The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Volker Sick - One of the best experts on this subject based on the ideXlab platform.
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high speed imaging analysis of misfires in a spray guided direct injection engine
Proceedings of the Combustion Institute, 2011Co-Authors: Volker Sick, Brian Peterson, David L ReussAbstract:Abstract This study is an experimental investigation of rare misfire and partial burn cycles in a spray-guided Spark-ignited direct-injection optical engine. Spark discharge energy, discharge duration, flame imaging, velocity and equivalence ratio were measured every crank angle degree. Imaging was performed using high-speed 2-D particle image velocimetry (PIV) and planar laser inducted fluorescence (PLIF). The engine was operated near its optimum but produced rare and random partial burn and misfire cycles. Spark energy and Spark duration for the partial burn and misfire cycles fell within the range of those for the well-burned cycles, with a slight bias toward low-energy, short-duration discharges, indicating no abnormal Spark discharge events. PIV and PLIF measurements extracted from a 4 mm × 4 mm region adjacent to and downstream of the Spark Plug at Spark timing revealed that the partial burn and misfire cycles occur under lean mixtures and low velocities, but still within the range of values for the well-burned cycles. PIV and PLIF images of partial burn and misfire cycles were compared to well-burned cycles, which had similar velocities and equivalence ratios near the Spark Plug at the onset of Spark. Observations of the fuel distribution and flame areas for the partial burns and misfires showed that an early flame kernel was always formed, but failed to develop sufficiently to propagate to the fuel in the bowl. A flame kernel arriving late within the piston bowl found significantly leaner conditions and the mixture was not fully consumed leading to a partial burn. For misfire cycles, the mixture in the measurement plane was significantly leaner surrounding the flame kernel, which disappeared shortly after the Spark discharge. It is concluded that the partial burns and misfires are not the result of failed ignition, but failure during the flame propagation process.
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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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high speed laser induced fluorescence and Spark Plug absorption sensor diagnostics for mixing and combustion studies in engines
Applied Optics, 2009Co-Authors: Michael Cundy, Torsten Schucht, Olaf Thiele, Volker SickAbstract:Simultaneous high-speed in-cylinder measurements of laser-induced fluorescence of biacetyl as a fuel tracer and mid-infrared broadband absorption of fuel and combustion products (water and carbon dioxide) using a Spark Plug probe are compared in an optical engine. The study addresses uncertainties and the applicability of absorption measurements at a location slightly offset to the Spark Plug when information about mixing at the Spark Plug is desired. Absorbance profiles reflect important engine operation events, such as valve opening and closing, mixing, combustion, and outgassing from crevices.
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Development of a high-speed UV particle image velocimetry technique and application for measurements in internal combustion engines
Experiments in Fluids, 2008Co-Authors: Claudia Fajardo, Volker SickAbstract:A flexible, high-frame rate particle image velocimetry technique that can be applied to operating internal combustion engines in highly luminous combustion situations was developed. Two high-repetition rate diode-pumped Nd:YAG lasers operated at 355 nm and a CMOS camera were used to devise a system that allowed measurements of velocity fields near the Spark Plug in a firing engine at a rate of 6 kHz for 500 consecutive cycles. The 6 kHz acquisition rate enables recording one velocity field every other crank angle at 2,000 RPM engine speed. Sample results such as individual and average flow fields and kinetic energy evolutions are presented.
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flow field assessment in a fired spray guided Spark ignition direct injection engine based on uv particle image velocimetry with sub crank angle resolution
Proceedings of the Combustion Institute, 2007Co-Authors: Claudia M Fajardo, Volker SickAbstract:Abstract A new, high-speed, UV particle image velocimetry (PIV) technique has been developed and applied to a fired, spray-guided Spark-ignition direct-injection (SIDI) engine operated at 600 rpm in stratified mode. The technique involves the use of a single, frequency-tripled Nd-YAG laser operated at 16 kHz. A single CMOS camera, synchronized with the laser, was focused onto an 11 × 11 mm 2 field-of-view between the Spark Plug and the injector. Raw PIV images were recorded just before fuel injection (45 °BTDC) through the early stages of flame propagation (25 °BTDC). With this temporal resolution, approximately four instantaneous velocity fields per crank angle were obtained. The use of 355 nm laser light, combined with short exposure time (i.e., 50 μs), successfully eliminated detection of combustion product luminosity, making the flame front easily identifiable. The deformation of the plasma channel 250 μs after Spark timing was also captured. The velocity fields provided information about the flow characteristics in this portion of the engine cycle. Specifically, the spatially averaged velocity magnitude in the vicinity of the Spark Plug increased by a factor of three over the crank angle range considered. The quasi two-dimensionality of the flow before fuel injection was assessed via continuity. An increase in the shear strain rate was noted in 50% of the engine cycles. The increase in shear strain rate, combined with high stratification at the time of ignition and extension of the plasma channel, could prevent flame kernel development in SIDI engines.
David L Reuss - One of the best experts on this subject based on the ideXlab platform.
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the role of spray enhanced swirl flow for combustion stabilization in a stratified charge disi engine
Combustion and Flame, 2016Co-Authors: Wei Zeng, David L Reuss, Magnus SjobergAbstract:Abstract Implementation of spray-guided stratified-charge direct-injection Spark-ignited (DISI) engines is inhibited by the occurrence of misfire and partial burns. Engine-performance tests demonstrate that increasing engine speed induces combustion instability, but this deterioration can be prevented by generating swirling flow during the intake stroke. In-cylinder pressure-based heat-release analysis reveals that the appearance of poor-burn cycles is not solely dependent on the variability of early flame-kernel growth. Cycles can experience burning-rate regression during later combustion stages and may or may not recover before the end of the cycle. Thermodynamic analysis and optical diagnostics are used here to clarify why swirl improves the combustion repeatability from cycle to cycle. The fluid dynamics of swirl/spray interaction was previously demonstrated using high-speed PIV measurements of in-cylinder motored flow. It was found that the sprays of the multi-hole injector redistribute the intake-generated swirl flow momentum, thereby creating a better-centered higher angular-momentum vortex with reduced variability. The engine operation with high swirl was found to have significant improvement in cycle-to-cycle variations of both flow pattern and flow momentum. This paper is an extension of the previous work. Here, PIV measurements and flame imaging are applied to fired operation for studying how the swirl flow affects variability of ignition and subsequent combustion phases. PIV results for fired operation are consistent with the measurements made of motored flow. They demonstrate that the Spark-plasma motion is highly correlated with the direction of the gas flow in the vicinity of the Spark-Plug gap. Without swirl, the plasma is randomly stretched towards either side of the Spark Plug, causing variability in the ignition of the two spray plumes that are straddling the Spark Plug. In contrast, swirl flow always convects the Spark plasma towards one spray plume, causing a more repeatable ignition. The swirl decreases local RMS velocity, consistent with an observed reduction of early-burn variability. Broadband flame imaging demonstrates that with swirl, the flame consistently propagates in multiple directions to consume fuel–air mixtures within the piston bowl. In contrast, operation without swirl displays higher variability of flame-spread patterns, occasionally causing the appearance of partial-burn cycles.
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high speed imaging analysis of misfires in a spray guided direct injection engine
Proceedings of the Combustion Institute, 2011Co-Authors: Volker Sick, Brian Peterson, David L ReussAbstract:Abstract This study is an experimental investigation of rare misfire and partial burn cycles in a spray-guided Spark-ignited direct-injection optical engine. Spark discharge energy, discharge duration, flame imaging, velocity and equivalence ratio were measured every crank angle degree. Imaging was performed using high-speed 2-D particle image velocimetry (PIV) and planar laser inducted fluorescence (PLIF). The engine was operated near its optimum but produced rare and random partial burn and misfire cycles. Spark energy and Spark duration for the partial burn and misfire cycles fell within the range of those for the well-burned cycles, with a slight bias toward low-energy, short-duration discharges, indicating no abnormal Spark discharge events. PIV and PLIF measurements extracted from a 4 mm × 4 mm region adjacent to and downstream of the Spark Plug at Spark timing revealed that the partial burn and misfire cycles occur under lean mixtures and low velocities, but still within the range of values for the well-burned cycles. PIV and PLIF images of partial burn and misfire cycles were compared to well-burned cycles, which had similar velocities and equivalence ratios near the Spark Plug at the onset of Spark. Observations of the fuel distribution and flame areas for the partial burns and misfires showed that an early flame kernel was always formed, but failed to develop sufficiently to propagate to the fuel in the bowl. A flame kernel arriving late within the piston bowl found significantly leaner conditions and the mixture was not fully consumed leading to a partial burn. For misfire cycles, the mixture in the measurement plane was significantly leaner surrounding the flame kernel, which disappeared shortly after the Spark discharge. It is concluded that the partial burns and misfires are not the result of failed ignition, but failure during the flame propagation process.
Nobuyuki Kawahara - One of the best experts on this subject based on the ideXlab platform.
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Local fuel concentration measurement through Spark-induced breakdown spectroscopy in a direct-injection hydrogen Spark-ignition engine
International Journal of Hydrogen Energy, 2016Co-Authors: Kazi Mostafijur Rahman, Nobuyuki Kawahara, Eiji Tomita, Daichi Matsunaga, Yasuo Takagi, Yuji MiharaAbstract: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.
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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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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.
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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, 2003Co-Authors: Eiji Tomita, Nobuyuki Kawahara, Masahiro Shigenaga, Atsushi Nishiyama, Robert W. DibbleAbstract: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.
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in situ measurement of hydrocarbon fuel concentration near a Spark Plug in an engine cylinder using the 3 392 μm infrared laser absorption method application to an actual engine
Measurement Science and Technology, 2003Co-Authors: Eiji Tomita, Nobuyuki Kawahara, Atsushi Nishiyama, Masahiro ShigenagaAbstract:An infrared absorption method with a 3.392 µm He–Ne laser was used to determine the hydrocarbon fuel concentration near the Spark Plug in a Spark-ignition engine. Iso-octane was used for the fuel. The pressure and temperature dependence of the molar absorption coefficient was clarified. The molar absorption coefficients of a multi-component fuel such as gasoline were estimated by using the coefficient of each component and considering the mass balance. A sensor was developed and installed in a Spark Plug, which was substituted in place of an ordinary Spark Plug in a Spark-ignition engine. Light can pass from the sensor through the engine cylinder to measure the fuel concentration. The effects of liquid droplets inside the engine cylinder, mechanical vibrations and other gases such as H2O and CO2 on the measurement accuracy were considered. Four main conclusions were drawn from this study. First, the pressure and temperature effects on the molar absorption coefficient of liquid fuel vapour were determined independently in advance using a constant-volume vessel. The pressure and temperature dependence of the molar absorption coefficient was determined under engine firing conditions. Second, the molar absorption coefficients of a multi-component hydrocarbon fuel such as gasoline were estimated by considering the molar fraction of each component. Third, in situ measurements of the hydrocarbon fuel concentration in an actual engine were obtained using the Spark Plug sensor and the molar absorption coefficient of iso-octane. The concentration near the Spark Plug just before ignition was almost in agreement with the mean value that was obtained from the measurement of the flow rate made with a burette, which represented the mean value averaged over many cycles. And fourth, no liquid droplets were observed at near-idling conditions. The effects of other gases, such as CO, CO2 and H2O, can be neglected.
Eiji Tomita - One of the best experts on this subject based on the ideXlab platform.
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Local fuel concentration measurement through Spark-induced breakdown spectroscopy in a direct-injection hydrogen Spark-ignition engine
International Journal of Hydrogen Energy, 2016Co-Authors: Kazi Mostafijur Rahman, Nobuyuki Kawahara, Eiji Tomita, Daichi Matsunaga, Yasuo Takagi, Yuji MiharaAbstract: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.
-
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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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.
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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, 2003Co-Authors: Eiji Tomita, Nobuyuki Kawahara, Masahiro Shigenaga, Atsushi Nishiyama, Robert W. DibbleAbstract: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.
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in situ measurement of hydrocarbon fuel concentration near a Spark Plug in an engine cylinder using the 3 392 μm infrared laser absorption method application to an actual engine
Measurement Science and Technology, 2003Co-Authors: Eiji Tomita, Nobuyuki Kawahara, Atsushi Nishiyama, Masahiro ShigenagaAbstract:An infrared absorption method with a 3.392 µm He–Ne laser was used to determine the hydrocarbon fuel concentration near the Spark Plug in a Spark-ignition engine. Iso-octane was used for the fuel. The pressure and temperature dependence of the molar absorption coefficient was clarified. The molar absorption coefficients of a multi-component fuel such as gasoline were estimated by using the coefficient of each component and considering the mass balance. A sensor was developed and installed in a Spark Plug, which was substituted in place of an ordinary Spark Plug in a Spark-ignition engine. Light can pass from the sensor through the engine cylinder to measure the fuel concentration. The effects of liquid droplets inside the engine cylinder, mechanical vibrations and other gases such as H2O and CO2 on the measurement accuracy were considered. Four main conclusions were drawn from this study. First, the pressure and temperature effects on the molar absorption coefficient of liquid fuel vapour were determined independently in advance using a constant-volume vessel. The pressure and temperature dependence of the molar absorption coefficient was determined under engine firing conditions. Second, the molar absorption coefficients of a multi-component hydrocarbon fuel such as gasoline were estimated by considering the molar fraction of each component. Third, in situ measurements of the hydrocarbon fuel concentration in an actual engine were obtained using the Spark Plug sensor and the molar absorption coefficient of iso-octane. The concentration near the Spark Plug just before ignition was almost in agreement with the mean value that was obtained from the measurement of the flow rate made with a burette, which represented the mean value averaged over many cycles. And fourth, no liquid droplets were observed at near-idling conditions. The effects of other gases, such as CO, CO2 and H2O, can be neglected.
Fenghua Liu - One of the best experts on this subject based on the ideXlab platform.
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numerical study of cold start performances of a medium compression ratio direct injection twin Spark Plug synchronous ignition engine fueled with methanol
Fuel, 2021Co-Authors: Changming Gong, Jingzhen Sun, Yulin Chen, Fenghua LiuAbstract:Abstract The cold-start mixture preparation, combustion and emissions behaviors of a medium compression ratio direct-injection twin-Spark Plug synchronous ignition engine fueled with methanol were numerically simulated. Simulation results display that the methanol injection timing, ignition timing and the global equivalence ratio had an important influence on the concentration distribution of methanol-air mixture, the flow velocity, and the density of the flame surface during cold start. Ignition delay period reached the shortest at injection timing 70°CA BTDC. Ignition delay period for injection timing 130°CA BTDC and 50°CA BTDC increased 209% and 45.5% compared to injection timing 70°CA BTDC, respectively. Ignition delay period reached the shortest at ignition timing 21°CA BTDC. Ignition delay period of twin-Spark Plug was shorter than that of single-Spark Plug at the same equivalence ratio. There existed the maximum in-cylinder pressure, maximum heat release rate, maximum in-cylinder temperature, lowest unburned methanol and soot emissions, and highest NOX emissions at injection timing 70°CA BTDC. The maximum in-cylinder pressure, maximum heat release rate, and maximum in-cylinder temperature gradually increased with the advance of ignition timing. Injection timing 70°CA BTDC, ignition timing 21°CA BTDC, and equivalence ratio 0.9 could obtain the best cold start performance compromise using twin-Spark Plug ignition mode. At equivalence ratio 1.0, twin-Spark Plug ignition had better combustion performances, lower unburned methanol and soot emissions, and higher NOX emissions compared with single-Spark Plug ignition. Twin-Spark Plug synchronous ignition had more advantageous to cold starting ignition compared with single-Spark Plug ignition for a medium compression ratio direct-injection Spark-ignition methanol engine.
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Numerical study of twin-Spark Plug arrangement effects on flame, combustion and emissions of a medium compression ratio direct-injection methanol engine
Fuel, 2020Co-Authors: Changming Gong, Jingzhen Sun, Fenghua LiuAbstract:Abstract The effects of twin-Spark Plug arrangement on flame, combustion and emissions of a medium compression ratio direct injection methanol engine were numerically investigated. Computational results showed that at approximately A (ratio of distance of twin-Spark Plug and cylinder diameter) = 0.65, the burning and exothermic were the most reasonable compared to other twin-Spark Plug locations. A = 1.00 was the worst twin-Spark Plug arrangement. The maximum in-cylinder pressure and the maximum in-cylinder temperature were decreased with increasing A. Ignition delay were increased with increasing A. The A = 0.65 had the shortest combustion duration and the maximum heat release rate. The maximum in-cylinder pressure of A = 1.00 was approximately 57.5% lower than A = 0.25. The ignition delay of A = 1.00 was approximately 2.4 times longer than A = 0.25. The combustion duration of A = 0.67 was approximately 12% and 52.2% lower than A = 0.25 and A = 1.00, respectively. Unburned methanol and soot were increased gradually with increasing A, and at the A > 0.75, the unburned methanol and soot emissions were increased rapidly as increasing A. The unburned methanol of A = 1.00 was approximately 4.6 times higher than A = 0.25. The variations in emitted NOX emissions showed opposite tendencies with the variations in unburned methanol and soot emissions. The optimum arrangement of the twin-Spark Plug for application of actual engine was approximately A = 0.65.
