Large Outdoor Fire Dynamics

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. 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 "Large outdoor fires are increasingly frequent, as climate and weather patterns change. The exceptionally high costs of recent forest and wildland-urban interface fires have drawn international attention. This systematic overview sets out useful engineering equations and computational models for analysing large outdoor fire dynamics, and presents practical approaches to risk assessment. It details the broad range of items needed for analysing risks and for designing plans to improve resilience in the built environment. This book shows professional engineers and researchers how to use or develop analytical tools, and also serves graduate courses"-- Provided by publisher This systematically sets out useful engineering equations and computational models for analysing large outdoor fire dynamics, and presents practical approaches to risk assessment. It details the items needed for analysing risks and for designing plans to improve resilience in the built environment - for professionals and graduate students.