Soot Quantification of Single-Hole Diesel Sprays by Means of Extinction Imaging

Pastor, Javier; García-Oliver, José M; Novella, Ricardo; Xuan, Tiemin

doi:10.4271/2015-24-2417

Cited by 15 publications

(23 citation statements)

References 19 publications

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“…The DBI optical setup (Figure 2(b)) and all optical components are pretty similar compared to the ones in Pastor et al 30 The only difference is the camera settings. Here, the exposure time of the camera was set to 6.62 µs with 264 × 640 pixels image resolution running at 35 kHz and the pixel/mm ratio is 7.71.…”

Section: Experimental Toolsmentioning

confidence: 98%

“…The DBI optical setup ( Fig. 2(b)) and all optical components are pretty similar with the ones in reference 30 . The only difference is the camera settings.…”

Section: Diffused Background-illumination Extinction Imagingmentioning

confidence: 99%

“…Here, the exposure time of the camera was set to 6.62 µs with 264 × 640 pixels image resolution running at 35 kHz and the pixel/mm ratio is 7.71. The theoretical knowledge about this technique, the detailed configuration of the setup and the processing methodology to obtain the soot optical thickness ( KL ) can be referenced from Pastor et al 30…”

Section: Experimental Toolsmentioning

confidence: 99%

See 2 more Smart Citations

Optical study on characteristics of non-reacting and reacting diesel spray with different strategies of split injection

Desantes

García-Oliver

García

et al. 2018

International Journal of Engine Research

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Even though studies on split-injection strategies have been published in recent years, there are still many remaining questions about how the first injection affects the mixing and combustion processes of the second one by changing the dwell time between both injection events or by the first injection quantity. In this article, split-injection diesel sprays with different injection strategies are investigated. Visualization of n-dodecane sprays was carried out under both non-reacting and reacting operating conditions in an optically accessible two-stroke engine equipped with a single-hole diesel injector. High-speed Schlieren imaging was applied to visualize the spray geometry development, while diffused background-illumination extinction imaging was applied to quantify the instantaneous soot production (net result of soot formation and oxidation). For non-reacting conditions, it was found that the vapor phase of second injection penetrates faster with a shorter dwell time and independently of the duration of the first injection. This could be explained in terms of one-dimensional spray model results, which provided information on the local mixing and momentum state within the flow. Under reacting conditions, interaction between the second injection and combustion recession of the first injection is observed, resulting in shorter ignition delay and lift-off compared to the first injection. However, soot production behaves differently with different injection strategies. The maximum instantaneous soot mass produced by the second injection increases with a shorter dwell time and with longer first injection duration.

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Section: Experimental Toolsmentioning

confidence: 98%

“…The DBI optical setup ( Fig. 2(b)) and all optical components are pretty similar with the ones in reference 30 . The only difference is the camera settings.…”

Section: Diffused Background-illumination Extinction Imagingmentioning

confidence: 99%

Section: Experimental Toolsmentioning

confidence: 99%

See 1 more Smart Citation

Optical study on characteristics of non-reacting and reacting diesel spray with different strategies of split injection

Desantes

García-Oliver

García

et al. 2018

International Journal of Engine Research

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“…Steep refractive index gradients are not only observed at the boundary of a high-temperature combusting fuel spray, but can be observed near the liquid boundary of a non-reacting spray where the fuel vapor is cooler than the ambient gases. Thus, DBIEI, as it has been previously demonstrated in the literature [5,6,9,15], is subject to uncertainties caused by beam steering. The purpose of the present work is to lay out an optical arrangement that eliminates quantitative uncertainties in liquid boundary and soot measurements induced by beam steering when applying DBIEI.…”

Section: Introductionmentioning

confidence: 95%

“…With regard to soot quantification, the same optical approach has been used to measure the time-resolved optical thickness of high-pressure combusting sprays at rates exceeding 40 kHz [6,8,9]. This high-speed DBI soot extinction imaging (DBIEI-soot) diagnostic proved to be a simple and costeffective approach for quantifying soot at speeds exceeding those achieved by high-speed planar laser-induced incandescence (PLII) [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Diffuse back-illumination setup for high temporally resolved extinction imaging

et al. 2017

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This work presents the development of an optical setup for quantitative, high-temporal resolution line-of-sight extinction imaging in harsh optical environments. The application specifically targets measurements of automotive fuel sprays at high ambient temperature and pressure conditions where time scales are short and perceived attenuation by refractive index gradients along the optical path (i.e., beam steering) can be significant. The illumination and collection optics are optimized to abate beam steering, and the design criteria are supported by well-established theoretical relationships. The general effects of refractive steering are explained conceptually using simple ray tracing. Three isolated scenarios are analyzed to establish the lighting characteristics required to render the observed radiant flux unaffected by the steering effect. These criteria are used to optimize light throughput in the optical system, enabling minimal exposure times and high-temporal resolution capabilities. The setup uses a customized engineered diffuser to transmit a constant radiance within a limited angular range such that radiant intensity is maximized while fulfilling the lighting criteria for optimal beam-steering suppression. Methods for complete characterization of the optical system are detailed. Measurements of the liquid-vapor boundary and the soot volume fraction in an automotive spray are presented to demonstrate the resulting improved contrast and reduced uncertainty. The current optical setup reduces attenuation caused by refractive index gradients by an order of magnitude compared to previous high-temporal resolution setups.

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In-flame soot quantification of diesel sprays under sooting/non-sooting critical conditions in an optical engine

Xuan

Pastor

García-Oliver

et al. 2019

Applied Thermal Engineering

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Because of the challenge of meeting stringent emissions regulations for internal combustion engines, some advanced low temperature combustion modes have been raised in recent decades to improve combustion efficiency. Therefore, detailed understanding and capability for accurate prediction of in-flame soot processes under such low sooting conditions are becoming necessary. Nowadays, a lot of investigations have been carried out to quantify in-flame soot in Diesel sprays under high sooting conditions by means of different optical techniques. However, no information of soot quantification can be found for sooting/non-sooting critical conditions. In current study, the instantaneous soot production in a two-stroke optical engine under low sooting conditions has been measured by means of a Diffused back-illumination extinction technique (DBI) and two-color method (2C) simultaneously. The fuels used were n-dodecane and n-heptane, which have been injected separately though two different injectors equipped with single-hole nozzles. A large cycle-to-cycle variation on soot production can be observed under such operating conditions, however the in-cylinder heat release traces were quite repeatable. It is the same with the well-known trends of soot amount to operating conditions that the probability of sooting cycles increases with higher ambient temperature, higher ambient density and lower injection pressure. Both techniques present a pretty good agreement on soot amount when the peak of KL value is close to 1. However, the KL value of twocolor method becomes bigger than that of DBI and the difference increases with lower sooting conditions.

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Soot Quantification of Single-Hole Diesel Sprays by Means of Extinction Imaging

Cited by 15 publications

References 19 publications

Optical study on characteristics of non-reacting and reacting diesel spray with different strategies of split injection

Optical study on characteristics of non-reacting and reacting diesel spray with different strategies of split injection

Diffuse back-illumination setup for high temporally resolved extinction imaging

In-flame soot quantification of diesel sprays under sooting/non-sooting critical conditions in an optical engine

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