Abstract
In this work a number of laser techniques have been applied in new ways for combustion diagnostics in engines. The applications cover small two-stroke engines, ordinary spark ignition (SI) engines, direct-injection spark ignition (DISI) engines, and heavy-duty diesel truck engines. In an investigation of unmodified two-stroke engines running at high engine speed, it has been shown that cycle-resolved laser diagnostics are applicable to real-world engines. The emission of unburned fuel was detected at the exhaust port with successful discrimination against other unburned hydrocarbons. Although a few problems remain to be solved in order to get quantitative concentration data, valuable information can nonetheless be attained using this technique. The technique would benefit from the use of a non-fluorescing lubricant, as that would decrease the background fluorescence. Laser-based techniques also provide a useful tool for studying the fuel dynamics inside the cylinder. In the development of DISI engines it is of particular importance to acquire knowledge about the distribution of fuel around the spark plug. Numerical computer codes are often used as design tools in these applications. Laser techniques are capable of yielding instantaneous multi-point concentration information with high spatial and temporal resolution, making them ideal both for validation of CFD simulations
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Citation Formats
Andersson, Oeivind.
Development and application of laser techniques for studying fuel dynamics and NO formation in engines.
Sweden: N. p.,
2000.
Web.
Andersson, Oeivind.
Development and application of laser techniques for studying fuel dynamics and NO formation in engines.
Sweden.
Andersson, Oeivind.
2000.
"Development and application of laser techniques for studying fuel dynamics and NO formation in engines."
Sweden.
@misc{etde_20135009,
title = {Development and application of laser techniques for studying fuel dynamics and NO formation in engines}
author = {Andersson, Oeivind}
abstractNote = {In this work a number of laser techniques have been applied in new ways for combustion diagnostics in engines. The applications cover small two-stroke engines, ordinary spark ignition (SI) engines, direct-injection spark ignition (DISI) engines, and heavy-duty diesel truck engines. In an investigation of unmodified two-stroke engines running at high engine speed, it has been shown that cycle-resolved laser diagnostics are applicable to real-world engines. The emission of unburned fuel was detected at the exhaust port with successful discrimination against other unburned hydrocarbons. Although a few problems remain to be solved in order to get quantitative concentration data, valuable information can nonetheless be attained using this technique. The technique would benefit from the use of a non-fluorescing lubricant, as that would decrease the background fluorescence. Laser-based techniques also provide a useful tool for studying the fuel dynamics inside the cylinder. In the development of DISI engines it is of particular importance to acquire knowledge about the distribution of fuel around the spark plug. Numerical computer codes are often used as design tools in these applications. Laser techniques are capable of yielding instantaneous multi-point concentration information with high spatial and temporal resolution, making them ideal both for validation of CFD simulations and for testing designs. The feasibility of using laser diagnostics in the development of DISI engines has been shown. Future research should be aimed at simplifying the procedure for quantifying the data, since a fairly simple and reliable technique would be an important asset for the industry. In a more fundamental study, it has been shown that it is possible to simultaneously detect a substance in both liquid and vapour phase. Water was used in the study since it is easily produced in both phases. Liquid drops were detected using spontaneous Raman scattering, whereas the vapour surrounding them was detected using two-photon induced fluorescence. The two signals were imaged on different portions of the same CCD camera. Water is used in a number of combustion applications, but it would be a great advantage if this technique could be developed for application in fuel sprays. It could then be used as an alternative to the fluorescent-exciplex technique commonly used for two-phase detection in such applications. The exciplex technique requires an oxygen-free atmosphere and can thus not be used in real combustion environments. Fuel dynamics have also been studied in DME sprays, both in a combustion vessel and in an optical diesel truck engine. The studies were made using laser-Rayleigh imaging and provided interesting information about the general development and autoignition of these sprays. Among other things it was found that autoignition occurred differently in the two environments. In the vessel, the sprays ignited around the periphery where fuel/air mixtures were close to stoichiometric. In the engine, however ignition occurred volumetrically throughout the cross section of the spray vortex. There is reason to believe that mixtures were fuel-rich in this region. The explanation for the different behaviours is assumed to be found in the temperature and density conditions of the atmospheres into which the sprays were injected. The results show that sprays can behave quite differently in different environments. A thorough study of the effects of temperature, density, and EGR on autoignition in sprays is highly desirable, since current models do not seem to give a general description of the phenomenon. Both the measurements in the DISI engine and the NO measurements in the SI engine show that laser spectroscopic techniques can be used for improving and developing computer-based design tools. In the case of the DISI engine, the data were used to validate results from CFD codes used for engine design. The NO data provided a database for development of a model for combustion and pollution formation in SI engines. Future improvements of internal combustion engines rely, in part, on the availability of new and improved measurement techniques. The aim of the presented work has been to bring laboratory laser techniques closer to industrial applications, and to investigate industrially relevant phenomena. The increasing industrial interest in laser-based combustion diagnostics over recent years has shown that these techniques have evolved from a purely academic to a more practical level. It is the author's humble hope that this work can contribute somewhat to this development.}
place = {Sweden}
year = {2000}
month = {Nov}
}
title = {Development and application of laser techniques for studying fuel dynamics and NO formation in engines}
author = {Andersson, Oeivind}
abstractNote = {In this work a number of laser techniques have been applied in new ways for combustion diagnostics in engines. The applications cover small two-stroke engines, ordinary spark ignition (SI) engines, direct-injection spark ignition (DISI) engines, and heavy-duty diesel truck engines. In an investigation of unmodified two-stroke engines running at high engine speed, it has been shown that cycle-resolved laser diagnostics are applicable to real-world engines. The emission of unburned fuel was detected at the exhaust port with successful discrimination against other unburned hydrocarbons. Although a few problems remain to be solved in order to get quantitative concentration data, valuable information can nonetheless be attained using this technique. The technique would benefit from the use of a non-fluorescing lubricant, as that would decrease the background fluorescence. Laser-based techniques also provide a useful tool for studying the fuel dynamics inside the cylinder. In the development of DISI engines it is of particular importance to acquire knowledge about the distribution of fuel around the spark plug. Numerical computer codes are often used as design tools in these applications. Laser techniques are capable of yielding instantaneous multi-point concentration information with high spatial and temporal resolution, making them ideal both for validation of CFD simulations and for testing designs. The feasibility of using laser diagnostics in the development of DISI engines has been shown. Future research should be aimed at simplifying the procedure for quantifying the data, since a fairly simple and reliable technique would be an important asset for the industry. In a more fundamental study, it has been shown that it is possible to simultaneously detect a substance in both liquid and vapour phase. Water was used in the study since it is easily produced in both phases. Liquid drops were detected using spontaneous Raman scattering, whereas the vapour surrounding them was detected using two-photon induced fluorescence. The two signals were imaged on different portions of the same CCD camera. Water is used in a number of combustion applications, but it would be a great advantage if this technique could be developed for application in fuel sprays. It could then be used as an alternative to the fluorescent-exciplex technique commonly used for two-phase detection in such applications. The exciplex technique requires an oxygen-free atmosphere and can thus not be used in real combustion environments. Fuel dynamics have also been studied in DME sprays, both in a combustion vessel and in an optical diesel truck engine. The studies were made using laser-Rayleigh imaging and provided interesting information about the general development and autoignition of these sprays. Among other things it was found that autoignition occurred differently in the two environments. In the vessel, the sprays ignited around the periphery where fuel/air mixtures were close to stoichiometric. In the engine, however ignition occurred volumetrically throughout the cross section of the spray vortex. There is reason to believe that mixtures were fuel-rich in this region. The explanation for the different behaviours is assumed to be found in the temperature and density conditions of the atmospheres into which the sprays were injected. The results show that sprays can behave quite differently in different environments. A thorough study of the effects of temperature, density, and EGR on autoignition in sprays is highly desirable, since current models do not seem to give a general description of the phenomenon. Both the measurements in the DISI engine and the NO measurements in the SI engine show that laser spectroscopic techniques can be used for improving and developing computer-based design tools. In the case of the DISI engine, the data were used to validate results from CFD codes used for engine design. The NO data provided a database for development of a model for combustion and pollution formation in SI engines. Future improvements of internal combustion engines rely, in part, on the availability of new and improved measurement techniques. The aim of the presented work has been to bring laboratory laser techniques closer to industrial applications, and to investigate industrially relevant phenomena. The increasing industrial interest in laser-based combustion diagnostics over recent years has shown that these techniques have evolved from a purely academic to a more practical level. It is the author's humble hope that this work can contribute somewhat to this development.}
place = {Sweden}
year = {2000}
month = {Nov}
}