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Light sheet fluorescence microscopic imaging for high-resolution visualization of spray dynamics

Berrocal, Edouard LU ; Kristensson, Elias LU and Zigan, Lars (2018) In International Journal of Spray and Combustion Dynamics 10(1). p.86-98
Abstract

In this study, the use of light sheet fluorescence microscopic imaging is demonstrated for viewing the dynamic of atomizing sprays with high contrast and resolution. The technique presents several advantages. First, liquid fluorescence gives a more faithful representation of the structure of liquid bodies, droplets, and ligaments than Mie scattering does. The reason for this is that the signal is emitted by the fluorescing dye molecules inside the liquid itself and not generated at the air–liquid interfaces. Second, despite the short depth of field (∼200 µm) obtained when using the long range microscope, the contribution of out-of-focus light is much smaller on a light sheet configuration than for line-of-sight detection, thus providing... (More)

In this study, the use of light sheet fluorescence microscopic imaging is demonstrated for viewing the dynamic of atomizing sprays with high contrast and resolution. The technique presents several advantages. First, liquid fluorescence gives a more faithful representation of the structure of liquid bodies, droplets, and ligaments than Mie scattering does. The reason for this is that the signal is emitted by the fluorescing dye molecules inside the liquid itself and not generated at the air–liquid interfaces. Second, despite the short depth of field (∼200 µm) obtained when using the long range microscope, the contribution of out-of-focus light is much smaller on a light sheet configuration than for line-of-sight detection, thus providing more clearly sectioned images. Finally, by positioning the light sheet on the spray periphery, toward the camera objective, the effects due to multiple light scattering phenomena can be reduced to some extent. All these features provide, for many spray situations, good fidelity images of the liquid fluid, allowing the extraction of the velocity vectors at the liquid boundaries. Here, double frame images were recorded with a sCMOS camera with a time delay of 5 µs between exposures. A typical pressure-swirl atomizer is used producing a water hollow-cone spray, which was imaged in the near-nozzle region and further downstream for injection pressures between 20 bar and 100 bar. Furthermore, near-nozzle spray shape visualization of a direct-injection spark ignition injector was conducted, describing the disintegration of the liquid fuel and droplet formation. Such data are important for the validation of computational fluid dynamics models simulating liquid breakups in the near-field spray region.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Atomization, faithful imaging, liquid fluorescence, microscopic imaging, spray dynamics
in
International Journal of Spray and Combustion Dynamics
volume
10
issue
1
pages
13 pages
external identifiers
  • scopus:85041961504
ISSN
1756-8277
DOI
10.1177/1756827717734078
language
English
LU publication?
yes
id
431a56cc-dd84-43c0-9c40-a34b49781792
date added to LUP
2018-02-20 12:44:18
date last changed
2018-05-29 12:26:14
@article{431a56cc-dd84-43c0-9c40-a34b49781792,
  abstract     = {<p>In this study, the use of light sheet fluorescence microscopic imaging is demonstrated for viewing the dynamic of atomizing sprays with high contrast and resolution. The technique presents several advantages. First, liquid fluorescence gives a more faithful representation of the structure of liquid bodies, droplets, and ligaments than Mie scattering does. The reason for this is that the signal is emitted by the fluorescing dye molecules inside the liquid itself and not generated at the air–liquid interfaces. Second, despite the short depth of field (∼200 µm) obtained when using the long range microscope, the contribution of out-of-focus light is much smaller on a light sheet configuration than for line-of-sight detection, thus providing more clearly sectioned images. Finally, by positioning the light sheet on the spray periphery, toward the camera objective, the effects due to multiple light scattering phenomena can be reduced to some extent. All these features provide, for many spray situations, good fidelity images of the liquid fluid, allowing the extraction of the velocity vectors at the liquid boundaries. Here, double frame images were recorded with a sCMOS camera with a time delay of 5 µs between exposures. A typical pressure-swirl atomizer is used producing a water hollow-cone spray, which was imaged in the near-nozzle region and further downstream for injection pressures between 20 bar and 100 bar. Furthermore, near-nozzle spray shape visualization of a direct-injection spark ignition injector was conducted, describing the disintegration of the liquid fuel and droplet formation. Such data are important for the validation of computational fluid dynamics models simulating liquid breakups in the near-field spray region.</p>},
  author       = {Berrocal, Edouard and Kristensson, Elias and Zigan, Lars},
  issn         = {1756-8277},
  keyword      = {Atomization,faithful imaging,liquid fluorescence,microscopic imaging,spray dynamics},
  language     = {eng},
  month        = {03},
  number       = {1},
  pages        = {86--98},
  series       = {International Journal of Spray and Combustion Dynamics},
  title        = {Light sheet fluorescence microscopic imaging for high-resolution visualization of spray dynamics},
  url          = {http://dx.doi.org/10.1177/1756827717734078},
  volume       = {10},
  year         = {2018},
}