Low-speed aeroelastic interactions in tandem flags under streamlined and bluff-body wake flows
Physics of Fluids,
Journal Year:
2025,
Volume and Issue:
37(4)
Published: April 1, 2025
This
study
examines
the
aeroelastic
interactions
of
triangular
steel
flags
in
tandem
configuration
for
flow
speed
(U)
up
to
9.0
m/s,
with
inter-flag
gap
(Gf)
ranging
from
0.1
5
times
leading
flag's
characteristic
length
(L).
The
flag
is
subjected
both
streamlined
and
vortex-induced
flows
(VIFs).
Wind
tunnel
experiments
reveal
a
subcritical
bifurcation
route
limit
cycle
oscillations
(LCOs)
under
flow,
while
VIF
alters
supercritical
route.
First,
identical
natural
frequency
3.59
Hz
(first
bending
mode)
flutter
near
7.4
m/s
are
tested
flow.
dynamics
remains
largely
unchanged
compared
its
standalone
dynamics,
trailing
response
highly
sensitive
position
wake
flag.
Phase
including
locking
bounded
phase
differences,
emerges
at
different
regimes
depicting
synergistic
destructive
coherence.
For
closely
spaced
(Gf
=
0.1L),
LCO
amplitudes
suppressed
by
50%,
larger
gaps,
increase
1.5
times.
non-identical
much
higher
(5.48
Hz)
onset
(U>
m/s),
advanced
matches
that
oscillates
close
across
wide
range
gaps
speeds
but
exhibits
small-amplitude
LCOs
driven
very
low
speeds.
Finally,
placed
downstream
cylindrical
bluff
body
examine
impact
conditions.
Small-amplitude
aperiodic
observed
below
critical
speed,
which,
turn,
induce
sufficiently
strong
trigger
transitions
periodic
speeds,
strongly
oscillations,
one
locked
comprehensive
nonlinear
analysis
presented
can
be
utilized
enhancing
multi-flag
energy
harvesting,
fluid
mixing,
heat
transfer.
Language: Английский
Energy extraction from a pitching airfoil
Fareeha Pervaiz,
No information about this author
Neil Cagney
No information about this author
Physics of Fluids,
Journal Year:
2025,
Volume and Issue:
37(4)
Published: April 1, 2025
This
paper
experimentally
investigates
the
effects
of
various
oscillation
parameters
on
energy
extraction
efficiency
a
National
Advisory
Committee
for
Aeronautics
0015
airfoil
in
forced
pitching
motion
about
its
quarter-chord
at
Reynolds
number
80
000.
The
reduced
frequency,
k,
amplitude,
A,
and
mean
angle
attack,
αmean,
are
systematically
varied,
pressure
distribution
around
center-span
is
recorded.
Flow
visualization
used
to
reveal
vortex
dynamics.
highest
cycle-averaged
achieved
0.24%,
k=0.480,
A=10°,
αmean=18°;
this
case,
two
large
vortices
formed,
with
primary
detaching
from
leading
edge
as
attack
maximum,
such
that
resulting
low
near
trailing
coincides
downstroke.
All
cases
experience
negative
most
upstroke,
which
associated
flow
reattachment
along
airfoil's
upper
surface.
A
framework
understand
impact
dynamics
proposed,
divides
surface
into
quadrants
based
time
position
relative
axis.
Increasing
k
both
cause
delay
formation
detachment
vortex.
αmean
results
significant
changes
flow,
no
being
formed
angles
(below
static
stall
angle)
higher
(above
angle).
Language: Английский