Comparison of the Lift-Off Lengths Obtained by Simultaneous OH-LIF and OH* Chemiluminescence Imaging in an Optical Heavy-Duty Diesel Engine

Li, Zheming; Yu, Xin; Lequien, Guillaume; Lind, Ted; Jansons, Marcis; Andersson, Öivind; Richter, Mattias

doi:10.4271/2015-24-2418

Cited by 4 publications

(5 citation statements)

References 31 publications

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“…Considering the relation between OH and OH * , OH PLIF signal appears at a distance which is distinctly further downstream than the onset of the OH * signal, and reported FLOL values [1]). This is in line with previous studies in internal combustion engines with similar thermodynamic conditions [16,52]. Downstream of the FLOL, it seems that the contour of OH * in Figure 6 intersects the OH PLIF signal exactly at the maximum.…”

Section: Relations Between Detected Speciessupporting

confidence: 92%

“…Absolute values from these simulations predict OH * concentrations up to seven orders of magnitude below those of OH, similar to values reported by Li et al [52]. Based on the applied reaction mechanism, the highest concentration of OH * is predicted during ignition on the fuel-rich side of the stoichiometric mixture fraction, indicated by the white arrow and magnified in the insert.…”

Section: Relations Between Detected Speciessupporting

confidence: 86%

“…In an internal combustion engine with simultaneous detection of OH PLIF and OH * , an offset between OH * emission and OH PLIF along a plane was considered to be caused by asymmetries in the flame shape, including OH * not in the plane of the laser sheet [16]. More recently, these observations were studied in more detail by comparing optical engine results to a lifted methane diffusion flame and numerical simulations [52], where it was additionally shown how the collection angle in combination with a thin laser sheet further biases the increased LOL based on OH PLIF. The collection angle, however, is of no concern for OH PLIF in a combustion vessel.…”

Section: Relations Between Detected Speciesmentioning

confidence: 99%

See 2 more Smart Citations

Characterization of Spray A flame structure for parametric variations in ECN constant-volume vessels using chemiluminescence and laser-induced fluorescence

Maes

Meijer

Dam

et al. 2016

Combustion and Flame

111

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The transient and quasi-steady flame structure of reacting fuel sprays produced by single-hole injectors has been studied using chemiluminescence imaging and Planar Laser-Induced Fluorescence (PLIF) in various constant-volume facilities at different research institutes participating in the Engine Combustion Network (ECN). The evolution of the high-temperature flame has been followed based on chemiluminescence imaging of the excited-state hydroxyl radical (OH *), and PLIF of ground-state OH. Regions associated with low-temperature chemical reactions are visualized using formaldehyde (CH 2 O) PLIF with 355-nm excitation. We compare the results obtained by different research institutes under nominally identical experimental conditions and fuel injectors. In spite of design differences among the various experimental facilities, the results are consistent. This lends confidence to studies of transient behavior and parameter variations performed by individual research groups. We present results of the transient flame structures at Spray A reference conditions, and include parametric variations around this baseline, involving ambient temperature, oxygen concentration and injection pressure. Key results are the observed influence of an entrainment wave on the transient flame behavior, model-substantiated explanations for the high-intensity OH * lobes at the lift-off length and differences with OH PLIF, and a general analogy of the flame structures with a spray cone along which the flame tends to locate for the applied parametric variations.

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Section: Relations Between Detected Speciessupporting

confidence: 92%

Section: Relations Between Detected Speciessupporting

confidence: 86%

Section: Relations Between Detected Speciesmentioning

confidence: 99%

See 1 more Smart Citation

Characterization of Spray A flame structure for parametric variations in ECN constant-volume vessels using chemiluminescence and laser-induced fluorescence

Maes

Meijer

Dam

et al. 2016

Combustion and Flame

111

View full text Add to dashboard Cite

show abstract

“…Time-resolved OH* chemiluminescence imaging provides spatial and temporal information on the heat release rate during the combustion. 11–15 Our spectroscopy study for similar operating conditions shows that OH* bandpass imaging is highly affected by broadband chemiluminescence of relatively large molecules, like HCO*, CH 2 O* and CO 2 *, especially for HCCI points. 21 However, it is observed that broadband chemiluminescence can be used as a measure for the heat release rate as well.…”

Section: Methodsmentioning

confidence: 82%

“…OH* chemiluminescence imaging offers line-of-sight information across the volume imaged, and its time-dependent intensity is known as an indicator for the temporal behavior of heat release rate. [12][13][14][15] This feature is commonly used in the literature. Zegers et al 14 investigated the position and size of PPC combustion clouds by analyzing OH* chemiluminescence images in a heavy-duty optical engine.…”

Section: Introductionmentioning

confidence: 99%

Combustion stratification study of partially premixed combustion using Fourier transform analysis of OH* chemiluminescence images

Najafabadi

Somers

Johansson

et al. 2017

International Journal of Engine Research

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A relatively high level of stratification (qualitatively: lack of homogeneity) is one of the main advantages of partially premixed combustion over the homogeneous charge compression ignition concept. Stratification can smooth the heat release rate and improve the controllability of combustion. In order to compare stratification levels of different partially premixed combustion strategies or other combustion concepts, an objective and meaningful definition of ''stratification level'' is required. Such a definition is currently lacking; qualitative/quantitative definitions in the literature cannot properly distinguish various levels of stratification. The main purpose of this study is to objectively define combustion stratification (not to be confused with fuel stratification) based on high-speed OH* chemiluminescence imaging, which is assumed to provide spatial information regarding heat release. Stratification essentially being equivalent to spatial structure, we base our definition on two-dimensional Fourier transforms of photographs of OH* chemiluminescence. A light-duty optical diesel engine has been used to perform the OH* bandpass imaging on. Four experimental points are evaluated, with injection timings in the homogeneous regime as well as in the stratified partially premixed combustion regime. Two-dimensional Fourier transforms translate these chemiluminescence images into a range of spatial frequencies. The frequency information is used to define combustion stratification, using a novel normalization procedure. The results indicate that this new definition, based on Fourier analysis of OH* bandpass images, overcomes the drawbacks of previous definitions used in the literature and is a promising method to compare the level of combustion stratification between different experiments.

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Digital Holography for Investigating Front-Edge Instabilities of Liquid Jets in Supersonic Crossflows

Johnson

Menon

Mazumdar

2023

AIAA SCITECH 2023 Forum

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Comparison of the Lift-Off Lengths Obtained by Simultaneous OH-LIF and OH* Chemiluminescence Imaging in an Optical Heavy-Duty Diesel Engine

Cited by 4 publications

References 31 publications

Characterization of Spray A flame structure for parametric variations in ECN constant-volume vessels using chemiluminescence and laser-induced fluorescence

Characterization of Spray A flame structure for parametric variations in ECN constant-volume vessels using chemiluminescence and laser-induced fluorescence

Combustion stratification study of partially premixed combustion using Fourier transform analysis of OH* chemiluminescence images

Digital Holography for Investigating Front-Edge Instabilities of Liquid Jets in Supersonic Crossflows

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