1st Edition

Fluid Mechanics Aspects of Fire and Smoke Dynamics in Enclosures





ISBN 9781138029606
Published March 30, 2016 by CRC Press
386 Pages

USD $120.00

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Book Description

This book aims at fulfilling the need for a handbook at undergraduate and starting researcher level on fire and smoke dynamics in enclosures, giving fluid mechanics aspects a central role. Fluid mechanics are essential at the level of combustion, heat transfer and fire suppression, but they are described only cursorily in most of the existing fire safety science literature, including handbooks.

The scope of this handbook ranges from the discussion of the basic equations for turbulent flows with combustion, through a discussion on the structure of flames, to fire and smoke plumes and their interaction with enclosure boundaries. Using this knowledge, the fire dynamics and smoke and heat control in enclosures are discussed. Subsequently, a chapter is devoted to the effect of water and the related fluid mechanics aspects. The book concludes with a chapter on CFD (Computational Fluid Dynamics), the increasingly popular calculation method in the field of fire safety science.

Table of Contents

Introduction
The candle flame
The importance of chemistry, heat transfer and fluid mechanics in fires
Chemistry 
Heat transfer
Fluid mechanics and turbulence
Combustion and fire
Fire modelling

Turbulent flows with chemical reaction 
Fluid properties – state properties – mixtures
Fluid properties 
Mass density 
Viscosity
Specific heat
Conduction coefficient
Diffusion coefficient
State properties
Pressure
Temperature 
Internal energy 
Enthalpy
Entropy 
Equation of state
Mixtures 
Combustion
Chemical reaction
Thermodynamics
Enthalpy 
Temperature 
Chemical kinetics
Transport equations
Conservation of mass
Momentum equations
Conservation of energy 
Convection 
Conduction 
Radiation
Transport of species
Mixture fraction
Bernoulli
Hydrostatics
Buoyancy
Non-dimensional numbers
Fluid properties
Flow properties
Scaling laws
Turbulence
Reynolds number
Reynolds averaging
Turbulence modeling
Energy cascade
Turbulent scales
Turbulence modelling
Boundary layer flow
Internal flows – pressure losses
Entrainment
Impinging flow
Evaporation
Pyrolysis

Turbulent flames and fire plumes 
Flammability 
Flammability limits – threshold temperature
Addition of gases 
Flammability of liquid fuels
Premixed flames 
Laminar premixed flame structure
Laminar burning velocity
The effect of turbulence
Diffusion flames
Laminar diffusion flame structure 
The effect of turbulence 
Jet flames 
Extinction of flames 
Premixed flames
Diffusion flames 
Fire plumes
Free fire plumes
Average flame height
Temperature evolution 
Kelvin-Helmholtz instability
The effect of wind 1
Transition from buoyancy-driven to momentum-driven jets
Correlations
Interaction with non-combustible walls
Interaction with non-combustible ceiling
The effect of ventilation 
Reduced oxygen at ambient temperature
Oxygen-enriched fire plumes
Vitiated conditions
Fire whirls 
Flame spread
Flame spread velocity – a heat balance 
Opposed flow flame spread over a thermally thick fuel
Opposed flow flame spread over a thermally thin fuel 
Concurrent flow flame spread over a thermally thick fuel 
Concurrent flow flame spread over a thermally thin fuel
Gas phase phenomena
Horizontal surface 
Natural convection
Concurrent airflow
Counter-current airflow
Vertical surface
Inclined surface
Parallel vertical plates configuration 
Corner configuration

Smoke plumes 
Introduction
Axisymmetric plume
Theory and mathematical modelling
Model development under the Boussinesq approximation
Experiments 
Line plume
Description of the configuration
Conservation equations 
Experimental studies 
Transition from line to axisymmetric plume
Wall and corner interaction with plumes
Detailed example: line plume bounded by an adiabatic wall
General correlations for wall and corner configurations
Interaction of a plume with a ceiling 
Description of a ceiling-jet
Alpert’s Integral model
Simplified correlations 
Additional considerations 
Smoke layer build-up in a room
Balcony and window spill plumes 
Balcony spill plumes
Window plumes
Scaling laws and buoyant releases 
Exercises 
Analytical solution for the Line plume problem
Design of a reduced-scale helium/air mixture experiment of a car fire in a tunnel 

Fire and smoke dynamics in enclosures
Some fundamentals on flows through openings 
Growing fire 
Fire source
Fuel-controlled growing fire
Ventilation-controlled growing fire
Smoke dynamics 
Flows through openings
Horizontal openings
Vertical openings
Natural and mechanical ventilation
Zone modeling 
Fully developed fire 
Fire source
Smoke dynamics
Flows through openings 
Horizontal openings
Vertical openings
Natural and mechanical ventilation
Zone modeling
Pulsating fire
Backdraft
Fires in well-confined enclosures

Driving forces in smoke and heat control
Buoyancy – the stack effect
Natural stack effect
Fire-induced buoyancy
Pressurization
Natural ventilation
Mechanical ventilation
Vertical ventilation
Horizontal ventilation
Tunnels
Other underground structures
Smoke extraction 
The effect of wind
Positive pressure ventilation 
Air curtains
Exercises

Impact of water on fire and smoke dynamics
Individual evaporating water droplet 
Heat and mass transfer
Flow equations
Sprays of water droplets
Characterization of sprays
Region near the nozzle
Water flow rate
Droplet size and velocity distribution
Spray cone angle
Spray-induced momentum
Water curtains
Heat absorption by water 
Interaction of water with smoke 
Sprinkler and water mist sprays
Water curtain
Fire fighting
Interaction of water with flames
Water as fire suppressant

Introduction to fire modelling in computational fluid dynamics
Introduction
Laminar diffusion flames
Instantaneous transport equations
Combustion modelling
Infinitely fast chemistry 
Finite-rate chemistry
Turbulence modelling
DNS
RANS
LES
Turbulent non-premixed combustion
Infinitely fast chemistry with a presumed PDF
Flame sheet model
Chemical equilibrium model
Steady Laminar Flamelet Modelling (SLFM)
Finite rate chemistry
Eddy Break-Up (EBU) model and Eddy Dissipation Model (EDM)
Eddy Dissipation Concept (EDC) 
Conditional Moment Closure (CMC)
Transported PDF models 
Radiation modelling
Models for radiative transfer 
The P-1 Radiation Model
The Finite Volume Method (FVM)
Models for the absorption coefficient
Turbulence Radiation Interaction (TRI)
The soot problem
Soot nature, morphology and general description of its chemistry
Importance of soot modelling
Sootiness and radiation 
Interaction of soot with carbon monoxide
The sootiness of fuels
The laminar smoke point height
The Threshold Sooting Index (TSI)
Soot modelling
Laminar flames
Turbulent flames 
Basics of numerical discretization
Discretization schemes 
Description of a 1-D example 
Explicit scheme 
Implicit scheme
Initial and boundary conditions
Properties of numerical methods 
Consistency
Stability
Convergence
Conservativeness
Boundedness
Pressure-velocity coupling
The importance of the computational mesh
Boundary conditions
Fire source
Gaseous fuel 
Liquid fuel
Solid fuel
Turbulence inflow boundary conditions
Walls
Velocity
Temperature
Open boundary conditions (natural ventilation)
Velocity and scalars
Pressure
Mechanical ventilation and pressure effects
Fixed velocity
Fan curves and pressure effects
Examples of cfd simulations
Non-reacting buoyant plume
Test case description
Simulation set-up
Results
Hot air plume impinging on a horizontal plate
Test case description
Simulation set-up
Results
Free-burning turbulent buoyant flame 
Test case description
Simulation set-up
Results
Over-ventilated enclosure fire 
Test case description
Simulation set-up and Results 
Interaction of a hot air plume with a water spray 
Test case description
Simulation set-up 
Results 
Underventilated enclosure fire with mechanical ventilation
Test case description
Simulation set-up
Results
Fire spread modelling

References
Subject Index

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Author(s)

Biography

Prof. Bart Merci obtained his PhD, entitled ‘Numerical Simulation and Modelling of Turbulent Combustion’, at the Faculty of Engineering at Ghent University in the year 2000. As postdoctoral fellow of the Fund for Scientific Research – Flanders (FWOVlaanderen), he specialized in numerical simulations of turbulent non-premixed combustion, with focus on turbulence – chemistry interaction and turbulence – radiation interaction. He reoriented his research towards fire safety science, taking the fluid mechanics aspects as central research topic. He became lecturer at Ghent University in 2004 and Full Professor in 2012. He is the head of the research unit ‘Combustion, Fire and Fire Safety’ in the Department of Flow, Heat and Combustion Mechanics. Since 2009, Bart Merci coordinates the ‘International Master of Science in Fire Safety Engineering’, with Lund University and The University of Edinburgh as partners. He has been the President of The Belgian Section of The Combustion Institute since 2009 and Associate Editor of Fire Safety Journal since 2010. He is member of the Executive Committee of the International Association for Fire Safety Science. He is author of more than 100 journal papers.

Dr. Tarek Beji obtained his PhD, entitled "Theoretical and Experimental Investigation on Soot and Radiation in Fires", at the University of Ulster in 2009. He joined Ghent University in 2011 as a post-doctoral researcher in the department of Flow, Heat and Combustion Mechanics and worked on the novel topic of fire forecasting. Since 2012 he has been very active in a large international collaborative research program called PRISME, focusing on mechanical ventilation and fire dynamics in nuclear facilities. Since he joined Ghent University he participated actively in the 'International Master of Science in Fire Safety Engineering' as lecturer and member of the program steering committee.

Reviews

"Using this book people can learn to understand how fires developed and how they can be controlled. The book transfers knowledge from general fluid dynamics and combustion science to the area of fire safety science. Using this approach the accuracy of the prediction of fire will be higher than in traditional approaches more based on empirical correlations. The approach taken in the book is forward looking. The book will be relevant for a long time."

Professor D.J.E.M. Roekaerts, Delft University of Technology, Department Process and Energy, section Fluid Mechanics, Delft, The Netherlands

 

"Merci and Beji’s new book on fire dynamics with emphasis on the fluids mechanics aspects is a solid contribution to the literature in the field. Its comprehensive discussion of fluid mechanics principles applied to plumes, fire behavior in enclosures and CFD models is unparalleled. 
The book could be used as a text for use in fourth year undergraduate or first year graduate level courses or as a high level review for fire safety researchers and engineers. [It is] a valuable addition to the library of any fire safety researcher or engineer."

Prof. Jim Milke, University of Maryland, in 'Fire Science Reviews'.

 

"The text builds all relevant topics on fire and smoke dynamics around fluid mechanics, which is unique and valuable in light of many worthy works on fire dynamics and fire safety engineering. The authors, drawing on their extensive research and teaching experience, strike a good balance between presenting well-known basic fluid mechanics principles and showcasing some state-of-the-art experimental and numerical research insights. [...]

This will be a challenging textbook for an upper-level undergraduate course in a related STEM field, but it is highly recommended for a graduate-level elective course and more so as a comprehensive handbook for practicing engineers in fire dynamics analysis, fire suppression, and fire safety risk analysis.

Summing Up: Highly recommended. Graduate students; faculty and professionals."

B. Tao, Wentworth Institute of Technology in 'Choice', February 2017 issue.