An Experimental Investigation on the Effect of Diluent Addition on Flame Characteristics in a Single Cylinder Optical Diesel Engine

Founti, M.; Hardalupas, Y.; Hong, Christopher; Keramiotis, Christos; Ramaswamy, Kumara Gurubaran; Soulopoulos, N.; Taylor, A. M. K. P.; Touloupis, Dimitrios P.; Vourliotakis, George

doi:10.4271/2015-24-2438

Cited by 8 publications

(7 citation statements)

References 31 publications

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“…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: 81%

“…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%

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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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Section: Methodsmentioning

confidence: 81%

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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“…The engine configuration and the instrumentation have been described in detail in recent previous works (Hong, 2015;Founti et al, 2015). The piston features a cylindrical bowl design, through which optical access to the combustion chamber is facilitated.…”

Section: Experimental Apparatus and Methodologymentioning

confidence: 99%

“…However, the dominant mechanisms can vary significantly depending on the engine operating conditions, thus obscuring the establishment of a clear optimization strategy. The scope of the present work is to expand acknowledged operating conditions and to visualise this behaviour in a previously characterized single cylinder optically accessed Ricardo Hydra CI engine equipped with a Ford York I4 2.2 L engine cylinder head (Hong, 2015;Founti et al, 2015), aiming to gain some further understanding about the mechanisms determining the soot reduction mechanisms under a post injection scheme. Measurements were performed in the latter engine with respect to various post injection timings and fuel amounts.…”

Section: Introductionmentioning

confidence: 99%

Towards Identifying Flame Patterns in Multiple, Late Injection Schemes on a Single-Cylinder Optical Diesel Engine

Hardalupas

Hong

Keramiotis

et al. 2016

Combustion Science and Technology

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“…Chemiluminescence gives a holistic view on the combustion stratification inside the combustion chamber [11]. Based on Chemiluminescence and high speed imaging, the effect of fuel injection strategies on combustion stratification was investigated for PRF55 [9].…”

Section: Combustion Stratification For Naphtha From CI Combustion To Ppcmentioning

confidence: 99%

Combustion Stratification for Naphtha from CI Combustion to PPC

Vallinayagam

Vedharaj

et al. 2017

SAE Technical Paper Series

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This study demonstrates the combustion stratification from conventional compression ignition (CI) combustion to partially premixed combustion (PPC). Experiments are performed in an optical CI engine at a speed of 1200 rpm for diesel and naphtha (RON = 46). The motored pressure at TDC is maintained at 35 bar and fuelMEP is kept constant at 5.1 bar to account for the difference in fuel properties between naphtha and diesel. Single injection strategy is employed and the fuel is injected at a pressure of 800 bar. Photron FASTCAM SA4 that captures in-cylinder combustion at the rate of 10000 frames per second is employed. The captured high speed video is processed to study the combustion homogeneity based on an algorithm reported in previous studies.Starting from late fuel injection timings, combustion stratification is investigated by advancing the fuel injection timings. For late start of injection (SOI), a direct link between SOI and combustion phasing is noticed. At early SOI, combustion phasing depends on both intake air temperature and SOI. In order to match the combustion phasing (CA50) of diesel, the intake air temperature is increased to 90°C for naphtha. The combustion stratification from CI to PPC is also investigated for various level of dilution by displacing oxygen with nitrogen in the intake. The start of combustion (SOC) was delayed with the increase in dilution and to compensate for this, the intake air temperature is increased. The mixture homogeneity is enhanced for higher dilution due to longer ignition delay. The results show that high speed image is initially blue and then turned yellow, indicating soot formation and oxidation. The luminosity of combustion images decreases with early SOI and increased dilution. The images are processed to generate the level of stratification based on the image intensity. The level of stratification is same for diesel and naphtha at various SOI. When O 2 concentration in the intake is decreased to 17.7% and 14.7%, stratification level is decreased. NO X emission for both diesel and naphtha show a decreasing trend from CI to PPC.Comparing diesel and naphtha, the soot emission is lower for naphtha. NO X and soot emissions at various SOI are correlated with high speed images of combustion to explain the combustion stratification.

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An Experimental Investigation on the Effect of Diluent Addition on Flame Characteristics in a Single Cylinder Optical Diesel Engine

Cited by 8 publications

References 31 publications

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

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

Towards Identifying Flame Patterns in Multiple, Late Injection Schemes on a Single-Cylinder Optical Diesel Engine

Combustion Stratification for Naphtha from CI Combustion to PPC

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