The Experts below are selected from a list of 4338 Experts worldwide ranked by ideXlab platform
Eiji Tomita - One of the best experts on this subject based on the ideXlab platform.
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Jet-guided combustion characteristics and local Fuel Concentration measurements in a hydrogen direct-injection spark-ignition engine
Proceedings of the Combustion Institute, 2012Co-Authors: Nobuyuki Kawahara, Eiji Tomita, Takashi FujitaniAbstract:Abstract Spark-ignition (SI) hydrogen engines based on direct injection (DI) promise significant advantages in terms of thermal efficiency and power output, and present a means of overcoming problems related to knocking, backfiring, and preignition. A better understanding of the effects of hydrogen jets on the Fuel Concentration distribution and mixing process in a DISI engine should provide new and useful insights into combustion optimization. The objective of the present work was to gain a deeper comprehension of the characteristics of late-injection hydrogen combustion. An experimental combustion setup was applied to a fired, jet-guided DISI engine operated at 600 rpm in stratified mode. GDI injector with the jet directed toward the spark plug was used to develop the stratified combustion concept. A high-speed camera synchronized with the spark was focused on a 52 mm-diameter field of view through a window at the bottom of the piston crown. A series of single-shot images captured at different intervals was used to study the time evolution of the flame distribution. Variations in the Fuel injection timing relative ignition timing were found to impact the development of the early flame, as well as the flame propagation. This research also employed spark-induced breakdown spectroscopy (SIBS) to measure the local Fuel–air Concentration in the spark gap at the time of ignition under stratified-charge conditions.
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In situ Fuel Concentration measurement near a spark plug in a spray-guided direct-injection spark-ignition engine using infrared absorption method
Experiments in Fluids, 2010Co-Authors: Nobuyuki Kawahara, Eiji Tomita, Takuya Kadowaki, Tetsuya Honda, Hideaki KatashibaAbstract:Vaporized Fuel Concentration in a spray-guided direct-injection spark-ignition (SG-DISI) engine was measured using an optical sensor installed in a spark plug. A laser infrared absorption method was applied to quantify the instantaneous gasoline Concentration near the spark plug. This paper discusses the feasibility of obtaining in situ air–Fuel ratio measurements with this sensor installed inside an SG-DISI engine cylinder. First, the effects of the spray plume from a multi-hole injector on the vaporized Fuel Concentration measurements near the spark-plug sensor were examined using a visible laser. We determined the best position for the sensor in the engine, which was critical due to the spray and vapor plume formation. Then, a 3.392-μm He–Ne laser that coincided with the absorption line of the hydrocarbons was used as a light source to examine the stratified mixture found during ultra-lean engine operation. A combustible mixture existed around the spark plug during the injection period when a preset air–Fuel ratio of 45.0 was used with different Fuel injection timings and net mean effect pressure conditions. The effects of the orientation of the spark plug on the measured results and ignitability of the SG-DISI engine were examined. Orienting the spark plug vertically to one of the spray plumes provided more accurate results and better engine reliability. The study demonstrated that it was possible to qualify the air–Fuel ratio near the spark plug during the injection period using the developed spark-plug sensor in an SG-DISI engine.
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Fuel Concentration measurement of premixed mixture using spark induced breakdown spectroscopy
Spectrochimica Acta Part B: Atomic Spectroscopy, 2009Co-Authors: Nobuyuki Kawahara, Eiji Tomita, S Takemoto, Y IkedaAbstract:Abstract This study determined the local equivalence ratio of a CH 4 /air mixture in a laminar premixed flame using spark-induced breakdown spectroscopy (SIBS) with a fiber-coupled intensified charge coupled device (ICCD) spectrometer. Spectrally resolved emission spectra of plasma generated by a spark plug were investigated for their potential to measure local Fuel Concentrations in a premixed mixture. The influence of key parameters, such as the camera gate timing and spark energy, on the intensity of radical emission was illustrated. The intensity ratio of CN/NH had a greater sensitivity to the equivalence ratio than did that of CN/OH, and the local equivalence ratio could be obtained with high resolution by measuring the local intensity ratios of CN/NH. Moreover, a spark-plug sensor with an optical fiber was developed for application in spark-ignition engines. The atomic emission intensity during the breakdown and arc phases of spark discharge could be obtained using the fiber-optic spark-plug sensor. The H α /O intensity showed better linearity than the CN/NH intensity ratio in lean mixtures. The results presented here confirm the use of SIBS as a diagnostic tool for spark-ignition engines.
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In situ Fuel Concentration measurement near spark plug in spark-ignition engines by 3.39 μm infrared laser absorption method
Proceedings of the Combustion Institute, 2007Co-Authors: Eiji Tomita, Sadami Yoshiyama, Nobuyuki Kawahara, Akihiko Kakuho, Teruyuki Itoh, Yoshisuke HamamotoAbstract:Recently, improving the thermal efficiency and reducing the exhaust emissions of internal combustion engines have become crucial. To this end, it is important to determine the Fuel Concentration in the vicinity of the spark plug near the spark timing, because initial combustion affects the subsequent main combustion in spark-ignition engines. In this study, a fiber optic system linked to an optical sensor installed in the spark plug, by means of which light can pass through the combustion chamber, was developed to determine the Fuel Concentration near the spark plug using an IR absorption method. A He−Ne laser with a wavelength of 3.39 μ m that coincides with the absorption line of hydrocarbons was used as a light source. By exchanging an ordinary spark plug for this spark plug with the optical sensor, successive measurement of Fuel Concentration before the spark timing near the spark plug was performed in a port-injection spark-ignition engine Fueled with iso-octane under the firing condition. The effects of pressure and temperature on the molar absorption coefficient of Fuel were clarified in advance. The air/Fuel ratio averaged for many cycles near the spark plug with this optical system agreed with that measured with a buret, which represented the mean value averaged over a protracted period. Next, this sensor was applied to determine the air/Fuel ratio quantitatively in a direct-injection gasoline engine. As a result, it was clarified that the air/Fuel ratio and its standard deviation near the spark plug have a strong relationship to stable engine operation.
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cycle resolved measurements of the Fuel Concentration near a spark plug in a rotary engine using an in situ laser absorption method
Proceedings of the Combustion Institute, 2007Co-Authors: Nobuyuki Kawahara, Eiji Tomita, Kenta Hayashi, Michihiko Tabata, Kouhei Iwai, Ryoji KagawaAbstract:Cycle-resolved measurements of the Fuel Concentration near a spark plug in a commercial rotary engine were performed. An in situ laser infrared (IR) absorption method was developed using a spark plug sensor and a 3.392-μm He–Ne laser as the light source. This wavelength coincided with the absorption line of hydrocarbons. The newly developed IR spark plug sensor had a higher signal-to-noise ratio than its previous version due to the optimization of its quartz lens and two optical fibers. The new sensor provided quantitative cycle-resolved Fuel Concentration measurements around the spark plug with a high temporal resolution. At lean preset air/Fuel (A/F) ratios, Fuel was mixed with the surrounding air gradually by the rotor motion in the plug hole of the rotary engine. Strong mixture inhomogeneities were measured during the compression stroke; the magnitude of these inhomogeneities decreased throughout the compression stroke. Cycle-resolved measurements were made to investigate the effects of the Fuel Concentration near the spark plug on the combustion characteristics of the commercial rotary engine. There was a strong correlation between the Fuel Concentration measured with the spark plug sensor and the combustion characteristics during the initial combustion period, which occurred faster when conditions were slightly richer than stoichiometric near the spark plug. The indicated mean effective pressure (IMEP) was slightly related to the A/F ratio near the spark plug. It was possible to measure the cycle-resolved A/F ratio near the spark plug and investigate its cycle-to-cycle fluctuations to achieve stable operation using the newly developed spark plug sensor.
Nobuyuki Kawahara - One of the best experts on this subject based on the ideXlab platform.
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In-Situ Fuel Concentration Measurement Using an IR Spark Plug Sensor by Laser Infrared Absorption Method - Application to a Rotary Engine-
2020Co-Authors: Nobuyuki KawaharaAbstract:Cycle-resolved measurements of the Fuel Concentration near a spark plug in both a commercial spark-ignition piston engine and a commercial rotary engine were performed. An in situ laser infrared (IR) absorption method was developed using a spark plug sensor and a 3.392-μm He–Ne laser as the light source. This wavelength coincided with the absorption line of hydrocarbons. The newly developed IR spark plug sensor had a higher signal-to-noise ratio than its previous version due to the optimization of its quartz lens and two optical fibers. The new sensor provided quantitative cycle-resolved Fuel Concentration measurements around the spark plug with a high temporal resolution. At lean preset air/Fuel (A/F) ratios, Fuel was mixed with the surrounding air gradually near the spark plug. Strong mixture inhomogeneities were measured during the compression stroke; the magnitude of these inhomogeneities decreased throughout the compression stroke. There was a strong correlation between the Fuel Concentration measured with the spark plug sensor and the combustion characteristics during the initial combustion period, which occurred faster when conditions were slightly richer than stoichiometric near the spark plug. The indicated mean effective pressure (IMEP) was slightly related to the A/F ratio near the spark plug. It was possible to measure the cycle-resolved A/F ratio near the spark plug and investigate its cycle-to-cycle fluctuations to achieve stable operation using the newly developed spark plug sensor.
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Jet-guided combustion characteristics and local Fuel Concentration measurements in a hydrogen direct-injection spark-ignition engine
Proceedings of the Combustion Institute, 2012Co-Authors: Nobuyuki Kawahara, Eiji Tomita, Takashi FujitaniAbstract:Abstract Spark-ignition (SI) hydrogen engines based on direct injection (DI) promise significant advantages in terms of thermal efficiency and power output, and present a means of overcoming problems related to knocking, backfiring, and preignition. A better understanding of the effects of hydrogen jets on the Fuel Concentration distribution and mixing process in a DISI engine should provide new and useful insights into combustion optimization. The objective of the present work was to gain a deeper comprehension of the characteristics of late-injection hydrogen combustion. An experimental combustion setup was applied to a fired, jet-guided DISI engine operated at 600 rpm in stratified mode. GDI injector with the jet directed toward the spark plug was used to develop the stratified combustion concept. A high-speed camera synchronized with the spark was focused on a 52 mm-diameter field of view through a window at the bottom of the piston crown. A series of single-shot images captured at different intervals was used to study the time evolution of the flame distribution. Variations in the Fuel injection timing relative ignition timing were found to impact the development of the early flame, as well as the flame propagation. This research also employed spark-induced breakdown spectroscopy (SIBS) to measure the local Fuel–air Concentration in the spark gap at the time of ignition under stratified-charge conditions.
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In situ Fuel Concentration measurement near a spark plug in a spray-guided direct-injection spark-ignition engine using infrared absorption method
Experiments in Fluids, 2010Co-Authors: Nobuyuki Kawahara, Eiji Tomita, Takuya Kadowaki, Tetsuya Honda, Hideaki KatashibaAbstract:Vaporized Fuel Concentration in a spray-guided direct-injection spark-ignition (SG-DISI) engine was measured using an optical sensor installed in a spark plug. A laser infrared absorption method was applied to quantify the instantaneous gasoline Concentration near the spark plug. This paper discusses the feasibility of obtaining in situ air–Fuel ratio measurements with this sensor installed inside an SG-DISI engine cylinder. First, the effects of the spray plume from a multi-hole injector on the vaporized Fuel Concentration measurements near the spark-plug sensor were examined using a visible laser. We determined the best position for the sensor in the engine, which was critical due to the spray and vapor plume formation. Then, a 3.392-μm He–Ne laser that coincided with the absorption line of the hydrocarbons was used as a light source to examine the stratified mixture found during ultra-lean engine operation. A combustible mixture existed around the spark plug during the injection period when a preset air–Fuel ratio of 45.0 was used with different Fuel injection timings and net mean effect pressure conditions. The effects of the orientation of the spark plug on the measured results and ignitability of the SG-DISI engine were examined. Orienting the spark plug vertically to one of the spray plumes provided more accurate results and better engine reliability. The study demonstrated that it was possible to qualify the air–Fuel ratio near the spark plug during the injection period using the developed spark-plug sensor in an SG-DISI engine.
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Fuel Concentration measurement of premixed mixture using spark induced breakdown spectroscopy
Spectrochimica Acta Part B: Atomic Spectroscopy, 2009Co-Authors: Nobuyuki Kawahara, Eiji Tomita, S Takemoto, Y IkedaAbstract:Abstract This study determined the local equivalence ratio of a CH 4 /air mixture in a laminar premixed flame using spark-induced breakdown spectroscopy (SIBS) with a fiber-coupled intensified charge coupled device (ICCD) spectrometer. Spectrally resolved emission spectra of plasma generated by a spark plug were investigated for their potential to measure local Fuel Concentrations in a premixed mixture. The influence of key parameters, such as the camera gate timing and spark energy, on the intensity of radical emission was illustrated. The intensity ratio of CN/NH had a greater sensitivity to the equivalence ratio than did that of CN/OH, and the local equivalence ratio could be obtained with high resolution by measuring the local intensity ratios of CN/NH. Moreover, a spark-plug sensor with an optical fiber was developed for application in spark-ignition engines. The atomic emission intensity during the breakdown and arc phases of spark discharge could be obtained using the fiber-optic spark-plug sensor. The H α /O intensity showed better linearity than the CN/NH intensity ratio in lean mixtures. The results presented here confirm the use of SIBS as a diagnostic tool for spark-ignition engines.
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In situ Fuel Concentration measurement near spark plug in spark-ignition engines by 3.39 μm infrared laser absorption method
Proceedings of the Combustion Institute, 2007Co-Authors: Eiji Tomita, Sadami Yoshiyama, Nobuyuki Kawahara, Akihiko Kakuho, Teruyuki Itoh, Yoshisuke HamamotoAbstract:Recently, improving the thermal efficiency and reducing the exhaust emissions of internal combustion engines have become crucial. To this end, it is important to determine the Fuel Concentration in the vicinity of the spark plug near the spark timing, because initial combustion affects the subsequent main combustion in spark-ignition engines. In this study, a fiber optic system linked to an optical sensor installed in the spark plug, by means of which light can pass through the combustion chamber, was developed to determine the Fuel Concentration near the spark plug using an IR absorption method. A He−Ne laser with a wavelength of 3.39 μ m that coincides with the absorption line of hydrocarbons was used as a light source. By exchanging an ordinary spark plug for this spark plug with the optical sensor, successive measurement of Fuel Concentration before the spark timing near the spark plug was performed in a port-injection spark-ignition engine Fueled with iso-octane under the firing condition. The effects of pressure and temperature on the molar absorption coefficient of Fuel were clarified in advance. The air/Fuel ratio averaged for many cycles near the spark plug with this optical system agreed with that measured with a buret, which represented the mean value averaged over a protracted period. Next, this sensor was applied to determine the air/Fuel ratio quantitatively in a direct-injection gasoline engine. As a result, it was clarified that the air/Fuel ratio and its standard deviation near the spark plug have a strong relationship to stable engine operation.
Volker Sick - One of the best experts on this subject based on the ideXlab platform.
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simultaneous flow field and Fuel Concentration imaging at 4 8 khz in an operating engine
Applied Physics B, 2009Co-Authors: Brian Peterson, Volker SickAbstract:High-speed particle image velocimetry (PIV) and planar laser induced fluorescence (PLIF) techniques are combined to acquire flow field and Fuel Concentration in a spray-guided spark-ignited direct-injection (SG-SIDI) engine under motored and fired operation. This is a crucial step to enable studies that seek correlations between marginal engine operation (misfires or partial burns) and local, instantaneous mixture and flow conditions. Correlated flow and Fuel data are extracted from a 4 mm×4 mm sub-region directly downstream the spark plug to characterize the in-cylinder conditions next to the spark plug during the spray and ignition event. Values of equivalence ratio, velocity magnitude, shear strain rate, and vorticity all increase during the spray event and decrease an order of magnitude during the duration of the spark event.
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Tracer-LIF diagnostics: quantitative measurement of Fuel Concentration, temperature and Fuel/air ratio in practical combustion systems
Progress in Energy and Combustion Science, 2005Co-Authors: Christof Schulz, Volker SickAbstract:Abstract The safe, clean, and reliable operation of combustion devices depends to a large degree on the exact control of the Fuel/air mixing process prior to ignition. Therefore, quantitative measurement techniques that characterize the state of the fresh gas mixture are crucial in modern combustion science and engineering. This paper presents the fundamental concepts for how to devise and apply quantitative measurement techniques for studies of Fuel Concentration, temperature, and Fuel/air ratio in practical combustion systems, with some emphasis on internal combustion engines. The paper does not attempt to provide a full literature review of quantitative imaging diagnostics for practical combustion devices; rather it focuses on explaining the concepts and illustrating these with selected examples. These examples focus on application to primarily gaseous situations. The photophysics of organic molecules is presented in an overview followed by discussions on specific details of the temperature-, pressure-, and mixture-dependence of the laser-induced fluorescence strength of aliphatic ketones, like acetone and 3-pentanone, and toluene. Models that describe the fluorescence are discussed and evaluated with respect to their functionality. Examples for quantitative applications are categorized in order of increased complexity. These examples include simple mixing experiments under isothermal and isobaric conditions, Fuel/air mixing in engines, temperature measurements, and mixing studies where Fuel and oxygen Concentrations vary. A brief summary is given on measurements of Fuel Concentrations in multiphase systems, such as laser‐induced exciplex spectroscopy. Potentially adverse effects that added tracers might have on mixture formation, combustion, and the faithful representation of the base Fuel distribution are discussed. Finally, a brief section describes alternative techniques to tracer-based measurements that allow studies of Fuel/air mixing processes in practical devices. The paper concludes with a section that addresses key issues that remain as challenges for continued research towards the improvement of quantitative, tracer-based LIF measurements.
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tracer lif diagnostics quantitative measurement of Fuel Concentration temperature and Fuel air ratio in practical combustion systems
Progress in Energy and Combustion Science, 2005Co-Authors: Christof Schulz, Volker SickAbstract:Abstract The safe, clean, and reliable operation of combustion devices depends to a large degree on the exact control of the Fuel/air mixing process prior to ignition. Therefore, quantitative measurement techniques that characterize the state of the fresh gas mixture are crucial in modern combustion science and engineering. This paper presents the fundamental concepts for how to devise and apply quantitative measurement techniques for studies of Fuel Concentration, temperature, and Fuel/air ratio in practical combustion systems, with some emphasis on internal combustion engines. The paper does not attempt to provide a full literature review of quantitative imaging diagnostics for practical combustion devices; rather it focuses on explaining the concepts and illustrating these with selected examples. These examples focus on application to primarily gaseous situations. The photophysics of organic molecules is presented in an overview followed by discussions on specific details of the temperature-, pressure-, and mixture-dependence of the laser-induced fluorescence strength of aliphatic ketones, like acetone and 3-pentanone, and toluene. Models that describe the fluorescence are discussed and evaluated with respect to their functionality. Examples for quantitative applications are categorized in order of increased complexity. These examples include simple mixing experiments under isothermal and isobaric conditions, Fuel/air mixing in engines, temperature measurements, and mixing studies where Fuel and oxygen Concentrations vary. A brief summary is given on measurements of Fuel Concentrations in multiphase systems, such as laser‐induced exciplex spectroscopy. Potentially adverse effects that added tracers might have on mixture formation, combustion, and the faithful representation of the base Fuel distribution are discussed. Finally, a brief section describes alternative techniques to tracer-based measurements that allow studies of Fuel/air mixing processes in practical devices. The paper concludes with a section that addresses key issues that remain as challenges for continued research towards the improvement of quantitative, tracer-based LIF measurements.
Hyungrok Do - One of the best experts on this subject based on the ideXlab platform.
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Impacts of N2 and CO2 diluent gas composition on flame emission spectroscopy for Fuel Concentration measurements in flames
International Journal of Heat and Mass Transfer, 2020Co-Authors: Sungkyun Oh, Youchan Park, Guwon Seon, Wontae Hwang, Hyungrok DoAbstract:Abstract Flame emission spectroscopy (FES) is used to determine methane Fuel Concentration in a premixed flat-flame burner with varying diluent composition. Spectral profiles of the molecular emission bands of OH* (306.4 nm), CH* (431.5 nm), and C2* (520 nm) in the UV-to-visible range are recorded and analyzed for various equivalence ratios (0.72
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Instantaneous monitoring of local Fuel Concentration in a liquid hydrocarbon-Fueled flame using a LIBS plug
Energy, 2017Co-Authors: Hyungrok DoAbstract:Abstract A portable device composed of photodiodes and bandpass filters was developed to measure local Fuel Concentration in a liquid hydrocarbon-Fueled spray flame. The plasma emission spectra in and around the flame were selectively captured using such simplified device or plug instead of using a laboratory standard laser-induced breakdown spectroscopy (LIBS) system consisting of an ICCD and a spectrometer. The hydrogen (656 nm) and oxygen (777 nm) atomic lines were selected to determine the Fuel Concentration in atmospheric pressure. The H/O signal intensity ratio was found to be a strong function of the Fuel Concentration, and thus a calibration curve for the Concentration measurements was established and validated using conventional LIBS. The proposed scheme to measure the local equivalence ratio of spray flames using a bundled layout of multiple LIBS plugs alongside the combustor wall may offer simple and highly robust diagnostics, especially under the harsh combustion conditions within air-breathing engines.
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Establishing the Controlling Parameters of Ignition in High-Speed Flow
54th AIAA Aerospace Sciences Meeting, 2016Co-Authors: Timothy Ombrello, Hyungrok Do, Campbell D Carter, Ez Hassan, Brendan Mcgann, David M. Peterson, Philip Ivancic, Edward A. LukeAbstract:An experimental and numerical investigation targeting the establishment of the controlling parameters of ignition in a high-speed reacting flow was performed. Nanosecond-gated Laser-Induced Breakdown Spectroscopy (n-LIBS) was used to quantify Fuel Concentration at multiple locations within a cavity-based flameholder and validate highfidelity non-reactive hybrid RANS/LES simulations. The n-LIBS technique simultaneously provided an ignition source and was used along with the simulations to define an a priori ignition probability. The ignition probability based upon Fuel Concentration at the point of energy deposition provided a reasonable first level comparison to experiments. Inclusion of where the ignition kernel was being transported within the cavity based upon Fuel Concentration provided improved agreement to experiments. More controlling parameters, such as the velocity and shear at the energy deposition location and along the path taken by the ignition kernel need to be considered to better replicate the experimental results and provide a more robust ignition probability mapping.
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simultaneous gas density and Fuel Concentration measurements in a supersonic combustor using laser induced breakdown
30th International Symposium on Combustion, 2015Co-Authors: Hyungrok Do, Campbell D Carter, Timothy Ombrello, Stephen HammackAbstract:Abstract Laser-induced breakdown is used for quantitative gas property measurements (gas density and ethylene Fuel Concentration) in a cavity flameholder in a supersonic crossflow. A plasma is produced by a focused laser beam (Nd:YAG, 532 nm) in the cavity to measure gas properties at the location of the plasma and to ignite cavity flames. Plasma energy ( PE ), defined by the laser pulse energy absorbed/scattered in the plasma, and plasma emission spectra are recorded for estimating gas density and species Concentration, respectively. To obtain correlations of PE vs. gas density and emission spectra vs. Fuel Concentration, calibration experiments are conducted using a variable-pressure (0–900 mbar)/temperature (300–900 K) chamber and a Hencken burner installed in a variable-pressure (50–900 mbar) combustion chamber. Total measurement time is sufficiently short, ∼80 ns after laser arrival at the plasma region, to capture the high intensity portion of the emission and to minimize effects of plasma displacement (in the high-speed flow). Specifically, the laser pulse energy incident and transmitted (through the plasma) are measured, and the plasma emission spectra are captured during a 50-ns gate, after an approximate 30-ns time delay (relative to onset of emission from the plasma volume) to avoid strong background emission from the plasma.
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hydrocarbon Fuel Concentration measurement in reacting flows using short gated emission spectra of laser induced plasma
Combustion and Flame, 2013Co-Authors: Hyungrok Do, Campbell D CarterAbstract:Abstract Laser Induced Breakdown Spectroscopy (LIBS) is used to measure hydrocarbon Fuel Concentration in reacting flows. Emission spectra of the plasma induced by a focused-laser beam (Nd:YAG laser at 532 nm) are correlated with hydrocarbon Fuel Concentration in regions upstream (reactants) and downstream (combustion products) of a flame and adjacent to the combustion reaction zone. Nitrogen (568 nm) and hydrogen (656 nm) atomic emission lines are selected to establish a correlation between the line intensities and Fuel Concentration. These correlations are effective in a wide range of Fuel mole fraction (7–90% methane/air and 5–93% ethylene/air mixtures) and independent of flow velocity. Nevertheless, the correlation depends on gas species in the plasma. Three individual correlations for premixed methane/air, ethylene/air and combustion product gases are established. For the application of the LIBS in high-speed flows, the emission spectrum is captured employing a 10-ns time gate approximately 25 ns after initial emission of radiation (from the probe region). The 25-ns gate delay is chosen to avoid broadband thermal emission from the high-temperature plasma core and achieve high spectrum signal intensity with reasonable signal-to-noise ratio of the atomic emission lines.
Christof Schulz - One of the best experts on this subject based on the ideXlab platform.
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Tracer-LIF diagnostics: quantitative measurement of Fuel Concentration, temperature and Fuel/air ratio in practical combustion systems
Progress in Energy and Combustion Science, 2005Co-Authors: Christof Schulz, Volker SickAbstract:Abstract The safe, clean, and reliable operation of combustion devices depends to a large degree on the exact control of the Fuel/air mixing process prior to ignition. Therefore, quantitative measurement techniques that characterize the state of the fresh gas mixture are crucial in modern combustion science and engineering. This paper presents the fundamental concepts for how to devise and apply quantitative measurement techniques for studies of Fuel Concentration, temperature, and Fuel/air ratio in practical combustion systems, with some emphasis on internal combustion engines. The paper does not attempt to provide a full literature review of quantitative imaging diagnostics for practical combustion devices; rather it focuses on explaining the concepts and illustrating these with selected examples. These examples focus on application to primarily gaseous situations. The photophysics of organic molecules is presented in an overview followed by discussions on specific details of the temperature-, pressure-, and mixture-dependence of the laser-induced fluorescence strength of aliphatic ketones, like acetone and 3-pentanone, and toluene. Models that describe the fluorescence are discussed and evaluated with respect to their functionality. Examples for quantitative applications are categorized in order of increased complexity. These examples include simple mixing experiments under isothermal and isobaric conditions, Fuel/air mixing in engines, temperature measurements, and mixing studies where Fuel and oxygen Concentrations vary. A brief summary is given on measurements of Fuel Concentrations in multiphase systems, such as laser‐induced exciplex spectroscopy. Potentially adverse effects that added tracers might have on mixture formation, combustion, and the faithful representation of the base Fuel distribution are discussed. Finally, a brief section describes alternative techniques to tracer-based measurements that allow studies of Fuel/air mixing processes in practical devices. The paper concludes with a section that addresses key issues that remain as challenges for continued research towards the improvement of quantitative, tracer-based LIF measurements.
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tracer lif diagnostics quantitative measurement of Fuel Concentration temperature and Fuel air ratio in practical combustion systems
Progress in Energy and Combustion Science, 2005Co-Authors: Christof Schulz, Volker SickAbstract:Abstract The safe, clean, and reliable operation of combustion devices depends to a large degree on the exact control of the Fuel/air mixing process prior to ignition. Therefore, quantitative measurement techniques that characterize the state of the fresh gas mixture are crucial in modern combustion science and engineering. This paper presents the fundamental concepts for how to devise and apply quantitative measurement techniques for studies of Fuel Concentration, temperature, and Fuel/air ratio in practical combustion systems, with some emphasis on internal combustion engines. The paper does not attempt to provide a full literature review of quantitative imaging diagnostics for practical combustion devices; rather it focuses on explaining the concepts and illustrating these with selected examples. These examples focus on application to primarily gaseous situations. The photophysics of organic molecules is presented in an overview followed by discussions on specific details of the temperature-, pressure-, and mixture-dependence of the laser-induced fluorescence strength of aliphatic ketones, like acetone and 3-pentanone, and toluene. Models that describe the fluorescence are discussed and evaluated with respect to their functionality. Examples for quantitative applications are categorized in order of increased complexity. These examples include simple mixing experiments under isothermal and isobaric conditions, Fuel/air mixing in engines, temperature measurements, and mixing studies where Fuel and oxygen Concentrations vary. A brief summary is given on measurements of Fuel Concentrations in multiphase systems, such as laser‐induced exciplex spectroscopy. Potentially adverse effects that added tracers might have on mixture formation, combustion, and the faithful representation of the base Fuel distribution are discussed. Finally, a brief section describes alternative techniques to tracer-based measurements that allow studies of Fuel/air mixing processes in practical devices. The paper concludes with a section that addresses key issues that remain as challenges for continued research towards the improvement of quantitative, tracer-based LIF measurements.
