This
paper
reports
the
experimental
results
of
vortex-induced
vibration
(VIV)
a
lazy-wave
flexible
riser
filled
with
different
fluid
media,
including
water
and
helium
as
typical
liquid
light
gas
examples.
The
configuration
was
produced
by
mounting
buoyancy
module
approximately
triple
diameter
on
one-third
length
measured
from
base.
VIV
tests
were
carried
out
in
depth-averaged
reduced
velocity
(U¯r)
range
9.32–23.19
using
non-intrusive
optical
measurement
couple
high-speed
cameras.
indicate
that
not
only
excited
mode
in-plane
response
but
also
amplitude
is
significantly
adjusted
when
internal
changes,
while
out-of-plane
has
no
obvious
modification.
Both
water-
helium-filled
risers
experience
space-varying
dominant
frequency.
However,
segment
possessing
higher
frequency
shortened
compared
to
water-filled
one.
When
shifts
helium,
transition
first
second
becomes
incomplete,
smoother
U¯r
grows.
It
found
starting
position
related
well
direction.
Then,
influenced
affecting
are
quantified
terms
spatial
distribution
comparison
natural
frequencies.
more
vulnerable
oscillation
module,
hence,
coupling
between
responses
weaker
than
riser.
impact
enhanced,
reverse
effect
weakened.
Physical Review Fluids,
Год журнала:
2024,
Номер
9(7)
Опубликована: Июль 1, 2024
This
work
presents
a
reduced-order
model-based
feedback
control
strategy
for
suppressing
vortex-induced
vibration
(VIV)
of
spring-mounted
cylinder
using
the
balanced
proper
orthogonal
decomposition
(BPOD)
method.
The
BPOD
model,
closely
aligned
with
full-order
model
(FOM),
is
employed
to
design
an
active
flow
blowing
and
suction
actuators,
effectively
VIV
up
Re
=
100
by
adjusting
or
eliminating
unstable
eigenmodes.
optimal
strategies,
robust
variations
in
Reynolds
numbers,
highlight
significant
gain
margins
when
positioning
velocity
probes
near
x/D
3.0,
though
probe
placement
wavemaker
regions
might
be
suboptimal.
The
role
of
the
added
mass
coefficient
in
vortex
induced
vibration
(VIV)
bluff
body
is
complex
and
elusive.
It
certain
that
decoding
relationship
between
pattern
will
benefit
prediction
prevention
VIV.
We
present
a
study
on
VIV
long
flexible
cylinder
forced
rigid
cylinder,
combination
experimental
optical
measurements
high-fidelity
numerical
simulation.
focus
uniform
flow
over
at
fixed
Reynolds
number,
Red
=
900,
but
systematically
varied
motion
amplitude
in-line
(Axd)
cross-flow
direction
(Ayd),
as
well
phase
angle
(θ)
motions.
show
θ∈[π2,3π2]
associated
with
negative
coefficients
(Cmy
<
0),
there
strong
correlation
shedding
mode
“2P”
or
“P+S”
Cmy
0.
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.
