The
pump
as
turbine
(PAT)
is
one
of
economical
and
essential
devices
that
widely
utilized
in
micro
hydropower
residual
energy
recovery.
change
field,
characterized
by
the
first
rate
(LK1)
second
(LK2),
investigated
main
flow
passage
components
PAT
under
five
different
rates
range
from
0.5QBEP
to
QBEP.
relationship
between
mean
partial
derivations
mechanical
non-monotonic
impeller,
it
shows
increasing
decreasing
trends
volute
draft
tube,
respectively.
regions
with
large
LK2
exhibit
positive
correlation
complex
internal
structures.
LK1
(MLK1)
impeller
initially
decreases
then
increases
slightly
increases,
opposite
are
observed
tube.
There
a
slope
segment
(MLK2)
which
corresponds
instability.
In
addition,
maximum
value
MLK2
2.54
its
corresponding
0.75QBEP.
As
standard
deviations
MLK1
significantly,
reaches
steady
region.
Physics of Fluids,
Journal Year:
2024,
Volume and Issue:
36(2)
Published: Feb. 1, 2024
This
study
examines
the
S-characteristic,
a
key
factor
affecting
safe
grid
connection
and
operation
of
pumped-storage
units,
its
significant
impact
on
safety
power
stations.
We
conducted
numerical
simulations
model
experiments
to
investigate
vortex
motion
characteristics
in
vaneless
space
runner
passage
pump-turbines
operating
within
S-shaped
region,
along
with
an
analysis
pressure
pulsation
characteristics.
The
accuracy
these
was
validated
through
laser
Doppler
velocimetry
experiments,
particle
image
were
used
capture
space.
observed
that
vortices
generated
guide
vane
side
follow
flow
direction,
blocking
passage,
while
those
by
blades
move
opposite
direction.
Employing
entropy
production
theory
Liutex
method,
we
investigated
distribution
hydraulic
loss
region.
results
show
reduced
rates
lead
area,
which
become
main
contributors
energy
this
These
vortices,
mainly
arise
from
separation
blade
surfaces
due
suboptimal
inflow
conditions.
also
identifies
fluctuations
space,
induced
rotating
stall,
as
most
phenomenon,
significantly
impacts
performance
unit
both
upstream
downstream
directions.
Physics of Fluids,
Journal Year:
2025,
Volume and Issue:
37(3)
Published: March 1, 2025
With
the
climate
change
hazards
and
implementation
of
pumped-storage
hydropower
units
in
power
grid
increases,
maintaining
hydraulic
stability
hump
region
is
primordial
for
energy
transition
yet
presents
a
significant
challenge.
This
study
investigates
loss
characteristics
instability
pump-turbine
during
operation
using
both
model
testing
computational
fluid
dynamics
methods.
The
results
indicate
that
predominantly
occurs
guide
vane
(GV)
passage
draft
tube
(DT),
more
with
flow
reduction.
Specifically,
vaneless
space
linked
to
shear
vorticity,
while
rigid
vorticity
plays
prominent
role
GV
DT.
Analysis
Rortex
enstrophy
transport
equation
shows
pseudo-Lamb
term
dominant
factor
influencing
vortex
evolution.
Additionally,
combining
Reynolds-averaged
Navier–Stokes
equations
particle
image
velocimetry
experiments
reveals
near
zero-velocity
gradient
region,
effects
are
concentrated
core
on
runner
side,
primarily
wake
direction
motion.
Physics of Fluids,
Journal Year:
2024,
Volume and Issue:
36(4)
Published: April 1, 2024
Mixed-flow
pump
is
a
general
purpose
hydraulic
machinery
in
many
fields
of
fluid
transport
for
its
advantages
wide
efficient
operation
flow
rate
range,
but
stability
restricted
by
cavitation.
To
obtain
the
cross
effect
cavitation
and
on
pressure
pulsation,
high-precision
experimental
system
was
first
established
to
monitor
signals
at
four
key
positions,
obtaining
their
time
domain;
second,
based
this
tested
results,
frequency
domain
analysis
technique
continuous
wavelet
transform
adopted
capture
temporal
evolution;
third,
coherence
value
further
diagnose
development
speed
different
spatial
positions.
Primary
findings
are
as
follows:
(1)
secondary
peaks
induced
generated
discrete
disturbance
low-frequency
amplitudes
shaft
blade
passing
were
both
increased,
with
worse
continuity.
(2)
Under
1.0
QBEP,
mixed
had
best
anti-cavitation
performance.
0.8
internal
pattern
easily
be
disturbed
flow,
while
that
under
1.2
QBEP
fastest
speed.
(3)
action
unstable
potential
within
field
near
rotor–static
interface
downstream,
close
exchange
between
bubbles
mainstream;
thus,
pulsation
inside
volute
became
more
sensitive
development.
Machines,
Journal Year:
2022,
Volume and Issue:
10(2), P. 143 - 143
Published: Feb. 16, 2022
When
the
Francis-type
reversible
pump-turbine
runs
under
partial
load,
pressure
pulsation
amplitude
and
frequency
in
vaneless
space
are
high,
posing
a
serious
threat
to
stability
of
unit
operation.
Water
presents
weak
compressibility
high-head
pump-turbine,
thereby
affecting
amplitude–frequency
characteristics
pulsation.
This
study
used
numerical
simulations
model
prototype
particle
image
velocimetry
(PIV)
examine
internal
flow
field
determine
effect
on
The
were
verified
through
tests.
effects
water
propagation
law
throughout
passage
roughly
similar
but
exhibited
certain
differences.
Considering
water,
fluctuations
each
exhibit
varying
degrees
improvement,
which
is
more
obvious
at
scale.
Therefore,
wave
disturbance
caused
by
has
different
scale
Francis
pump-turbine.
Energies,
Journal Year:
2023,
Volume and Issue:
16(4), P. 1576 - 1576
Published: Feb. 4, 2023
Cavitation
can
cause
noise
in
the
water-jet
pump.
If
cavitation
occurs
pump,
hydraulic
components
pump
are
prone
to
erosion.
The
surface
erosion
reduces
energy
delivery
efficiency
and
increases
maintenance
costs.
decline
performance
will
lead
instability
of
entire
system.
In
this
paper,
flow
structure
is
studied
by
method
numerical
simulation
experiment,
which
provides
a
reference
for
prediction
improvement
cavitation.
Based
on
closed
test
platform,
order
reveal
physical
process
evolution,
high-speed
photography
used
capture
complex
phenomenon
After
that,
vortex
was
further
explored
simulation.
Through
impeller
blade
tip
leakage
Tip
Leakage
Vortex
(TLVC)
characteristics
under
different
conditions,
mechanism
separation
induced
region
conditions
were
revealed.
main
factors
affecting
development
wake
structures
summarized.
Energy Science & Engineering,
Journal Year:
2023,
Volume and Issue:
12(1), P. 102 - 116
Published: Nov. 15, 2023
Abstract
The
reversible
pump‐turbine
plays
an
important
role
in
hydropower
stations,
but
pressure
pulsation
during
their
operation
affects
performance
and
lifespan.
Accurate
prediction
of
signals
can
provide
basis
for
energy
planning
stable
pumped
storage
units,
thereby
promoting
sustainable
development
the
environment.
This
study
introduces
optimization
method
that
combines
long
short‐term
memory
(LSTM)
variable
mode
decomposition
(VMD)
to
enhance
accuracy
signals.
First,
by
decomposing
signal
into
multiple
relatively
subsequence
components
using
VMD,
characteristics
original
become
more
distinct.
Subsequently,
individual
LSTM‐based
time
series
models
were
constructed
each
modal
function,
hyperparameters
related
optimized
sparrow
search
algorithm.
To
validate
efficacy
proposed
approach,
this
paper
conducted
experiments
a
obtained
through
numerical
simulation.
experimental
data
was
divided
training
testing
sets,
with
former
used
train
LSTM
model
latter
validation.
results
show
VMD
effectively
improve
pump‐turbine.
