Physics of Fluids,
Год журнала:
2024,
Номер
36(11)
Опубликована: Ноя. 1, 2024
This
paper
presents
an
experimental
investigation
of
flow-induced
vibration
characteristics
cut-corner
prisms
with
various
aspect
ratios
(H*
=
1.0–13.33).
Experiments
were
conducted
in
a
recirculating
wind
tunnel
Reynolds
numbers
ranging
from
2651
to
7953,
based
on
the
prism's
side
length.
Four
prism
types
(square,
PS
0.2D,
0.5D,
and
0.8D,
where
is
length
parallel
incoming
flow)
exhibited
five
distinct
modes
as
speed
increased:
vortex-induced
(VIV),
transition
VIV
galloping,
pure
separated
weak
VIV-like
coupled
galloping.
Compared
square
prism,
mode
galloping
at
higher
ratios.
As
H*
increases,
end
effects
diminish,
resulting
more
concentrated
vortex
shedding
disappearance
splitting.
The
transitions
2S
(two
single
vortices
shed
per
cycle)
2
P
pairs
cycle).
Additionally,
largest
amplitude
0.8D
0.5D.
Unilateral
close-view
particle
image
velocimetry
results
show
that
decreases,
shear
layer
stretched
away
rear
due
effects,
altering
interaction
between
causing
modes.
study
provides
valuable
insights
for
optimizing
design
piezoelectric
energy
harvesters.
Applied Physics Letters,
Год журнала:
2024,
Номер
124(23)
Опубликована: Июнь 3, 2024
In
this
study,
we
propose
a
wind-direction
adaptive
piezoelectric
energy
harvester
employing
small
wing
passive
control
configuration
(WDEH-SW)
for
bidirectional
wind
harvesting.
Our
design
significantly
enhances
harvesting
capabilities,
addressing
the
limitations
of
traditional
harvesters
by
modifying
aerodynamic
characteristics
bluff
body
via
rotations.
Additionally,
introduce
criterion
determining
impact
direction
changes
on
efficiency.
Experimental
comparisons
with
conventional
galloping-based
and
vortex-induced
vibration-based
demonstrate
superior
performance
proposed
structure.
The
experiment
results
indicate
that
structure
effectively
adapts
to
in
direction,
thereby
preventing
significant
decrease
or
failure
Compared
unidirectional
harvester,
exhibits
34.6%
increase
1.63
μW
power
output,
an
overall
average
output
reaching
6.35
μW.
Notably,
WDEH-SW
shows
excellent
adaptability
high
both
medium
low
velocity
ranges,
providing
valuable
insights
designing
compact
harvesters.
This
study
showcases
promising
applications
self-powered
micro-devices,
particularly
straightforward
environments
such
as
car
train
tunnel
entrances
exits.
With
the
micro-miniaturization
of
offshore
wireless
sensors,
signal
lights,
and
other
devices
emergence
problem
self-powering
in
distant
sea,
how
to
harvest
energy
from
low-speed
currents
has
become
a
hot
spot
research
nowadays.
To
improve
output
power
conversion
efficiency
water
flow,
we
propose
vertical
cantilever
beam
circular
cylinders
fitted
with
rigid
splitter
plate
piezoelectric
harvester
(CSPPEH).
In
this
paper,
influence
length
attack
angle
on
CSPPEH
been
experimentally
investigated.
The
vibration
response
mechanism
involving
mutual
transition
between
vortex-induced
galloping
was
analyzed
through
particle
image
velocimetry
flow
field
visualization.
experimental
results
indicate
that
characteristics
increase
initially
then
decrease
plates
(L/D
=
0–2.4)
at
0°,
which
can
be
explained
by
theoretical
model
harvester.
It
is
found
optimal
occur
1.40D
an
90°.
maximum
values
for
amplitude,
swing
angle,
voltage,
power,
density
are
4.96D,
21.7°,
42.68
V,
910.81
μW,
1.94
mW/cm3,
respectively.
Efficiency
up
2.2%
0.4D
90°
plate.
Compared
bare
cylinder
harvester,
significantly
improved.
demonstration
continuous
charging
discharging
capacitors
light
emitting
diode
lights
performed
show
practicability
designed
CSPPEH.
Overall,
present
study
enables
applications
realizing
self-powered
sensing
under
low-water-speed
environments.
Physics of Fluids,
Год журнала:
2022,
Номер
34(11)
Опубликована: Окт. 22, 2022
While
it
is
known
that
rigid
splitter
plates
play
significant
roles
in
flow
control,
the
exact
of
them
flow-induced
vibration
(FIV)
have
not
been
systematically
investigated.
This
has
motivated
present
work
to
experimentally
investigate
FIV
a
cylinder
equipped
with
an
upstream
plate
(USP),
downstream
(DSP),
and
symmetrically
arranged
water
tunnel
Reynolds
number
1100–7700.
The
length
range
L*
=
0–3.6
(L*=L/D,
L
length,
D
diameter).
response
characteristics,
vortex
evolution,
fluid
force,
pressure
fields
are
thoroughly
analyzed.
Both
USP
DSP
can
succeed
oscillation
mitigation
drag
reduction.
However,
dramatic
galloping
observed
for
0.4–3.2.
low-pressure
region
forms
near
beneficial
trigger
galloping.
For
USP,
only
vortex-induced
found,
transition
branches
corresponds
variation
frequency
phase
jumps
total
transverse
force
force.
mode
from
2S
2P
disappears
long
length.
Flow
visualization
reveals
induced
by
alters
shedding.
Furthermore,
high-pressure
tip
yielding
obstructive
suppresses
growth
oscillation.
With
combination
DSP,
weak
excited
narrow
1.0–1.8,
linear
increase
also
broken
due
existence
USP.
