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Large Outdoor Fire Dynamics

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Large Outdoor Fire Dynamics provides the essential knowledge for the hazard evaluation of large outdoor fires, including wildland, WUI (wildland-urban interface), and urban fires. The spread of outdoor fires can be viewed as a successive occurrence of physical and chemical processes – solid fuel combustion, heat transfer to surrounding combustibles, and ignition of heated combustibles – which are explained herein. Engineering equations frequently used in practical hazard analyses are derived and then integrated to implement a computational code predicting fire spread among discretely distributed combustibles. This code facilitates learning the procedure of hazard evaluation for large outdoor fires.

Chapters cover underlying assumptions for analyzing fire spread behavior in large outdoor fires, namely, wind conditions near the ground surface and fundamentals of heat transfer; the physical mechanism of fire spread in and between combustibles, specifically focusing on fire plumes (both reacting and non-reacting) and firebrand dispersal; and the spatial modeling of 3D objects and developing the computational framework for predicting fire spread.

The book is ideal for engineers, researchers, and graduate students in fire safety as well as mechanical engineering, civil engineering, disaster management, safety engineering, and planning. Companion source codes are available online.

Author(s): Keisuke Himoto
Publisher: CRC Press
Year: 2022

Language: English
Pages: 414
City: Boca Raton

Cover
Half Title
Title Page
Copyright Page
Table of Contents
Preface
Nomenclature
Chapter 1 Introduction
1.1 Large Outdoor Fires
1.1.1 Definition
1.1.2 Examples
Chapter 2: Wind
Chapter 3: Heat Transfer
Chapter 4: Fire Sources
Chapter 5: Fire Plumes – Quiescent Environment
Chapter 6: Fire Plumes – Windy Environment
Chapter 7: Ignition and Fire Spread Processes
Chapter 8: Firebrands
Chapter 9: Spatial Data Modeling
Chapter 10: Fire Spread Simulation
1.2 Scope of this Book
Chapter 2 Wind
2.1 Surface Wind
2.1.1 Stratified Structure of the Atmosphere
2.1.2 Geostrophic and Surface Winds
2.1.3 Vertical Wind Velocity Profile in the Atmospheric Boundary Layer
2.2 Statistical Features of Wind
2.2.1 Characteristic Values at a Specific Location
2.2.2 Time Variation at a Specific Site
2.3 Topographic Effects
2.3.1 Effect of Terrain
(1) Combined Effect of Terrain and Solar Radiation
(2) Mechanical Effect of Terrain
2.3.2 Effect of Obstacles
Chapter 3 Heat Transfer
3.1 Heat Conduction
3.1.1 Heat Conduction Equation
3.1.2 Thermo-Physical Properties
(1) Thermal Conductivity of Wood Materials
(2) Specific Heat of Wood Materials
3.1.3 Steady Conduction
(1) Plane Wall
(2) Composite Plane Wall
Worked .example 3.1
Suggested Solution
Worked .example 3.2
Suggested Solution
3.1.4 Transient Conduction
(1) Specified Temperature Boundary Condition
(2) Convection Boundary Condition
(3) Specified Heat Flux Boundary Condition
(4) Interface Boundary Condition
Worked .example 3.3
Suggested Solution
3.2 Convective Heat Transfer
3.2.1 Heat Transfer Coefficient
3.2.2 Forced Convection
(1) Boundary Layer Approximation
(2) Similarity Law and Dimensionless Parameters
(3) Mean Nusselt Number
Worked .example 3.4
Suggested Solution
3.2.3 Natural Convection
(1) Similarity Law and Dimensionless Parameters
(2) Mean Nusselt Number
Worked .example 3.5
Suggested Solution
3.3 Radiative Heat Transfer
3.3.1 Thermal Radiation
3.3.2 Radiation Intensity and Emissive Power
3.3.3 Blackbody Radiation
3.3.4 Radiation Properties of Real Surfaces
3.3.5 Radiation By Gases
Worked .example 3.6
Suggested Solution
3.3.6 Radiative Heat Exchange Between Surfaces
3.3.7 View Factor
Worked .example 3.7
Suggested Solution
3.3.8 Analytical Solutions for View Factors
(1) Parallel to a Rectangle
(2) Perpendicular to a Rectangle
(3) Right Opposite a Circle
(4) Perpendicular to a Circular Cylinder
Worked .example 3.8
Suggested Solution
Worked .example 3.9
Suggested Solution
3.3.9 Point Source Models for Radiative Heat Transfer
(1) Single-Point Source Model
(2) Multi-Point Source Model
Worked .example 3.10
Suggested Solution
Chapter 4 Fire Sources
4.1 Form of Combustion
4.1.1 Combustion of Gaseous Fuels
4.1.2 Combustion of Liquid and Solid Fuels
(1) Mass Loss Rate (Mass Burning Rate)
(2) Combustion of Charring Materials
4.2 Heat Release in Combustion
4.2.1 Heat of Combustion
4.2.2 Estimation of the Heat of Combustion Using Chemical Formulae
Worked .example 4.1
Suggested Solution
4.2.3 Estimation of the Heat of Combustion During Incomplete Combustion Using Equivalent Ratio
Worked .example 4.2
Suggested Solution
4.3 Fire Source in Wildland Fires
4.3.1 Type and Structure of Fuels in Wildland Fires
4.3.2 Transient Burning Process of Individual Fuel Components
Worked .example 4.3
Suggested Solution
4.3.3 Combustion of Homogeneous Porous Fuel
4.4 Fire Source in Urban Fires
4.4.1 Fuels in Compartment Fires
4.4.2 Development Process of a Compartment Fire
4.4.3 Fully Developed Compartment Fire
(1) Mass Loss Rate (Mass Burning Rate)
(2) Mass Flow Rate Due to Ventilation
(3) Heat Release Rate (HRR)
(4) Heat Loss Rate
Worked .example 4.4
Suggested Solution
4.4.4 Compartment Gas Temperature
Worked .example 4.5
Suggested Solution
Chapter 5 Fire Plumes – Quiescent Environment
5.1 Basic Characteristics of Fire Plumes
5.1.1 Self-Similarity
5.1.2 Intermittency and Domain Segmentation
5.2 Point Fire Source
5.2.1 Governing Equations
(1) Plume Regime
(2) Flame Regime
5.2.2 Dimensional Analysis
5.2.3 Virtual Origin
5.2.4 Flame Height
Worked .example 5.1
Suggested Solution
Worked .example 5.2
Suggested Solution
Worked .example 5.3
Suggested Solution
5.3 Line Fire Source
5.3.1 Governing Equations
5.3.2 Dimensional Analysis
5.3.3 Flame Height
Worked .example 5.4
Suggested Solution
5.4 Flame Ejection From an Opening (Window Flame)
5.4.1 Thermal Behavior Along the Trajectory
5.4.2 Trajectory of the Centerline
5.4.3 Flame Geometry
Worked .example 5.5
Suggested Solution
Worked .example 5.6
Suggested Solution
5.5 Other Fire Sources
5.5.1 Rectangular Fire Sources
5.5.2 Group Fires
Worked .example 5.7
Suggested Solution
Chapter 6 Fire Plumes – Windy Environment
6.1 Basic Characteristics of Fire Plumes
6.2 Non-Reacting Fire Plumes Downwind of a Point Fire Source
6.2.1 Governing Equations
6.2.2 Dimensional Analysis
Worked .example 6.1
Suggested Solution
6.2.3 Trajectory
Worked .example 6.2
Suggested Solution
6.3 Non-Reacting Fire Plumes Downwind of a Line Fire Source
6.3.1 Governing Equations
6.3.2 Dimensional Analysis
Worked .example 6.3
Suggested Solution
6.3.3 Trajectory
Worked .example 6.4
Suggested Solution
6.4 Flame Geometry
6.4.1 Flame Length
6.4.2 Flame Base Drag
6.4.3 Tilt Angle
Worked .example 6.5
Suggested Solution
Chapter 7 Ignition and Fire Spread Processes
7.1 Ignition Process of a Solid
7.2 Time to Ignition
7.2.1 Thermal Thickness of a Solid
7.2.2 Ignition of a Thermally Thin Solid Under Constant Exposures
(1) Convection Boundary Condition
(2) External Radiation Boundary Condition
7.2.3 Ignition of a Thermally Thick Solid Under Constant Exposures
(1) Convection Boundary Condition
(2) Specified Heat Flux Boundary Condition
(3) External Radiation With Heat Loss From the Surface
(4) Engineering Correlations
(5) Critical Conditions for Ignition
Worked .example 7.1
Suggested Solution
7.2.4 Ignition of a Thermally Thick Solid Under Time-Varying Exposures
Worked .example 7.2
Suggested Solution
7.3 Fire Spread in a Continuous Fuel Bed
7.3.1 Rate of Fire Spread Based On Surface Temperature
7.3.2 Rate of Fire Spread Based On Incident Heat Flux
Worked .example 7.3
Suggested Solution
7.4 Fire Spread Between Discrete Fuel Objects
7.4.1 Rate of Fire Spread
7.4.2 Critical Separation Distance for Fire Spread
Worked .example 7.4
Suggested Solution
7.4.3 Probability of Fire Spread
(1) When Both and Follow a Normal Distribution
(2) When Both and Follow a Log-Normal Distribution
7.4.4 Vulnerability Curves for Fire Spread
Chapter 8 Firebrands
8.1 Process of Fire Spread
8.1.1 Process of Fire Spread (Single Fire Source)
Worked .example 8.1
Suggested Solution
8.1.2 Process of Fire Spread (Multiple Fire Sources)
Worked .example 8.2
Suggested Solution
8.2 Generation
8.2.1 Shape and Mass
Worked .example 8.3
Suggested Solution
8.2.2 Quantity
8.3 Dispersion
8.3.1 Motion of a Lofted Firebrand (Translation and Rotation)
(1) Equation of Motion
(2) Coordinate Conversion By Euler Angle
(3) Coordinate Conversion By Quaternions
8.3.2 Combustion of Airborne Firebrands
8.3.3 Range of Firebrand Dispersal
Worked .example 8.4
Suggested Solution
8.4 Ignition
8.4.1 Factors Affecting Ignition
(1) Deposited Firebrands
(2) Recipient Fuel
(3) Deposition of Firebrands On Fuel Bed
(4) Ambient Environment
8.4.2 Probability of Ignition
(1) Bernoulli Trial
(2) Logistic Model
Chapter 9 Spatial Data Modeling
9.1 Spatial Coordinate System
9.1.1 3D Rectangular Coordinate System
9.1.2 Vector
(1) Inner Product
(2) Outer Product
Worked .example 9.1
Suggested Solution
9.2 Description of a 3D Object
9.2.1 Surface Model
Worked .example 9.2
Suggested Solution
9.2.2 Multi-Point Model
9.3 Geometric Computations in 3D Space
9.3.1 Lines
(1) Distance Between a Point and a Line
(2) Distance Between Lines
Worked .example 9.3
Suggested Solution
Worked .example 9.4
Suggested Solution
9.3.2 Plane Surfaces
(1) Distance Between a Point and a Plane Surface
(2) Intersection of a Line and a Polygon
(3) Area of a Polygon
Worked .example 9.5
Suggested Solution
Chapter 10 Fire Spread Simulation
10.1 An Overview of the Model Development History
10.1.1 Development of Predictive Methods
(1) Flame Propagation in Ideal Combustible Spaces
(2) Fire Spread in Actual Combustible Spaces
10.1.2 Presented Simulation Model
10.2 Setup and Execution of the Simulation Model
10.2.1 Source Code
10.2.2 Setup of an Execution Environment
10.2.3 Execution of the Code
10.3 Theoretical Framework of the Simulation Model
10.3.1 Overall Structure
10.3.2 INIT: Data Input and Setup
(1) INIT1: Read From Files
(2) INIT2: Objects
(3) INIT3: Adjacency
(4) INIT4: From UTM Coordinates to Longitude and Latitude
10.3.3 NDAT: Data Update and Output
(1) NDAT: Data Status
(2) OUTP: Data Output
(3) RSLT: Data Summary
10.3.4 FIRE: Burning Behavior of Objects
(1) HRR: Heat Release Rate
(2) HTRF: Ignition Due to External Heating
10.3.5 SPRD: Fire Spread Behavior Between Objects
(1) XRAD: Flames
(2) FPLM: Fire Plumes
(3) SPOT: Firebrands
10.4 Case Study
10.4.1 Simulation Conditions
(1) Outline of the Simulation: O.csv
(2) Vertices of the Fuel Objects: V.csv
(3) Face Polygons Composing Combustible Objects: P.csv
10.4.2 Simulation Results
References
Index