US
20090001222A1
(19)
United
States
(12)
Patent
Application
Publication
(10)
Pub.
No.:
US
2009/0001222
A1
McKeon
(43)
Pub.
Date:
Jan.
1
2009
9
(54)
CONTROL
OF
AERODYNAMIC
FORCES
BY
Publication
Classi?cation
VARIABLE
WETTED
SURFACE
(51)
Int
Cl
MORPHOLOGY
B64C
21/10
(2006.01)
(75)
Inventor:
Beverley
J.
McKeon,
Tujunga,
CA
B62D
35/00
(200601)
(Us)
(52)
US.
Cl.
....................
..
244/204;
296/181.5;
114/382;
137/1;
137/561
R
Correspondence
Address:
(57)
ABSTRACT
Hiscock
&
Barclay,
LLP
One
Park
Place,
300
South
State
Street
Systems
and
methods
for
providing
dynamic
control
to
a
Syracuse,
NY
13202-2078
(US)
vehicle
in
a
dynamic
?uid.
The
systems
and
methods
of
the
invention
relate
to
one
or
more
morphable
surfaces
that
can
be
(73)
Assignee;
California
Institute
of
Technology,
controlled
by
a
controller
and
an
actuator
in
an
active
manner
Pasadena,
CA
(Us)
to
provide
asperities
that
interact
With
a
?uid
moving
across
the
morphable
surfaces.
By
controlling
the
siZe,
shape
and
(21)
APPL
NO.
12/117
959
location
of
the
asperities,
one
can
exert
control
authority
over
a
the
motion
of
the
vehicle
relative
to
the
?uid,
including
a
22
13-1
(12
M
9
2008
speed,
a
direction
and
an
attitude
of
the
vehicle.
Examples
of
(
)
1e
ay
’
materials
that
provide
suitable
morphable
surfaces
include
.
.
ionic
polymer
metal
composites
and
shape
memory
poly
Related
U's'
Apphcatlon
Data
mers,
both
of
Which
types
of
material
are
commercially
avail
(60)
Provisional
application
No,
60/
928,737,
?led
on
May
able.
Useful
morphable
surface
systems
have
been
examined
10,
2007.
and
are
described.
1%
,5
//
-/
Patent
Application
Publication
Jan.
1,
2009
Sheet
1
0f
8
US
2009/0001222
A1
POLYMER
+
METAL
(Pt)
—
MIIIATERIAL
a).
POSITIVE
W
b).
NO
-—><—MATERIAL
c).
NEGATIVE
FIG.
1
PRIOR
ART
_
%
H,
a
@
SIDE
CHAIN
HYDRATED
CATION
-
WATER
FIXED
MOBILE
Na(H2O)+
ANION
CATION
FIG.
2
PRIOR
ART
Patent
Application
Publication
Jan.
1,
2009
Sheet
2
0f
8
US
2009/0001222
A1
FIG.
3
PRIOR
ART
FIG.
4
PRIOR
ART
Patent
Application
Publication
Jan.
1,
2009
Sheet
3
0f
8
US
2009/0001222
A1
FIG.
5
Patent
Application
Publication
Jan.
1,
2009
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4
0f
8
US
2009/0001222
A1
DEAD
CENTER
FLUTE
FIG.
6
PRIOR
ART
Patent
Application
Publication
Jan.
1,
2009
Sheet
5
0f
8
US
2009/0001222
A1
FIG.
7
Patent
Application
Publication
Jan.
1,
2009
Sheet
6
0f
8
US
2009/0001222
A1
FIG.
9
FIG.
10
Patent
Application
Publication
Jan.
1,
2009
Sheet
7
0f
8
US
2009/0001222
A1
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Patent
Application
Publication
US
2009/0001222
A1
CONTROL
OF
AERODYNAMIC
FORCES
BY
VARIABLE
WETTED
SURFACE
MORPHOLOGY
CROSS-REFERENCE
TO
RELATED
APPLICATIONS
[0001]
This
application
claims
priority
to
and
the
bene?t
of
co-pending
US.
provisional
patent
application
Ser.
No.
60/928,737,
?led
May
10,
2007,
Which
application
is
incor
porated
herein
by
reference
in
its
entirety.
This
application
is
related
to
co-pending
US.
patent
application
Ser.
No.
12/106,
638,
?led
Apr.
21,
2008,
Which
application
is
incorporated
herein
by
reference
in
its
entirety.
FIELD
OF
THE
INVENTION
[0002]
The
invention
relates
to
aerodynamic
applications
in
general
and
particularly
to
control
of
aerodynamic
forces
in
applications
that
employ
morphing
surfaces.
BACKGROUND
OF
THE
INVENTION
[0003]
Various
methods
and
systems
have
been
used
to
attempt
to
control
boundary
layer
?oW
in
aerodynamic
sys
tems.
These
include
passive
methods
for
boundary
layer
con
trol
including
static
roughness,
passive,
compliant
surfaces,
and
active
methods
such
as
?aps,
rudders
and
ailerons.
In
particular,
several
research
initiatives
have
sought
to
utiliZe
morphing
concepts
for
?oW
control
purposes.
The
most
notable
large-scale
agency-sponsored
efforts
include
the
DARPA
Micro
Adaptive
FloW
Control
(MAFC)
program
and
micro-aero
adaptive
control
in
the
NASA
Morphing
project,
both
of
Which
have
exploited
smart
structures
and
advanced
discrete
MEMs
actuator
concepts
that
require
loW
actuation
energy
to
target
control
of
large-scale
aerodynamic
?oWs
and
multi-point
adaptability
in
aircraft
operations.
[0004]
There
is
a
rich
technical
literature
that
describes
laminar
?oW,
turbulent
?oW,
transitions
betWeen
the
tWo
?oW
regimes,
and
the
interaction
of
?oW
regimes
With
various
surface
conditions,
such
as
surface
roughness.
[0005]
Classical
results
for
turbulent
boundary
layers,
such
as
ToWnsend’s
hypothesis
that
the
outer-scaling
layer
is
not
affected
by
the
roughness
other
than
through
the
friction
velocity,
and
the
logarithmic
scaling
of
the
mean
velocity
With
the
effective
roughness
amplitude,
6,
as
the
scaling
lengthscale,
hold
only
When
k
is
small
compared
to
the
boundary
layer
thickness,
6,
i.e.,
k/6<<1,
Which
is
not
alWays
satis?ed
in
loWer
Reynolds
number
experiments.
The
latter
scaling
also
only
holds
When
the
?oW
has
reached
equilib
rium.
[0006]
In
laminar
?oWs,
roughness
is
knoWn
to
enhance
linear
receptivity
to
external
disturbances,
leading
to
increases
in
the
disturbance
groWth
rates
and
reductions
in
the
critical
Reynolds
number
for
transition
to
turbulence.
[0007]
In
practical
airfoil
?oWs,
under
certain
conditions
in-?ight
Wing
icing
may
lead
to
the
generation
of
a
temporary
static
roughness
distribution,
With
detrimental,
or
at
least
unplanned,
implications
for
the
aerodynamic
performance
of
the
vehicle.
[0008]
Previous
patents
in
the
?eld
of
?oW
control
include
US.
Pat.
No.
4,516,747,
issued
May
14,
1985
to
LurZ
entitled
“Method
and
apparatus
for
controlling
the
boundary
layer
?oW
over
the
surface
of
a
body,”
US.
Pat.
No.
5,961,080
issued
Oct.
5,
1999
to
Sinha,
entitled
“System
for
ef?cient
control
of
?oW
separation
using
a
driven
?exible
Wall,”
and
an
Jan.
1,
2009
International
Application
published
under
the
PCT
as
Inter
national
Publication
No.
WO
2006/040532
A1,
published
Apr.
20,
2006,
in
the
names
of
Morrison,
J.
F.,
Dearing
S.
S.,
Arthur,
G.
G.,
McKeon,
B.
J
and
Cui,
Z.,
entitled
“Intelligent
Fluid
FloW
Surfaces.”
US.
Pat.
No.
4,516,747
describes
a
system
for
boundary
layer
control
by
damping
of
laminar
instability
or
turbulent
velocity
?uctuations
using
sensors
and
vibration
transmitters.
US.
Pat.
No.
5,961,080
describes
a
?exible
Wall
that
can
be
used
either
to
drive
or
sense
an
external
?oW
by
means
of
sub-surface
capacitive
transducers.
International
Publication
No.
WO
2006/
040532
A1
describes
distributed
“active”,
or
time-dependent,
dimples
fabricated
from
electrostrictive
polymer
With
surface-deposited
elec
trodes.
In
particular,
International
Publication
No.
WO
2006/
040532
A1
teaches
that
the
use
of
dimples
is
“much
more
effective
than
surface
roughness.”
International
Publication
No.
WO
2006/040532
A1
describes
designs
and
manufactur
ing
methods
that
are
speci?cally
intended
to
achieve
a
de?ec
tion
of
a
continuous
sheet
to
provide
depressions
or
dimples
in
the
continuous
sheet
in
preference
to
protrusions.
[0009]
A
number
of
problems
in
applying
previous
?oW
control
methods
and
systems
have
been
observed.
One
draW
back
to
using
passive
devices
for
?oW
control
lies
in
degraded
aerodynamic
performance
in
?oW
regimes
aWay
from
those
Where
the
control
is
useful.
Some
drawbacks
in
using
some
active
devices
can
be
the
complexity
of
a
control
system,
and
the
need
for
expendables
such
as
gases
or
liquids
that
are
consumed,
Which
add
Weight,
and
Which
limit
the
duration
of
operation
of
the
system
by
virtue
of
being
available
in
only
a
?nite
amount.
[0010]
There
is
a
need
for
improved
aerodynamic
control
surface
systems
and
methods.
SUMMARY
OF
THE
INVENTION
[0011]
In
one
aspect,
the
invention
relates
to
a
vehicle
con
?gured
to
operate
using
a
morphable
skin
to
manipulate
vis
cous
boundary
layer
processes.
The
vehicle
comprises
a
vehicle
having
a
surface;
a
morphable
skin
having
?rst
and
second
surfaces,
the
?rst
surface
of
the
morphable
skin
being
attached
to
at
least
a
portion
of
the
surface
of
the
vehicle,
the
second
surface
of
the
morphable
skin
con?gured
to
exhibit
a
morphable
con?guration
relative
to
the
surface
of
the
vehicle;
an
actuator
in
operative
communication
With
the
morphable
skin,
the
actuator
con?gured
to
apply
a
control
signal
to
the
morphable
skin;
and
a
controller
in
communication
With
the
actuator,
the
controller
con?gured
to
provide
a
command
to
the
actuator
to
control
at
least
one
of
a
speed,
a
direction
and
an
attitude,
the
command
based
at
least
in
part
on
a
deviation
of
a
perceived
speed,
direction
or
attitude
from
a
desired
speed,
direction
or
attitude.
In
response
to
a
command
signal
provided
to
the
actuator,
the
actuator
controls
the
second
surface
of
the
skin
so
that
the
skin
assumes
a
modi?ed
surface
con?guration
relative
to
the
surface
of
the
vehicle
so
as
to
control
an
aerodynamic
force
to
exert
a
control
authority
over
at
least
one
of
the
speed,
the
direction
and
the
attitude
of
the
vehicle.
[0012]
In
one
embodiment,
the
morphable
skin
comprises
an
ionic
polymer
metal
composite.
In
one
embodiment,
the
vehicle
further
comprises
electrodes
in
electrical
communi
cation
With
the
morphable
skin.
In
one
embodiment,
the
con
trol
signal
is
an
electrical
signal
applied
to
the
electrodes.
[0013]
In
one
embodiment,
the
morphable
skin
comprises
a
shape
memory
material.
In
one
embodiment,
the
controller
is
an
input/
output
device
con?gured
to
be
operated
by
a
human
US
2009/0001222
A1
operator.
In
one
embodiment,
the
controller
is
a
general
pur
pose
programmable
computer
con?gured
to
operate
With
commands
provided
by
software
recorded
on
a
machine
readable
medium.
In
one
embodiment,
the
modi?ed
surface
con?guration
relative
to
the
surface
of
the
vehicle
comprises
a
surface
asperity
of
the
order
of
l
millimeter.
In
one
embodi
ment,
the
modi?ed
surface
con?guration
relative
to
the
sur
face
of
the
vehicle
comprises
a
surface
asperity
having
a
height
of
the
order
of
l
0
percent
or
less
than
a
boundary
layer
thickness
of
a
?uidpassing
over
the
apparatus.
In
one
embodi
ment,
the
modi?ed
surface
con?guration
relative
to
the
sur
face
of
the
vehicle
comprises
a
surface
asperity
having
a
height
represented
by
the
relation
m*v/u1,
in
Which
v
is
a
?uid
kinematic
viscosity,
uT
is
a
friction
velocity
equal
to
a
square
root
of
a
ratio
of
Wall
shear
stress
r
to
a
?uid
density
p,
and
0§m§l00.
In
one
embodiment,
the
modi?ed
surface
con
?guration
relative
to
the
surface
of
the
vehicle
has
a
response
frequency
of
the
order
of
l
kiloHertZ.
In
one
embodiment,
the
modi?ed
surface
con?guration
relative
to
the
surface
of
the
vehicle
has
a
response
frequency
of
less
than
the
order
of
the
viscous
frequency,
given
by
u12/v,
in
Which
v
is
a
?uid
kine
matic
viscosity,
and
uT
is
a
friction
velocity
equal
to
a
square
root
of
a
ratio
of
Wall
shear
stress
'5
to
a
?uid
density
p.
[0014]
In
another
aspect,
the
invention
features
a
method
of
operating
a
vehicle.
The
method
comprises
the
steps
of:
pro
viding
a
vehicle
having
a
surface;
providing
a
morphable
skin
having
?rst
and
second
surfaces,
the
?rst
surface
of
the
mor
phable
skin
attached
to
at
least
a
portion
of
the
surface
of
the
vehicle,
the
second
surface
of
the
morphable
skin
con?gured
to
exhibit
a
morphable
con?guration
relative
to
the
surface
of
the
vehicle;
providing
an
actuator
in
operative
communica
tion
With
the
morphable
skin,
the
actuator
con?gured
to
apply
a
control
signal
to
the
morphable
skin;
providing
a
controller
in
communication
With
the
actuator,
the
controller
con?gured
to
provide
a
command
to
the
actuator
to
control
at
least
one
of
a
speed,
a
direction
and
an
attitude,
the
command
based
at
least
in
part
on
a
deviation
of
a
perceived
speed,
direction
or
attitude
from
a
desired
speed,
direction
or
attitude;
and
apply
ing
a
control
signal
to
the
morphable
skin
from
the
actuator.
In
response
to
the
control
signal,
the
second
surface
of
the
mor
phable
skin
is
caused
to
assume
a
modi?ed
surface
con?gu
ration
relative
to
the
surface
of
the
vehicle
to
exert
a
control
authority
over
at
least
one
of
the
speed,
the
direction
and
the
attitude
of
the
vehicle.
[0015]
In
one
embodiment,
the
morphable
skin
comprises
an
ionic
polymer
metal
composite.
In
one
embodiment,
the
method
of
operating
a
vehicle
further
comprises
the
step
of
providing
electrodes
in
electrical
communication
With
the
morphable
skin.
In
one
embodiment,
the
control
signal
is
an
electrical
signal
applied
to
the
electrodes.
[0016]
In
one
embodiment,
the
morphable
skin
comprises
a
shape
memory
material.
In
one
embodiment,
the
controller
comprises
an
input/output
device
con?gured
to
be
operated
by
a
human
operator.
In
one
embodiment,
the
controller
is
a
general
purpose
programmable
computer
con?gured
to
oper
ate
With
commands
provided
by
softWare
recorded
on
a
machine-readable
medium.
In
one
embodiment,
the
modi?ed
surface
con?guration
relative
to
the
surface
of
the
vehicle
comprises
a
surface
asperity
of
the
order
of
l
millimeter.
In
one
embodiment,
the
modi?ed
surface
con?guration
relative
to
the
surface
of
the
vehicle
comprises
a
surface
asperity
having
a
height
of
the
order
of
10
percent
or
less
than
a
boundary
layer
thickness
of
a
?uid
passing
over
the
appara
tus.
In
one
embodiment,
the
modi?ed
surface
con?guration
Jan.
1,
2009
relative
to
the
surface
of
the
vehicle
comprises
a
surface
asperity
having
a
height
represented
by
the
relation
m*v/uT,
in
Which
v
is
a
?uid
kinematic
viscosity,
uT
is
a
friction
velocity
equal
to
a
square
root
of
a
ratio
of
Wall
shear
stress
'5
to
a
?uid
density
p,
and
0<m§l00.
In
one
embodiment,
the
modi?ed
surface
con?guration
relative
to
the
surface
of
the
vehicle
is
attained
in
a
time
of
the
order
of
l
millisecond.
In
one
embodi
ment,
the
modi?ed
surface
con?guration
relative
to
the
sur
face
of
the
vehicle
has
a
response
frequency
of
less
than
the
order
of
the
viscous
frequency,
given
by
uT2/v,
in
Which
v
is
a
?uid
kinematic
viscosity,
and
u1
is
a
friction
velocity
equal
to
a
square
root
of
a
ratio
of
Wall
shear
stress
'5
to
a
?uid
density
p.
[0017]
The
foregoing
and
other
objects,
aspects,
features,
and
advantages
of
the
invention
Will
become
more
apparent
from
the
folloWing
description
and
from
the
claims.
BRIEF
DESCRIPTION
OF
THE
DRAWINGS
[0018]
The
objects
and
features
of
the
invention
can
be
better
understood
With
reference
to
the
draWings
described
beloW,
and
the
claims.
The
draWings
are
not
necessarily
to
scale,
emphasis
instead
generally
being
placed
upon
illustrat
ing
the
principles
of
the
invention.
In
the
draWings,
like
numerals
are
used
to
indicate
like
parts
throughout
the
various
vieWs.
[0019]
FIG.
1
is
a
diagram
that
illustrates
the
basic
principle
of
strain
generation
in
an
ionic
polymer
metal
composite
(IPMC)
under
an
electric
?eld
of
positive,
negligible
and
negative
sign.
[0020]
FIG.
2
is
a
diagram
that
illustrates
the
IPMC
actua
tion
in
cantilevered
con?guration,
demonstrating
bending
toWards
the
anode,
for
a
cation
exchange
membrane.
[0021]
FIG.
3
is
a
Scanning
Electron
Microscope
image
of
a
polymer
ion
exchange
membrane
(PIEM)
after
“composit
ing”
process
in
Which
the
PIEM
is
metalliZed
With
a
layer
of
platinum
particles
concentrated
near
the
surface.
[0022]
FIG.
4
is
a
Scanning
Electron
Microscope
image
of
an
IPMC
With
a
platinum
surface
electrode.
[0023]
FIG.
5
is
an
image
of
an
aluminum
mold
used
for
generating
roughness
pattern
in
shape
memory
polymer.
[0024]
FIG.
6
is
a
draWing
that
illustrates
standard
tWist
drill
bit
tip
geometry.
[0025]
FIG.
7
is
a
cross
sectional
diagram
that
illustrates
the
pro?le
of
the
NACA
2412
airfoil.
[0026]
FIG.
8
is
an
image
shoWing
a
cross
section
ofa
test
article
shoWing
the
applied
layers
and
the
slightly
modi?ed
pro?le.
[0027]
FIG.
9
is
a
diagram
that
illustrates
the
cross
section
of
the
ridge
asperity.
[0028]
FIG.
10
is
a
diagram
that
illustrates
the
cross
section
of
a
plurality
of
bump
asperities.
[0029]
FIG.
11
is
a
diagram
that
shoWs
drag
vs.
time
for
an
angle
of
attack
(AoA)
of
(P150,
With
roughness
of
the
order
of
1
mm
at
the
forWard
station.
[0030]
FIG.
12
is
a
diagram
that
shoWs
lift
vs.
time
for
an
angle
of
attack
(AoA)
of
(P150,
With
roughness
of
the
order
of
1
mm
at
the
forWard
station.
DETAILED
DESCRIPTION
OF
THE
INVENTION
[0031]
This
application
describes
the
use
of
controlled
changes
to
the
global
morphology
of
surfaces
beloW
external
or
internal
?oWs
to
manipulate
viscous
boundary
layer
pro
cesses.
In
describing
the
invention,
reference
Will
be
made
to