physical factors driving the spread of a
TRANSCRIPT
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ire esearchentrephysical factors drivingphysical factors driving
the spread of a bushfirethe spread of a bushfire
John DoldJohn Dold
wildfire 2009, Lyndhurst, New Forestwildfire 2009, Lyndhurst, New Forest
Fire Research CentreFire Research CentreUniversity of Manchester, UKUniversity of Manchester, UK
[email protected]@man.ac.ukwww.frc.manchester.ac.ukwww.frc.manchester.ac.uk
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ire esearchentrephysical factors drivingphysical factors driving
the spread of a bushfirethe spread of a bushfire
John DoldJohn Dold
wildfire 2009, Lyndhurst, New Forestwildfire 2009, Lyndhurst, New Forest
Fire Research CentreFire Research CentreUniversity of Manchester, UKUniversity of Manchester, UK
[email protected]@man.ac.ukwww.frc.manchester.ac.ukwww.frc.manchester.ac.uk
Note: bushfire = wildfire (almost)
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ire esearchentrephysical factors drivingphysical factors driving
the spread of a bushfirethe spread of a bushfire
John DoldJohn Dold
wildfire 2009, Lyndhurst, New Forestwildfire 2009, Lyndhurst, New Forest
Fire Research CentreFire Research CentreUniversity of Manchester, UKUniversity of Manchester, UK
[email protected]@man.ac.ukwww.frc.manchester.ac.ukwww.frc.manchester.ac.uk
Note: bushfire = wildfire (almost)
subtitle: know your enemy
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ire esearchentrephysical factors drivingphysical factors driving
the spread of a bushfirethe spread of a bushfire
John DoldJohn Dold
wildfire 2009, Lyndhurst, New Forestwildfire 2009, Lyndhurst, New Forest
Fire Research CentreFire Research CentreUniversity of Manchester, UKUniversity of Manchester, UK
[email protected]@man.ac.ukwww.frc.manchester.ac.ukwww.frc.manchester.ac.uk
Note: bushfire = wildfire (almost)
subtitle: know your enemy
and your friend
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ire esearchentre
topics
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ire esearchentre
topics
bushfire chemistry
spread rate and intensity
steady and unsteady fires
some other factors in wildfires
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ire esearchentre
how the vegetation responds to heating
fast pyrolysis vapourises the fuel (around 350C)
http://jack-pyrolysis.mov/http://vapour.mov/http://pyrolysis.mov/http://paper-smoke.mov/ -
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ire esearchentre
how the vegetation responds to heating
fast pyrolysis vapourises the fuel (around 350C)
an electric toaster testan electric toaster test
http://jack-pyrolysis.mov/http://vapour.mov/http://pyrolysis.mov/http://paper-smoke.mov/ -
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ire esearchentre
how the vegetation responds to heating
fast pyrolysis vapourises the fuel (around 350C)
an electric toaster testan electric toaster test
a barbeque testa barbeque test
http://jack-pyrolysis.mov/http://vapour.mov/http://pyrolysis.mov/http://paper-smoke.mov/ -
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ire esearchentre
how the vegetation responds to heating
fast pyrolysis vapourises the fuel (around 350C)
an electric toaster testan electric toaster test
a barbeque testa barbeque test
schrubland fire (Portugal)schrubland fire (Portugal)
http://paper-smoke.mov/http://paper-smoke.mov/http://pyrolysis.mov/http://jack-pyrolysis.mov/http://vapour.mov/http://pyrolysis.mov/http://paper-smoke.mov/ -
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ire esearchentre
how the vegetation responds to heating
fast pyrolysis vapourises the fuel (around 350C)
an electric toaster testan electric toaster test
a barbeque testa barbeque test
schrubland fire (Portugal)schrubland fire (Portugal)
a crown firea crown fire(courtesy Jack Cohen, USDA)(courtesy Jack Cohen, USDA)
http://paper-smoke.mov/http://paper-smoke.mov/http://pyrolysis.mov/http://paper-smoke.mov/http://paper-smoke.mov/http://jack-pyrolysis.mov/http://vapour.mov/http://pyrolysis.mov/http://paper-smoke.mov/ -
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ire esearchentre
how the vegetation responds to heating
fast pyrolysis vapourises the fuel (around 350C)
an electric toaster testan electric toaster test
a barbeque testa barbeque test
schrubland fire (Portugal)schrubland fire (Portugal)
a crown firea crown fire(courtesy Jack Cohen, USDA)(courtesy Jack Cohen, USDA)
compare: a chip-pan
reaches flash-pointat about 330C
compare: a chip-pan
reaches flash-pointat about 330C
http://paper-smoke.mov/http://paper-smoke.mov/http://pyrolysis.mov/http://paper-smoke.mov/http://paper-smoke.mov/http://jack-pyrolysis.mov/http://vapour.mov/http://pyrolysis.mov/http://paper-smoke.mov/ -
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ire esearchentre
how the vegetation responds to heating
fast pyrolysis vapourises the fuel (around 350C)
an electric toaster testan electric toaster test
a barbeque testa barbeque test
schrubland fire (Portugal)schrubland fire (Portugal)
a crown firea crown fire(courtesy Jack Cohen, USDA)(courtesy Jack Cohen, USDA)
compare: a chip-pan
reaches flash-pointat about 330C
compare: a chip-pan
reaches flash-pointat about 330C
slow pyrolysisproduces charcoal
(mainly below 300C)
slow pyrolysisproduces charcoal
(mainly below 300C)
http://paper-smoke.mov/http://paper-smoke.mov/http://pyrolysis.mov/http://paper-smoke.mov/http://paper-smoke.mov/http://jack-pyrolysis.mov/http://vapour.mov/http://pyrolysis.mov/http://paper-smoke.mov/ -
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ire esearchentre
how the vegetation responds to heating
fast pyrolysis vapourises the fuel (around 350C)
an electric toaster testan electric toaster test
a barbeque testa barbeque test
schrubland fire (Portugal)schrubland fire (Portugal)
a crown firea crown fire(courtesy Jack Cohen, USDA)(courtesy Jack Cohen, USDA)
compare: a chip-pan
reaches flash-pointat about 330C
compare: a chip-pan
reaches flash-pointat about 330C
slow pyrolysisproduces charcoal
(mainly below 300C)
slow pyrolysisproduces charcoal
(mainly below 300C)
cellulose
levoglucosan
d-glucose
fastpyrolysis
C6H10O5
C6H12O6
slowpyrolysis
chare.g.
growth
plant
e.g.
http://paper-smoke.mov/http://paper-smoke.mov/http://pyrolysis.mov/http://paper-smoke.mov/http://paper-smoke.mov/http://vapour.mov/http://jack-pyrolysis.mov/http://jack-pyrolysis.mov/http://paper-smoke.mov/http://paper-smoke.mov/http://paper-smoke.mov/http://paper-smoke.mov/http://paper-smoke.mov/http://paper-smoke.mov/http://paper-smoke.mov/http://vapour.mov/http://paper-smoke.mov/http://pyrolysis.mov/http://vapour.mov/http://jack-pyrolysis.mov/http://jack-pyrolysis.mov/http://vapour.mov/http://pyrolysis.mov/http://paper-smoke.mov/ -
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ire esearchentre
vegetation vapour burns above about 900C
bushfire flames are (normally) turbulent diffusion flamesbushfire flames are (normally) turbulent diffusion flames
a small experimental fire
simply: air and fuel vapour have to mix to release heat.simply: air and fuel vapour have to mix to release heat.
http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/ -
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ire esearchentre
vegetation vapour burns above about 900C
bushfire flames are (normally) turbulent diffusion flamesbushfire flames are (normally) turbulent diffusion flames
a small experimental fire
simply: air and fuel vapour have to mix to release heat.simply: air and fuel vapour have to mix to release heat.
Slow mixing (in large flames) cant maintain the temperatureSlow mixing (in large flames) cant maintain the temperatureso flames go out, leaving black smoke (soot)so flames go out, leaving black smoke (soot)
http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/ -
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ire esearchentre
vegetation vapour burns above about 900C
bushfire flames are (normally) turbulent diffusion flamesbushfire flames are (normally) turbulent diffusion flames
a small experimental fire
simply: air and fuel vapour have to mix to release heat.simply: air and fuel vapour have to mix to release heat.
Slow mixing (in large flames) cant maintain the temperatureSlow mixing (in large flames) cant maintain the temperatureso flames go out, leaving black smoke (soot)so flames go out, leaving black smoke (soot)
Buncefield fuel-depot fire (11 December 2005)
C
http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/ -
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ire esearchentre
vegetation vapour burns above about 900C
bushfire flames are (normally) turbulent diffusion flamesbushfire flames are (normally) turbulent diffusion flames
a small experimental fire
simply: air and fuel vapour have to mix to release heat.simply: air and fuel vapour have to mix to release heat.
Slow mixing (in large flames) cant maintain the temperatureSlow mixing (in large flames) cant maintain the temperatureso flames go out, leaving black smoke (soot)so flames go out, leaving black smoke (soot)
Buncefield fuel-depot fire (11 December 2005)
Weston Pier fire (29 July 2008)
i b b b 900C
http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/ -
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ire esearchentre
vegetation vapour burns above about 900C
bushfire flames are (normally) turbulent diffusion flamesbushfire flames are (normally) turbulent diffusion flames
a small experimental fire
simply: air and fuel vapour have to mix to release heat.simply: air and fuel vapour have to mix to release heat.
Slow mixing (in large flames) cant maintain the temperatureSlow mixing (in large flames) cant maintain the temperatureso flames go out, leaving black smoke (soot)so flames go out, leaving black smoke (soot)
Buncefield fuel-depot fire (11 December 2005)
Weston Pier fire (29 July 2008)
i b b b 900C
http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/ -
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ire esearchentre
vegetation vapour burns above about 900C
bushfire flames are (normally) turbulent diffusion flamesbushfire flames are (normally) turbulent diffusion flames
a small experimental fire
simply: air and fuel vapour have to mix to release heat.simply: air and fuel vapour have to mix to release heat.
Slow mixing (in large flames) cant maintain the temperatureSlow mixing (in large flames) cant maintain the temperatureso flames go out, leaving black smoke (soot)so flames go out, leaving black smoke (soot)
Buncefield fuel-depot fire (11 December 2005)
Weston Pier fire (29 July 2008)
a crown fire (courtesy Jack Cohen)
t ti b b b t 900C
http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/ -
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ire esearchentre
vegetation vapour burns above about 900C
bushfire flames are (normally) turbulent diffusion flamesbushfire flames are (normally) turbulent diffusion flames
a small experimental fire
simply: air and fuel vapour have to mix to release heat.simply: air and fuel vapour have to mix to release heat.
Slow mixing (in large flames) cant maintain the temperatureSlow mixing (in large flames) cant maintain the temperatureso flames go out, leaving black smoke (soot)so flames go out, leaving black smoke (soot)
Buncefield fuel-depot fire (11 December 2005)
Weston Pier fire (29 July 2008)
a crown fire (courtesy Jack Cohen)
a small experimental fire
h d t fl l th hit k ?h d t fl l th hit k ?
http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/http://jack-crowning.mov/ -
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ire esearchentre
why dont flames always consume the white smoke?why dont flames always consume the white smoke?
wh dont flames alwa s cons me the white smoke?h d t fl l th hit k ?
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ire esearchentre
why dont flames always consume the white smoke?why dont flames always consume the white smoke?
vegetation vapour is produced at about 350Cbut it does not burn below about 900C
why dont flames always consume the white smoke?why dont flames always consume the white smoke?
http://short_palasca.mov/http://short_palasca.mov/ -
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ire esearchentre
why don t flames always consume the white smoke?why don t flames always consume the white smoke?
vegetation vapour is produced at about 350Cbut it does not burn below about 900C
For it to burn with enough energy to exceed 900C,the vapour must exceed about 7% by mass in air
so it must exceed this flash-point concentration to burn
why dont flames always consume the white smoke?why dont flames always consume the white smoke?
http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/ -
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ire esearchentre
why don t flames always consume the white smoke?why don t flames always consume the white smoke?
vegetation vapour is produced at about 350Cbut it does not burn below about 900C
For it to burn with enough energy to exceed 900C,the vapour must exceed about 7% by mass in air
so it must exceed this flash-point concentration to burn
more dilute vegetation vapour does not burn
why dont flames always consume the white smoke?why dont flames always consume the white smoke?
http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/ -
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ire esearchentre
why don t flames always consume the white smoke?why don t flames always consume the white smoke?
vegetation vapour is produced at about 350Cbut it does not burn below about 900C
For it to burn with enough energy to exceed 900C,the vapour must exceed about 7% by mass in air
so it must exceed this flash-point concentration to burn
more dilute vegetation vapour does not burn
even above the flash-point concentration:
Vapour stays unburnt unless it is heated above 900C
why dont flames always consume the white smoke?why dont flames always consume the white smoke?
http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/ -
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ire esearchentre
why don t flames always consume the white smoke?why don t flames always consume the white smoke?
vegetation vapour is produced at about 350Cbut it does not burn below about 900C
For it to burn with enough energy to exceed 900C,the vapour must exceed about 7% by mass in air
so it must exceed this flash-point concentration to burn
more dilute vegetation vapour does not burneven above the flash-point concentration:
Vapour stays unburnt unless it is heated above 900C
In principle, there could be a delayed flash overas long as the concentration remains above about 7%
Arnold & Buck (1954)
why dont flames always consume the white smoke?why dont flames always consume the white smoke?
http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/ -
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ire esearchentre
why don t flames always consume the white smoke?why don t flames always consume the white smoke?
vegetation vapour is produced at about 350Cbut it does not burn below about 900C
For it to burn with enough energy to exceed 900C,the vapour must exceed about 7% by mass in air
so it must exceed this flash-point concentration to burn
more dilute vegetation vapour does not burneven above the flash-point concentration:
Vapour stays unburnt unless it is heated above 900C
In principle, there could be a delayed flash overas long as the concentration remains above about 7%
Arnold & Buck (1954)
This may have happened in some large fires . . .
why dont flames always consume the white smoke?why dont flames always consume the white smoke?
http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/ -
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ire esearchentre
why don t flames always consume the white smoke?why don t flames always consume the white smoke?
vegetation vapour is produced at about 350Cbut it does not burn below about 900C
For it to burn with enough energy to exceed 900C,the vapour must exceed about 7% by mass in air
so it must exceed this flash-point concentration to burn
more dilute vegetation vapour does not burneven above the flash-point concentration:
Vapour stays unburnt unless it is heated above 900C
In principle, there could be a delayed flash overas long as the concentration remains above about 7%
Arnold & Buck (1954)
This may have happened in some large fires . . .
Corsica, 2000
http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/http://short_palasca.mov/ -
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plume
bushfire anatomy
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d
flame depth
flame length
flame angle
q heat flux
pyrolysisrate
m
load
u
normal wind
n
air flow
char
vegetation
R(t )R(tb)
air flow
spread rate
ire esearchentre
bushfire anatomy
plume
bushfire anatomy
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d
flame depth
flame length
flame angle
q heat flux
pyrolysisrate
m
load
u
normal wind
n
air flow
char
vegetation
R(t )R(tb)
air flow
spread rate
ire esearchentre
bushfire anatomy
flame length
flame angle
q heat flux
load
vegetation
Tpm
pre-heating
plume
tbushfire anatomy
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d
flame depth
flame length
flame angle
q heat flux
pyrolysisrate
m
load
u
normal wind
n
air flow
char
vegetation
R(t )R(tb)
air flow
spread rate
ire esearchentre
s o y
pyrolysisrate
mass pyrolysing
(flame depth)
plume
entrebushfire anatomy
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d
flame depth
flame length
flame angle
q heat flux
pyrolysisrate
m
load
u
normal wind
n
air flow
char
vegetation
R(t )R(tb)
air flow
spread rate
ire esearchentre
y
flame and flow interaction
plume
entrebushfire anatomy
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d
flame depth
flame length
flame angle
q heat flux
pyrolysisrate
m
load
u
normal wind
n
air flow
char
vegetation
R(t )R(tb)
air flow
spread rate
ire esearchentre
y
flame and flow interaction
pyrolysisrate
mass pyrolysing
(flame depth)
flame length
flame angle
q heat flux
load
vegetation
Tpm
pre-heating
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plume
entreintensity and spread rate
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d
flame depth
flame length
flame angle
q heat flux
pyrolysisrate
m
load
u
normal wind
n
air flow
char
vegetation
R(t )R(tb)
air flow
spread rate
ire esearch
a fire spreads as the flash-point moves forwards
q
m
plume
hentre
intensity and spread rate
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d
flame depth
flame length
flame angle
q heat flux
pyrolysisrate
m
load
u
normal wind
n
air flow
char
vegetation
R(t )R(tb)
air flow
spread rate
ire esearch
a fire spreads as the flash-point moves forwards
q
m
so the rate of temperature rise determines the spread rate
temperature rises faster for a more intense flame
and in finer & drier parts of the vegetation
while wetter vegetation requires more energy to heat up
plume
i hentre
intensity and spread rate
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d
flame depth
flame length
flame angle
q heat flux
pyrolysisrate
m
load
u
normal wind
n
air flow
char
vegetation
R(t )R(tb)
air flow
spread rate
ire esearch
a fire spreads as the flash-point moves forwards
q
m
so the rate of temperature rise determines the spread rate
temperature rises faster for a more intense flame
and in finer & drier parts of the vegetation
while wetter vegetation requires more energy to heat up
inside the flaming region, pyrolysis feeds into flame intensity
pyrolysisrate
plume
ire esearchentre
intensity and spread rate
-
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d
flame depth
flame length
flame angle
q heat flux
pyrolysisrate
m
load
u
normal wind
n
air flow
char
vegetation
R(t )R(tb)
air flow
spread rate
ire esearch
a fire spreads as the flash-point moves forwards
q
m
so the rate of temperature rise determines the spread rate
temperature rises faster for a more intense flame
and in finer & drier parts of the vegetation
while wetter vegetation requires more energy to heat up
inside the flaming region, pyrolysis feeds into flame intensity
pyrolysisrate
rate at which biomass pyrolyses determines flame intensity(roughly: vapourising 7 gm/s of dry vegetation gives 100 kW of intensity)
plume
ire esearchentre
effects of wind and slope
-
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u
normal wind
n
air flow
air flow
ire esearch
plume
ire esearchentre
effects of wind and slope
-
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u
normal wind
n
air flow
air flow
ire esearch
wind and moderate slope:
plume
ire esearchentre
effects of wind and slope
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u
normal wind
n
air flow
air flow
wind and moderate slope:
push the flames closer to the vegetation surface
which increases the rate of heating up to flash point
plume
ire esearchentre
effects of wind and slope
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u
normal wind
n
air flow
air flow
wind and moderate slope:
push the flames closer to the vegetation surface
which increases the rate of heating up to flash point
which increases the rate of spread
plume
ire esearchentre
intensity changes lag behind spread rate
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d
flame depth
flame length
flame angle
q heat flux
pyrolysisrate
m
load
u
normal wind
n
air flow
char
vegetation
R(t )R(tb)
air flow
spread rate
plume
ire esearchentre
intensity changes lag behind spread rate
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d
flame depth
flame length
flame angle
q heat flux
pyrolysisrate
m
load
u
normal wind
n
air flow
char
vegetation
R(t )R(tb)
air flow
spread rate
a slow steady flame spread:
schematic illustrations
steady spread rate and intensity
plume
ire esearchentre
intensity changes lag behind spread rate
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d
flame depth
flame length
flame angle
q heat flux
pyrolysisrate
m
load
u
normal wind
n
air flow
char
vegetation
R(t )R(tb)
air flow
spread rate
a slow steady flame spread:
schematic illustrations
steady spread rate and intensity
after a jump in spread rate:
higher steady spread rate and intensity
intensity grows asflame depths grows
until conditionsbecome steady again
ire esearchentre
topics
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bushfire chemistry
turning vegetation into fuel vapour (at about 350C)
burning the fuel vapour with air (above about 900C)
spread rate and intensity
heating fresh vegetation causes flame spread
intensity builds up with flame depth as the flame spreads
steady and unsteady fires
some other factors in wildfires
ire esearchentre
spread rate depends on:
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fuel properties (including moisture)
topography (slope)
weather (wind)
ire esearchentre
spread rate depends on:
fire trianglefire triangle
f t d fif d fi
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fuel properties (including moisture)
topography (slope)
weather (wind)
for steady firesfor steady fires
spreadrate
fuel
spreadrate
fuel
weath
er
weather
topo
graphy
topo
graphy
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ire esearchentre
spread rate depends on:
fire trianglefire triangle
for steady firesf t d fi
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fuel properties (including moisture)
topography (slope)
weather (wind)
for steady firesfor steady fires
spreadrate
fuel
spreadrate
fuel
weath
er
weath
er
topo
graphy
topo
graphy
intensity varies mainly with flame-depth
i.e. how far the flame spreads while
the vegetation burns downit changes more slowly than spread rate
(flame depth builds up more slowly)
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ire esearchentre
spread rate depends on:
fire trianglefire triangle
for steady firesfor steady fires
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fuel properties (including moisture)
topography (slope)
weather (wind)
for steady firesfor steady fires
spreadrate
fuel
spreadrate
fuel
weath
er
weath
erto
po
graphy
topo
graphy
intensity varies mainly with flame-depth
i.e. how far the flame spreads while
the vegetation burns downit changes more slowly than spread rate
(flame depth builds up more slowly)
and intensity
spread
rate
fuel
topography w
eather
intensity
spread
rate
fuel
topography w
eather
intensity
fire squarefire square
for all firesfor all fires
ire esearchentre
spread rate depends on:
fire trianglefire triangle
for steady firesfor steady fires
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fuel properties (including moisture)
topography (slope)
weather (wind)
for steady firesfor steady fires
spreadrate
fuel
spreadrate
fuel
weath
er
weath
erto
po
graphy
topo
graphy
intensity varies mainly with flame-depth
i.e. how far the flame spreads while
the vegetation burns downit changes more slowly than spread rate
(flame depth builds up more slowly)
and intensity
spread
rate
fuel
topography w
eather
intensity
spread
rate
fuel
topography w
eather
intensity
fire squarefire square
for all firesfor all fires
for steady fires intensity and spread rate change together
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ire esearchentre
fire eruption (an extreme form of unsteady fire)
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Palasca, Corsica 2000( this fire killed 2 people, creating a lake of fire )
about 6 hectares burnt in 60 seconds
ire esearchentre
fire eruptionseruptive fires
are responsible
http://short_palasca.mov/http://short_palasca.mov/ -
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are responsible
for many deaths
they are poorly understood
fatalities often include experienced firefighters
ire esearchentre
an erupting field experiment. Gestosa, Portugal 2008
http://plot_1002.mov/ -
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ire esearchentre
an erupting field experiment. Gestosa, Portugal 2008
http://plot_1002.mov/http://plot_1002.mov/ -
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ire esearchentre
an erupting field experiment. Gestosa, Portugal 2008
http://plot_1002.mov/http://6x8_canyon.mov/http://6x8_canyon.mov/ -
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ignition (0 seconds) flow still separated (30 sec.)
flow attached (37 sec.) 40 metre spread (70 sec.)
ire esearchentre
an erupting field experiment. Gestosa, Portugal 2008
http://6x8_canyon.mov/http://6x8_canyon.mov/http://6x8_canyon.mov/http://6x8_canyon.mov/ -
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ignition (0 seconds) flow still separated (30 sec.)
flow attached (37 sec.)
40 metre spread (70 sec.)
ire esearchentre
an erupting field experiment. Gestosa, Portugal 2008
http://6x8_canyon.mov/http://6x8_canyon.mov/http://6x8_canyon.mov/http://6x8_canyon.mov/ -
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ignition (0 seconds) flow still separated (30 sec.)
flow attached (37 sec )
40 metre spread (70 sec )
ire esearchentre
topics
http://6x8_canyon.mov/http://6x8_canyon.mov/ -
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bushfire chemistry
turning vegetation into fuel vapour (at about 350C)burning the fuel vapour with air (above about 900C)
spread rate and intensity
heating fresh vegetation causes flame spread
intensity builds up with flame depth as the flame spreads
steady and unsteady fires
wind gusts are common and cause fires to change speed
occasionally fires can erupt (if air-flow becomes attached)
some other factors in wildfires
ire esearchentre
Canberras fire-tornado (18 Jan 2003)
http://firewhirl_n.mov/ -
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ire esearchentre
Canberras fire-tornado (18 Jan 2003)
http://firewhirl_n.mov/http://firewhirl_n.mov/ -
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Tom Bates made this videoTom Bates made this video
ire esearchentre
Canberras fire-tornado (18 Jan 2003)
http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/ -
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Tom Bates made this videoTom Bates made this video
the tornado travelled 16 km (with a 2 km gap)
felling a 100 m belt of mature pines
lifting an 8 ton roof from a water tower
damaging cars, houses, etc.
ire esearchentre
Canberras fire-tornado (18 Jan 2003)
http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/ -
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Tom Bates made this videoTom Bates made this video
the tornado travelled 16 km (with a 2 km gap)
felling a 100 m belt of mature pines
lifting an 8 ton roof from a water tower
damaging cars, houses, etc.
ire esearchentre
Canberras fire-tornado (18 Jan 2003)
http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/ -
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Tom Bates made this videoTom Bates made this video
the tornado travelled 16 km (with a 2 km gap)
felling a 100 m belt of mature pines
lifting an 8 ton roof from a water tower
damaging cars, houses, etc.
ire esearchentre
Canberras fire-tornado (18 Jan 2003)
http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/ -
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Tom Bates made this videoTom Bates made this video
the tornado travelled 16 km (with a 2 km gap)
felling a 100 m belt of mature pines
lifting an 8 ton roof from a water tower
damaging cars, houses, etc.
ire esearchentre
some more fire whirls
http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl_n.mov/http://firewhirl4.mov/ -
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source: US Forest Service
these can develop into long flaming structuresthey can also spearhead the spread of a fire
http://firewhirl4.mov/http://firewhirl6.mov/ -
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ire esearchentreother topics
smouldering of peat
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smouldering of peat
above ground, flames lose heat in all directionsbut heat from peat burning underground stays in the peat
so smouldering peat is harder to extinguish
ire esearchentreother topics
smouldering of peat
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smouldering of peat
above ground, flames lose heat in all directionsbut heat from peat burning underground stays in the peat
so smouldering peat is harder to extinguish
embers and spotfires
rising hot air can transport burning pieces of vegetation
potentially igniting new fires if they land when still alight
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ire esearchentreother topics
smouldering of peat
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smouldering of peat
above ground, flames lose heat in all directionsbut heat from peat burning underground stays in the peat
so smouldering peat is harder to extinguish
embers and spotfires
rising hot air can transport burning pieces of vegetation
potentially igniting new fires if they land when still alight
spotfires can form some distance from a parent fire
embers are a main cause of housefire ignitions
ire esearchentretopics covered
bushfire chemistry
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turning vegetation into fuel vapour (at about 350C)
burning the fuel vapour with air (above about 900
C)spread rate and intensity
heating fresh vegetation causes flame spread
intensity builds up with flame depth as the flame spreads
steady and unsteady fires
wind gusts are common and cause fires to change speed
occasionally fires can erupt (if air-flow becomes attached)
some other factors in wildfiresfire whirls
underground peat fires
fire spread by embers (spotfires)
ire esearchentrephysical factors driving a bushfire
acknowledging: with financial assistance fromacknowledging: with financial assistance from
-
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79/81
Malcolm Gill
Jim GouldPeter EllisNeil CooperMatt DutkiewiczRick McRaePhil CheneyPat BarlingJeff CuttingCliff Stevens
Domingos ViegasAlbert SimeoniForman Williams Eilis LeslieCharlie Westbrook Victoria John Gregory SivashinskyJ Barry Greenberg Rodney Weber Anna Zinoviev
E. P. S. R. C.
Bushfire C. R. C.Leverhulme TrustA. D. F. A.MIMSAWE
errors and omissions are theresponsibility of John Dold
www.maths.manchester.ac.uk/~jwd
Malcolm Gill
Jim GouldPeter EllisNeil CooperMatt DutkiewiczRick McRaePhil CheneyPat BarlingJeff CuttingCliff Stevens
Domingos ViegasAlbert SimeoniForman Williams Eilis LeslieCharlie Westbrook Victoria John Gregory SivashinskyJ Barry Greenberg Rodney Weber Anna Zinoviev
E. P. S. R. C.
Bushfire C. R. C.Leverhulme TrustA. D. F. A.MIMSAWE
errors and omissions are the
responsibility of John Dold
www.maths.manchester.ac.uk/~jwd
ire esearchentrephysical factors driving a bushfire
acknowledging: with financial assistance fromacknowledging: with financial assistance from
-
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80/81
Malcolm Gill
Jim GouldPeter EllisNeil CooperMatt DutkiewiczRick McRaePhil CheneyPat BarlingJeff CuttingCliff Stevens
Domingos ViegasAlbert SimeoniForman Williams Eilis LeslieCharlie Westbrook Victoria John Gregory SivashinskyJ Barry Greenberg Rodney Weber Anna Zinoviev
E. P. S. R. C.
Bushfire C. R. C.Leverhulme TrustA. D. F. A.MIMSAWE
errors and omissions are theresponsibility of John Dold
www.maths.manchester.ac.uk/~jwd
Malcolm Gill
Jim GouldPeter EllisNeil CooperMatt DutkiewiczRick McRaePhil CheneyPat BarlingJeff CuttingCliff Stevens
Domingos ViegasAlbert SimeoniForman Williams Eilis LeslieCharlie Westbrook Victoria John Gregory SivashinskyJ Barry Greenberg Rodney Weber Anna Zinoviev
E. P. S. R. C.
Bushfire C. R. C.Leverhulme TrustA. D. F. A.MIMSAWE
errors and omissions are the
responsibility of John Dold
www.maths.manchester.ac.uk/~jwd
ire esearchentrephysical factors driving a bushfire
acknowledging: with financial assistance fromacknowledging: with financial assistance from
-
8/14/2019 Physical Factors Driving the Spread of A
81/81
Malcolm Gill
Jim GouldPeter EllisNeil CooperMatt DutkiewiczRick McRaePhil CheneyPat BarlingJeff CuttingCliff Stevens
Domingos ViegasAlbert SimeoniForman Williams Eilis LeslieCharlie Westbrook Victoria John Gregory SivashinskyJ Barry Greenberg Rodney Weber Anna Zinoviev
E. P. S. R. C.
Bushfire C. R. C.Leverhulme TrustA. D. F. A.MIMSAWE
errors and omissions are theresponsibility of John Dold
www.maths.manchester.ac.uk/~jwd
Malcolm Gill
Jim GouldPeter EllisNeil CooperMatt DutkiewiczRick McRae
Phil CheneyPat BarlingJeff CuttingCliff Stevens
Domingos ViegasAlbert SimeoniForman Williams Eilis LeslieCharlie Westbrook Victoria John Gregory SivashinskyJ Barry Greenberg Rodney Weber Anna Zinoviev
E. P. S. R. C.
Bushfire C. R. C.Leverhulme TrustA. D. F. A.MIMSAWE
errors and omissions are the
responsibility of John Dold
www.maths.manchester.ac.uk/~jwd