Physics of Fluids,
Год журнала:
2024,
Номер
36(12)
Опубликована: Дек. 1, 2024
A
nonstationary
numerical
simulation
was
performed
on
the
outlet
pressure
stabilization
and
periodic
variable-pressure
condition
of
a
pump
turbine
model
in
pumping
condition.
The
objective
to
dissect
flow
mechanism
force
characteristics
components
within
probe
into
stability
under
such
working
conditions.
Additionally,
alterations
runner
state,
distribution,
pulsation,
as
well
forces
exerted
top
cover
during
this
process
were
analyzed.
results
demonstrated
that
internal
pattern
conditions
fluctuated
periodically
accordance
with
pressure.
An
augmented
frequency
variation
led
an
elevation
amplitude
change.
Nevertheless,
hysteresis
difference
observed
changes
channel
pattern.
pulsation
area
influenced
by
rotation,
static
dynamic
interferences
lobe-free
area,
unsteady
induced
Journal of Marine Science and Engineering,
Год журнала:
2023,
Номер
11(6), С. 1218 - 1218
Опубликована: Июнь 13, 2023
Runaway
is
a
common
phenomenon
in
pump-turbines
for
hydropower
and
ocean
power,
accompanied
by
strong
instability,
which
can
easily
lead
to
accidents.
This
study
reveals
the
stability
during
runaway
process
of
pump-turbine,
mainly
exploring
guide
vane
rejection
happening
transition
conditions
when
dealing
with
or
power.
Through
model
experiments
computational
fluid
dynamics
numerical
simulations,
pressure
pulsation
reaching
was
compared
under
different
opening
angles.
The
amplitude
measured
experiment
increases
increase
opening,
but
there
are
also
local
changes
size
peak.
simulation
results
show
that
angle
12
degrees,
vortex
flow
area
between
runner
unit
increases,
leading
instability.
When
20
intensity
does
not
change
much
distribution
becomes
uniform,
resulting
decrease
fluctuations.
field
causes
dissipation
energy.
Relationships
be
found
among
velocity
field,
intensity,
entropy
production.
great
significance
ensuring
stable
operation
pump-turbines.
Processes,
Год журнала:
2024,
Номер
12(3), С. 508 - 508
Опубликована: Фев. 29, 2024
The
flow
field
structure
and
pressure
pulsation
characteristics
in
two
series
of
trailing
edges
a
centrifugal
pump
are
investigated
using
the
SST
k-w
turbulence
model.
Series
1
involves
varying
impeller
exit
angle,
2
shape.
entropy
generation
rate
analysis
method
is
used
to
evaluate
numerical
simulation
results.
Vortex
cores
within
identified
by
applying
Ω
criterion.
influence
different
edge
configurations
on
energy
loss
pumps
explored.
dynamic
mode
decomposition
(DMD)
analyze
pulsations
at
volute
considering
unsteady
flows
with
shapes.
findings
suggest
that
shapes
can
be
adjust
proportions
various
components
pump.
In
1,
efficiency
remains
nearly
constant
changes
outlet
angle
both
sides
edge.
2,
enhanced
1.18%
elliptical
shape
(EBS)
compared
original
(OTE)
greater
rates
accompanied
outlet.
DMD
results
demonstrate
noticeable
impact
distribution
modes
volute.
Moreover,
inhomogeneity
coefficient
under
modes.
This
study
holds
great
significance
for
selecting
appropriate
pumps.
Machines,
Год журнала:
2023,
Номер
11(10), С. 965 - 965
Опубликована: Окт. 16, 2023
The
existence
of
vortex
ropes
inside
the
draft
tube
significantly
impacts
hydraulic
efficiency
and
operational
stability,
few
studies
on
formation
mechanism
loss
problems
have
been
explored.
Hence,
in
this
paper,
we
build
an
inherent
correlation
between
local
entropy
production
rate
(LEPR)
dynamics
motion,
by
incorporating
identification
method
Ω~R
with
theory,
using
OpenFOAM-v2212
software.
From
analysis
caused
turbulence
dissipation
(EPTD)
is
responsible
for
majority
energy
form
rate,
accounting
about
87%
total
(TEPR)
different
load
operations.
Comparatively,
wall
shear
stress
(EPWS)
can
account
up
to
12%,
while
due
direct
(EPDD)
plays
a
minor
role
TEPR.
rotating
rope
movement
unit
at
part
conditions
leads
more
intense
LEPR.
Therefore,
determine
rope,
TEPR
cross-section
be
used
assess
characteristics
tube.
Processes,
Год журнала:
2023,
Номер
11(10), С. 2903 - 2903
Опубликована: Окт. 2, 2023
The
pump
turbine
is
a
crucial
component
of
pumped
storage
hydropower
plants.
When
operated
at
constant
speed,
it
does
not
respond
well
to
variations
in
the
grid
frequency.
To
improve
hydraulic
efficiency
units,
variable-speed
units
have
been
introduced.
However,
mechanism
turbines
has
extensively
studied
numerically.
In
this
study,
flow
characteristics
were
computed
under
two
typical
pumping
modes,
maximum
head
and
minimum
rate
condition,
as
condition.
results
aligned
with
experimental
results,
changing
trends
thrust
these
modes
discussed.
error
for
Hmax,
Qmin
condition
was
1.3%,
Hmin,
Qmax
−1.9%.
These
values
fell
within
reasonable
range.
research
findings
indicate
that
passage
exhibited
higher
velocity,
which
84.87
m/s,
increased
turbulence,
larger
pressure
fluctuations,
poorer
unit
stability.
On
other
hand,
both
axial
radial
forces
greater,
there
sudden
changes
extreme
fluctuations
over
certain
period
time.
It
recommended
avoid
operating
conditions
during
operations.
