________________________________3-16
3.2.4.3. ECFM Model ________________________________________________________3-18
3.2.5. Probability Density Function Approach ____________________________________3-23
3.2.5.1. PDF Transport Equation _____________________________________________3-24
3.2.5.2. Monte Carlo Simulation ______________________________________________3-25
3.2.6. Characteristic Timescale Model ___________________________________________3-27
3.2.7. Steady Combustion Model________________________________________________3-28
3.3. NO Formation Models_______________________________________________________3-30
x
3.3.1. Zeldovich Model Formulation _____________________________________________3-30
3.3.2. Advanced NO Model Formulation_________________________________________3-32
x
3.3.2.1. Thermal NO Mechanism _____________________________________________3-33
x
3.3.2.2. Prompt NO Mechanism______________________________________________3-34
x
3.3.2.3. Fuel NO Mechanism_________________________________________________3-36
x
3.4. Soot Formation and Oxidation Model__________________________________________3-41
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FIRE Version 8 Vol 2: Combustion
3.4.1. Theoretical Background__________________________________________________3-42
3.4.1.1. The Soot Formation Process __________________________________________3-42
3.4.1.2. The Mathematical Model______________________________________________3-44
3.4.2. Advanced Soot Model ____________________________________________________3-46
3.5. References__________________________________________________________________3-47
3.6. Related Publications_________________________________________________________3-52
4. Combustion Input Data__________________________________________4-1
4.1. Control______________________________________________________________________4-1
4.2. Ignition Models ______________________________________________________________4-1
4.2.1. Spark Ignition____________________________________________________________4-2
4.2.2. Auto Ignition_____________________________________________________________4-4
4.2.2.1. Diesel________________________________________________________________4-4
4.2.2.2. Diesel_MIL___________________________________________________________4-5
4.2.2.3. HCCI________________________________________________________________4-5
4.2.2.4. Knock _______________________________________________________________4-6
4.2.2.5. AnB Knock___________________________________________________________4-6
4.2.2.6. Empirical Knock Model________________________________________________4-7
4.3. Combustion Models___________________________________________________________4-8
4.3.1. Eddy Breakup Model______________________________________________________4-9
4.3.1.1. Model Constants_____________________________________________________4-10
4.3.1.2. Time Scale __________________________________________________________4-10
4.3.2. Turbulent Flame Speed Closure Model_____________________________________4-11
4.3.2.1. Model Constants_____________________________________________________4-12
4.3.3. Coherent Flame Model___________________________________________________4-13
4.3.3.1. Time Scale __________________________________________________________4-15
4.3.4. PDF Model______________________________________________________________4-16
4.3.4.1. Rate Coefficient Treatment ___________________________________________4-17
4.3.4.2. Time Scale __________________________________________________________4-19
4.3.5. Characteristic Timescale Model ___________________________________________4-20
4.3.5.1. Model Constants_____________________________________________________4-21
4.3.5.2. Time Scale __________________________________________________________4-21
4.3.6. Steady Combustion Model________________________________________________4-22
4.3.6.1. Model Constants_____________________________________________________4-22
4.3.7. User Defined Reaction Rate_______________________________________________4-23
4.3.8. Time Dependent Activation of Combustion_________________________________4-23
4.3.8.1. Combustion Models __________________________________________________4-23
4.3.8.2. Auto Ignition Models_________________________________________________4-24
4.4. Emission Models ____________________________________________________________4-24
4.4.1. NOx Models_____________________________________________________________4-25
4.4.2. Soot Model______________________________________________________________4-26
4.5. 2D Results__________________________________________________________________4-28
4.5.1. General Information_____________________________________________________4-29
4.5.2. Auto Ignition Models_____________________________________________________4-29
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Vol 2: Combustion FIRE Version 8
4.5.3. Emission Models_________________________________________________________4-29
4.6. 3D Results__________________________________________________________________4-30
4.6.1. General Information_____________________________________________________4-30
4.6.2. CFM Models ____________________________________________________________4-32
4.6.3. Auto Ignition Models_____________________________________________________4-32
4.6.4. Emission Models_________________________________________________________4-33
4.6.5. Optional Output from Knock Models_______________________________________4-33
4.6.5.1. Knock ______________________________________________________________4-33
4.6.5.2. AnB Knock__________________________________________________________4-33
AST.08.0205.0699 – 17-May-2004 iii
FIRE Version 8 Vol 2: Combustion
List of Figures
Figure 3-1: Empirical Knock Model....................................................................................................................3-10
Figure 3-2: Geometrical Definition of the Thermal Flame Thickness.............................................................3-15
Figure 4-1: Combustion Parameter Tree.............................................................................................................4-1
Figure 4-2: Ignition Models Window....................................................................................................................4-2
Figure 4-3: Spark Ignition Window......................................................................................................................4-2
Figure 4-4: Auto Ignition Window for Diesel.......................................................................................................4-4
Figure 4-5: Auto Ignition Window for AnB Knock..............................................................................................4-6
Figure 4-6: Combustion Models Window..............................................................................................................4-8
Figure 4-7: Eddy Breakup Model Window...........................................................................................................4-9
Figure 4-8: Coherent Flame Model Window......................................................................................................4-13
Figure 4-9: PDF Model Window..........................................................................................................................4-16
Figure 4-10: PDF Model Window for User Defined Coefficients......................................................................4-18
Figure 4-11: Characteristic Timescale Model Window......................................................................................4-20
Figure 4-12: Steady Combustion Model Window...............................................................................................4-22
Figure 4-13: Time Dependent Activation of Combustion Models.....................................................................4-23
Figure 4-14: Emission Models Window..............................................................................................................4-24
Figure 4-15: Advanced Soot Model Window.......................................................................................................4-26
Figure 4-16: 2D Results Window........................................................................................................................4-28
Figure 4-17: 3D Results Window........................................................................................................................4-30
iv AST.08.0205.0699 – 17-May-2004
Vol 2: Combustion FIRE Version 8
1. INTRODUCTION
This manual describes the usage, files and the theoretical background of the FIRE
Combustion Module.
1.1. Scope
This document is for users of the FIRE Combustion Module and anyone interested in
combustion theory and modeling.
1.2. Symbols
The following symbols are used throughout this manual. Safety warnings must be strictly
observed during operation and service of the system or its components.
Caution: Cautions describe conditions, practices or procedures which
!
could result in damage to, or destruction of data if not strictly observed or
remedied.
(cid:14)
Note: Notes provide important supplementary information.
Convention Meaning
For emphasis, to introduce a new term or for manual titles.
Italics
monospace To indicate a command, a program or a file name,
messages, input / output on a screen, file contents or
object names.
SCREEN-KEYS A SCREEN font is used for the names of windows and
keyboard keys, e.g. to indicate that you should type a
command and press the ENTER key.
MenuOpt A MenuOpt font is used for the names of menu options,
submenus and screen buttons.
1.3. Configurations
Software configurations described in this manual were in effect on the publication date of
this manual. It is the user’s responsibility to verify the configuration of the equipment
before applying procedures in this manual.
17-May-2004 1-1
FIRE Version 8 Vol 2: Combustion
1.4. Documentation
FIRE documentation is available in PDF format and consists of the following:
Volume 1 Volume 2
Release Notes CFD Solver
Installation Guide 1D Coupling
CFD Workflow Manager – User’s Guide Aftertreatment
Primer Combustion
Module Tutorials FEM Interface
Application Examples General Gas Phase Reactions
Multiphase
Porosity
Radiation
Single Phase Boiling
Species Transport
Spray
Thin Walls
User-Functions
Wallfilm
The Supported Platforms & Known Issues document is delivered on paper with the CD and
will then be updated on the Internet CFD Service World.
1-2 17-May-2004