Purdue University - School of Aeronautics and Astronautics
Molecular SensorsTemperature Sensitive
PaintJohn Sullivan
Professor – School of Aeronautics and AstronauticsDirector - Center for Advanced Manufacturing
Purdue University
Special Government Employee – NASA
West Lafayette, IN 47907-2022Telephone (765)494-1279
Fax (765)[email protected]
Purdue University - School of Aeronautics and Astronautics
Objective
• Measure temperature distribution and heat transfer distribution on a hydraulic experiment at Beihang University in the next three weeks.
Purdue University - School of Aeronautics and Astronautics
Lamp LED
CCD camera
Temperature Sensitive Paint
Luminescent
MoleculeExcitation
Emission
QuantitativeHeat Flux
Mach 10 –Tunnel 9
Feature Detection-Transition-Vortices-Separation
High-mass planetary probes are affected by transitionLaminar flow results in 2-8 times less aeroheating
Purdue University - School of Aeronautics and Astronautics
TSP -Temperature Sensitive Paint PSP - Pressure Sensitive Paint
E m is s io n
O p tic a lF ilte r
E x cita tio nU V L a m pL a s e rF la s h L a m p
D etec to rC C DP M TP D
B in d e r P o ly m e r P o ro u s S o lid
L u m in e s c e n t M o le c u le
Calib rate O u tp u tfor Tem p eratu reor P res s u re
Photo-physical process:
-absorb a photon
-transition to excited state
-Oxygen quenching (PSP)
or thermal quenching (TSP)
=> Pressure and/or temperature
dependent luminescent intensity
and luminescent lifetime
Purdue University - School of Aeronautics and Astronautics
Temperature Sensitive Paint High temperature causes non-radiative decay “thermal quenching”• Obeys Arrhenius relation: For limited temp. range
lT T Tref ref
nI(T)
I
E
Rref g( )
1 1
• Similar molecules to PSP, but in oxygen impermeable binder
I
T
to
C~
1 5%0
Purdue University - School of Aeronautics and Astronautics
Luminescent Paint (TSP/PSP)
coated model
Excitation
short-pass filter
excitation source
Acquisition
photodetector
long-pass filter
Iref/IP/Pref
Data Processing
Iref/I
P/Pref
calibration
surface maplow costeasy to apply
Purdue University - School of Aeronautics and Astronautics
Current State of the Art of PSP/TSP
•Temperature Sensitive Paint–T= -196 C to 200 C M=.01 to 10–Accuracy 1 Degree Centigrade Resolution <. 01 C–Time Response 1 sec Typical (<1 ms demonstrated)
•Pressure Sensitive Paint–P=.001 to 2 atm M=.05 to 5–Accuracy 1.0 mbar Resolution .5 mbar–Time response .5 sec Typical
( 1 microsec demonstrated)
Purdue University - School of Aeronautics and Astronautics
Basic Photophysics
Purdue University - School of Aeronautics and Astronautics
Jablonski Diagram
f ph kic kisc
kisc
S0
T1S1
(triplet state)
(ground state)
(singlet state)
vibration intersystem crossing (ISC)
internal conversion (IC)
fluorescence phosphorescenceexcitation
kic
kic
S2
Sn
Purdue University - School of Aeronautics and Astronautics
Data Reduction Methods
Purdue University - School of Aeronautics and Astronautics
Data Reduction Methods
• Intensity Reference• Multi-luminophore Paint• Time Based Methods
Purdue University - School of Aeronautics and Astronautics
Intensity Reference
• Wind Off / Wind On• Corrects for non-uniform model
motion, nonuniform concentration
ref
refref
p
pTBTA
I
I)()(
Purdue University - School of Aeronautics and Astronautics
Multi-luminophore Paint
• Luminescent molecules with different pressure and temperature sensitivities, overlapping excitations and different emission wavelengths
Purdue University - School of Aeronautics and Astronautics
Time Based Methods
• Direct Decay• Phase Based
Purdue University - School of Aeronautics and Astronautics
Direct Decay• Modulated Light Source
– Pulse, Sine wave, square wave• Point Systems• Camera Systems with image intensifier
Time
Intensity
Purdue University - School of Aeronautics and Astronautics
Phase Based• Lock-in Amplifier• FLIM (Fluorescent Lifetime Imaging Method)
t(arb)
0 5 10 15
am
plit
ude(a
rb)
0
1
2
3
ExcitationEmission
ref
P
PD(t)C(t)ref
tan()=
Purdue University - School of Aeronautics and Astronautics
Temperature Sensitive PaintTSP
Same or similar Luminophore as in PSP
Oxygen impermeable binder
Purdue University - School of Aeronautics and Astronautics
Temperature Sensitive PaintThermographic Phosphors Infrared CameraTemperature Sensitive Liquid CrystalsArray of Thermocouples
Global Surface Temperature Measurements
Toolbox
Purdue University - School of Aeronautics and Astronautics
Temperature Sensitive Paint
• Surface Temperature– Correction for Pressure Sensitive Paint
• Transition Detection• Quantitative Heat Transfer• Shear Stress - Heat transfer Analogy
Purdue University - School of Aeronautics and Astronautics
Temperature Sensitive Paint Calibrations
Purdue University - School of Aeronautics and Astronautics
TSP Time Response
c
h
Laser Pulse Heating
density of polymer c specific heat paint thickness h convection heat transfer coefficient
Purdue University - School of Aeronautics and Astronautics
Ruthenium based TSP tris(2,2’-bipyridyl)ruthenium - Ru(bpy)
Wavelength (nm)
200 300 400 500 600 700 800 900
Inte
nsity
(ar
b un
its)
0
100
200
300
400
Excitation Emission
UVUVlamplamp
BlueBlueLEDs LEDs
Greenlaser
Excitation and Emission Spectrum of a Ruthenium Based Paint
Purdue University - School of Aeronautics and Astronautics
EuTTA based TSP Europium III Thenoyltrifluoroacetonate EuTTA
Excitation Spectrum Emission Spectrum
Purdue University - School of Aeronautics and Astronautics
EuTTA in Model Airplane Dope
Purdue University - School of Aeronautics and Astronautics
Applications Temperature Sensitive Paint
(TSP)
• Transition Detection– Low Speed– Cryogenic Wind Tunnel
• Quantitative Heat Transfer– Camera Based – M=10– Scanning System Laser Spot Heating
Purdue University - School of Aeronautics and Astronautics
Transition DetectionLow Speed
TSP –EuTTA in dope
Wing heated with photographic spot lampsto ~20 C above ambient
8 bit Camera
Purdue University - School of Aeronautics and Astronautics
Raw Image(false color)
ResultsLow Speed Transition
Purdue University - School of Aeronautics and Astronautics
Quantitative Heat Transfer
Purdue University - School of Aeronautics and Astronautics
Heat Transfer Data Reduction• Model make out of Thermally Insulating material• Measure
• Match the temperature to analytic solution for a semi-infinite body (Cook-Felderman)
• Make Model out of a Conductor with a thin insulator on the surface
)(tTsurface
)(/ modelsurface TTkq
Method 1
Method 2
1 model k
1 model k
Purdue University - School of Aeronautics and Astronautics
Tunnel #9M=10Run time ~1.0 sec1.5 meter Diameter
Purdue University - School of Aeronautics and Astronautics
TSP - EuTTA in dopeMetal modelInsulating Layer – mylar film (model airplane monokote) 50 microns thick
Raw Image
Purdue University - School of Aeronautics and Astronautics
Purdue University - School of Aeronautics and Astronautics
Purdue University - School of Aeronautics and Astronautics
Mach-6 Quiet Tunnel
National Aeronautics and Space Administration
www.nasa.gov 35
-1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1x 10
4
Qpa
ints
[W
/m2 ]
run8.tif
-1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1x 10
4
QH
FS-4
[W
/m2 ]
HIFiRE-5 Model
Quiet Flow, α=0
Re = 2.6*106 /ft
Purdue University - School of Aeronautics and Astronautics
Temperature profile of machining acquired with TSP sensor (Rubpy)
350 400 450 500 550 600
250
300
350
400
450
20
30
40
50
60
70
80
Area of
Interestworkpiece
Cutting toolChip
degree C
350 400 450 500 550 600
250
300
350
400
450
20
30
40
50
60
70
80
Area of
Interestworkpiece
Cutting toolChip
350 400 450 500 550 600
250
300
350
400
450
20
30
40
50
60
70
80
Area of
Interest
350 400 450 500 550 600
250
300
350
400
450
20
30
40
50
60
70
80
Area of
Interestworkpiece
Cutting toolChip
degree C
Temperature profiles from TSP measurement of grinding stainless steel at spark-out condition
TSP Measurements ofMaterial Temperature