Quantitative Two-Dimensional Measurements of Nitric Oxide and Temperature Distributions in a Transparent Square Piston SI Engine

Bräumer, A.; Sick, Volker; Wolfrum, J.; Drewes, Volker H.; Zahn, M.; Maly, R.

doi:10.4271/952462

Cited by 28 publications

(13 citation statements)

References 16 publications

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“…Similar results are reported by Arcoumanis et al [8]. Induction generated differences in mean flow structure are found to survive compression, resulting in a significant speed dependence of the near-TDC flow structure [64,74,104,106]. Induction generated differences in mean flow structure are found to survive compression, resulting in a significant speed dependence of the near-TDC flow structure [64,74,104,106].…”

Section: Mean Flow Structuressupporting

confidence: 79%

“…The low temperature chemistry (< 900 K) is started by the RO2 isomeration processes producing OH radicals by QOOH decomposition consuming some fuel and liberating some heat at low rates. The reasons have been clarified in recent studies by the fluid dynamic part following auto-ignition [42,105,106]: contrary to general assumptions, auto-ignition occurs not uniformly throughout the end-gas region but in localized spots embedded in the inhomogeneous end-gas -in exothermic centers -with specific induction (time to ignition) and excitation times (time of heat release) [107][108][109]. This process may exhibit a distinct two-stage ignition behavior and a negative temperature coefficient (NTC) region in the overall reaction.…”

Section: Knocking Combustionmentioning

confidence: 99%

“…Discussion of this topic and selected applications can be found in references [36,50,60,62,106]. Discussion of this topic and selected applications can be found in references [36,50,60,62,106].…”

Section: Ensemble Averaging Vs Cycle-resolved Analysismentioning

confidence: 99%

“…Although the majority of studies report a near-linear scaling of the mean flow velocities with engine speed [13,16,19,27,65,106], non-linear behavior is often observed-chiefly in those studies that report spatial profiles of the mean velocities. Monaghan and Pettifer [74] performed a detailed, early study of speed effects on the in-cylinder flow structure.…”

Section: Mean Flow Structuresmentioning

confidence: 99%

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Flow and Combustion in Reciprocating Engines

Arcoumanis¹,

Kamimoto²

2009

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Section: Mean Flow Structuressupporting

confidence: 79%

Section: Knocking Combustionmentioning

confidence: 99%

Section: Ensemble Averaging Vs Cycle-resolved Analysismentioning

confidence: 99%

Section: Mean Flow Structuresmentioning

confidence: 99%

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Flow and Combustion in Reciprocating Engines

Arcoumanis¹,

Kamimoto²

2009

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“…The equivalence ratio is never much larger than one making prompt NO unlikely, as confirmed by the measurements of BrŠumer et al (1995). Moreover, the volume occupied by the flamelets where prompt NO could be produced is negligible as compared to the volume occupied by the burned gases.…”

Section: Introductionmentioning

confidence: 48%

Modeling Turbulent Combustion and Pollutant Formation in Stratified Charge Si Engines

Duclos

Baritaud

Fusco

1997

Rev. Inst. Fr. Pét.

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copyright C 1997, Institut Français du Pétrole extended to rich or diluted combustion. NO and CO reaction rates are computed conditionally based on the burned gas temperature with two contributions: a source term function of the flamelet density and unburned gas composition and temperature, and another source term including equilibrium and kinetic mechanisms in the burned gas. The coupled combustion and pollutant models are implemented in the Kiva-2 code and tested on a simple engine geometry for a set of operating conditions including variation of equivalence ratio, dilution by residual gases and fuel stratification. The ability of the model to reproduce observed trends for combustion rate is demonstrated. The influence of the local laminar flame on the burn rate is pointed out.A much larger production rate of NO and CO during combustion resulting in higher computed NO levels for most of the operating conditions, and similar final CO levels after combustion completion is observed for the conditional averaging as compared to the usual ensemble averaging procedures. The predicted levels of emissions are comparable to measured engine values. MODELIZACIîN DE LA COMBUSTIîN TURBULENTA Y DE LA FORMACIîN DE CONTAMINANTES EN LOS MOTORES DE ENCENDIDO CONTROLADO CON CARGA ESTRATIFICADASe ha aplicado un mŽtodo por el cual se implementan los promedios condicionales a las modelizaciones de la combusti-n y de la formaci-n de contaminantes en los motores de encendido controlado con carga estratificada. Un sistema de ecuaciones describe, durante la combusti-n, las composiciones y temperaturas locales no consumidos aoen. Se ha adoptado el modelo de llama coherente (CFM) para simular la combusti-n, que se ha aplicado a continuaci-n a las combustiones en mezclas ricas o diluidas. Las tasas de reacciones relativas al NO y al COA se calculan tomando como condiciones de referencia las temperaturas de los gases consumidos y considerando dos contribuciones : un primer tŽrmino fuente dependiente de la densidad de llamas de reducidas dimensiones, de la temperatura y de la composici-n de los gases nuevos, mientras que otro tŽrmino tiene en cuenta los mecanismos de equilibrio y de la cinŽtica de los gases consumidos. Los modelos acoplados de combusti-n y de formaci-n de contaminantes se han introducido en el c-digo digital Kiva-2 y sometidos a prueba con una geometr'a sencilla de motos, y ello para un conjunto de condiciones de funcionamiento que incluyen variaciones de riqueza, de diluci-n por los gases residuales y de estratificaci-n del carburante. Para las tasas de combusti-n, se ha demostrado la capacidad del modelo para poder reproducir las tendencias observadas. Se hace resaltar de forma evidente la influencia respecto a la tasa de combusti-n de la llama laminar local.La introducci-n de los promedios condicionales, comparada con los procedimientos habituales que utilizan promedios de conjuntos, conduce a tasas de producci-n de NO y de CO m ‡s importantes durante la combusti-n, y por consiguiente, niveles calculados de NO m ‡s elevad...

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Laser‐Based Combustion Diagnostics

Wolfrum

Dreier

Ebert

et al. 2000

Encyclopedia of Analytical Chemistry

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In laser spectroscopy the interaction of light emitted from various types of laser sources – tunable or nontunable in their output frequency – with the atomic or molecular species of interest is used to probe the sample through a variety of spectral responses. In order to perform laser spectroscopy suitable laser sources must be selected which meet the requirements of the chosen spectroscopic method. This means that the laser has to provide radiation which is in the wavelength range of interest, has the appropriate emission characteristics (lineshape) and a suitable energy to perform the measurements. Further requirements are pulse length (milliseconds to femtoseconds or continuous wave), repetition rate and beam profile. Nowadays, laser radiation can be generated with most of the required parameters necessary for the respective spectroscopic application, either directly or by generating new radiation frequencies by frequency mixing of one or several laser beams in a nonlinear medium (gas, liquid, solid). As an example, the most direct probe is absorption of laser radiation (LAS, laser absorption spectroscopy) by suitable spectroscopically allowed transitions in atoms or molecules which are known from conventional spectroscopic methods. The increase or decrease in the laser radiation transmitted through the sample is then a measure of the amount of substance probed in the sample which characteristically absorbs at the required wavelength. Laser light scattering methods, elastic (Rayleigh scattering (RS)) or inelastic (spontaneous Raman scattering (SRS)), are other techniques to probe the medium. In the first method, which is nonspecies specific, the density of the medium can be interrogated, whereas the second is able to probe all species with Raman‐active vibration–rotation transitions. There are several advantages in using laser spectroscopy instead of conventional spectroscopic techniques using conventional thermal light sources. The spectral brightness of laser beams is many orders of magnitude higher than that of thermal radiation sources, which correspondingly increase the detection sensitivity of laser spectroscopic techniques. In addition, the small linewidth of the emitted radiation increases dramatically the spectral resolution such that minor details of the spectroscopic branch investigated can be resolved. This enables more quantitative interpretations of all parameters influencing the lineshape and intensity of the probed transition, and as such the physical and chemical environment of the probed species: temperature, pressure, velocity, chemical species and so on. It makes laser spectroscopic techniques much more selective than conventional methods, which often are not able to separate closely spaced spectral features from different species. A third advantage of laser spectroscopic techniques is connected with the variable pulse duration and repetition frequency of lasers: the very short pulse lengths can be used successfully to probe the sample within time periods which are short compared to any other physical or chemical time development – flow, chemical reaction, pressure changes and so on. Finally, the small spatial regions which can be probed by focusing diffraction limited laser beams makes laser spectroscopic techniques ideally suited for applications where high spatial resolution is required. All these advantages of laser spectroscopy are beneficial when the various techniques are applied as a diagnostic tool in combustion processes: flames constitute a complex interaction of fast chemistry with flow fields and surfaces and, therefore, a detailed understanding of combustion events often needs in situ, species‐specific optical diagnostics with high spatial and temporal resolution. In many applications laser spectroscopy is a developed technique and can even be applied by untrained people. However, numerous laser spectroscopic techniques require detailed theoretical knowledge of the spectroscopy underlying the respective technique, and use sophisticated equipment in order to obtain meaningful results. Future development is aimed towards simplifying experimental set‐ups, data evaluation and maintenance. This development runs parallel to the breathtaking development in laser technology.

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Quantitative Two-Dimensional Measurements of Nitric Oxide and Temperature Distributions in a Transparent Square Piston SI Engine

Cited by 28 publications

References 16 publications

Flow and Combustion in Reciprocating Engines

Flow and Combustion in Reciprocating Engines

Modeling Turbulent Combustion and Pollutant Formation in Stratified Charge Si Engines

Laser‐Based Combustion Diagnostics

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