Combustion Science and Technology,
Journal Year:
2024,
Volume and Issue:
unknown, P. 1 - 23
Published: Dec. 4, 2024
The
phenomenon
of
pipe
diameter
change
often
exists
in
urban
natural
gas
pipelines.
To
study
the
impact
variation
on
propagation
characteristics
combustible
deflagration
and
provide
theoretical
basis
for
prevention
emergency
treatment
pipeline
explosion
accidents,
this
work
uses
a
self-developed
circular
test
bench
with
length
12
m
an
inner
90
mm
to
methane
variable
Under
four
experimental
conditions
cross-sectional
area
ratio
(VR)
1.0,
0.6,
0.4,
0.2,
schlieren
images
process
methane/air
premixed
concentration
9.5%
were
captured
by
high-speed
camera.
Combined
traditional
pressure
flame
signal
point
source
information,
research
results
show
that
existence
pipelines
can
structure
shape,
causing
front
transform
into
tulip
advance.
speed
under
different
is:
VR
=
0.4
>
0.2
0.6.
influence
velocity
depends
suppression
effect
reflected
wave
generated
cross-section
coupling
reduced
aperture
section
acceleration
effect.
When
acts
front,
decreases,
severe
cases,
it
will
cause
stagnation
backfire.
Energies,
Journal Year:
2025,
Volume and Issue:
18(4), P. 885 - 885
Published: Feb. 13, 2025
The
early
stages
of
hydrogen–air
and
methane–air
flame
dynamics
the
development
evolution
tulip
flames
in
closed
tubes
various
aspect
ratios
a
semi-open
tube
are
studied
by
solving
fully
compressible
reactive
Navier–Stokes
equations
using
high-order
numerical
method
coupled
to
detailed
chemical
models
for
stoichiometric
hydrogen/air
methane/air
mixtures.
use
adaptive
mesh
refinement
(AMR)
provides
adequate
resolution
reaction
zone,
pressure
waves,
flame–pressure
wave
interactions.
purpose
this
study
is
gain
deeper
insight
into
influence
kinetics
on
combustion
regimes
leading
formation
its
subsequent
evolution.
simulations
highlight
effect
thickness,
velocity,
order
intensity
rarefaction
generated
during
deceleration
phase,
which
principal
physical
mechanism
formation.
obtained
results
explain
most
experimentally
observed
features
formation,
e.g.,
faster
with
shape
compared
slower
flames.
ACS Omega,
Journal Year:
2025,
Volume and Issue:
unknown
Published: Feb. 17, 2025
With
the
advancement
of
hydrogen
energy,
hydrogen-blended
fuels
have
gained
widespread
application
in
industrial
and
energy
sectors,
drawing
significant
attention
to
explosion
characteristics
safety
risks
associated
with
hydrogen/propane
(H2/C3H8)
gas
mixtures.
To
effectively
mitigate
these
risks,
this
study
investigates
inerting
effects
various
nitrogen
(N2)
carbon
dioxide
(CO2)
dilution
ratios
on
H2/C3H8
The
CHEMKIN-Pro
software
was
employed
simulate
properties
mixtures,
analyzing
parameters
such
as
adiabatic
pressure,
flame
temperature,
concentrations
key
radicals,
heat
release
rate,
sensitivity
elementary
reactions.
results
indicate
that
an
increase
CO2
ratio
corresponds
a
linear
decrease
both
pressure
temperature.
Furthermore,
higher
leads
decline
rate
generation
rates
H,
O,
OH
H
radicals
experiencing
most
notable
reduction.
Sensitivity
analysis
reactions
reveals
reaction
R1:
+
O2
=
O
has
promoting
effect,
while
R410:
C3H8
H2
iC3H7
exhibits
pronounced
inhibitory
effect.
suppresses
transforms
intermediates
through
specific
pathways
(such
R52:
CH
HCO
CO
R79:
CH2
CH2O
CO),
thus
reducing
overall
This
offers
important
theoretical
insights
into
role
inert
gases
providing
foundation
for
management
clean
technologies.
To
reveal
the
effects
of
buoyancy
on
spherical
CH4
flame
and
pressure
under
dilution
conditions,
a
series
explosion
experiments
were
conducted
in
20L
container.
Furthermore,
schlieren
technology
was
used
to
capture
flames
for
assessing
effect.
The
change
overpressure
is
recorded
couple
with
shape
analyzing
characteristics
explosion.
results
indicate
that
methane
process
goes
through
two
stages:
stage
initial
ignition
development
stage.
During
ignition,
addition
CO2
causes
significantly.
Due
differences
buoyancy,
exhibits
different
shapes
such
as
spherical,
ellipsoidal,
"ω"-shaped
flame.
With
increasing
CO2,
effect
appears
earlier
enhanced.
Additionally,
expansion
speed
decreases
due
combined
inertization.
difference
between
horizontal
upward
speeds
linearly
increase
concentration
CO2.
For
cases
high
can
stagnate
when
less
than
0.5
m/s.
development,
leads
smoother
surface.
cellular
structure
suppressed,
rise
rate
delayed
peak
reduced.
Coupled
analysis
rate,
it
be
observed
denser
while
surface
low
rate.
At
same
size
number
are
almost
similar.
In
this
study,
the
active
suppression
employing
non-premixed
inert
gases
(N2,
CO2,
and
air)
on
premixed
CH4/H2/air
explosions
is
studied.
The
effect
of
injection
time,
tinject,
which
time
interval
between
instant
initial
gas
ignition
set
from
0
ms
to
210
ms,
flame
propagating
behavior
explosion
overpressure
dynamics
discussed.
induces
a
turbulence-enhancing
leads
acceleration.
Increasing
enhances
turbulence
intensity,
further
wrinkles,
oscillates
flame.
When
tinject
>
120
dominance
replaced
by
an
inhibition
effect.
dilution
effects
compete
control
maximum
velocity
overpressure.
enhancement
accelerates
early
laminar
flame,
increasing
Darrieus-Landau
instability.
middle
late
stages
propagation
are
controlled
Rayleigh-Taylor
instability,
growth
rate
instability
first
increases
then
decreases
with
injection.
Most
importantly,
CO2-injection
has
best
acceleration
mid-
or
late-flame
oscillations
compared
N2-and
air-injection.
