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Surface Temperature

Measurements from a Stator Vane

Doublet in a Turbine Engine

Afterburner Flame Using a

YAG:Tm Thermographic Phosphor

J.I. Eldridge, NASA Glenn Research Center

D.G. Walker and S.L. Gollub, Vanderbilt University

T.P. Jenkins, MetroLaser, Inc.

S.W. Allison, Emerging Measurements

https://ntrs.nasa.gov/search.jsp?R=20150021279 2018-08-30T08:26:53+00:00Z

Jeff Eldridge

• In a NASA career spanning over twenty-five years, Dr. Eldridge has

most recently worked towards developing spectroscopy-based

health monitoring tools for both space and turbine engine

applications. He has coauthored over 70 publications and has made

over 50 conference presentations and invited tutorials/lectures.

• Dr. Eldridge is a senior scientist of the Optics and

Photonics Branch at NASA Glenn Research Center.

2

Background• Thermographic phosphors for temperature measurements exhibit unique

advantages over thermocouples and pyrometers for turbine engine

environments.– Non-contact

– No interference from reflected radiation

– Insensitive to surface emissivity

– Intrinsically surface sensitive

• AFRL VAATE project successfully demonstrated temperature measurements from thermographic phosphor coated Honeywell stator vane doublet in afterburner flame of AEDC J85-GE-5 turbojet test engine.

Component Testing in Engine Afterburner Flame

Vane doublet with temperature

sensing coating in test fixture.

Afterburner flame from

J85 test engine.

• However, overwhelmed by reflected combustion radiation during Honeywell HTF7000 engine test.

• Challenge: Develop thermographic phosphor that emits at wavelength coinciding with greatly reduced reflected radiation intensity.

350 400 450 500 550 600 650

Inte

ns

ity (

arb

. u

nit

s)

Wavelength nm

Thermographic Phosphor Emission vs. Blackbody Background Intensity

YAG:Tm

YAG:Dy

YSZ:Eu

1200°C blackbody

1800°C blackbody

2000°C blackbody

367 nm455 nm

461 nm

484 nm

497 nm606 nm

591 nm

582 nm x190

x2.5

Thermographic Phosphor Emission vs. Blackbody

Background Intensity

• Blue emission effective for low thermal background produced by hot

surface.

• UV emission will be necessary for low thermal background from

reflected combustor radiation.

Objectives

• Implement blue and UV emission bands from YAG:Tm for

engine probe measurements.

• Demonstrate temperature measurements from YAG:Tm-

coated Honeywell stator vane doublet in afterburner

flame of UTSI J85-GE-5 turbojet test stand.

– Monitor vane surface temperature

– Steady-state conditions

– Engine acceleration

Characterize and Calibrate YAG:Tm Luminescence

Decay Temperature Dependence

(blue and UV Emission)

350 400 450 500

Inte

nsit

y (

arb

. u

nit

s)

Wavelength nm

SPPS YAG:Tm-Coated Button355 nm excitation

355 nm

360 nm

362 nm

365 nm 368 nm455 nm

461 nm

486 nm

Emission Spectrum from YAG:Tm-Coating355 nm excitation

0

5

10

15

20

25

30

Ene

rgy

(10

3cm

-1)

3H6

3F4

3H5

3H4

3F3

3F2

1G4

1D23

65

nm

35

5 n

m

45

6 n

m

1D2→3H6

1D2→3F4

UV blue

UV emission will be needed in presence of reflected combustor radiation.

0

100

200

300

400

500

600

700

Ene

rgy

(cm

-1)

27500

27600

27700

27800

27900

28000

28100

28200

Ene

rgy

(10

3cm

-1)

Stark Energy Levels Associated with 3H6→1D2 Absorption and

1D2→3H6 Emission in YAG:Tm Luminescence

0

5

10

15

20

25

30

Ene

rgy

(10

3cm

-1)

3H6

3F4

3H5

3H4

3F3

3F2

1G4

1D2

36

5 n

m

35

5 n

m

3H6(1)

3H6(2)

3H6(3)3H6(4)3H6(5)3H6(6)

3H6(7)

3H6(8)

1D2(1)

1D2(2)

1D2(3)

1D2(5)1D2(4)

27500

27600

27700

27800

27900

28000

28100

28200

Ener

gy (

10

3cm

-1)

27500

27600

27700

27800

27900

28000

28100

28200

Ener

gy (

10

3cm

-1)

27500

27600

27700

27800

27900

28000

28100

28200

Ener

gy (

10

3cm

-1)

0

100

200

300

400

500

600

700

Ene

rgy

(10

3cm

-1)

0

100

200

300

400

500

600

700

Ene

rgy

(10

3cm

-1)

0

100

200

300

400

500

600

700

Ene

rgy

(10

3cm

-1)

357 nm

359 nm

362.5 nm

364.5 nm

367 nm

Five

absorption/emission

bands

1 2 3 4 5

Skipped forbidden transitions between like symmetry Stark levels & transitions involving 3H6(9-13)

0

10000

20000

30000

40000

50000

60000

70000

340 345 350 355 360 365 370

Inte

nsit

y (

arb

.un

its)

Wavelength nm

YAG:Tm(0.8%) Powder Slurry Excitation SpectraEmission @460nm

YAG:Nd third harmonic excitation @354.7 nm

3H6→1D2

1

2

34

5

YAG:Tm(0.8%) Powder Excitation & Emission Spectra

3H6→1D2

350 355 360 365 370 375 380

Inte

nsit

y (

arb

.un

its)

Wavelength nm

YAG:Tm Emission @352nm Excitation powder

352 nm excitation

1

2

3

4 5

1D2→3H6

Excitation Spectrum

@460 nm Emission

Emission Spectrum

@352 nm Excitation

YAG:Nd 3rd harmonic at 355 nm

excites into phonon sideband.

Bandpass

filter

FWHM

5550

5650

5750

5850

5950

6050

6150

6250

Ene

rgy

(cm

-1)

5550

5650

5750

5850

5950

6050

6150

6250

Ene

rgy

(cm

-1)

5550

5650

5750

5850

5950

6050

6150

6250

Ene

rgy

(cm

-1)

5550

5650

5750

5850

5950

6050

6150

6250

Ene

rgy

(cm

-1)

5550

5650

5750

5850

5950

6050

6150

6250En

erg

y (c

m-1

)

27500

27600

27700

27800

27900

28000

28100

28200

Ene

rgy

(10

3cm

-1)

27500

27600

27700

27800

27900

28000

28100

28200

Ene

rgy

(10

3cm

-1)

27500

27600

27700

27800

27900

28000

28100

28200

Ene

rgy

(10

3cm

-1)

27500

27600

27700

27800

27900

28000

28100

28200

Ene

rgy

(10

3cm

-1)

27500

27600

27700

27800

27900

28000

28100

28200

Ene

rgy

(10

3cm

-1)

27500

27600

27700

27800

27900

28000

28100

28200

Ene

rgy

(10

3cm

-1)

Stark Energy Levels Associated with 3H6→1D2 Absorption and

1D2→3F4 Emission in YAG:Tm Luminescence

0

5

10

15

20

25

30

Ene

rgy

(10

3cm

-1)

3H6

3F4

3H5

3H4

3F3

3F2

1G4

1D2

45

6 n

m

35

5 n

m

3F4(1)

1D2(1)

1D2(2)

1D2(3)

1D2(5)1D2(4)

445.3 nm

448.1 nm

450.4 nm

452.7 nm

453.9 nm

Nine emission bands

1 2 3 4 5

3F4(2)

3F4(3)

3F4(4)

3F4(5)

3F4(6)

3F4(7)

3F4(8)

3F4(9)

6 7 8 9

455.1 nm

457.1 nm

459.6 nm

460.8 nm

Skipped forbidden transitions between like symmetry Stark levels & transitions terminating in 3F4(8,9)

440 450 460 470 480

Inte

ns

ity (

arb

.un

its

)

Wavelength nm

YAG:Tm Emission

Coating vs. Powder 355nm Excitation

SPPS coating

powder

YAG:Tm 1D2→3F4 Emission Spectra

1D2→3F4

Emission Spectrum

@355 nm Excitation

1

23

4

5

6

7

89

Bandpass

filter

FWHM

• The 1D2→3F4 emission is more complex than the 1D2→

3H6 emission.

• Broad background in SPPS coating suggests somewhat more disordered structure.

0.00001

0.0001

0.001

0.01

0.0E+00 5.0E-05 1.0E-04 1.5E-04

Inte

nsi

ty (

V)

Time (s)

SPPS YAG:Tm on SS, Batch 1, #G 456nm Decay, 512 Scan Average

15°C

182°C

288°C

384°C

489°C

587°C

636°C

683°C

733°C

782°C

832°C

881°C

930°C

954°C

979°C

1004°C

1028°C

1053°C

1077C

1101°C

0.00001

0.0001

0.001

0.01

0.0E+00 5.0E-05 1.0E-04 1.5E-04

Inte

nsi

ty (

V)

Time (s)

SPPS YAG:Tm on SS, Batch 1, #G 365nm Decay, 512 Scan Average

15°C

184°C

288°C

385°C

489°C

587°C

636°C

684°C

733°C

783°C

832°C

881°C

930°C

954°C

979°C

1004°C

1029°C

1053°C

1078C

1102°C

SPPS YAG:Tm(1.0%) Coating Emission Decay Curves

456 nm Decay

365 nm Decay

1D2→3F4

3H6→1D2

Decay behavior os 365nm emission matches

behavior observed at 456nm emission.

Decay rate (slope) sensitive to temperature

for T > 800°C.

-7.00E+00

-6.50E+00

-6.00E+00

-5.50E+00

-5.00E+00

-4.50E+00

-4.00E+00

-3.50E+00

-3.00E+00

-2.50E+00

-2.00E+00

0.00E+00 2.00E-06 4.00E-06 6.00E-06 8.00E-06 1.00E-05

ln (

Inte

nsity(

V))

Time (sec)

PLA=100, 456nm emission

data

fit

600 ns

60%

10%1 = 961 ns

2 = 5.42 µs

Fitting Procedure for Emission Decay

Fitting Window Selection Based on Probe Data

Model for Emission Decay

12

/

2

/

1 ;

DecayialBiexponent

21

tteIeII

Probe

autofluorescence

spike

Back-reflection of

laser pulse along 50 m

fiber optic cable

1. Select 600 ns as I0. (avoids backreflection peak)

2. Intensity-based fitting window from 60% to 10% I0.

3. Fit with double exponential.

4. Discard1.5. Use 2 for temperature indication.

-8.00E+00

-7.00E+00

-6.00E+00

-5.00E+00

-4.00E+00

-3.00E+00

-2.00E+00

0.00E+00 5.00E-07 1.00E-06 1.50E-06 2.00E-06 2.50E-06 3.00E-06

ln (

Inte

nsity(

V))

Time (sec)

PLA=104, 456nm emission

data

fit

600 ns

60%

10%

= 499 ns

Fitting Procedure for Emission Decay

When fit to double exponential is unstable at high temperatures

Fit with single exponential instead

/0

Decay al ExponentiSingle

teII

Simple model with quenching due to thermally activated nonradiative decay

(by cross-over to charge transfer state).

Modeling Decay Time Temperature Dependence

SPPS YAG:Tm 365 & 456nm emission bands

1

𝝉=

𝟏

𝝉𝑹+

𝟏

𝝉𝑵𝑹𝒆− ∆𝑬

𝒌𝑻

1.00E-07

1.00E-06

1.00E-05

1.00E-04

0 200 400 600 800 1000 1200

De

cay

Tim

e (

s)

T (°C)

456 nm

365 nm

fit

Transitioning from Coupon Specimens to Engine

Component Testing

YAG:Tm coated Honeywell stator vane doubletYAG:Tm coated superalloy coupon

YSZ

NiPtAl (Howmet)

25 m

200 m

Vane

YAG:Tm

EB-PVD

(Penn

State)

SPPS

(UConn)SPPS = solution precursor

plasma spray

EB-PVD = electron-beam

physical vapor deposition

NiPtAl (Chromalloy)

25 m

Rene N5

YAG:TmSPPS

(UConn)

2.54 cm diam

1 cm

30.0°.

FOV-Pressure Side FOV-Suction

Side

.

Turbine Vane Doublet

Probe Design for Vane Measurements

Final probe design by Rob Flori, Honeywell.

Constraints for probe design•Do not protrude into gas flow.

•Limited space: integrated excitation & collection.

•End of probe exposed to gas flow temperatures.

•Temperature-sensitive optical components require

cooling.

1x1000µm diam excitation fiber

82x200µm diam excitation fibers

Fiber bundle cross-section

Cooling Fixture for Mounting in Afterburner Flame at

UTSI J85 Test StandHigh-Velocity Exhaust Gas up to 1760ºC

Air-purge

cooling

Water-

cooling

Mounted vane doublet

J85-GE-5 Turbojet Test Stand

0.001

0.01

0.1

1

0.0E+00 5.0E-07 1.0E-06 1.5E-06 2.0E-06 2.5E-06 3.0E-06 3.5E-06 4.0E-06

Inte

nsi

ty (

V)

Time (s)

YAG:Tm 456 nm Decay vs. Temperature from Probe

PLA=96

PLA=98

PLA=100

PLA=102

PLA=104

600 ns

YAG:Tm Emission Decay at Steady-State Afterburner Conditions

456 nm decay

0.001

0.01

0.1

0.0E+00 5.0E-06 1.0E-05 1.5E-05 2.0E-05

Inte

nsi

ty (

V)

Time (s)

YAG:Tm 456 nm Decay vs. Temperature from Probe

PLA=98

PLA=100

PLA=102

PLA=104

Measurements acquired at:

• PLA = 15 (idle)

• PLA = 90 (full military)

• PLA = 94 (with afterburner)

• PLA = 96

• PLA = 98

• PLA = 100

• PLA = 102

• PLA = 104

Each decay was averaged over 16 laser

pulses (20 pulses/s)

PLA = 98 is onset of obvious temperature sensitivity.

0.0001

0.001

0.01

0.1

0.0E+00 5.0E-06 1.0E-05 1.5E-05 2.0E-05 2.5E-05 3.0E-05 3.5E-05

Inte

nsi

ty (

V)

Time (s)

YAG:Tm 365 nm Decay vs. Temperature from Probe

456 nm decay

365 nm decay

0.0001

0.001

0.01

0.1

0.0E+00 5.0E-06 1.0E-05 1.5E-05 2.0E-05

Inte

nsi

ty (

V)

Time (s)

YAG:Tm 365 nm Decay vs. Temperature from Probe

PLA=96

PLA=98

PLA=100

PLA=102

YAG:Tm Emission Decay at Steady-State Afterburner Conditions

Comparison of 456 nm & 365 nm Decay

456 vs 365 nm Decay

PLA = 98

600 ns

2 µs

365 nm Decay

PLA = 96 to 104

2 µs • Much longer, more intense probe

autofluorescence distortion out to 2 µs.

• Can only use decay past 2 µs.

• Data not useable beyond onset of temperature

sensitivity at PLA = 98.

Only 456 nm emission decay could be used

to make temperature measurements for

afterburner tests with probe.

1.0E-07

1.0E-06

1.0E-05

1.0E-04

90 94 96 98 100 102 104

De

cay

Tim

e (

s)

PLA

Decay Time vs PLA Setting

YAG:Tm Emission Decay Time vs. PLA Throttle Setting

Temperature-sensitive range

PLA = 98 is onset of obvious sensitivity of decay time to temperature.

Temperature vs. PLA Throttle Setting(temperature determined from YAG:Tm decay time)

PLA Temp°C

SD°C

98 958.9 +10.0-11.1

100 1114.4 +12.6-11.2

102 1258.0 +4.3-4.1

104 1297.4 +12.3-10.6

• ±5°C at 1250°C!

• 1297°C highest temperature for thermographic phosphor field measurement!

100

101

102

103

104

105

900

950

1000

1050

1100

1150

1200

1250

1300

1350

1400

0 10 20 30 40

PLA

T (°

C)

Time (s)

PLA Ramp 456 nm Emission

Temperature

PLA

T = 1310 ± 14°C

0.001

0.01

0.1

0.0E+00 1.0E-06 2.0E-06 3.0E-06 4.0E-06 5.0E-06 6.0E-06 7.0E-06

Inte

nsi

ty (

V)

Time (s)

456 nm Emission Decay During PLA Ramp

PLA=101

PLA=102

PLA=104

PLA=103

Temperature Measurements During Throttle Accelerationfrom PLA = 94 to 104

~1 Hz temperature reading acquisition rate

Probe Artifacts and Recommended Remedies

• Laser back reflection spike at 530 ns using 50 m

collection fiber optic.

– Remedy: Locate PMT near engine & use short collection fiber.

• Probe introduces distortion of initial decay that is much

more severe for 365 vs. 456 nm emission.

– Greater distortion prevented useful 365 nm emission decay data

from afterburner tests.

– Distortion associated with Raman scattering inside fiber optics

that is worse for 365 nm emission because it is near 355 nm

excitation wavelength.

– Remedy: appropriate short-pass filter at output of laser delivery

fiber and long-pass filter before collection fibers.

Conclusions

• Successfully demonstrated temperature measurements in lab

environment for both blue and UV emission band decays from

YAG:Tm.

• Successfully demonstrated temperature measurements (static &

dynamic) up to 1300°C from YAG:Tm-coated Honeywell stator vane

doublet in afterburner flame of UTSI J85-GE-5 turbojet test stand

using blue YAG:Tm emission band decay.

• Redesign of engine probe optics will allow implementation of UV

YAG:Tm emission band decay for superior rejection of background

reflected combustion radiation.

Acknowledgments

• Funding from NASA Aeronautics Research Mission Directorate.

• AFRL VAATE Project for foundational research and leveraging of

VAATE probe design & cooling mount for afterburner testing.

• Honeywell for providing stator vane doublet & critical aspects of

probe design.

• AEDC/UTSI Propulsion Research Facility Team for conducting J85

afterburner tests.

• Penn State (Doug Wolfe) for EB-PVD coatings.

• UConn (Eric Jordan & Jeff Roth) for SPPS coatings.

• Dave Beshears (EMCO) for testing assistance.