The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform

Nobuyuki Kawahara - One of the best experts on this subject based on the ideXlab platform.

  • Local Fuel concentration measurement through spark-induced breakdown spectroscopy in a direct-injection hydrogen spark-ignition engine
    International Journal of Hydrogen Energy, 2016
    Co-Authors: Kazi Mostafijur Rahman, Nobuyuki Kawahara, Eiji Tomita, Daichi Matsunaga, Yasuo Takagi, Yuji Mihara
    Abstract:

    Abstract Quantitative measurements of Local Fuel concentrations were conducted in a direct-injection hydrogen spark-ignition research engine using the spark-induced breakdown spectroscopy (SIBS) technique. For SIBS measurements, a new sensor was developed from a commercially available M12-type spark plug with no major modifications to the electrodes. The new plug sensor showed better durability and required less maintenance when used in a hydrogen research engine. Emission spectra from the plasma generated by the spark plug were collected through an optical fibre housed in the centre electrode of the plug and resolved spectrally for atomic emissions of Hα, O(I), and N(I). The main focus of the present work was to characterise the effects of ambient pressure at ignition timing on spectral line emissions and to improve the accuracy of SIBS measurements by taking into account the pressure dependency of atomic emissions. A significant effect of the corresponding pressure at ignition timing was observed on spark-induced breakdown spectroscopic measurements and emission line characteristics. Retarded spark timing (i.e. higher ambient pressure at the ignition site) resulted in lower spectral line intensities as well as weaker background emissions. It is well established that with relatively higher pressure and density of atoms or molecules, the cooling of expanding plasma accelerates, and the collision probability increases, leading to both a weaker broadband continuum and atomic emissions. A “calibration MAP” representing the correlation of air excess ratio (relative air/Fuel ratio) with both intensity ratio and pressure at ignition timing was created and subsequently used for quantitative measurements of Local Fuel concentrations for both port injection and direct injection strategies to demonstrate and explore the effects of pressure dependency of atomic emission on the accuracy of the SIBS measurements. Local stratification of the Fuel mixture in the vicinity of the spark gap location associated with direct injection strategies was confirmed; the coefficient of variation of the Local air excess ratio was relatively small for measurements made using the calibration map. This demonstrated that the measurement accuracy of Local Fuel concentrations through a spark plug sensor can be improved significantly when the pressure dependency of atomic emissions is taken into account.

  • Jet-guided combustion characteristics and Local Fuel concentration measurements in a hydrogen direct-injection spark-ignition engine
    Proceedings of the Combustion Institute, 2012
    Co-Authors: Nobuyuki Kawahara, Eiji Tomita, Takashi Fujitani
    Abstract:

    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.

  • Fuel concentration measurement of premixed mixture using spark induced breakdown spectroscopy
    Spectrochimica Acta Part B: Atomic Spectroscopy, 2009
    Co-Authors: Nobuyuki Kawahara, Eiji Tomita, S. Takemoto, Y. Ikeda
    Abstract:

    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.

  • in situ measurement of hydrocarbon Fuel concentration near a spark plug in an engine cylinder using the 3 392 μm infrared laser absorption method discussion of applicability with a homogeneous methane air mixture
    Measurement Science and Technology, 2003
    Co-Authors: Eiji Tomita, Nobuyuki Kawahara, Masahiro Shigenaga, Atsushi Nishiyama, Robert W. Dibble
    Abstract:

    A fibre optic system was developed to determine the Fuel concentration near a spark plug using an infrared absorption method. The system was linked to an optical sensor installed in the spark plug, from which light could pass through the combustion chamber. By using this modified spark plug, successive measurements of the Fuel concentration near the spark plug before ignition were performed in a spark-ignition engine burning homogeneously mixed methane–air. The Fuel concentration was determined from the Lambert–Beer law by considering the dependence of the methane molar absorption coefficient on pressure and temperature. Three main conclusions were drawn from this study. First, the methane molar absorption coefficient was greater for lower pressures and decreased with increasing temperature and pressure above atmospheric pressure. The temperature and pressure effects were offset by each other, since the temperature effects were positive and the pressure effects were negative. Second, precise time-series data for the Local Fuel concentration were obtained by considering the in-cylinder pressure and temperature from an estimate of the methane molar absorption coefficient. And third, the measured air/Fuel ratio near the spark plug before ignition agreed with the preset value when the developed optical sensor was used under motoring and firing conditions.

Eiji Tomita - One of the best experts on this subject based on the ideXlab platform.

  • Local Fuel concentration measurement through spark-induced breakdown spectroscopy in a direct-injection hydrogen spark-ignition engine
    International Journal of Hydrogen Energy, 2016
    Co-Authors: Kazi Mostafijur Rahman, Nobuyuki Kawahara, Eiji Tomita, Daichi Matsunaga, Yasuo Takagi, Yuji Mihara
    Abstract:

    Abstract Quantitative measurements of Local Fuel concentrations were conducted in a direct-injection hydrogen spark-ignition research engine using the spark-induced breakdown spectroscopy (SIBS) technique. For SIBS measurements, a new sensor was developed from a commercially available M12-type spark plug with no major modifications to the electrodes. The new plug sensor showed better durability and required less maintenance when used in a hydrogen research engine. Emission spectra from the plasma generated by the spark plug were collected through an optical fibre housed in the centre electrode of the plug and resolved spectrally for atomic emissions of Hα, O(I), and N(I). The main focus of the present work was to characterise the effects of ambient pressure at ignition timing on spectral line emissions and to improve the accuracy of SIBS measurements by taking into account the pressure dependency of atomic emissions. A significant effect of the corresponding pressure at ignition timing was observed on spark-induced breakdown spectroscopic measurements and emission line characteristics. Retarded spark timing (i.e. higher ambient pressure at the ignition site) resulted in lower spectral line intensities as well as weaker background emissions. It is well established that with relatively higher pressure and density of atoms or molecules, the cooling of expanding plasma accelerates, and the collision probability increases, leading to both a weaker broadband continuum and atomic emissions. A “calibration MAP” representing the correlation of air excess ratio (relative air/Fuel ratio) with both intensity ratio and pressure at ignition timing was created and subsequently used for quantitative measurements of Local Fuel concentrations for both port injection and direct injection strategies to demonstrate and explore the effects of pressure dependency of atomic emission on the accuracy of the SIBS measurements. Local stratification of the Fuel mixture in the vicinity of the spark gap location associated with direct injection strategies was confirmed; the coefficient of variation of the Local air excess ratio was relatively small for measurements made using the calibration map. This demonstrated that the measurement accuracy of Local Fuel concentrations through a spark plug sensor can be improved significantly when the pressure dependency of atomic emissions is taken into account.

  • Jet-guided combustion characteristics and Local Fuel concentration measurements in a hydrogen direct-injection spark-ignition engine
    Proceedings of the Combustion Institute, 2012
    Co-Authors: Nobuyuki Kawahara, Eiji Tomita, Takashi Fujitani
    Abstract:

    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.

  • Fuel concentration measurement of premixed mixture using spark induced breakdown spectroscopy
    Spectrochimica Acta Part B: Atomic Spectroscopy, 2009
    Co-Authors: Nobuyuki Kawahara, Eiji Tomita, S. Takemoto, Y. Ikeda
    Abstract:

    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.

  • in situ measurement of hydrocarbon Fuel concentration near a spark plug in an engine cylinder using the 3 392 μm infrared laser absorption method discussion of applicability with a homogeneous methane air mixture
    Measurement Science and Technology, 2003
    Co-Authors: Eiji Tomita, Nobuyuki Kawahara, Masahiro Shigenaga, Atsushi Nishiyama, Robert W. Dibble
    Abstract:

    A fibre optic system was developed to determine the Fuel concentration near a spark plug using an infrared absorption method. The system was linked to an optical sensor installed in the spark plug, from which light could pass through the combustion chamber. By using this modified spark plug, successive measurements of the Fuel concentration near the spark plug before ignition were performed in a spark-ignition engine burning homogeneously mixed methane–air. The Fuel concentration was determined from the Lambert–Beer law by considering the dependence of the methane molar absorption coefficient on pressure and temperature. Three main conclusions were drawn from this study. First, the methane molar absorption coefficient was greater for lower pressures and decreased with increasing temperature and pressure above atmospheric pressure. The temperature and pressure effects were offset by each other, since the temperature effects were positive and the pressure effects were negative. Second, precise time-series data for the Local Fuel concentration were obtained by considering the in-cylinder pressure and temperature from an estimate of the methane molar absorption coefficient. And third, the measured air/Fuel ratio near the spark plug before ignition agreed with the preset value when the developed optical sensor was used under motoring and firing conditions.

Y. Ikeda - One of the best experts on this subject based on the ideXlab platform.

  • Fuel concentration measurement of premixed mixture using spark induced breakdown spectroscopy
    Spectrochimica Acta Part B: Atomic Spectroscopy, 2009
    Co-Authors: Nobuyuki Kawahara, Eiji Tomita, S. Takemoto, Y. Ikeda
    Abstract:

    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.

Yuji Mihara - One of the best experts on this subject based on the ideXlab platform.

  • Local Fuel concentration measurement through spark-induced breakdown spectroscopy in a direct-injection hydrogen spark-ignition engine
    International Journal of Hydrogen Energy, 2016
    Co-Authors: Kazi Mostafijur Rahman, Nobuyuki Kawahara, Eiji Tomita, Daichi Matsunaga, Yasuo Takagi, Yuji Mihara
    Abstract:

    Abstract Quantitative measurements of Local Fuel concentrations were conducted in a direct-injection hydrogen spark-ignition research engine using the spark-induced breakdown spectroscopy (SIBS) technique. For SIBS measurements, a new sensor was developed from a commercially available M12-type spark plug with no major modifications to the electrodes. The new plug sensor showed better durability and required less maintenance when used in a hydrogen research engine. Emission spectra from the plasma generated by the spark plug were collected through an optical fibre housed in the centre electrode of the plug and resolved spectrally for atomic emissions of Hα, O(I), and N(I). The main focus of the present work was to characterise the effects of ambient pressure at ignition timing on spectral line emissions and to improve the accuracy of SIBS measurements by taking into account the pressure dependency of atomic emissions. A significant effect of the corresponding pressure at ignition timing was observed on spark-induced breakdown spectroscopic measurements and emission line characteristics. Retarded spark timing (i.e. higher ambient pressure at the ignition site) resulted in lower spectral line intensities as well as weaker background emissions. It is well established that with relatively higher pressure and density of atoms or molecules, the cooling of expanding plasma accelerates, and the collision probability increases, leading to both a weaker broadband continuum and atomic emissions. A “calibration MAP” representing the correlation of air excess ratio (relative air/Fuel ratio) with both intensity ratio and pressure at ignition timing was created and subsequently used for quantitative measurements of Local Fuel concentrations for both port injection and direct injection strategies to demonstrate and explore the effects of pressure dependency of atomic emission on the accuracy of the SIBS measurements. Local stratification of the Fuel mixture in the vicinity of the spark gap location associated with direct injection strategies was confirmed; the coefficient of variation of the Local air excess ratio was relatively small for measurements made using the calibration map. This demonstrated that the measurement accuracy of Local Fuel concentrations through a spark plug sensor can be improved significantly when the pressure dependency of atomic emissions is taken into account.

Takashi Fujitani - One of the best experts on this subject based on the ideXlab platform.

  • Jet-guided combustion characteristics and Local Fuel concentration measurements in a hydrogen direct-injection spark-ignition engine
    Proceedings of the Combustion Institute, 2012
    Co-Authors: Nobuyuki Kawahara, Eiji Tomita, Takashi Fujitani
    Abstract:

    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.