Fuel Jet in Cross-flow: Experimental Study of Fuel ...the lab’s high temperature jet in cross-flow facility (schematic of the test section shown in Figure 2). The facility consisted

ILASS Americas, 25th Annual Conference on Liquid Atomization and Spray Systems, Pittsburgh, PA, May 2013

Fuel Jet in Cross-flow: Experimental Study of Fuel Concentration and Temperature

Distributions at Elevated Temperature of the Crossing Flow using Planar Laser-

Induced Phosphorescence

Z. P. Tan*, E. Lubarsky

*, O. Bibik, D. Shcherbik and B. T. Zinn

School of Aerospace Engineering

Georgia Institute of Technology

Atlanta, Georgia 30332-0150 USA

Abstract

This paper describes an experimental investigation of concentration- and temperature-distributions across a

spray from injection of liquid Jet-A into cross-flowing air (JICF) at elevated temperatures encountered in

modern gas turbines. Fuel was injected at room temperature from a 0.671mm dia. orifice (flow coefficient

𝐶𝐷 = 0.683) on the wall of a rectangular air channel (25.4×31.75mm), where air temperature was 𝑇 ≤ 600𝐾.

Thus, Jet-A may exist in liquid or gaseous phases within the spray-pattern, and local temperature of fuel may

exceed 𝑇 > 300𝑜𝐶 at which conventional jet-fuel fluorescence used for concentration-measurements becomes

ineffective. Therefore, a new Planar Laser-Induced Phosphorescence (PLIP) technique to measure local

concentrations in all phases in the expected temperature range was developed and implemented, along with Mie-

scattering for droplets-detection. In PLIP, liquid Jet-A is uniformly-seeded with micron-size phosphor before

being injected into cross-flow; the resulting spray will be illuminated by planar laser (355nm), and subsequently

give off phosphorescence and Mie-scattering signals. The phosphorescence signals will have many bands with

intensities that are overall proportional to concentration, but differently sensitive to temperature. Thus, intensity

ratios between two bands (collected by separate cameras) will be used to determine local temperatures, and

corrected for local Jet-A concentrations. Initially, nano-sized Dysprosium-based phosphor (Dy:YAG) was

investigated for PLIP, but bench-top tests showed that it had weak phosphorescence not good enough for CCD

cameras, even though temperature-sensitivity was good. Therefore, the phosphor of choice was switched to

Europium-based YVO4:Eu, which the same bench-top tests showed had much higher emission intensities.

Initial in-rig spray-test at elevated temperature confirmed that YVO4:Eu phosphorescence in spray was visible

to a camera without intensifier, even at short exposures suitable for PLIP. Next, a three-camera imaging-system

(required for PLIP/Mie-based technique) is to be applied to rig-tests for detailed spray-characterization

(concentration/temperature-distributions and phases), which will cover spray-pattern of ~70×30 jet-diameters

(along and across the spray, respectively).

* Corresponding authors: [email protected], [email protected]


1

Introduction

In support of future gas-turbine

development, the study of spray characteristics

(including column break-up point, spray trajectory,

gas/liquid interface, concentration distribution and

temperature) when liquid fuel (Jet-A) is injected as

a jet into high-temperature (T) cross-flowing air

(JICF) is a very important overarching goal for

researchers. The high-T cross-flow simulates

increasing combustor temperatures in modern gas

turbines, where significant vaporization of fuel can

occur prior to combustion. This paper details the

development of a new optical diagnostic technique

specially suited for such high-T multi-phase flow

JICF studies.

In the past, characterization of spatial

distributions of liquid- and gaseous-phase fuel

using a combination of Jet-A planar laser-induced

fluorescence (PLIF) and Mie-scattering imaging

techniques have been attempted for high-T JICF.

PLIF relies on exciting liquid and gaseous Jet-A by

266nm or 355nm laser-sheet; the fluorescence

emission given off during relaxation allows a CCD

camera to image both phases of the fuel. Mie-

scattering is based on the scattering of laser light

off droplets, and so allows detection of liquid fuel

exclusively. Subtracting Mie from PLIF data,

profiles of gaseous fuel can be found. It was found

in the past that liquid-phase fuel detected using

Mie-scattering correlated well with shadowgraph

data [1]. However, because Jet-A fluorescence

intensity strongly depends on temperature and

approaches zero at higher-temperatures, PLIF

cannot be applied to high-T gaseous-fuel-detection.

Thus, a new PLIF-replacement technique

based on phosphorescence, called the two-line

intensity-ratio method of Planar Laser-Induced

Phosphorescence (PLIP) was developed. The

technique have been used in the past in similar

forms by different investigators, with promising

potential for solving PLIF’s short-comings, as well

as adding precise temperature/concentration-

detection capabilities. Concentration measurement

in JICF using PLIP is a unique new application

developed by the authors of this paper.

For the application of PLIP, two common

methods exist: 1) decay-rate method, and 2) two-

line intensity-ratio method. The first method

involves using the temperature-depending emission

rate of decay from special phosphorescing agents,

which can be used to extract 2D temperature profile

of a sample that is excited by pulse laser [2],[3].

The rate of decay can be measured either by

directing emission signal after a single pulse onto

an array of imaging sensors for successive

exposures (as done by Omrane et al.) or captured

using a high-speed video camera [4]. However, for

both methods of imaging, because sprayed droplets

can move very quickly, multiple sequential

exposures will lead to large spatial error that is not

acceptable. Thus, for spray diagnostics, the two-

line intensity-ratio method is more suitable.

The concept of two-line intensity-ratio PLIP is

based on phosphors with different emission bands

whose intensities exhibit different temperature-

sensitivities, while having negligible sensitivity to

pressure and oxygen collisional quenching (all of

which affected PLIF). To apply PLIP, test fuels are

seeded by phosphor particles and excited by laser-

sheet in a test-channel. Two different bands of the

resulting phosphorescence emission are captured

by separate cameras (or one camera with a

stereoscope), and the ratio of their intensities

correlated directly to local temperatures. Brubach

et al. [5] demonstrated the viability of intensity-

ratio PLIP in sprays of liquid n-dodecane using

Mg4GeO5.5F:Mn phosphor. A good linear response

of intensity-ratio to temperature was obtained in the

range of 300-440K, but Brubach also concluded

that the particular choice of phosphor produced

data with higher standard deviations for high

temperatures, partly due to spray evaporation.

A notable research which extended the

intensity-ratio method to higher temperatures,

multi-phase reacting-flow was conducted by

Hasegawa et al. [6] In Hasegawa’s experiment,

measurements were done on 50-50 mix of iso-

octane/n-heptane and air, which had some

similarity with Jet-A/air mix. The fuel mixture was

seeded with a Dysprosium-based phosphor

(Dy:YAG), injected into a simulated diesel engine

cylinder with transparent optical access section,

and subsequently combusted. Dy:YAG is a

common choice among researchers for high-

temperature or reacting-flow PLIP due to its high

functional temperature and wide temperature range

[7],[8]. Hasegawa’s measurements were done

before and after peak combustion, demonstrating

Dy:YAG’s good flexibility with different

conditions/mixture compositions. Data from their

experiment provided 2D temperature profiles at

different phases of the engine cycle, which agreed

to within 5% of calculation for ignition of diesel

engine. However, Hasegawa noted a 2% mixture T-

drop as a result of phosphor seeding, where the

median particle size was 4𝜇𝑚.

Hasegawa’s experiment successfully

demonstrated phosphor thermometry, but it did not

provide distinction between liquid and gas phases,

or information on fuel concentration distribution

within the test section, both of which were

important to studying fuel jet in cross-flow. For this


2

purpose, liquid/gas distinction can be accomplished

by adding provision for Mie-scattering imaging that

only detects liquid. And, if fuel can be uniformly

seeded with known phosphor particle concentration,

2D fuel concentration distributions can be found

from absolute phosphorescence intensity after

correcting for temperature effects. Thus, a three-

camera system needs to be developed for spray

diagnostics (2 phosphorescence cameras and 1

Mie), along with selection of the suitable phosphor

for PLIP application in JICF.

In summary, the general goal of this JICF

study is to characterize the concentration,

temperature and phases of a Jet-A spray in high-T

cross-flowing air. Meanwhile, the specific

objectives covered in the paper are: 1) development

of PLIP system and assessment of suitable

phosphorescing agents on a bench-top setup, and 2)

concept verification of PLIP using simplified

camera system in high-T JICF rig.

Test Results

Experimental Procedures

Dy:YAG powders supplied by the Georgia

Tech Research Institute (GTRI) and Phosphor

Technology Ltd in UK (which also supplied

Hasegawa et al.) were tested on a bench-top setup

(Figure 1). The powders were dry-coated on

ceramic bars (representing 100% Dy:YAG

concentration) and diluted in Jet-A/water (at

similar % anticipated for JICF study), then placed

in front of a spectrometer that recorded

phosphorescence spectra during pulse excitation by

Nd:YAG laser. The laser’s 3rd

harmonic (355nm)

was used for excitation, similar to Hasegawa’s

experiment, while other harmonics were diverted

away. To investigate Dy:YAG’s intensity-ratio

response to T, the powder was also dry-coated onto

a quartz cube and placed on top of heater, while

spectrometer recorded phosphorescence emission

spectra at different temperatures up to ~650oC. This

method of investigating intensity-ratio temperature-

sensitivity was similar to a previous study at

Georgia Tech [9], where Dy:YAG was also

investigated and shown nearly linear intensity-ratio

trend between 7 to 1087 oC.

In latter period of PLIP development when

Dy:YAG was deemed unsuitable and the phosphor

of choice was switched to YVO4:Eu, identical

bench-top tests were performed again. After

confirming YVO4:Eu to have appropriate

characteristics for JICF study, a 0.5gal sample of

Jet-A seeded with ~1wt.% YVO4:Eu was tested in

the lab’s high temperature jet in cross-flow facility

(schematic of the test section shown in Figure 2).

The facility consisted of a 1in × 1.25in channel that

can supply 75m/s of airflow at close to 500oC in the

test-section. Three windows around the fuel

injector allowed optical access for phosphor-

excitation and camera-imaging. Only one color-

camera was used initially for concept-verification.

Figure 3 shows the fuel system used to inject

seeded-Jet-A. Fuel can be filled into a 1gal tank

from an external line, and YVO4:Eu paste (or

seeded fuel) can be introduced from the top of tank.

Ultrasound actuators at the bottom of the tank

increased uniformity of the phosphor concentration

in Jet-A (crucial for concentration measurement).

The fuel system was pressurized with nitrogen, and

injection was regulated by the fuel supply control

valve. When not injecting, the line to injector was

purged with nitrogen to ensure Jet-A does not coke

due to high temperatures.

Bench-top Characterization of Dyprosium-doped

Phosphor (Dy:YAG)

Unlike Hasegawa’s experiment using micron-

sized Dy:YAG, the PLIP development of this paper

attempted application of nano-sized particles, in

order to 1) minimize abrasion damage to injector

nozzle, and 2) minimize effect of phosphor

particles on spray. This came with the disadvantage

that grinding down phosphor crystals to nano-size

reduces their phosphorescence efficiency. Since

Phosphor Technology Ltd. (UK) only sold micron-

sized Dy:YAG, Georgia Tech Research Institute

(GTRI) was commissioned to investigate and

produce experimental nano-Dy:YAG (<~50nm)

that can form a stable colloidal solution in Jet-A.

Figure 4 presents the spectra of Dy:YAG

phosphorescence from GTRI and UK samples

taken with spectrometer, superimposed on literature

spectra taken from Goss et al. [10]. The samples in

this plot were coated on dry ceramic such that they

should represent maximum emission from pure

phosphor powder. Measurements were repeated for

coatings applied using glue binder and using water

alone (which when evaporated left pure phosphor).

The differences caused by binder were negligible.

In general, the measured spectra matched Goss’

results at the appropriate temperature very well,

validating the quality of available powder and ease

of repeatability using simple optical setups.

However, it was noticed that GTRI’s nano-

phosphor provided significantly lower intensities

than UK’s micron-sized phosphor.

After dry-ceramic measurements, spectra of

GTRI’s Dy:YAG in Jet-A were captured. Phosphor

concentrations in the mixtures were 1 weight%

unless otherwise stated. To isolate phosphorescence


3

from Jet-A fluorescence, spectra for pure Jet-A and

Dy:YAG in water (non-fluorescing) were also

measured and plotted together with Jet-A/Dy:YAG

spectrum in Figure 5. At room T/p,

phosphorescence signals (in dotted circle) were

very low, with significant interference from Jet-A

fluorescence (apparent when contrasted against

non-fluorescing seeded water). But despite having

poor signal-to-noise ratio, when the spectra of

seeded-water and seeded-Jet-A (subtracted by pure

Jet-A fluorescence) are plotted together with dry-

phosphor spectrum in Figure 6, the characteristic

Dy:YAG band patterns can be easily identified.

The amount of fluorescence interference was also

expected to reduce at higher T regions (as observed

in the group’s earlier PLIF works).

To characterize Dy:YAG’s effectiveness for

temperature measurement, the coated dry-ceramic

sample was heated on an electric heater while its

phosphorescence spectra were taken. It was

observed that phosphorescence intensity did not

vary monotonously with T, or in fact vary in the

same direction across different bands. When

normalized by the peak-intensity in 496nm,

however, (as done in Goss’ paper) the signals in

other wavelengths all showed substantial rising

trend with T (Figure 7). They also showed that

there are multiple bands which can be used to

compare against the 496nm band for intensity-ratio

temperature-measurement method, providing some

flexibility in application.

Despite having well-defined and

reproducible spectra in Jet-A, Dy:YAG had low

emission intensity at low T that overlapped with

Jet-A fluorescence, especially nano-size Dy:YAG.

Because temperatures of injected fuel in the JICF

study can range from room-temperature to 500oC,

the contribution of Jet-A fluorescence will be an

unknown factor. Thus, Dy:YAG was found to be

unsuitable for temperature/concentration

measurements, and another type of phosphor was

investigated.

Bench-top Characterization of Europium-doped

Phosphor (YVO4:Eu)

Since Dy:YAG had insufficient performance

for high-T JICF study, GTRI suggested YVO4:Eu.

This new phosphor was untested in combustion

imaging settings because it had more limited T

range for intensity-ratio T-measurement method.

However, the limitation was acceptable for spray

experiments.

Using the same bench-top setup as Dy:YAG

investigation, spectra of both Dy:YAG and micron-

size YVO4:Eu each mixed to 1wt.% in Jet-A were

taken. Plot of the results in Figure 8 confirmed that

at room T/p YVO4:Eu’s bands of interest (orange

dotted box) were situated further from Jet-A

fluorescence, and were approximately 20 times

stronger in intensity than Dy:YAG’s bands (blue

boxes). When subjected to varying T’s, YVO4:Eu

also displayed bands with varying temperature

sensitivities, much like Dy:YAG. The 618-620nm

band was strongest and denoted “Main-band”,

where it will play the role of denominator in two-

line intensity-ratio thermometry. Figures 9 and 10

provide more detailed views of the bands, when

normalized by Main-band. When T rises, the

second peak and most other bands rise

monotonically with respect to Main-band, which is

required for intensity-ratio PLIP.

Figure 11 shows that when the source of

excitation is 355nm in wavelength, the absolute

intensities of YVO4:Eu phosphorescence rise then

drop with T. This is because 355nm is situated on

the shoulder of YVO4:Eu’s bell-shaped absorption

spectrum, which shifts for stronger absorption and

hence stronger absolute emission as T rises.

Intensities will eventually drop at much higher T

due to opening-up of other non-phosphorescent

relaxation pathways. This was the cause of

increased data noise particularly for the highest

temperature test-point in Figures 9 and 10. The

unique behavior of rising and dropping intensity

can be used to balance the effects from decreasing

fuel/phosphor concentrations along the length of

spray while fuel T rises, to reduce over/under-

exposing cameras.

In Figure 12, intensity ratio trends are

displayed for three combinations of bands, each

with the Main-band as denominator. All three

trends were almost linear (constant sensitivity)

throughout the T range of ~50-500oC, but the

combination using 535-618nm as numerator was

most attractive, since it included the widest range

of integrated intensities for numerator, hence the

strongest signal-to-noise ratio. To transition from

spectrometer one-point measurement to 2D spray

imaging, CCD cameras with appropriate filters

have to be used. As included in Figure 12,

simulated off-the-shelf Semrock Filters can closely

match the preferred bands-combination.

More bench-top tests were also run to assess

the performance of nano-YVO4:Eu provided by

GTRI. The spectra of nano-Eu were found to be

very similar to micron-Eu, except for the reversed

order of the strongest and second strongest peaks.


4

Using the same bands as micron-Eu, intensity ratios

of nano-Eu provided similar T-sensitivity to

micron-Eu. But, nano-YVO4:Eu had very weak

signals and was particularly difficult to capture

within the spectrometer’s limited dynamic range.

As a matter of fact, under the same conditions,

micron-size YVO4:Eu was up to 30 times brighter

than nano-Eu. Thus, if injector material is resistant

to abrasion, micron-size YVO4:Eu is preferred.

The degree to which micron-particles influence

spray characteristics is a subject for future

investigations.

Concept-verification Experiment at High Crossing

Flow Temperature

Following bench-top characterization of

YVO4:Eu, a high-temperature JICF test was

conducted to get visual evidence of Eu-

phosphorescence for concept-verification. While

the final optical system for phosphorescence

imaging will include three cameras (one for Mie-

scattering, and one each for the two

phosphorescence bands), only a simplified one-

camera system was installed for the first test. The

camera can capture fluorescence, Mie-scattering

and Eu-phosphorescence simultaneously in color at

1280x1024px resolution, and was synchronized to

355nm Nd:YAG laser pulse rate of 10Hz. Test

conditions for the first test were set to high-T and

relatively low-p, which promoted vaporization of

fuel so multi-phase flow-detection can be tested.

Found in Figure 13 are 150-frames-averaged

images representing one set of test conditions with

and without YVO4:Eu seeding. First, with only

pure Jet-A at high-T, low-p, the fuel fluoresced

strongly (blue) near the injector when it was still

cold. Then as it was heated by hot ambient air,

fluorescence disappeared, and only Mie-scattering

signal (green) remained. Further down, as droplets

vaporized into gaseous Jet-A, Mie-scattering

disappeared too, and the spray was no longer

visible. With seeded Jet-A, the same trends with

fluorescence and Mie-scattering occurred, but the

gaseous portion of spray glowed orange with

phosphorescence. Regions with fluorescence and

Mie-scattering were also brighter, due to

underlying phosphorescence signal. In general, the

in-rig phosphorescence test showed promising

results for YVO4:Eu. It produced easily visible

signals without requiring any special camera

intensifier, and had no issue providing detection

capability for gaseous fuel.

It is also worth remarking that Dy:YAG and

YVO4:Eu powders were both not naturally soluble

in liquid Jet-A. Undisturbed, micron-size phosphor

particles will quickly agglomerate and sediment at

the fuel tank’s bottom. During tests with seeded

fuel, sedimentation was a noticeable concern.

Figure 14 shows concentrations of phosphor in

seeded Jet-A at different tank depths after 2hr in

the tank. During the entire period, three 40W

ultrasonic transducers mounted on the tank’s

bottom provided ultrasonic agitation to the mixture.

The figure suggests that majority of YVO4:Eu

powder sank to the bottom, leaving a highly

concentrated lower zone, and a nearly uniform-

concentration upper zone. At the point of writing,

other techniques are being investigated to more

effectively disperse phosphor, including: fuel

recirculation/sediment re-deposition, more

powerful ultrasound, and surface-coating treatment.

Concluding Remarks and Future Plans

Despite efforts at optimization, Dy:YAG

phosphor, which was used by Hasegawa and

many other researchers (mostly in the form of

surface coating T measurement), was found to

be unsuitable for cross-flow spray studies

because of its weak phosphorescence signals.

This is especially the case when the spray

consist of Jet-A, which had natural

fluorescence wavelengths that overlap with

Dy:YAG phosphorescence.

Extensive bench-top tests and subsequent

high-T jet in cross-flow test showed that

YVO4:Eu had brighter phosphorescence

emission than Dy:YAG, and also emission

bands of interest in longer wavelengths

(further away from Jet-A fluorescence). It had

more limited applicable T-range compared to

Dy:YAG, but was adequate for spray

experiments. As such, YVO4:Eu is the

preferable phosphor for detecting temperature,

concentration distribution, and gas/liquid fuel

interface in JICF studies.

For future work, a 3-camera optical diagnostic

system for the high-temperature rig will be

completed, and the PLIP technique will be

fully tested for concentration, temperature and

phase-detection capabilities. At the same time,

investigation into nano-size phosphors and

more phosphor dispersion techniques will

continue.


5

References

1. Gopala, Y. et al., “Liquid Fuel Jet in

Crossflow- Trajectory Correlations based on

the Column Breakup Point,” 48th AIAA

Aerospace Sciences Meeting Including the

New Horizons Forum and Aerospace

Exposition, Orlando, Florida, USA, January

2010.

2. Omrane, A. et al., “Development of

Temperature Measurements Using

Thermographic Phosphors: Applications for

Combustion Diagnostics.”

3. Omrane, A. et al., “2D-Temperature Imaging

of Single Droplets and Sprays Using

Thermographic Phosphors,” Appl. Phys. B, 79:

431-434 (2004).

4. Someya, S. et al., “Lifetime-based Phosphor

Thermometry of an Optical Engine Using a

High-speed CMOS Camera,” International

Journal of Heat and Mass Transfer, 54: 3927-

3932 (2011).

5. J. Brubach et al., “Spray Thermometry Using

Thermographic Phosphors,” Appl. Phys. B, 83:

499-502 (2006).

6. Hasegawa, R. et al., “Two-dimensional Gas-

phase Temperature Measurements Using

Phosphor Thermometry,” Appl. Phys. B, 88:

291-296 (2007).

7. Alden, M. et al., “Thermographic Phosphors

for Thermometry: A Survey of Combustion

Applications,” Progress in Energy and

Combustion Science, 37: 422-461 (2011).

8. Heyes, A. L., “On the Design of Phosphors for

High-Temperature Thermometry,” Journal of

Luminescence, 129: 2004-2009 (2009).

9. Jain, N. et al., “Characterization of

Thermophosphor Particles for Simultaneous

Imaging of Velocity and Temperature,” 49th

AIAA Aerospace Sciences Meeting Including

the New Horizons Forum and Aerospace

Exposition, Orlando, Florida, USA, January

2011.

10. Goss, L. P. et al., “Surface Thermometry by

Laser-Induced Fluorescence,” Rev. Sci. Intrum.,

60: 3702 (1989).

Figure 1. Pictures and schematic of samples and bench-top phosphor-characterization setup.


6

Figure 2. Schematic of jet in cross-flow test section.

Figure 3. Schematic of cross-flow rig’s fuel system.


7

Figure 4. Spectra of GTRI and UK Dy:YAG coated on ceramic with and without glue binder, at room T/p.

Background: spectra of Dy:YAG as measured by Goss et al. [10].

Figure 5. Spectra of pure Jet-A, and GTRI Dy:YAG mixed in Jet-A and water at 1wt.% concentration. Peak for

water mixture at ~532nm was due to misaligned 532nm laser that lit the sample during measurement.

0

500

1000

1500

2000

2500

427.8 447.8 467.8 487.8 507.8

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eve

l

Wavelength (nm)

Dy:YAG Coated Ceramic Phosphorescence (355nm Laser)

GTRI w/ Binder

GTRI w/o Binder

UK w/ Binder

UK w/o Binder

0

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1000

1500

2000

2500

3000

3500

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300 350 400 450 500 550 600 650 700

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Dy:YAG Phosphorescence (355nm Laser, GTRI second batch)

DyYAG in Jet-A

DyYAG in Water

Jet-A Only (Normalized)


8

Figure 6. Phosphorescence spectra from samples on dry-ceramic (arbitrarily scaled to fit), in water, and in Jet-A

(minus Jet-A fluorescence).

Figure 7. Dy:YAG spectra at different temperatures, normalized by the 496nm peak.

0

50

100

150

200

250

300

450 460 470 480 490 500 510 520 530

Inte

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Dy:YAG Phosphorescence (355nm Laser, GTRI second batch)

DyYAG in Jet-A w/ Fluor Subtracted

DyYAG in Water

GTRI 1st Batch Ceramic (arbitrary absolute intensity)

0

0.2

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49

6.9

5nm

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ize

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496nm-Normalized Spectra of GTRI Dy:YAG at Different T's

50oC

150oC

250oC

350oC

450oC

552oC

650oC


9

Figure 8. Comparison of Dy:YAG and YVO4:Eu spectra. Dotted boxes contain the bands of interest for

intensity-ratio PLIP: Dy:YAG (blue) and YVO4:Eu (orange).

Figure 9. Main-band-normalized spectra of YVO4:Eu (zoomed in at 600-640nm region).

0

0.2

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600 605 610 615 620 625 630 635 640

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Peak-Normalized Spectra of YVO4:Eu at Different T's

59oC

150oC

249oC

350oC

450oC


10

Figure 10. Main-band-normalized spectra of YVO4:Eu (zoomed in at 530-600nm region).

Figure 11. Absolute intensity variations of three bands at different T’s, with 355nm laser excitation.

Peak-Normalized Spectra of YVO4:Eu at Different T's

0

0.05

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YVO4:Eu Integral Intensity vs. T @ 355nm Excitation

Main-band (618-620nm)

Band 1 (600-618nm)

Band 2 (535-592nm)


11

Figure 12. Intensity ratios using different combinations of bands. Intensity ratio trend using off-the-shelf

Semrock filters (simulated with data from Semrock) is also included.

Figure 13. Averaged spray images from cross-flow test with/without YVO4:Eu-seeding.

0

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YVO4:Eu Intensity Ratios vs. T

(535-592nm)/(618-620nm)

(600-618nm)/(618-620nm)

(535-618nm)/(618-620nm)

Simulated Semrock Filters set


12

Figure 14. Concentration results from tank-sampling test. Left-side of abscissa represents top of tank, and vice-

versa. Horizontal iso-concentration lines are established from known-concentration samples. Initial tank mixture

was 1wt.% phosphor.

Documents

Fuel Jet in Cross-flow: Experimental Study of Fuel ...the lab’s high temperature jet in cross-flow facility (schematic of the test section shown in Figure 2). The facility consisted