2013/4/6

1

Unsteady Pressure-Sensitive Paint

Techniques for Dynamic Wind-

Tunnel Testing

Keisuke ASAI (asai@aero.mech.tohoku.ac.jp)

Dept. of Aerospace Engineering

Tohoku University

Sendai, Japan

Workshop on Next Generation Transport Aircraft March 29, 2013, Mary Gates Hall, UW Campus

Prof. Martin Gouterman

Visit to University of Washington in 1995

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UW: Birthplace of Pressure-Sensitive Paint

"Oxygen Quenching of Luminescence of Pressure Sensitive Paint for Wind Tunnel Research," M.

Gouterman, J. Chem. Ed., 74, 697 (1997).

"Luminescent Barometry for Aerodynamic Measurements," J. Gallery, M. Gouterman, J. B. Callis, G. E.

Khalil, B. G. McLachlan, and J. H. Bell, Rev. Sci. Instrum., 65, 712 (1994).

"Sub-Millisecond Response Times of Oxygen Quenched Luminescent Coatings," A. Baron, J. D. S.

Danielson, M. Gouterman, J. R. Wan, J. B. Callis, and B. G. McLachlan, Rev. Sci. Instrum., 64, 3394 (1993).

"Video Luminescent Barometry: The Induction Period," R. H. Uibel, G. E. Khalil, M. Gouterman, J.

Gallery, and J. B. Callis, AIAA Paper No. 93-0179, 31st Aerospace Sciences Meeting, Reno, NV

(January 1993).

University of Washington Department of Chemistry

Dr. Kavandi served as a mission specialist on

STS-91 (June 2-12, 1998), STS-99 (February

11-22, 2000) and STS-104/ISS Assembly Flight

7A (July 12-24, 2001).

Dr. Kavandi currently serves as Director, Flight

Crew Operations, NASA Johnson Space Center.

.

In 1986, while still working for Boeing, she was

accepted into graduate school at the University

of Washington, where she began working

toward her doctorate in analytical chemistry.

She has obtained Doctorate in Analytical

Chemistry from the University of Washington -

Seattle in 1990

Her doctoral dissertation involved the

development of a pressure-indicating coating

that uses oxygen quenching of porphyrin

photoluminescence to provide continuous

surface pressure maps of aerodynamic test

models in wind tunnels. Her work on pressure

indicating paints has resulted in two patents.

.

Astronaut Janet L. Kavandi -mission specialist

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Pressure- and Temperature-Sensitive Paints

・Pressure-Sensitive Paint [PSP]

・Temperature-Sensitive Paint [TSP]

model

Excitation light Emission light

PSP or TSP

Oxygen/thermal

Quenching gas molecule

Example of molecular sensors

（metal complex compound）

Excitation

light

Excited singlet state (S1)

Triplet state (T1)

Intersystem crossing

Ground state (S0)

Oxygen quenching A

dso

rptio

n

Th

erm

al q

uen

ch

ing

Flu

ore

sc

en

ce

Th

erm

al q

uen

ch

ing

Ph

osp

ho

res

ce

nce

Excited oxygen

Jablonsky energy-level diagram

Principle of measurement

Oxygen quenching → PSP

Thermal quenching → TSP

N N

NN

Pt

CH2CH3 CH2CH3

CH2CH3

CH2CH3

CH2CH3CH2CH3

H3CH

2C

H3CH

2C

Demo of PSP Response : Oxygen quenching

O2

N2

UV illumination

PSP： Platinum Porphyrine + TLC Plate

Stern-Volmer

Relationship

]O[1 200 qkI

I

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Pressure Sensitive Paint (1st Generation)

Sensor: Platinum Octaethylporphyrin (PtOEP)

Binder: Polydimethylsiloxyan (PDMS)

N N

NN

Pt

CH2CH3 CH2CH3

CH2CH3

CH2CH3

CH2CH3CH2CH3

H3CH

2C

H3CH

2C

380nm 650nm

PtOEP

Absorption/emission spectra

I ref

/I

T=20degC

P/Pref

Pressure

Stern-Volmer

Equation

Washington Univ. (USA)

PSP

Calibration

Imaging Method

painted model

CCD camera

bandpass filter

illumination source

PC with digitizing

board

● Excitation: Xe arc, LED

● Emission: CCD camera

PSP/TSP measurement system (imaging)

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Wind-off image

Iref

Wind-on image

I

T correction T correction

Pressure 0.4

0.5

0.6

0.7

0.8

P/Pt

ref

ref

P

PTBTA

TPI

TPI )()(

),(

),(

Image

registration

Processing of PSP images

Pressure map（pseudo color ）

Normalization

Stern-Volmer

Relationship

Image

registration

Iref / I (ratioing)

Wind-off image Iref Wind-on image I

MITSUBISHI REGIONAL JET (MRJ)

JAXA PSP systems applied to develop MRJ

Both high-speed (transonic) and low-speed

* Estimate load on the main wings

* Validate aerodynamic model

Experimental Results@TWT1 (M=0.8, AoA=4deg)

Application of PSP Technique to a

Domestic Civil Aircraft Development

K. Mitsuo, et al.

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Flow around Shuttle Cock (U= 30 m/s)

Collaboration with Akita Univ.

60 deg 90 deg

a = 0 deg 20 deg 30 deg

Model Painted with PSP

Surface Pressure Distribution over World Cup Soccer Balls (2012)

smooth

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

2004

Application to Sport Aerodynamics

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

2010

Prof. Seo (Yamagata Univ.)

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- Karman vortex cause undesirable

periodic forcing during the high winds

- It is important for engineers to account

for the possible effects of vortex

shedding when designing a wide range

of structures

(tall building, bridge, chimney, etc)

A Kármán vortex street is a term used in fluid dynamics for a repeating pattern of swirling vortices caused

by the unsteady separation of flow of a fluid over bluff bodies. It is named after the engineer and fluid

dynamicist, Theodore von Kármán[1] and is responsible for such phenomena as the "singing" of

suspended telephone or power lines, and the vibration of a car antenna at certain speeds.

commons.wikimedia.org

Theodore von Kármán

Unsteady Flow: Kármán Vortex Street

Tacoma Narrows Bridge collapse

(Nov., 7, 1940)

Requirements for fast PSP

Fast response time

High luminescent intensity Thickness

O2

O2

O2

O2

O2

O2 O2

O2

A key is

“Porous Binder”

mD

h2

Time

constant Diffusion of O2

(Dm)

Fast-responding PSP

O2 O2

O2 O2

O2

O2

(ex) silicone polymer (Poly(DMS))

Dm＝O(10-10)m2/sec

h=10mm = O(１)sec

Faster response thinner

lower intensity and SNR

h Diffusion Theory

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Silica-gel thin-layer chromatography plate (TLC-PSP)

Fast Response PSP

Anodized-aluminum (AA-PSP)

Polymer/ceramic (PC-PSP)

Ultra fine ceramic powder

1 mm

Anodized aluminum

(Asai et al., 1997)

Polymer/ceramic

(Scroggin et al., 1999)

Ultra fine ceramic powder

(Kameda et al., 2008)

Porous materials for fast-response PSP

Frequency characteristics of PC-PSP

- The amplitude attenuation starts at about 1 kHz and it reaches -3 dB at the

frequency of 3.8 kHz.

- The phase delay increases in the frequency range over 1 kHz.

- Frequency response of PC-PSP is that of 1st order system of which time constant

is determined by luminescent lifetime of sensor molecules

Amplitude characteristics Phase delay characteristics

3 dB attenuation

-6

-5

-4

-3

-2

-1

0

1

100 1000 10000

h=20mm

h=30mm

h=300mm

Gai

n[d

B]

Frequency[Hz]

-60

-50

-40

-30

-20

-10

0

100 1000 10000

Phas

e sh

ift[

deg

.]

Frequnecy[Hz]

PtTFPP, T=20℃, P=100 kPa

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• Time-series PSP images are acquired with a CMOS high-speed camera under continuous excitation.

• Acquisition timing of every camera image and reference signal (phase information) are measured simultaneously.

• After image acquisition, PSP images are sorted by phases of filtered reference signal (ex. BP, POD) and averaged.

• This technique yields a series of high-SNR instantaneous pressure images.

Ref sensor

Excitation

light

Camera

Data Logger

Pressure variation

Continuous excitation

Image acquisition

Acquisition timing Time-series

PSP images (Yorita, et al, AIAA Paper 2010-307)

Conditional Image Averaging (1)

Application to flow around square cylinder

100 m

m Lateral plate

100 m

m

Square cylinder model

Pressure Transducer

H

D

z y x

W

x/D = 0.5 z/H = 0.5

PSP 3-D Square Cylinder

• Free-stream velocity : 50 m/s (Re=1.4x105)

• Incidence angle : 0 degree

-1.0

-0.5

0

0.5

1.0

0 0.01 0.02 0.03 0.04 0.05

Am

pli

tud

e [k

Pa]

Time [sec]

Experimental condition

Pressure variation on lateral side surface

Time-series pressure transducer data Amplitude spectrum

f ≈ 150 Hz

Turn table (PSP)

• Height H = 100 mm

• Width W = 40 mm

• Length L = 40 mm

* One high-frequency pressure transducer is provided

on the center point of the side surface

100

101

0 100 200 300 400 500Am

pli

tude

spec

tral

den

sity

Frequency [Hz]

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Time-series pressure image

(Raw images)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5x 10

-3

1.005

1.000

0.995

Phase-averaged pressure image

(Conditional image averaging)

PP /

Time-resolved pressure map

Application to flow around square cylinder

38/19 Japanese-German Seminar on Molecular Imaging Technology for Interdisciplinary Research Feb.21 (Tue) – Feb. 24 (Fri), 2012

0 - 45 45 - 90 90 - 135 135 - 180

180 - 225 225 - 270 270 - 315 315 - 360

Phase

[deg]

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5x 10

-3

1.005

1.000

0.995

- The pressure variations on the side surface were successfully visualized.

- High fluctuating-pressure regions appear at the bottom rear part.

- The PSP data are in good agreement with the pressure transducer data.

0.996

0.998

1.000

1.002

1.004

0 60 120 180 240 300 360

PSPPressure transducer

Pre

ssu

re r

atio

P/P

ref

Phase [degrees]

Comparison with pressure transducer

PP /

Application to flow around square cylinder

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200 400 600 800

100

200

300

400

500

600

700

95

96

97

98

99

100

x =

)(/ _ UnsteadyPP aveon

)(_ SteadyP aveon

Turn table (PSP)

Application of conditional image sampling

2D unsteady pressure distribution on a ground plane (V=50m/sec)

The peak frequency is 150 Hz and the pressure

amplitude is on the order of several hundred Pa.

Absolute pressure variation P

“Hybrid Flight Simulator”

6 DoF eqs. of motion

（Flight Dynamics）

Manipulator control

(Servo compensation）

air data

Intertia

Control

Motion

table

Motion analysis (PC)

model

attitude

(real time)

Attitude

Deformation

Servo

balance

6 DoF

Robot

Manipulator

Imaging Camera

CFRP model

HEXA

Parallel Robot

Interface

Optical

Model

Deformation

Optical

Model

Attitude

Pressure

Sensitive

Paint

3D

Meas.

Schematic

Optical

Model

Deformation

Optical

Model

Attitude

Pressure

Sensitive

Paint

3D

Meas.

Parallel (HEXA)

Serial (PA10)

Next-Generation Dynamic Wind-Tunnel

Testing – Tohoku University, Japan

2013/4/6

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50/38

Application to Dynamic Wind-Tunnel Testing

U = 30 m/s AoA = 35 deg.

1-DoF Roll Oscillation

( f = 1 Hz, Df = ±30 deg )

Cp with temp correction

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

1

2Cp with temp correction

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

1

Cp with temp correction

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

1

22

0

-2

-4

-6

-8

Cp

Without correction With correction

Ratio Iref/I without correction Ratio Iref/I with correction Ratio Iref/I with correction

Cp with temp correction

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

1

2 1.04

1

0.98

1.02

0.96

0.94

Iref/I

Intensity ratio of Reference paint

Oscillated Delta Wing (Phase-lock Method + Binary PSP)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

400 500 600 700 800

Rel

ati

ve

Inte

nsi

ty

Wave length [nm]

(Pressure CH)

PtTFPP

650nm (Reference CH)

BAM-G

518nm

51/38

Application to Dynamic Wind-Tunnel Testing

Time History of Cp

at x/c = 0.5 on Right Wing

Oscillated Delta Wing (Phase-lock Method + Binary PSP)

Cp with temp and def correction

-7

-6

-5

-4

-3

-2

-1

0

1

2

Cp with temp and def correction

-7

-6

-5

-4

-3

-2

-1

0

1

2

Cp with temp and def correction

-7

-6

-5

-4

-3

-2

-1

0

1

2

Cp with temp and def correction

-7

-6

-5

-4

-3

-2

-1

0

1

2

Cp with temp and def correction

-7

-6

-5

-4

-3

-2

-1

0

1

2

Cp with temp and def correction

-7

-6

-5

-4

-3

-2

-1

0

1

2

Cp with temp and def correction

-7

-6

-5

-4

-3

-2

-1

0

1

2

Cp with temp and def correction

-7

-6

-5

-4

-3

-2

-1

0

1

2

Cp with temp and def correction

-7

-6

-5

-4

-3

-2

-1

0

1

2

Cp with temp and def correction

-7

-6

-5

-4

-3

-2

-1

0

1

2

Cp with temp and def correction

-7

-6

-5

-4

-3

-2

-1

0

1

2

Cp with temp and def correction

-7

-6

-5

-4

-3

-2

-1

0

1

2

f 25deg f 0deg

f 25deg f 0deg

-8

-6

-4

-2

0

-30 -20 -10 0 10 20 30

Bi-PSP corr.Bi-PSP uncorr.Pressure Sensor

Cp

Roll Angle

1-DoF Roll Oscillation

( f = 1 Hz, Df = ±30 deg )

f 20deg f 20deg

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Unsteady PSP Technique: Next Step

Effects of wing flexibility on dynamic stability

54/38

Unsteady PSP Technique: Next Step

Effects of wing flexibility on dynamic stability

The failure occurred during a flight on the

Hawaiian island of Kauai on June 26, 2003.

September 08, 2004

NASA Releases Report on Crash of Helios Solar Plane

The National Aeronautics and Space Administration (NASA) released on September 3rd its final report on the crash of

Helios, a solar-powered "flying wing" that suffered structural failure and fell into the Pacific Ocean during a long-duration

test flight last summer. A review of the flight data concluded that atmospheric turbulence caused the plane's wing tips to

bend upward abnormally and then caused the entire wing to oscillate. The growing oscillations caused the Helios to gain

speed until it suffered a structural failure. The accident investigation board determined that the mishap resulted from the

inability to predict, using available analysis methods, the aircraft's increased sensitivity to turbulence following modifications

to allow long-duration flights. Specifically, the addition of a hydrogen-air fuel cell pod and two hydrogen storage tanks placed

significant loads along the length of the flying wing, reducing the safety margins for the aircraft. See the press release from

the NASA Dryden Flight Research Center or go directly to the full report