Fluid Mechanics Aspects of Fire and Smoke Dynamics in Enclosures: 1st Edition (Paperback) book cover

Fluid Mechanics Aspects of Fire and Smoke Dynamics in Enclosures

1st Edition

By Bart Merci, Tarek Beji

CRC Press

386 pages

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pub: 2016-03-22
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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.

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.

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

About the Authors

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.

Subject Categories

BISAC Subject Codes/Headings:
SCI055000
SCIENCE / Physics
TEC009070
TECHNOLOGY & ENGINEERING / Mechanical
TEC063000
TECHNOLOGY & ENGINEERING / Structural