Quantitative analysis of highly transient fuel sprays by time-resolved x-radiography

Cai, Wenyi; Powell, Christopher F.; Yue, Yong; Narayanan, Suresh; Wang, Jin; Täte, Mark W.; Renzi, Matthew J.; Ercan, Ali; Fontes, Ernest; Grüner, Sol M.

doi:10.1063/1.1604161

Cited by 86 publications

(59 citation statements)

References 14 publications

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“…Methods based on side illumination of the jet by a laser sheet would have difficulties to discriminate between the continuous liquid jet and the products of atomization in dense sprays [18][19]. Methods, based on X-ray absorption [20][21][22] and ballistic imaging [23][24][25], are promising, but at present require very specialised equipment and are expensive to implement. Therefore, the proposed technique offers unique advantages for the quantification of the liquid jet.…”

mentioning

confidence: 99%

Structure of the Continuous Liquid Jet Core during Coaxial Air-Blast Atomisation

Charalampous

Hardalupas

Taylor

2009

International Journal of Spray and Combustion Dynamics

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This paper investigates the structure of the continuous liquid jet of a coaxial air-blast atomiser over a range of Weber numbers 60-1040, Reynolds numbers of liquid jet 5400-21700 and air to liquid momentum ratios of the two streams of 1.7-335. A novel optical technique, based on internal illumination of the liquid jet through the jet nozzle by a laser pulse, which excites a fluorescing dye introduced in the atomizing liquid, was used to obtain instantaneous measurements of the breakup length and the three dimensional location of the liquid core of the continuous liquid jet. The latter was achieved by simultaneously imaging the liquid jet from two directions normal to each other. Such measurements are usually prevented by droplets surrounding the liquid jet at the dense spray near the nozzle exit. The measurements showed that the break-up length of the liquid jet scaled well with the air to liquid momentum ratio. The standard deviation of the temporal fluctuations of the break-up length was around 10% of the mean breakup length for each considered flow condition. The instantaneous jet surface does not develop axi-symmetric wave structures but the time-averaged liquid jet is axi-symmetric around the nozzle axis, while the maximum deflection of the liquid jet occurs close to the breaking point.

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mentioning

confidence: 99%

Structure of the Continuous Liquid Jet Core during Coaxial Air-Blast Atomisation

Charalampous

Hardalupas

Taylor

2009

International Journal of Spray and Combustion Dynamics

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“…Compared to other experimental solutions also capable of diminishing the scattered light for line-of-sight detection, such as Ballistic imaging [2] and X-ray imaging [10,11], the current technique suppresses this undesired intensity contribution after image acquisition, limiting it to less optically dense media. However, the method is compatible with other filtering approaches, such as temporal-, spatial-and polarization filtering (as utilized for Ballistic imaging), which could increase the range of applicability even further.…”

Section: Resultsmentioning

confidence: 99%

“…However, it should be noted that to obtain measurable levels of absorption it is often required to add absorbers to the injected liquid. With careful calibration, this approach provides means to accurately measure the extinction of light through optically dense sprays, which, in turn, can be used for tomographic imaging [11].…”

Section: Introductionmentioning

confidence: 99%

Quantitative 3D imaging of scattering media using structured illumination and computed tomography

Kristensson¹,

Berrocal²,

Aldén³

2012

Opt. Express

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Abstract:An imaging technique capable of measuring the extinction coefficient in 3D is presented and demonstrated on various scattering media. The approach is able to suppress unwanted effects due to both multiple scattering and light extinction, which, in turbid situations, seriously hampers the performance of conventional imaging techniques. The main concept consists in illuminating the sample of interest with a light source that is spatially modulated in both the vertical and horizontal direction and to measure, using Structured Illumination, the correct transmission in 2D at several viewing angles. The sample is then reconstructed in 3D by means of a standard Computed Tomography algorithm. To create the adequate illumination, a novel "crossed" structured illumination approach is implemented. In this article, the accuracy and limitation of the method is first evaluated by probing several homogeneous milk solutions at various levels of turbidity. The unique possibility of visualizing an object hidden within such solutions is also demonstrated. Finally the method is applied on two different inhomogeneous scattering spray systems; one transient and one quasi-steady state.

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“…The ability to view the breakup and atomization processes in detail is needed to provide knowledge vital to improving the processes. Photography, holography, and x-ray imaging, which have been used for many years in such research, [3,4], have failed to provide views because noise from combine these methods. A critical question involves producing high quality digital holograms with picosecond gated pulses.…”

Section: Introductionmentioning

confidence: 99%

Probing Dense Sprays with Gated, Picosecond, Digital Particle Field Holography

Trolinger

Buckner

Tomov

et al. 2011

International Journal of Spray and Combustion Dynamics

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This paper describes work that demonstrated the feasibility of producing a gated digital holography system that is capable of producing high-resolution images of three-dimensional particle and structure details deep within dense particle fields of a spray. We developed a gated picosecond digital holocamera, using optical Kerr cell gating, to demonstrate features of gated digital holography that make it an exceptional candidate for this application. The Kerr cell gate shuttered the camera after the initial burst of ballistic and snake photons had been recorded, suppressing longer path, multiple scattered illumination. By starting with a CW laser without gating and then incorporating a picosecond laser and an optical Kerr gate, we were able to assess the imaging quality of the gated holograms, and determine improvement gained by gating. We produced high quality images of 50-200 µm diameter particles, hairs and USAF resolution charts from digital holograms recorded through turbid media where more than 98% of the light was scattered from the field. The system can gate pulses as short as 3 mm in pathlength (10 ps), enabling image-improving features of the system. The experiments lead us to the conclusion that this method has an excellent capability as a diagnostics tool in dense spray combustion research.

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Quantitative analysis of highly transient fuel sprays by time-resolved x-radiography

Cited by 86 publications

References 14 publications

Structure of the Continuous Liquid Jet Core during Coaxial Air-Blast Atomisation

Structure of the Continuous Liquid Jet Core during Coaxial Air-Blast Atomisation

Quantitative 3D imaging of scattering media using structured illumination and computed tomography

Probing Dense Sprays with Gated, Picosecond, Digital Particle Field Holography

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