Flame Lift-Off on Direct-Injection Diesel Sprays Under Quiescent Conditions

Siebers, Dennis L.; Higgins, Brian

doi:10.4271/2001-01-0530

Cited by 439 publications

(320 citation statements)

References 19 publications

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“…This type of analysis suggests how soot suppression is accomplished for the cases in which extra air is entrained 53 . Entrainment provides additional molecular oxygen, which can react rapidly with radical species such as vinyl and produce HO 2 radicals which then can abstract H atoms from the fuel or react further with the unsaturated species.…”

Section: Discussionmentioning

confidence: 99%

Chemical Kinetic Modeling Study of the Effects of Oxygenated Hydrocarbons on Soot Emissions from Diesel Engines

2006

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A detailed chemical kinetic modeling approach is used to examine the phenomenon of suppression of sooting in diesel engines by addition of oxygenated hydrocarbon species to the fuel. This suppression, which has been observed experimentally for a few years, is explained kinetically as a reduction in concentrations of soot precursors present in the hot products of a fuel-rich diesel ignition zone when oxygenates are included. Oxygenates decrease the overall equivalence ratio of the igniting mixture, producing higher ignition temperatures and more radical species to consume more soot precursor species, leading to lower soot production. The kinetic model is also used to show how different oxygenates, ester structures in particular, can have different soot-suppression efficiencies due to differences in molecular structure of the oxygenated species.4

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Section: Discussionmentioning

confidence: 99%

Chemical Kinetic Modeling Study of the Effects of Oxygenated Hydrocarbons on Soot Emissions from Diesel Engines

2006

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“…The lift-off length (LOL) was measured capturing the signal from OH* chemiluminescence following the ECN standard methodology [6], [9]. An ICCD camera (Andor I-star) fitted with a 100 mm f/2.8 UV lens and a 310±5 nm interferometric filter was used with a constant intensifier gating time widow included between 2.0 and 5.0 ms ASOI: in this way the steady part of the injection was averaged along the injection event and the shot-to-shot deviation was reduced.…”

Section: Lift-off Lengthmentioning

confidence: 99%

“…Higgins [9]: after filtering the image with a 3x3 pixel mean filter, two intensity profiles are obtained calculating the maximum intensity for each axial position in the upper and lower half of the image (Figure 5 left). The lift-off length was determined by finding the distances between the injector tip and the first axial locations above and below the spray centerline with intensity greater than 50% of the intensity peak shown in Figure 5 left-bottom.…”

Section: Lift-off Lengthmentioning

confidence: 99%

“… Broadband chemiluminescence technique, to measure ignition delay [7], [10]  OH* chemiluminescence to measure steady LOL [9], [11] Both techniques are deeply described in the literature. Moreover, a special effort has been made to study the spray disappearance phenomenon observed when a Schlieren setup is used to study a reacting Diesel spray [7], [12].…”

Section: Introductionmentioning

confidence: 99%

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Experimental characterization of diesel ignition and lift-off length using a single-hole ECN injector

Benajes

Payri

Bardi

et al. 2013

Applied Thermal Engineering

150

126

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“…On the other hand, there is also a wealth of information of spray processes under reactive conditions, but most of it is devoted to particular phenomena such as autoignition [9], lift-off length [10,11] or soot formation within the diffusion flame [12][13][14][15][16]. Compared to the detailed knowledge of inert spray flow, much less information is available in the literature on the evolution of the spray flow during the ignition and subsequent flame development.…”

Section: Introductionmentioning

confidence: 99%

An experimental analysis on the evolution of the transient tip penetration in reacting Diesel sprays

Desantes

Pastor

García-Oliver

et al. 2014

Combustion and Flame

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Schlieren imaging has helped deeply characterize the behavior of diesel spray when injected into an oxygen-free ambient. However, when considering the transient penetration of the reacting spray after autoignition, i.e. the Diesel flame, few studies have been found in literature. Differences among optical setups as well as among experimental conditions have not allowed clear conclusions to be drawn on this issue. Furthermore, soot radiation may have a strong effect on the image quality, which cannot be neglected.The present paper reports an investigation on the transient evolution of Diesel flame based upon schlieren imaging. Experimental conditions have spanned values of injection pressure, ambient temperature and density for typical Diesel engine conditions. An optimized optical setup has been used, which makes it possible to obtain results without soot interference. Based on observations for a long injection event (4 ms Energizing Time), the analysis has resorted to extensive comparison of inert and reacting sprays parameters, which have made it possible to define different phases after autoignition.Shortly after autoignition, axial and radial expansion of the spray have been observed in terms of axial penetration and radial cone angle. After that, during a stabilization phase, the reacting spray penetrates at a similar rate as the inert one. Later, the reacting spray undergoes an acceleration period, where it penetrates at a faster rate than the inert one. Finally, the flame enters a quasi-steady penetration phase, where the ratio of reacting and inert penetration stabilizes at a nearly constant value. The duration of the reacting spray penetration stages shows modifications when varying engine parameters such as air temperature, air density, injection pressure, and nozzle diameter. However, the proportionality between reacting and inert penetration has been observed to depend mainly on temperature, in agreement with observed reductions in entrainment when shifting from inert to reacting conditions.

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Flame Lift-Off on Direct-Injection Diesel Sprays Under Quiescent Conditions

Cited by 439 publications

References 19 publications

Chemical Kinetic Modeling Study of the Effects of Oxygenated Hydrocarbons on Soot Emissions from Diesel Engines

Chemical Kinetic Modeling Study of the Effects of Oxygenated Hydrocarbons on Soot Emissions from Diesel Engines

Experimental characterization of diesel ignition and lift-off length using a single-hole ECN injector

An experimental analysis on the evolution of the transient tip penetration in reacting Diesel sprays

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