Planar laser-induced-fluorescence imaging measurements of OH and hydrocarbon fuel fragments in high-pressure spray-flame combustion

Allen, Mark G.; McManus, Keith; Sonnenfroh, David M.; Paul, Phillip H.

doi:10.1364/ao.34.006287

Cited by 57 publications

(31 citation statements)

References 21 publications

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“…The combination of these two effects causes the OH concentration (and hence OH PLIF signal) to closely mark the reaction zone in high-pressure diffusion flames, with a large signal differential from the flame zone to the surrounding gas. This has recently been demonstrated by Allen et al [17] who found the OH signal from the diffusion-flame zone of a steady spray flame to become progressively thinner as pressure was increased from 1 to 9.5 bar. At diesel conditions, where pressures are 50 bar or higher, the effect should be even more dramatic, and OH PLIF is expected to closely mark the diffusion flame zones.…”

Section: Introductionmentioning

confidence: 55%

“…This rate is slow at atmospheric pressure, and OH often persists well away from the flame front making it a less useful marker of the reaction zone [3,5,10,13]. However, as ambient pressure is increased, the super-equilibrium OH concentrations in the flame zone are more rapidly reduced to the equilibrium levels outside the flame zone [12,17]. Furthermore, for diffusion flames, the equilibrium level itself falls rapidly outside of the flame zone [13].…”

Section: Introductionmentioning

confidence: 99%

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OH Radical Imaging in a DI Diesel Engine and the Structure of the Early Diffusion Flame

Dec¹,

Coy²

1996

SAE Technical Paper Series

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Laser-sheet imaging studies have considerably advanced our understanding of diesel combustion; however, the location and nature of the flame zones within the combusting fuel jet have been largely unstudied. To address this issue, planar laser-induced fluorescence (PLIF) imaging of the OH radical has been applied to the reacting fuel jet of a direct-injection diesel engine of the "heavy-duty" size class, modified for optical access. An Nd:YAG-based laser system was used to pump the overlapping Q19 and Q28 lines of the (1,O) band of the A+X transition at 284.01 nm, while the fluorescent emission from both the (0,O) and (1,l) bands (308 to 320 nm) was imaged with an intensified video camera. This scheme allowed rejection of elastically scattered laser light, PAH fluorescence, and laser-induced incandescence.OH PLIF is shown to be an excellent diagnostic for diesel diffusion flames. The signal is strong, and it is confined to a narrow region about the flame front because the threebody recombination reactions that reduce high flame-front OH concentrations to equilibrium levels occur rapidly at diesel pressures. No signal was evident in the fuel-rich premixed flame regions where calculations and burner experiments indicate that OH concentrations will be below detectable limits. Temporal sequences of OH PLIF images are presented showing the onset and development of the early diffusion flame up to the time that soot obscures the images. These images show that the diffusion flame develops around the periphery of the downstream portion of the reacting fuel jet about half way through the premixed burn spike. Although affected by turbulence, the diffusion flame remains at the jet periphery for the rest of the imaged sequence. The images also show many details of the diffusion flame structure including its upstream extent. Finally, the location and nature of the diffusion flames are discussed with respect to previously reported soot and fuel distributions.

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Section: Introductionmentioning

confidence: 55%

Section: Introductionmentioning

confidence: 99%

OH Radical Imaging in a DI Diesel Engine and the Structure of the Early Diffusion Flame

Dec¹,

Coy²

1996

SAE Technical Paper Series

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“…the attenuation of the laser sheet and fluorescence trapping, the thermal population of the level probed, the loss of population in the excited state by quenching and internal conversion and the collection efficiency of the detection system [21]. The crank angle dependent fluorescence of the seeded CH 2 O provides the pressure-and temperature-dependence of the LIF intensity (in air).…”

Section: Methods Of Quantificationmentioning

confidence: 99%

Time- and space-resolved quantitative LIF measurements of formaldehyde in a heavy-duty diesel engine

Donkerbroek¹,

Vliet²,

Somers³

et al. 2010

Combustion and Flame

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“…The molecular structures of these fuels are shown in Table 1 . By measuring the spatial locations of the PAH fluorescence signals and the evolution of PAHs [33][34][35][36][37][38][39][40][41] and through sampling investigations [42][43][44][45][46] , the evidences, linking the PAH fluorescence to the PAH molecules, have been shown in these literature studies. Through the present PAH-PLIF experiments, we aim to study the effects of molecular structure and hydroxyl functional group on the PAH formation and growth processes.…”

Section: Introductionmentioning

confidence: 99%

PAH formation in counterflow non-premixed flames of butane and butanol isomers

Singh

Sung

2016

Combustion and Flame

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Butane and butanol isomers Polycyclic aromatic hydrocarbon (PAH) Soot formation PAH-planar laser-induced fluorescence (PAH-PLIF) Laser-Induced incandescence (LII) Light extinction a b s t r a c t Using the planar laser-induced fluorescence (PLIF) technique in a counterflow non-premixed flame configuration, the formation of the polycyclic aromatic hydrocarbons (PAHs) for the butane isomers and the butanol isomers was investigated. For these C 4 fuels, the PAHs of various aromatic ring size groups (2, 3, 4, and larger aromatic rings) have been characterized and compared in non-premixed combustion configuration. In particular, the formation and growth of the PAHs of different aromatic ring sizes in these counterflow flames was examined by tracking the PAH-PLIF signals at various detection wavelengths. The fuel structure effects on the PAH formation and growth processes were also analyzed by comparing the PAH growth pathways for these C 4 fuels. Furthermore, PAH-PLIF experiments were conducted, by blending each of the branched-chain isomers with the baseline straight-chain isomer, in order to study the synergistic effects, as well as identify the relative importance of the H-abstraction-C 2 H 2 -addition (HACA) mechanism and the propargyl (C 3 H 3 ) recombination/addition pathways in the PAH formation and growth processes. A chemical kinetic model available in the literature that includes both the fuel oxidation and the PAH chemistry was also used to simulate and compare the PAH species up to A 4 rings. At the incipient stage of the PAH formation, the simulated results exhibited similar behavior to the experimental observations. The PAH formation pathways considered in the chemical kinetic model were further analyzed. In addition to propargyl, the present results demonstrated the important role of acetylene in the PAH formation and growth processes.

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Planar laser-induced-fluorescence imaging measurements of OH and hydrocarbon fuel fragments in high-pressure spray-flame combustion

Cited by 57 publications

References 21 publications

OH Radical Imaging in a DI Diesel Engine and the Structure of the Early Diffusion Flame

OH Radical Imaging in a DI Diesel Engine and the Structure of the Early Diffusion Flame

Time- and space-resolved quantitative LIF measurements of formaldehyde in a heavy-duty diesel engine

PAH formation in counterflow non-premixed flames of butane and butanol isomers

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