Three-dimensional measurement of the local extinction coefficient in a dense spray

Wellander, Rikard; Berrocal, Edouard; Kristensson, Elias; Richter, Mattias; Aldén, Marcus

doi:10.1088/0957-0233/22/12/125303

Cited by 31 publications

(22 citation statements)

References 28 publications

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“…From this data set, a final demodulated SLIPI image can be extracted, wherein the contribution from the multiply scattered light has been reduced (Berrocal et al 2008). However, due to the need for recording three sub-images, SLIPI has been mostly used for temporally averaged measurements of spray quantities such as droplet SMD in sprays (Mishra et al 2014), 3D-mapping of the droplet extinction coefficient (Wellander et al 2011), spray temperature using two-color LIF , as well as flame temperature using Rayleigh thermometry (Kempema and Long 2014). Note that SLIPI has also been demonstrated for 'instantaneous' imaging of rapidly occurring events (Kristensson et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Comparison between two-phase and one-phase SLIPI for instantaneous imaging of transient sprays

et al. 2017

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images with an intensity profile close to the corresponding single scattering case. Experimentally, this suppression renders both an improvement in image contrast and the removal of undesired stray light components that could be interpreted as signal. However, while 2p-SLIPI preserves most of the initial spatial resolution, 1p-SLIPI results in a loss of spatial resolution, where high-frequency image information is not visible anymore. Thus, there is a tradeoff between preserving the most detailed information of the spray structure-with 2p-SLIPI-and being able to record an SLIPI image from a single modulated image only-with 1p-SLIPI. The comparison and technical overview of these two methods presented in this paper can facilitate in selecting which approach is the most suitable for a given application for spray visualization.

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Section: Introductionmentioning

confidence: 99%

Comparison between two-phase and one-phase SLIPI for instantaneous imaging of transient sprays

et al. 2017

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“…While a number of techniques have been developed to investigate important phenomena such as liquid breakup processes in the optically dense near-field of sprays [5][6][7][8], relatively few of these techniques have focused on binary liquid mixing prior to the onset of significant breakup and atomization. Conventional methods such as mechanical patternators [9,10] are ineffective in regions where the jets have not fully broken up into droplets, and laser-induced fluorescence [11][12][13] and attenuation techniques [2] suffer from complex refraction patterns at the highly deformed phase interfaces that develop near the impingement point.…”

Section: Introductionmentioning

confidence: 99%

“…Hence, in addition to demonstrating the use of x-ray fluorescence for studies of liquid mixing, this work evaluates different methods to correct for signal reabsorption and ensure quantitative accuracy. This includes a radiographic technique that relies on time-intensive attenuation measurements along multiple lines of sight (analogous to [7]) to determine RPL and correct for x-ray fluorescence reabsorption, as well as a multiple-tracer approach that allows for corrections to be performed on an instantaneous basis. The latter takes advantage of the unique path-length dependent absorption of fluorescence generated from different tracer species seeded into each fluid.…”

Section: Introductionmentioning

confidence: 99%

Quantitative measurement of binary liquid distributions using multiple-tracer x-ray fluorescence and radiography

Halls¹,

Meyer²,

Kastengren³

2015

Opt. Express

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The complex geometry and large index-of-refraction gradients that occur near the point of impingement of binary liquid jets present a challenging environment for optical interrogation. A simultaneous quadrupletracer x-ray fluorescence and line-of-sight radiography technique is proposed as a means of distinguishing and quantifying individual liquid component distributions prior to, during, and after jet impact. Two different pairs of fluorescence tracers are seeded into each liquid stream to maximize their attenuation ratio for reabsorption correction and differentiation of the two fluids during mixing. This approach for instantaneous correction of xray fluorescence reabsorption is compared with a more time-intensive approach of using stereographic reconstruction of x-ray attenuation along multiple lines of sight. The proposed methodology addresses the need for a quantitative measurement technique capable of interrogating optically complex, nearfield liquid distributions in many mixing systems of practical interest involving two or more liquid streams. RightsThis paper was published in Optics Express and is made available as an electronic reprint with the permission of OSA. The paper can be be found at the following URL on the OSA website: https://www.osapublishing.org/search.cfm?q=&j=oe&v=23&i=2&p=1730. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means in prohibited and is subject to penalties under law. Abstract:The complex geometry and large index-of-refraction gradients that occur near the point of impingement of binary liquid jets present a challenging environment for optical interrogation. A simultaneous quadruple-tracer x-ray fluorescence and line-of-sight radiography technique is proposed as a means of distinguishing and quantifying individual liquid component distributions prior to, during, and after jet impact. Two different pairs of fluorescence tracers are seeded into each liquid stream to maximize their attenuation ratio for reabsorption correction and differentiation of the two fluids during mixing. This approach for instantaneous correction of xray fluorescence reabsorption is compared with a more time-intensive approach of using stereographic reconstruction of x-ray attenuation along multiple lines of sight. The proposed methodology addresses the need for a quantitative measurement technique capable of interrogating optically complex, near-field liquid distributions in many mixing systems of practical interest involving two or more liquid streams.

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“…Progress towards volumetrically resolved measurements in combustion processes were achieved through a combination of tomographic particle image velocimetry (PIV) [14] and flame front measurements [10,15], as well as a single-camera particle tracking technique for small-scale measurements [16]. Recently, fast-scanning setups have enabled the 3D imaging of structures [17,18], including those revealed from hydroxyl radicals through laser-induced fluorescence [19,20]. Common to all these studies is either the usage of multiple cameras or the assembly of quasi-3D images from sequences of images taken successively in various planes by rapidly scanning a laser light sheet across the object.…”

Section: Introductionmentioning

confidence: 99%

Plenoptic Single-Shot 3D Imaging of In-Cylinder Fuel Spray Geometry

Lillo

Greene

Sick

2014

Zeitschrift Für Physikalische Chemie

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Progress in understanding turbulent combustion requires access to information that is derived from instantaneous 3D images showing the contours of the flame front, the flow field, and other quantities. The experimental effort to acquire such information is typically extraordinarily high and therefore not as widely used as needed. The introduction of commercially available plenoptic cameras now provides a means to simplify some of these measurements as is described in this study. A single 29 mega-pixel plenoptic camera was used to record the Mie scattering signals from volumetrically illuminated fuel sprays. Instantaneous 3D images were acquired from within the cylinder of an optically accessible engine for three automotive fuel injectors of differing nominal spray angles. Current reconstruction algorithms do not yet take translucent imaging conditions into account and therefore a quantitative analysis of the full 3D structure of the sprays was not possible. However, the plenoptic system did prove capable of accurately reconstructing bulk spray features such as spray angles. The 3D spray images were validated with data from a conventional 2D imaging system. This study demonstrates the feasibility of using a single plenoptic camera to view spray geometry in 3D, even from within the challenging in-cylinder engine environment.

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Three-dimensional measurement of the local extinction coefficient in a dense spray

Cited by 31 publications

References 28 publications

Comparison between two-phase and one-phase SLIPI for instantaneous imaging of transient sprays

Comparison between two-phase and one-phase SLIPI for instantaneous imaging of transient sprays

Quantitative measurement of binary liquid distributions using multiple-tracer x-ray fluorescence and radiography

Plenoptic Single-Shot 3D Imaging of In-Cylinder Fuel Spray Geometry

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