Characterisation of the luminescence properties of BAM:Eu²⁺ particles as a tracer for Thermographic Particle Image Velocimetry
File(s)
Published version
Accepted version
Author(s)
Fond, B
Abram, Christopher
Beyrau, Frank
Type
Journal Article
Abstract
Thermographic phosphor particles are seeded into the flow as tracers for
simultaneous temperature and velocity measurements in fluids. Several studies using different
phosphors as gas phase tracers have been published in recent years. However little is known
about their emission characteristics when they are dispersed as individual particles in the
fluid. In this paper, the luminescence properties of BAM:Eu²⁺ particles, a phosphor with
favourable characteristics (short luminescence lifetime, blue emission spectrum, high
quantum efficiency) are thoroughly investigated in the gas-phase. Using a recently developed
particle counting tool, the emission intensity per particle is measured over a wide range of
conditions, including for various temperatures from 300 to 920 K, in air and in pure nitrogen.
The luminescence emission per particle is shown to drop with temperature, but to be
insensitive to the seeding density and to the oxygen content over the tested range.
Together with a spectroscopic study, and a statistical error analysis, these results are used to
predict the temperature precision of the technique under various conditions for different filter
combinations and to assess the current upper temperature limit of this phosphor for practical
applications. Potential additional sources of uncertainties are also investigated, including
cross dependencies of the measured intensity ratio on the seeding density, excitation fluence
and oxygen partial pressure in the gas phase. Only a weak dependence on the laser fluence is
observed, while the measured intensity ratio is shown to be insensitive to both seeding density
and the oxygen volume fraction. Finally, the saturation behaviour of the phosphorescence
emission is examined, through theoretical considerations and measurements performed with
different excitation schemes in an attempt to increase signal levels. In conclusion, this paper
confirms that BAM:Eu²⁺ is a very suitable tracer for measurements in turbulent flows up to
900 K.
simultaneous temperature and velocity measurements in fluids. Several studies using different
phosphors as gas phase tracers have been published in recent years. However little is known
about their emission characteristics when they are dispersed as individual particles in the
fluid. In this paper, the luminescence properties of BAM:Eu²⁺ particles, a phosphor with
favourable characteristics (short luminescence lifetime, blue emission spectrum, high
quantum efficiency) are thoroughly investigated in the gas-phase. Using a recently developed
particle counting tool, the emission intensity per particle is measured over a wide range of
conditions, including for various temperatures from 300 to 920 K, in air and in pure nitrogen.
The luminescence emission per particle is shown to drop with temperature, but to be
insensitive to the seeding density and to the oxygen content over the tested range.
Together with a spectroscopic study, and a statistical error analysis, these results are used to
predict the temperature precision of the technique under various conditions for different filter
combinations and to assess the current upper temperature limit of this phosphor for practical
applications. Potential additional sources of uncertainties are also investigated, including
cross dependencies of the measured intensity ratio on the seeding density, excitation fluence
and oxygen partial pressure in the gas phase. Only a weak dependence on the laser fluence is
observed, while the measured intensity ratio is shown to be insensitive to both seeding density
and the oxygen volume fraction. Finally, the saturation behaviour of the phosphorescence
emission is examined, through theoretical considerations and measurements performed with
different excitation schemes in an attempt to increase signal levels. In conclusion, this paper
confirms that BAM:Eu²⁺ is a very suitable tracer for measurements in turbulent flows up to
900 K.
Date Issued
2015-11-23
Date Acceptance
2015-10-28
Citation
Applied Physics B - Lasers and Optics, 2015, 121 (4), pp.495-509
ISSN
0946-2171
Publisher
Springer
Start Page
495
End Page
509
Journal / Book Title
Applied Physics B - Lasers and Optics
Volume
121
Issue
4
Copyright Statement
© The Author(s) 2015. This article is published with open access at Springerlink.com
License URL
Subjects
Science & Technology
Physical Sciences
Optics
Physics, Applied
Physics
GAS-PHASE THERMOMETRY
DEGRADATION MECHANISM
PHOSPHOR THERMOMETRY
HIGH-PRESSURE
TEMPERATURE
SATURATION
EXCITATION
EU2+
VELOCITY
FLOW
Optoelectronics & Photonics
0205 Optical Physics
0906 Electrical And Electronic Engineering
0913 Mechanical Engineering
Publication Status
Published