Soot in diesel fuel jets: effects of ambient temperature, ambient density, and injection pressure

Pickett, Lyle M.; Siebers, Dennis L.

doi:10.1016/j.combustflame.2004.04.006

Cited by 438 publications

(280 citation statements)

References 32 publications

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“…Such 408 a result is consistent with literature studies [29,31], and can be justified based on the reduction 409 in lift-off length (LoL) that occurs with ambient density, which increases the equivalence ratio at 410 the flame base, and hence induces higher soot formation. LoL values derived from OH* 411 chemiluminiscence images recorded simultaneously with the soot measurements (Appendix 1) 412 confirm such a reduction for the present test matrix.…”

supporting

confidence: 79%

Application of optical diagnostics to the quantification of soot in n-alkane flames under diesel conditions

Pastor

García-Oliver

García

et al. 2016

Combustion and Flame

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Mico Reche, C. (2016). Application of optical diagnostics to the quantification of soot in n-alkane flames under diesel conditions. Combustion and Flame. 164:212-223. doi:10.1016/j.combustflame.2015.11.018. Nevertheless, it could still be a good option for low sooting conditions. On the other hand, an 36 attempt to calibrate LII signal by means of LEM measurements has been reported. This approach 37 should make it possible to obtain additional information on the soot spatial distribution. 38 However, inconsistencies have been identified which stem from the inherent limitations of LII 39 technique in highly sooting conditions. 40 Application of optical diagnostics to the quantification of soot in

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supporting

confidence: 79%

Application of optical diagnostics to the quantification of soot in n-alkane flames under diesel conditions

Pastor

García-Oliver

García

et al. 2016

Combustion and Flame

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“…On the other hand, LOL has been identified as an important parameter for soot formation within Diesel flame, as it controls the amount of air entrained from the nozzle to the flame base [12]. That is why some authors have used semi-empirical equations [11] to estimate the cross-sectional equivalence ratio at the flame base to correlate with soot formation processes within the diffusion flame [38].…”

Section: Lift-off Length Measurementsmentioning

confidence: 99%

“…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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“…Thus, when the injection pressure was reduced, the first occurances of natural luminosity moved closer to the injector implying a shorter flame lift-off length. Consequently the soot volume fractions increased [18] [36]. In this sense, the peak of spectral intensity was also higher when the injection pressure was reduced as shown in figure 7.…”

Section: Operating Conditionsmentioning

confidence: 80%

“…In this sense, the peak of spectral intensity was also higher when the injection pressure was reduced as shown in figure 7. In fact, when the injection pressure was varied, no significant changes in the mixture fraction field were attained, nevertheless, it is well-known that the OH lift-off length is reduced due to a different balance between flow and flame velocities [36]. This behavior seems to be also valid for the LoL FLAME parameter.…”

Section: Operating Conditionsmentioning

confidence: 89%

In-cylinder soot radiation heat transfer in direct-injection diesel engines

Benajes

Martín

García

et al. 2015

Energy Conversion and Management

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HIGHLIGHTSOptoelectronic pyrometer provides similar results compared with a conventional method Lower injection pressure results in higher radiation Higher ambient temperature and higher in-cylinder gas density produce higher radiation Larger lift-off length reduces the soot volume fraction and the spectral intensity An increase on swirl number, load and CA50 provide a lower total radiation Lower values of EGR implies a decreased on radiation intensity KEYWORDSSoot; in-cylinder heat transfer; radiation; Optical pyrometer; ABSTRACTThe efficiency and CO 2 are one of the main concerns of automotive manufacturers.There are several strategies under investigation to solve this problem. In the present work, the research effort has been focused on improving knowledge of in-cylinder heat transfer and its impact on engine efficiency. In particular, soot radiation was studied since it can be considered a significant source of the efficiency losses in modern diesel engines. Considering previous studies, the portion of total chemical energy released during combustion lost due to radiation heat transfer varies widely from 0.5 up to 10%, depending on engine parameters and combustion process. Thus, the main objective of this work was to evaluate the amount of energy lost to soot radiation relative to the input fuel chemical energy during the combustion event under different operating conditions in a completely controlled environment provided by an optical engine. Under these simplified conditions, two-color method was applied by using high speed imaging pyrometer with cameras (two dimensional results) and optoelectronic pyrometer (zero dimensional results). Once a detailed comparison between both diagnostics was performed, optoelectronic pyrometer was used to characterize radiant energy losses in a fully instrumented 4-cylinder direct-injection light-duty diesel engine. In particular swirl ratio, EGR and combustion phasing effects on radiation heat transfer were evaluated.

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Soot in diesel fuel jets: effects of ambient temperature, ambient density, and injection pressure

Cited by 438 publications

References 32 publications

Application of optical diagnostics to the quantification of soot in n-alkane flames under diesel conditions

Application of optical diagnostics to the quantification of soot in n-alkane flames under diesel conditions

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

In-cylinder soot radiation heat transfer in direct-injection diesel engines

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