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中村, 卓人 ; 小林, 佳弘 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Nano meter size particulate matter (nano-PM) and polycyclic aromatic hydrocarbons (PAHs) have harmful effects for human health. It was thought that PAHs were a precursor of nano-PM. Then
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fundamental information of PAHs behavior in combustion process has been required to establish reduction technologies for nano-PM emission. In this paper, PAHs concentration, PM composition, and number concentration of PM in diffusion flames of methane (CH_4) and propane (C_3H_8) were investigated. As the result, benzene and toluene formed from fuel (methane or propane) had the two peaks at upstream and at downstream of PAHs-soot transition region in the flames. Moreover, concentration of PAHs formed from propane was higher than that formed from methane. In addition, both of soot and SOF compositions in PM formed from propane flame showed higher concentrations than those in methane flame.
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| 2.
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山本, 知恵美 ; 内野, 寿一 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Nanometer size particulate matter (Nano-PM) emitted from diesel engine has been received many anxieties due to its harmful potential for health. The objective of this study is to develop a
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standard Nano-PM generator using liquid fuels, and to investigate the relationship between the characteristics of PM and operation parameters of the generator. A fundamental pool flame of diesel fuel was used for generation of Nano-PM. Scanning Mobility Particle Sizer (SMPS3034) was used to measure the size distribution of PM, and the components of PM were analyzed using a combustion type exhaust gas analyzer (MEXA-1370PM). Thermal diluter was used to investigate the heating effect on size distribution of PM. Main parameters of the PM generator were height and pattern of diffusion flame. Two types of diffusion flame were formed on a fuel pool. One is a small flame where the flame tip was closed and no visible soot was observed. The other was an open tip flame that emitted visible soot from its tip. As for the size distribution of PM, peak diameter increased gradually with an increase of fuel consumption rate. Main component of Nano-PM exhausted from a closed flame was SOF, however dry soot was the main component of open flame. Under hot thermal dilution, number of large particles decreased but number of small particles increased.
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| 3.
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小林, 佳弘 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Nano meter size particulate matter (PM) and polycyclic aromatic hydrocarbons (PAHs) have harmful effects for human health. Investigations of the fundamental characteristic of PAHs behavior in
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combustion process were required for the establishment of the reduction technologies for nano-PM emission. In this paper, PAHs characteristics in diffusion flames of propane gas were investigated using laser diagnostic and gas sampling methods. A laser induced fluorescence (LIF) method was used to obtain the spatial distributions of PAHs. Spatial distributions of soot were also measured by a laser induced incandescence (LII) method. A transition region from PAHs to soot was defined from the results of LIF and LII. Further, PAH concentrations in the test flames were measured using a gas chromatography (GC), and the profiles of PAHs concentrations in the test flames were investigated. As the results, heavier molecules PAHs such as fluorene and pyrene were confirmed as precursors of soot.
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小林, 佳弘 ; 天谷, 賢児 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />In this study, formation mechanisms of PM (particulate matter) and its precursor (PAHs (polycyclic aromatic hydrocarbons)) were investigated as a fundamental PM study of diesel fuel
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combustion. A laminar diffusion flame of diesel fuel at a small pool-wick combustion equipment was used as the test flame. Spatial distributions of PAHs and soot in the flame were measured by a laser induced fluorescence (LIF) and a laser induced incandescence (LIT) methods. Emission spectra of PAHs fluorescence were analyzed by a spectroscope. Since the peak wavelength of the LIF spectrum of PAHs could be described as a function of the carbon number of PAHs, the molecular size of PAHs could be estimated. PAH species in the flame were measured using a gas chromatography (GC). LIF and GC data were compared for understanding the transition behavior from PAH to soot. These results suggested that the PAHs molecules rapidly grew up to the soot particles at nucleation area of PM. It was confirmed that relatively small PAHs species such as benzene and toluene existed in sooting region, however, the larger PAHs such as fluorine and pyrene could not be observed in the sooting region.
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| 5.
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小林, 佳弘 ; 斉藤, 孝充 ; 天谷, 賢児 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Since the engine combustion is affected by a variety of parameter such as well as fuel characteristics, it is very difficult to find out the clear effect of fuel property. In order to
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clarify the change of emission characteristic caused by fuel change, we propose a fundamental flame research method using a small pool-wick flame system. By using this system, PAHs (polycyclic aromatic hydrocarbons) formation mechanism in a flame was investigated as a fundamental study of diesel combustion. Characteristics of PAHs formation in a laminar diffusion flame were measured by a laser induced fluorescence (LIF) method. It was compared with PM charactersistics measured by a laser induced incandescence (LII) method. The effect of the lubricating oil contamination on the PAHs distributions in the flame was discussed. As the result, it was found that the PAHs concentration in the flame increased with increasing the lubricating oil contamination and it caused the increase of PM formation in the flame.
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佐藤, 桂司 ; 林田, 和宏 ; 宮川, 拓 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Laser induced fluorescence (LIF) method was applied to the measurement of PAHs (Polycyclic Aromatic Hydrocarbons) in a propane diffusion flame. Various PAHs were excited by a KrF excimer laser
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and a dye-laser pumped by the XeF excimer laser. By measuring the enission spectra of various PAHs vapors, it was found that the peak wavelength in the emission spectrom of LIF shifted to the longer wavelength side with an increase of PAHs carbon numbers. The carbon numbers of PAHs in a diffusion flame was presumed from the data of peak wavelength of emission spectrum. It was confirmed that the carbon numbers of PAHs in the diffusion flame increased as approaching to the flame surface. The maximum carbon number was about 26 at the layer close to the flame surface.
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| 7.
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林田, 和宏 ; 天谷, 賢児 ; 白井, 紘行 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />LIF thermometry in a sooting diffusion flame was newly proposed based on a spe
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ctral matching method. A tunable ArF excimer laser was used to excite the several absorption lines in the D^2Σ^+←X^2II(0, 1) band system of NO. In the case of sooting diffusion flame, emission spectrum consisted of NO and O_2 fluorescence, and off-resonance emissions related to the soot. The O_2 fluorescence and the off-resonance emissions overlapped on the NO fluorescence. However, the offresonance emissions near the vacuum ultraviolet region (VUV) were weaker than the NO fluorescence, and the ε(0, 3) band of the NO fluorescence, which appeared near the VUV region, was free from the O_2 fluorescence. Therefore, NO rotational temperature in a sooting diffusion flame could be measured by the spectral matching method using the ε(0, 3) band. By using this technique, NO rotational temperature in a propane diffusion flame could be measured.
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| 8.
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佐藤, 桂司 ; 林田, 和宏 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />In this paper, separation of laser-induced fluorescence (LIF) due to PAHs and incandescence (LII) due to soot by time-resolved measurement was demonstrated for the propane diffusion flame.
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Laser-induced fluorescence method for the measurement of polycyclic aromatic hydrocarbons (PAHs) in diffusion flame was developed. A KrF excimer laser was used for excite the PAHs. Strong laser-induced incandescence due to soot was appeared with fluorescence signal due to PAHs. In order to separate the signals into LII and the PAHs-LIF detected from diffusion flame, time-resolved measurement was carried out. A pico-second gate CCD camera with a image intensifier was used taking a time-resolved image. From the two different images, which were taken at different time-delay, PAHs-LIF and LII were obtained. Intensity distributions of PAHs-LIF and LII were measured on the flame axis. Overlap region of the LIF and LII was observed around the onset position of the yellow flame. In this region, LIF intensity decreased and LII intensity increased along the flow direction. It seemed that this region was transition region from the PAHs to soot and was attributed the presence of soot precursor.
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| 9.
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佐藤, 博之 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Effect of gravity level on the flickering motion was experimentally investigat
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ed for the propane and propane-hydrogen jet diffusion flames. A centrifuge was used for quantitative measurement of gravity effect, and frequency analysis was performed for the flickering flames. From the result of measurements under various gravity levels, it was clarified that the flickering frequency increased with an increase in the gravity level and it was correlated with two relationships expressed by the Strouhal number and the Froude number. One relationship was St∝Fr^<-0.41> for high Froude numbers (Fr≥100), and the other was St∝Fr^<-0.50> for low Froude numbers (Fr≤100). It meant that the Froude number gave the criterion of the flickering behavior and that flickering frequencies expressed by these two equations were affected by buoyancy in different ways. From the frequency analysis, it was found that oscillations of a flickering flame and a thermal convection around the flame were linked, but the characteristic of each flickering motion was different in the stability of periodicity.
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| 10.
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佐藤, 博之 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Quantitative investigation of the gravity effect was performed for acetone and kerosene pool fires. A centrifuge was used to examine the gravity effect. Small-scale pool fires were observed
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under various high gravity fields. Regions of stable flame, puffing flame and irregular oscillatory flame were mapped with the gravity level and pool diameter. Flame height decreased and oscillatory frequency increased with an increase in the gravity level. Behavior of the flame height was agreed quantitatively with the scaling prediction presented by Orloff and Heskestad. Puffing phenomena observed under various gravity fields were summarized with the Strouhal number and Froude number. As the result, we could obtain an empirical equation of St=0.517Fr^<-0.502>. From this equation, puffing frequency could be estimated for a flame of various pool diameter varying from 0.01 to 50 meters.
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