Temperature and pressure dependences of the laser-induced fluorescence of gas-phase acetone and 3-pentanone

Großmann, Frank; Monkhouse, P.; Ridder, M.; Sick, Volker; Wolfrum, J.

doi:10.1007/bf01080952

Cited by 144 publications

(54 citation statements)

References 8 publications

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“…Ketones are the most frequently used class of fluorescent tracers. Their properties have been extensively studied [7][8][9][10] and they have been applied to various practical situations [3][4][5]. The high vapor pressure makes acetone (boiling point 56°C) an ideal tracer for gaseous flows [11].…”

Section: Spectroscopic Conceptmentioning

confidence: 99%

Fiber optic spark plug sensor for UV-LIF measurements close to the ignition spark

et al. 2005

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Time-resolved observation of the fuel/air mixing process prior to ignition is crucial for the development of modern internal combustion engine concepts. The presented fiber optic sensor is designed for the acquisition of in-cylinder data in the area close to the ignition spark, based on UV-laser-induced fluorescence of organic fuel compounds. Excitation and fluorescence light are separately guided through silica fibers. The detection volume is defined by the optical design of the sensor head. Since the related components are completely integrated into a modified spark plug, the sensor can be applied to unmodified production line engines. We present the fundamental spectroscopic concept, the solution for the minimal invasive access through the spark plug and tracer spectra measured with a prototype.Keywords: Fiber optic sensor, Tracer LIF (laser induced fluorescence), Microoptical sensor, UV-LIF INTRODUCTIONRecent research on modern direct injection spark ignition (DISI) engines opened a promising concept for reducing fuel consumption and CO 2 exhaust. Most engines still provide a homogeneous fuel/air distribution throughout the whole combustion chamber, throttling the airflow to ensure stoichiometric conditions at part-load conditions and thus loosing energy (pumping losses). Modern DISI engines operate nearly unthrottled with a very lean fuel/air mixture to reduce those pumping losses. The safe, clean and reliable operation of any combustion device depends to a large degree on the exact control of the air-fuel mixing process prior to ignition. To insure ignition of the over-all fuel, it is necessary to provide a highly defined (i.e. stratified) distribution of the fuel vapor, which would be too lean for ignition under homogeneous conditions. Because of the spatially inhomogeneous equivalence ratio, the ignition performance is very sensitive to mixture distribution and timing. Therefore, quantitative measurement techniques that characterize the state of the unburned gas mixture are crucial in modern combustion science. The major problem in the development of DISI engines is the cyclic variation of the combustion process, which leads to high raw emissions of soot and hydrocarbons and causes inhomogeneous temperature distributions that are responsible for increased formation of nitric oxide. These emissions can only be partially reduced using state-of-the-art exhaust aftertreatment systems. Especially for the stratified mode the fuel/air composition at the start of combustion is an important factor for the ignition and combustion process of the individual cycle. The equivalence ratio determines ignitability and flame speed. For lean and rich mixtures the flame speed is reduced compared to stoichiometric composition. Thus the fuel/air mixing strongly affects cyclic variations of the combustion process. With the measurement technique presented in this paper we aim to get time-resolved in-situ information about the variations of the equivalence ratio and temperature close to the spark gap region, which are key...

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Section: Spectroscopic Conceptmentioning

confidence: 99%

Fiber optic spark plug sensor for UV-LIF measurements close to the ignition spark

et al. 2005

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“…Depending on the thermodynamic conditions and excitation wavelength, fluorescence emission of acetone may exhibit a significant temperature dependence. In these experiments, employing excitation at 266 nm the sensitivity to temperature change is fair [23][24][25][26] and in any case implies a decay of the …”

Section: Residual Gas Distributionmentioning

confidence: 99%

Nature of CAI Combustion and Air/Fuel Ratio Stratification Effects

Thirouard

Cherel

2006

Oil & Gas Science and Technology - Rev. IFP

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Résumé -Nature de la combustion CAI et impact de stratifications de richesse -La combustion CAI (Controlled Auto-Ignition) appliquée aux moteurs essence permet un fonctionnement en mélange pauvre avec de très faibles émissions d'oxyde d'azote. De ce fait, ce procédé de combustion présente un fort potentiel pour la réduction de consommation des motorisations essence. Les travaux décrits visent à approfondir la compréhension des phénomènes physiques et chimiques qui régissent l'auto-inflammation et les différentes étapes du déroulement de la combustion en fonctionnement CAI. En particulier, l'étude s'est intéressée à la phase d'apparition des précurseurs de l'auto-inflammation qui précède la phase de dégagement de chaleur et à l'analyse de la structure de zone de combustion. Ces travaux ont été réalisés sur moteur optique à l'aide de visualisation directe de la combustion et de fluorescence induite par laser pour la détection des intermédiaires de combustion OH et formaldéhyde. Il est apparu que le fort taux de dégagement de chaleur qui est caractéristique du fonctionnement CAI est dû à une combustion qui se déroule en volume, et qui localement présente un taux de réaction modéré. Le contrôle du taux de dégagement de chaleur ne peut par conséquent être maîtrisé que par une stratification du mélange visant à diminuer la quantité de gaz en combustion à un instant donné, ou par une dilution renforcée visant à diminuer le taux de réaction. De fait, l'influence de la qualité du mélange air/carburant/gaz résiduels sur l'auto-inflammation et le déroulement de la combustion a été étudiée. Pour cela, le mélange a été caractérisé à l'aide de technique de fluorescence induite laser sur traceur et le déroulement de la combustion a été observé à l'aide d'une caméra rapide intensifiée. Une analyse cycle à cycle de la répartition des sites d'auto-inflammation et du champ de richesse locale a montré que les premières zones de réaction apparaissaient préférentiellement dans les hétérogénéités du mélange les plus riches en carburant. De plus, il est apparu que le niveau de stratification de la charge obtenu par l'utilisation d'injection indirecte dissymétrique ne permet pas de modifier le déroulement de la combustion. Enfin, l'utilisation de l'injection directe a été testée et a montré qu'il était possible de contrôler le phasage de l'auto-inflammation par l'utilisation de stratégies d'injection appropriées simples ou multiples. La création d'une zone riche à délai réduit lors d'injection tardive et la pré-décomposition du carburant lors d'injection pendant la phase de recompression sont apparus être les principaux phénomènes responsables de l'impact de la stratégie d'injection sur le phasage de la combustion.Abstract -Nature of CAI Combustion and Air/Fuel Ratio Stratification Effects -The purpose of this study was to gain a better understanding of the fundamental aspects of the CAI combustion process in order to assess the possibilities of controlling CAI combustion through air/fuel mixture stratification. The experimental work wa...

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“…As the temperature increases, the peak intensity red-shifts so e.g. at 1000 K, the peak occurs at ~290 nm [40]. This spectral shift of the absorption spectra can be used for temperature measurements by choosing two excitation wavelengths on different wings of this band and taking the ratio of fluorescence signals from these two excitation wavelengths.…”

Section: Principle Of the Two-line Plif Thermometrymentioning

confidence: 99%

“…The main physical and photophysical properties required of a fluorescent tracer for in-cylinder LIF studies include: boiling point and transport properties closely match to the carrier fuel, absorption spectrum suitable for available laser wavelengths, satisfactory fluorescence quantum yield, and insensitivity to oxygen quenching [35]. Previous studies of the photophysical behaviour of 3-pentanone indicated its advantages over other common tracers [36][37][38][39]. Grossmann et al studied the temperature and pressure dependence of the LIF signal of gas-phase 3-pentanone and showed that after excitation at two different wavelengths the ratio of the fluorescence signal intensities reflects the local temperature.…”

Section: Introductionmentioning

confidence: 99%

“…Grossmann et al studied the temperature and pressure dependence of the LIF signal of gas-phase 3-pentanone and showed that after excitation at two different wavelengths the ratio of the fluorescence signal intensities reflects the local temperature. Since this temperature measurement is based on the ratio of signal intensities it is independent of local tracer concentrations and therefore allows measurements of two-dimensional temperature distributions in non-homogeneously mixed systems [40]. Einecke et al [41] reported the first application of the two-line PLIF technique for temperature distribution measurements in an optically accessible two-stroke engine with isooctane doped with 3-pentanone.…”

Section: Introductionmentioning

confidence: 99%

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Turbulent flame boundary and structure detection in an optical DISI engine using tracer-based two-line PLIF technique

Attar

Zhao

Herfatmanesh

et al. 2015

Experimental Thermal and Fluid Science

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"Turbulent flame boundary and structure detection in an optical DISI engine using tracer-based two-line PLIF technique", Experimental Thermal and Fluid Science, AbstractDesign and development of new combustion systems for Spark Ignition Direct Injection (DISI) engines requires thorough understanding of the combustion flame as it develops from the electric discharge and propagates across the combustion chamber. The main purpose of this work was to develop an experimental setup capable of investigating the premix turbulent flame boundary and structure inside the combustion chamber of a DISI engine. For this purpose the tracer-based two-line Planar Laser Induced Fluorescence (PLIF) technique was set up. In order to have a thermometry technique independent of the photophysical model of dopant tracer, a specially designed Constant Volume Chamber (CVC) was utilized for quasi in situ calibration measurement. The thermometry technique was evaluated by measurements of average in-cylinder charge temperature during compression stroke for both motoring and firing cycles and comparing the results with temperature values calculated from in-cylinder pressure data. The developed technique was successfully implemented to detect flame structure during combustion process in an optical engine. The present study demonstrated that as the two-line PLIF thermal images are independent of species concentration and flame luminosity they can be utilized as an accurate means for flame segmentation. The proposed technique has the potential to be utilized for study of premix flames in non-homogeneously mixed systems.

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Temperature and pressure dependences of the laser-induced fluorescence of gas-phase acetone and 3-pentanone

Cited by 144 publications

References 8 publications

Fiber optic spark plug sensor for UV-LIF measurements close to the ignition spark

Fiber optic spark plug sensor for UV-LIF measurements close to the ignition spark

Nature of CAI Combustion and Air/Fuel Ratio Stratification Effects

Turbulent flame boundary and structure detection in an optical DISI engine using tracer-based two-line PLIF technique

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