Long‐working‐distance microscope used for diesel injection spray imaging

Sjoeberg, Henrik; Manneberg, Göran; Cronhjort, Andreas

doi:10.1117/1.601113

Cited by 23 publications

(17 citation statements)

References 14 publications

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“…This indicates that @ 2 n=@x 2 increases from the ambient gas to the residual fluid, which in turn shows that the density also increases along that direction. We conclude from this The translucent appearance of the residual fuel (frames 1-4) allowed the fresh fuel to be independently tracked as it penetrates through the residual liquid fuel (frames [5][6][7][8][9][10][11][12]. See [29] or supplemental material for the full video [29].…”

Section: Emergence Of Fuel From the Orificementioning

confidence: 95%

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Microscopic imaging of the initial stage of diesel spray formation

Crua

Heikal

Gold³

2015

Fuel

119

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Detailed measurements of near-nozzle spray formation are essential to better understand and predict the physical processes involved in diesel fuel atomisation. We used long-range microscopy to investigate the primary atomisation of diesel, biodiesel and kerosene fuels in the near-nozzle region, both at atmospheric and realistic engine conditions. High spatial and temporal resolutions allowed a detailed observation of the very emergence of fuel from the nozzle orifice. The fluid that first exited the nozzle resembled mushroom-like structures, as occasionally reported by other researchers for atmospheric conditions, with evidence of interfacial shearing instabilities and stagnation points. We captured the dynamics of this phenomenon using an ultra-fast framing camera with frame rates up to 5 million images per second, and identified these structures as residual fluid trapped in the orifice between injections. The residual fluid has an internal vortex ring motion which results in a slipstream effect that can propel a microscopic ligament of liquid fuel ahead. We showed that this mechanism is not limited to laboratory setups, and that it occurs for diesel fuels injected at engine-like conditions with production injectors. Our findings confirm that fuel can remain trapped in the injector holes after the end of injection. Although we could not measure the hydrocarbon content of the trapped vapourised fluid, we observed that its density was lower than that of the liquid fuel, but higher than that of the in-cylinder gas. We conclude that high-fidelity numerical models should not assume in their initial conditions that the sac and orifices of fuel injectors are filled with in-cylinder gas. Instead, our observations suggest that the nozzle holes should be considered partially filled with a dense fluid

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Section: Emergence Of Fuel From the Orificementioning

confidence: 95%

“…Microscopic imaging experiments of diesel sprays have been reported in the literature (e.g. [5,[10][11][12][13]), although at atmospheric conditions and with varying degrees in the quality of the images produced. Satisfactory lighting can be particularly difficult to obtain at microscopic level.…”

Section: Introductionmentioning

confidence: 98%

Microscopic imaging of the initial stage of diesel spray formation

Crua

Heikal

Gold³

2015

Fuel

119

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“…Gasoline-like fuels are referred to as low reactivity fuels due to their low ignitability. Gasoline-like fuels that perform with high ignition delays, leading to longer mixing times due to their low reactivity, have recently been tested in advanced combustion strategies to improve the mixing of fuel and air [6][7][8][9][10][11]. It was reported that gasoline-like fuels are advantageous in achieving mid-to-high load conditions with significantly low fuel consumption and emissions, but with high emissions of HC and CO and combustion instability under low load conditions.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Spray Development Process of Gasoline-Biodiesel Blended Fuel Sprays in a Constant Volume Chamber

Kım

2020

Energies

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This study investigated gasoline–biodiesel blended fuel (GB) subjected to a fuel spray development process on macroscopic and microscopic scales. The four tested fuels were neat gasoline and gasoline containing biodiesel (5%, 20%, and 40% by volume) at three different ratios. The initial spray near the nozzle revealed that the spray penetration and spray tip velocity both decreased with decreasing biodiesel blending ratio. In addition, the different spray tip velocities at the start of spraying result in different atomization regimes between the fuels. The GB fuels with a low biodiesel blending ratio were disadvantaged in terms of spray atomization due to their lower spray penetration and tip velocity. The macroscopic spray penetration changes were similar to those observed in the microscopic spray. The fuel with the lower biodiesel blending ratio had a larger spray cone angle, indicating increased radial spray dispersion.

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“…1 The overall shape of a spray, and its penetration length into the receiving media, can be measured by means of photography, either direct or backlit by flash lamp or laser. 2 The extent of the vapor cloud surrounding the spray can be seen by means of schlieren imaging 3 or laser-induced fluorescence ͑LIF͒ of the fuel vapor. 4 However, measuring the internal properties of a spray, such as its breakup from bulk liquid into smaller droplets, their size and number density, is difficult.…”

Section: Introductionmentioning

confidence: 99%

Compensation method for attenuated planar laser images of optically dense sprays

Abugharbieh¹,

Persson²,

Rosén³

et al. 2000

Appl. Opt.

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We present a method for compensating laser attenuation in optically dense sprays, in particular for use in combustion engine research. Images of the fuel sprays are produced by planar laser imaging, where Mie scattered light from a cross section of the spray is imaged onto a CCD camera. The compensation scheme is based on the Beer-Lambert law, which is used here to sum up the loss of light along the path of the laser in the image, and to compensate iteratively, pixel by pixel, for this loss.

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Long‐working‐distance microscope used for diesel injection spray imaging

Cited by 23 publications

References 14 publications

Microscopic imaging of the initial stage of diesel spray formation

Microscopic imaging of the initial stage of diesel spray formation

Investigation of the Spray Development Process of Gasoline-Biodiesel Blended Fuel Sprays in a Constant Volume Chamber

Compensation method for attenuated planar laser images of optically dense sprays

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