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| 1.
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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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森田, 真一 ; 渡辺, 直樹 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Six-stroke diesel engine proposed here has six processes in one cycle, i.e. intake, 1st compression, 1st combustion, 2nd compression, 2nd combustion and exhaust. By the direct EGR in the 2nd
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combustion process, NO emission could be expected to decrease. However, much Soot was exhausted by a weak mixing in the 2nd combustion process. A high pressure injection with a common rail was introduced into the engine to improve the mixing in the second combustion process. As a result, more NO was exhausted while Soot was decreased due to better mixing. In this study, to decrease NO and Soot simultaneously, two stage fuel injection was applied to the 1st combustion. When the main injection timing for the 1st combustion process was extremely delayed, NO and Soot were decreased. It was considered that NO reduction was due to the 1st combustion of low temperature and EGR effect in the 2nd combustion. Also, Soot reduction was due to a relatively long ignition delay for the 2nd combustion
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| 3.
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林田, 和宏 ; 土師, 勝彦 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />In this study, effect of fuel properties on diffusion combustion of kerosene was investigated experimentally. Five types of kerosene, which distillation and composition properties were
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different, were used as the test fuel. Laminar diffusion flames of kerosene were formed by using wick combustion burner. Fuel consumption rate, flame temperature and flame luminosity of each flame were measured. As the results, fuel consumption rate proportionally increased with decreasing volume average boiling point, and both temperature and luminosity decreased as the aromatic content in the fuel increase. To investigate the effect on soot formation of fuel properties, concentration distributions of polycyclic aromatic hydrocarbons (PAHs) and soot were measured by laser-induced fluorescence (LIF) and laser-induced incandescence (LII). Both PAHs-LIF intensity on wick and LII intensity of soot emission increased with the content of aromatic compounds in the fuel became higher.
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| 4.
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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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| 5.
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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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| 6.
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佐々木, 徹 ; 天野, 俊輔 ; 渡辺, 哲也 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />A low NO_x combustor for kerosene-fueled micro gas turbine based on a new concept was proposed. The combustor consisted of primary and secondary combustion zones, and they were
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connected by a throat. A swirler was set between the primary and secondary combustion zones. In order to enhance recirculation of burned gas in the primary combustion zone, combustion air was introduced through the swirler and forced to flow upward to the combustor bottom. In this study, fundamental combustion characteristics such as lean combustion limit, exhaust gas composition and combustion gas temperature were measured using three fuel atomizers which rated flow rates were 3.0 gallon/h, 4.5 gallon/h and 6.0 gallon/h respectively. It was shown that the combustion stability and emission characteristics in the case of 3.0 gallon/h nozzle were superior to those in other cases. Further, gas velocity in the primary combustion zone was measured by Leaser Doppler Anemometer (LDA) and behavior of the recirculation of burned gas was investigated
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| 7.
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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 />Nano meter size particulate matter (PM) and polycyclic aromatic hydrocarbons (PAHs) have harmful effects for human health. Investigations of fundamental characteristic of formation behavior of
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PAHs in combustion process were required for the reduction of nano-PM emission. In this paper, PAHs characteristics in diffusion flames of paraffin fuels were investigated using laser diagnostic and gas sampling methods. Methane (CH_4), propane (C_3H_8) and hexane (C_6H_<14>) were used as the test fuels. A laser induced fluorescence (LIF) method was used to obtain the spatial distributions of PAHs which were precursor molecules of soot. 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). Profiles of PAHs concentrations of test flames were compared. As the results, it was found that the low carbon number fuels such as propane and methane are remained to some fuel at downstream part. And, these some fuels were changed to large PAHs at downstream part.
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| 8.
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佐々木, 徹 ; 天野, 俊輔 ; 渡辺, 哲也 ; 世取山, 幸作 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />A low NO_x combustor for kerosene-fueled micro gas turbine based on a new concept was proposed. The combustor consisted of primary and secondary combustion zones, and they were
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connected by a throat. A swirler was set between the primary and secondary combustion zones. In order to enhance recirculation of burned gas in the primary combustion zone, combustion air was introduced through the swirler and forced to flow upward to the combustor bottom. In this study, effects of configuration of primary combustion zone on combustion gas flow in it were investigated. The length of primary combustion zone, swirler vane angle, diameter of throat and height of guide vane were changed independently from the standard configuration. Distributions of gas flow in the primary combustion zone were measured with LDA. The relation between combustion stability and the distributions of gas flow was discussed, and it was found that appropriate combustion gas recirculation in the primary combustion zone was necessary to keep combustion stability high.
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| 9.
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星野, 浩之 ; 満山, 陽平 ; 齊藤, 正浩 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />In order to reveal the soot removal mechanism in Electric Diesel Particulate Trap (E-DPT), mechanism of soot trapping and re-burning of soot particles in exhaust gas was investigated using
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one channel electric diesel particulate trap (1 channel E-DPT). The E-DPT is capable to trap soot particles by applying DC electric field between electro-plates. The results showed that soot particles like a whisker grew up from negative electrode side toward positive one. Soot particles trapped on the plates formed many soot bridges in narrow space between electro-plates. Formation of soot particles depended on electric intensity. In the condition of F=200 kV/m, lumps of soot were observed instead of whisker like soot bridges and soot trapping and soot re-burning were balanced. Ignition of the soot lump was occurred at the contact point between the lump and electro-plate, however re-burning of whole the lump was rarely observed. Remained soot drifted to down stream. It is thought that many remained soot particles were discharged from the E-DPT. Incomplete reburning of soot lump caused soot removal efficiency deterioration of E-DPT. In the case of narrow space and high electric intensity (F=600kV/m, L=0.5mm), however, soot bridge re-burning was main phenomenon and soot lump re-burning was controlled
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| 10.
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山本, 克臣 ; 中路, 智晴 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />In order to reduce CO_2 emission from combustion systems with fossil fuel, it
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is necessary to increase thermal efficiency of them. Heat recovery from flue gas is very effective in increasing thermal efficiency of a small furnace. Through this heat recovery, temperature of flue gas decreased with increasing a recovery amount of heat. It is feared that a decrease of temperature newly causes secondary condensed particles in a stack, and these particles become a problem in future. In this study, therefore, particulate matters (PM) in a flue gas stream from a spray combustion furnace were sampled and their compositions and size distributions were measured. As the result, it was shown that the mass of volatile matters in PM and the number of particle gradually increased along the stack. It was found that, moreover, the condensation of volatile matters probably occurred under the condition that flue gas temperature was below 460℃. From these results, it was clear that secondary condensed particles were formed in the stack.
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| 11.
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倉持, 大輔 ; 川口, 知宏 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Ignition and combustion characteristics of diesel spray impinged on an extrude
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d wall, which was a top of cylindrical column, were experimentally investigated. Appearance positions of OH and C_2 radical luminosities and luminous flame kernel were stereoscopically observed using a two-way fiber optical system. The extruded column was fixed in a high temperature and high pressure combustion chamber. A diesel spray was impinged vertically to the extruded wall. Effects of cylindrical column diameter (D=5,10,15mm, ∞(flat wall)) on ignition and combustion characteristics were investigated. As the result, appearance position of OH luminosity was observed near the spray tip except for D=∞ (flat wall). The maximum volume of luminous flame impinged on the extruded wall was strongly influenced by the diameter of the column. In a condition of low-ambient temperature, the maximum volume of blue flame on the extruded column of 10 mm diameter was larger than those on other columns.
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| 12.
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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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| 13.
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太田, 貴之 ; 林, 義裕 ; 斉藤, 正浩 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Effects of nozzle hole shape on a spray behavior of diesel fuel were investigated experimentally. Characteristics of sprays injected from triangle hole and square hole were compared with those
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of spray injected from conventional circular hole. The areas of triangle hole and square hole were almost same as that of circular hole. The spray behavior was observed using a high-speed digital video camera. As the results, a free spray behavior of diesel fuel was strongly influenced by the nozzle hole shape. Further, sprays injected from triangle hole and circular hole were impinged on a wall and behavior of the sprays were investigated. Spray width and spray thickness were measured from photographs, and spray volume was estimated. In the case of triangle hole, the spray grew up asymmetrically after wall impingement. The spray volume was influenced by the nozzle hole shape and distance between nozzle tip and a wall.
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| 14.
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山本, 恭央 ; 齊藤, 正浩 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />In order to clarify the effect of water content on thermal decomposition process of disposal paper diaper with water-absorbent polymer quantitatively, thermal decomposition tests of the small
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diaper piece (0.2g) containing water up to 30 times of initial mass of sample were conducted in an image furnace. Mass reduction during thermal decomposition was measured by using an electric microbalance. The components of gas produced by the thermal decomposition were analyzed with FT-IR gas analyzer. The oxygen concentration in the furnace was set to 0% or 21%. It was found that thermal decomposition period became long with increasing water. In the condition of 0% oxygen concentration, the mass reduction slower than that in the condition of 21% oxygen concentration, and slow mass reduction continued after rapid mass reduction. In the case of the sample with no water under the 21% oxygen concentration, HC and CO were emitted simultaneously in the decomposition process. However, in the other cases, the peak emission of HC appeared later than that of CO regardless of water content.
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| 15.
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橋本, 健 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Six-stroke diesel engine proposed here has six processes in one cycle, i.e. intaka, 1st compression, 1st combustion, 2nd compression, 2nd combustion and exhaust. By the effect of direct EGR in the
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2nd combustion process, NO concentration could be expected to decrease. However, by a weak mixing in the 2nd combustion process, much soot was exhausted and NO concentration was hardly decreased compared with the conventional four-stroke diesel engine. To improve the fuel/air mixing at the 2nd combustion process, high pressure injection with common rail system was applied to the engine. As the result, NO concentration was increased owing to the increase of premixed combustion of 1st combustion process, although soot was reduced. Therefore, the 1st injection timing was extremely advanced to control the 1st combustion process. It changed 1st combustion process into HCCI-like combustion, and NO concentration was greatly decreased. Moreover, soot was reduced with no increase of NO concentration in the 2nd combustion process. As the result, trade-off curve of NO and soot was improved compared with the conventional four-stroke diesel engine. But CO concentration was increased.
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| 16.
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世取山, 幸作 ; 天野, 俊輔 ; 藤原, 秀智 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />A new low NO_x combustor for kerosene fueled micro gasturbine was proposed, and the combustion characteristics of prototype combustor were investigated. In order to enhance the recirculation in
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a primary combustion zone, a swirler was set between the primary and secondary combustion zones. Combustion air was introduced through the swirler and forced to flow upward to the combustor bottom, from where the fuel spray was supplied through a nozzle. To achieve high combustion stability and low emission in wide fuel air ratio, the optimum configuration of the primary combustion zone were investigated. The optimum one was found out by measuring the fundamental combustion characteristics such as lean combustion limit, flame luminosity, exhaust gas composition and combustion gas temperature.
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| 17.
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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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| 18.
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天野, 俊輔 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />A new concept of combustion liquid fuel suitable for Gas Turbine combustor was
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investigated. Combustion in high temperature and low oxgen concentration by Burnt Gas Recirculation (BGR/FGR/EGR) is an important technology for low NO_χ combustion of liquid fuel. Upward swirl was focused to produce forced recirculation flow of burnt gas. A combined method of analytical approach (Computational Fluid Dynamics: CFD) and experimental approach was used. Flow pattern produced by the upward swirl introduced into combustion zone from the direction of combustion zone exit was investigated. CFD showed that a kind of guide vanes to produce flow to inside of radial direction at the top of combustion zone had important role for the upward swirl to recirculate fully to the top of combustion zone. A prototype combustor with the design based on results of CFD with and without combustion was made and tested. Non-luminous flame was observed at lean combustion condition. These results showed that this new concept of the primary zone had a high potential as a low NO_χ combustion technology of liquid fuel.
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| 19.
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川口, 知宏 ; 長瀧, 翼 ; 天谷, 賢児 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Ignition and combustion characteristics of diesel spray impinging on a wall were experimentally investigated. Ignition position and appearance position of the luminous flame
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kernel were stereoscopically observed using a two-way fiber optical system. Flat
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| 20.
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林, 義裕 ; 若林, 千裕 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Mixture formation of diesel spray impinged on an extruded surface, which was a top of cylindrical column, was investigated experimentally. A diesel spray was impinged vertically to the
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extruded surface. The behaviors of impinged spray were observed using a high-speed drum camera. A spray volume was estimated from the photographs. Effect of cylindrical column diameter on spray behavior was investigated. Adhering fuel was measured by a primitive ""wiping by paper and mass measuring"" method under various conditions. Air-fuel ratio in spray was calculated from spray volume and adhering fuel. As the result, the behavior of diesel spray impinged on an extruded column was strongly influenced by the diameter of the extruded column. From the measured results, it is clear that the air-fuel ratio in spray in the extruded column diameter of 45mm was larger than those in the other columns.
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| 21.
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石井, 哲人 ; 佐藤, 博之 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />The effects of gravity on the fluctuation characteristics of turbulent diffusion flames were experimentally investigated. Super gravity fields were formed using a spin tester. The gravity
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level G was changed from 1 to 20, where G was defined as the value of super gravity per normal gravity. Flame states such as laminar, flickering and turbulent flames were observed under the various conditions of gravity level, G and Reynolds number, Re. The transition from laminar to turbulent and blow out limit were summarized on a G-Re map. Characteristics of turbulent fluctuation were measured by a laser light reflection method. Power spectra and auto-correlations were derived from the signal of laser intensity. As the result, it was found that the turbulent flame was begun to periodic oscillation with increasing the gravity level. Time scale of turbulent fluctuation in the super gravity became long than that in the normal gravity. Spectrum component in power spectrum shifted to the low frequency side when the gravity level became high. And the full width at half-maximum of autocorrelation peak became wider in the super gravity conditions.
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| 22.
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古賀, 大庸 ; 吉永, 摂理 ; 斉藤, 正浩 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Effects of H_2O, CO_2, CH_4 and C_2H_4 containing in automotive exhaust gas on NO removal by using a DC corona discharge were invistigated experimentally. In this experiment, N_2/O_2/NO
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mixture was used as a base gas of the simulated gas. To clarify the effect of the individual coexisting gas on NO removal, each coexisting gas was added to the base gas. The results showed that the existence of H_2O or C_2H_4 was effective for NO removal with low energy density. Also, when negative corona discharge was applied to the simulated exhaust gas (N_2/O_2/NO/H_2O/CO_2/C_2H_4 mixture), more than 90% DeNO_x was achieved. However, the by-products such as CO, O_3, HNO_3 and N_2O increased with increasing the energy density. It was found that the optimum energy density of corona discharge was about 250J/L for DeNO_x of simulated exhaust gas.
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| 23.
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林田, 和宏 ; 天谷, 賢児 ; 佐藤, 桂司 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Raman scattering technique with KrF excimer laser was applied to obtain a fuel concentration distribution in a sooting flame. In the case of sooting flame, fluorescence from polycyclic
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aromatic hydrocarbons (PAH) and laser-induced incandescence (LII) from soot particles appeared with Raman scattering. These background emissions overlappped on the Raman scattering. In order to separate the Raman scattering and the background emissions, polarization property of laser-induced emissions was utilized. Since the background emissions were depolarized whereas the Raman scattering was highly polarized, it is possible to subtract the background emissions from the overlapping signal of the Raman scattering and the background emissions. Subtracting the emission signals for the electric vector of the laser light perpendicular and parallel to the direction of observation allows to extract the precise Raman signals. By using this technique, detailed fuel concentration distribution in sooting flames could be obtained based on Raman scattering.
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| 24.
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新井, 雅隆 ; 天野, 俊輔 ; 藤原, 秀智
概要:
application/pdf<br />Journal Article<br />The combustion characteristics of a prototype micro-gasturbine combustor fueled by kerosene were investigated. In order to enhance the recirculation in a primary combustion zone, a swirler was
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set between the primary and secondary combustion zones. Primary combustion air was introduced through the swirler and forced to flow upward to the combustor bottom, from where the fuel spray was supplied through a nozzle. The fundamental combustion characteristics such as lean combustion limit, flame luminosity etc. showed that this prototype combustor had a high potential for lean combustion and wide flame holding. Since a strong forced recirculation flow was induced by the upward swirl, lean and non-luminous flame was maintained in the primary combustion zone. Further, burned gas recirculation and highly turbulent shear flow in the primary combustion zone, both of which were caused by the upward swirl, resulted the low NO_x emission characteristics.
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| 25.
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新井, 雅隆 ; 天谷, 賢児 ; 長瀧, 翼 ; 沖田, 秀樹
概要:
application/pdf<br />Journal Article<br />Ignition and combustion characteristics of diesel spray impinging on an inclined wall were experimentally investigated. Ignition position and appearance position of the
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luminous flame kernel were stereoscopically observed using a two-way fiber optical system. Flat impingement wall was fixed in a high temperature, high pressure combustion chamber. Inclined angle of the flat wall was set at 30 degees or right angle against the center axis of the injection spray. Distance from nozzle tip to the impingement point on the wall was set at 50mm. Effect of ambient temperature on ignition position was investigated. As the result, ignition positions were observed near the spray periphery in the both cases of 30 degrees and right angle impingements. However, the luminous flame appeared near the wall surface at downword side of inclined wall because the fuel rich region was formed around the downword side of spray impingement point.
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| 26.
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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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| 27.
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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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| 28.
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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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| 29.
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大畠, 克章 ; 斉藤, 正浩 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />The object of this study is to reduce nitrogen oxide using a DC corona discharge. The mixture of (N_2+O_2+NO) was used as the sample gas. After the mixture was passed through the reactor in which
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corona discharge field was formed, the gas collected at the exit of the reactor using a sampling bag. The components such as NO, NO_2 and N_2O etc. were analyzed with FT-IR and NOx meter. It was found that the characteristics of NO reduction by corona discharge differed remarkably whether or not the oxygen was existing in the mixture. From the measurement of spectrum of light emission by corona discharge in N_2 or (N_2+O_2) atmospheres, several N_2 bands were detected. In the case of N_2 atmoshere, the process of NO reduction was mainly controlled by N_2 radical produced in the corona discharge field. On the other hand, in the case of (N_2+O_2) atmosphere, NO converted to NO_2 by ozone which yielded by corona discharge.
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| 30.
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林田, 和宏 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />NO concentration measurement in the burnt gas from the catalytic combustion was carried out by using a laser-induced fluorescence method. A palladium catalyst supported on a cordierite honeycomb
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was used. The methance/air mixture, which was pre-heated to 530 K, was introduced into the catalyst honeycomb. To excite a NO molecule, an ArF excimer laser was used. Wavelength of the laser right was set at 193.375 nm. The laser sheet was introduced into the downstream of the honeycomb. In the case of a lean mixture, NO was observed after the honeycomb. On the other hand, in the case of a rich mixture, a blue flame at downstream from the honeycomb were observed, and NO was observed at the blue flame. In order to obtain the NO concentration from the NO fluorescence intensity, temperature dependency of the fluorescence intensity was investigated by using NO-N_2 mixture. Axial concentration distributions of NO were derived from the NO fluorescence intensity distributions. Furthermore, change of the NO emission level with equivalence ratio was investigated at the outlet of the honeycomb.
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| 31.
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河野, 雅文 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Effect of cetane number on ignition delay and ignition location of disesel spray was experimentally investigated. Five kinds of fuels, which had different cetane numbers of light fraction and
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heavy fraction of fuel, were used. As a result, the ignition delay was not so affected by the change of cetane number, however, the ignition location was strongly affected by a cetane number. When the light fraction cetane number was low, the ignition was not observed near the nozzle. And when the heavy fraction cetane number was high, the ignition was observed at the position far from the nozzle. Ignition position had an effect on flame development. When the ignition occurred near the nozzle, flame development rate was slow. When the ignition occurred at the position far from the nozzle, flame development rate was fast. In case of the ignition position was far from the nozzle, effect of the cetane number on flame development was remarkable.
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| 32.
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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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| 33.
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坂下, 直己 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Fuel droplet and vapor distributions in a spray flame formed in the hot air stream were measured by an exciplex fluorescence method. Kerosene was used as a test fuel. Kerosene was miscible
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with a small quantity of exciplex-forming dopants, TMPD (N, N, N', N'-tetramethyl-1,4-phenylene diamine) and naphthalene. A Nd : YAG laser (355nm) was used for excitation of the fuel. The fuel spray was injected from a swirl atomizer into an air stream. Air temperature was changed from room temperature to 1000k which was higher than the self-ignition temperature of a kerosene spray. Distributions of the fuel droplets and vapor were strongly affected by the air temperature. Furthermore it was confirmed that the fuel vapor was transported into recirculating flow area formed on the flame holder.
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| 34.
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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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| 35.
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高, 炅男 ; 樅山, 智裕 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Diesel spray impinged normally on a flat wall was investigated. Spray tip penetration and spray volumes of before and after impingement were measured on high speed photographs of the sprays
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which were injected by a single shot injection system into a high pressure chamber of cold state. The effects of the spray tip penetration, spray volume, entrainment mass and air-fuel ratio were discussed on the sprays of before and after impingement. The volume of the post-impingement spray was calculated using axi-symmetrical model. It was greatly affected by the distance between the injection nozzle and the wall. When the impingement distance was shorter than the break-up length of the original spray, the entrainment mass as well as the volume of post-impingement spray was the larger than that of the original spray at the same inspection time. To calculate the average spray concentration of after impingement spray, the fuel film stuck on the wall was measured. The average air-fuel ratio of the impingement spray increased faster than the free spray because the spray concentration in a space decreased by the fuel stuck on the wall.
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| 36.
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岩崎, 浩二 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Combustion characteristics and engine performances of a swirl-chamber type IDI diesel engine using two-stage injection were experimentally investigated. The injection timing and fuel allocation ratio
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between first and second injections were widely varied. Heat release rate was analyzed to evaluate the combustion phenomena in the engine. As the result, ignition delay period for two-stage injection became longer than that for single-stage injection when the amount of fuel in the first stage injection was small. However, when the amount of fuel in the first injection was large, there was no difference of ignition delay period between two-stage injection and single-stage injection. NO and Smoke emissions and fuel consumption were improved by two-stage injection when ingition delay period became long.
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| 37.
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斉藤, 正浩 ; 天谷, 賢児 ; 萩原, 五郎 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />To clarify the effect of water content on combustion characteristics of watery
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materials, combustion test of a high water-permeable balsa wood was performed using a thermogravimetric furnace. The furnace temperature is between 650℃ and 1000℃, and water contents in the small balsa pieces (0.3g) were varied up 70 wt%. Mass reduction during pre-heating, volatile matter combustion and char combustion were measured with a microbalance. Also, the variations of flame temperature and center temperature of the test piece during combustion process were measured. On the combustion of high water-contained balsa, it was found that ignition started before the water was evaporated completely. It means that two proceses, devolatilization of volatiles and vaporization of remaining water, are proceeding simultaneously during the volatile matter combustion. Ignition delay and retention time of volatile matter combustion increased with increasing the water content. The increases of flame temperature and center temperature of the test piece were prevented by the latent heat of water vaporization. The combustion rate of volatile matter was drastically reduced in proportion to the water content. Also, it was confirmed that a part of char burned during the latter stage of volatile matter combustion. The effect of water content on char combustion rate was small. From this study, it was concluded that the water content over 50 wt% affected remarkably to the volatile matter combustion.
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| 38.
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茂木, 俊夫 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Fundamental characteristics of the catalytic combustion of vaporized kerosene
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spray were studied experimentally. Palladium catalyst supported on the cordierite honeycomb monolith was used. Inlet temperature was elevated up to 700 K to evaporate the kerosene spray. Premixed gas of air and kerosene vapor was introduced into the catalyst. The catalytic combustion and gas phase reaction after catalyst were observed in this combustion system. The lean limit of the catalytic combustion was not affected by the space velocity and equivalence ratio of the mixture, but it was greatly affected by the inlet temperature. The parabolic shape blue flame that was supported on the catalyst was formed when the supplied mixture was not completely burned in the monolith. To clarify a reaction process in an combustive gas between the monolith and the blue flame, CO, HC(C_1～C_7) and NO were analyzed. When the blue flame was observed after the catalyst, the HC and CO were formed from the unburned composition of fuel and they were burned as the blue flame. The NO emission level of the catalytic combustion was very low compared with the gas phase reaction of lean mixture.
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| 39.
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林田, 和宏 ; 白井, 紘行 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Rotational temperature of NO molecule in methane/air premixed flame was estima
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ted by a spectral matching method. A tunable narrow band ArF excimer laser was used to excite the D^2Σ^+(ν′=0)←X^2Π(ν""=1) band system of NO. Laser beam irradiated a flame, and the laser induced fluorescence was resolved into a spectrum by using a spectroscope. On this spectrum, ε and δ bands of upper vibrational level of ν′=0 were analyzed. In order to use a spectral matching method, profiles of ε and δ band spectra were calculated theoretically in detail with reliable molecular constants and exact formula, and they were modulated by an experimental slit function. Since the profile of band spectrum was determined as a function of a rotational temperature, a rotational temperature could be estimated from the temperature where the profile of every band spectrum obtained theoretically is fitted to that of experimentally obtained. Applying a spectral matching method on the ε(0, 3), ε(0, 4) and δ(0, 2) band of NO, it was obtained that the rotational temperature is about 1000K. Obtained rotational temperature is almost agreed with a thermocouple temperature.
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| 40.
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岩崎, 浩二 ; 荻原, 五郎 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Combustion characteristics and engine performances of a two-stage injection DI diesel engine were experimentally investigated. Two-stage injection was achieved by using two injection pumps.
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Injection timing and fuel allocation ratio between first and second injection were widely controlled. Engine performance of a two-stage injection diesel engine was compared with that of a single injection diesel engine with early timing injection. The heat release rate was analyzed to understand the combustion phenomena in a two-stage injection diesel engine. As a result, NO emission of two-stage injeciton diesel engine was improved when the first injection timing is early. The various pattern of heat release rate appeared with the change of a fuel allocation ratio. It was greatly affected by the first injection spray impinged on the cylinder wall or the piston top. The trade-off tendency between NO and smoke was influenced by the fuel allocation ratio of sub-injection pump was high.
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| 41.
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新居, 利洋 ; 斉藤, 正浩 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />This paper reports the effects of applying methods of electric field on a sooting diffusion flame. Essentially, two types of electric fields were tested in this experiment. One is a uniform
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electric field formed between parallel plate electrodes. The other is a non-uniform field formed between needle and plate electrodes. In the uniform field, the flame shape was changed by positive ions moving in the fields. Soot emission was suppressed with increasing the applied voltage, because an increase of the flame surface temperature promoted the soot oxidation. In the non-uniform field, on the contrary, ionic wind was formed by corona discharge. The ionic wind blew from a needle electrode toward a plate electrode, irrespectively of the polarity of the needle. The flame was inclined toward the plate electrode by this ionic wind. As the result, the surrounding air was entrained in the flame, and the suface temperature of flame also increased with increasing applied voltage. The soot suppression efficiency of the non-uniform electric field was higher than that of the uniform one.
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| 42.
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長谷川, 和之 ; 茂木, 俊夫 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Behavior of a spray combustion in a hot air was studied experimentally. A kerosene spray was injected from swirl atomizer into a hot air stream. The air temperature was controlled from room
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temperature to 1 100 K which was higher than the self-ignition temperature of a kerosene spray. Flame shape and temperature distribution were measured to characterize the spray combustion appeared in the hot air stream. Flow state around the spray was visualized by a Schlieren method to analyze the behavior of the air entrainment into the flame. Furthermore, Mie scattering from the spray droplets by irradiation of the laser beam was observed to visualize the spray concentration in a flame. As the result, ignition point was shifted to the upstream side with an increase of air temperature. When the air temperature became higher than 800 K, the blue flame appeared at the bottom portion of the flame. Penetration of the spray became shorter with an increase of air temperature. Spatial distribution of the spray which were not vaporized in a flame was strongly affected by the air temperature.
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| 43.
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佐藤, 博之 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Flame lengths of gas jet diffusion flames were measured under various gravity
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evels. A spin tester was used to obtain a high gravity field which level was changed from normal gravity (G=1) to G-20. In order to investigate the fuel density effect on flame structure at high gravity level, two kinds of fuels (methane and propanw) and further methane-propane mixture fuel whose density was equivalent to the surrounding air were used. As the results, flame length decreased with an increase of gravity level regardless of the positive and negative buoyancy effect between the fuel and surroundings. To investigate the gravity effect on flame structure, length of blue flame which appeared at anchor portion of the flame was measured under various gravity levels. It was confirmed that the blue flame was expanded with an increase of the gravity level. This result was explained by the enhancement of the air entrainment at the anchor portion of the flame. Evaluation of flame length which was obtained by Altenkirch considering the relationship of fuel and required oxygen were used to evaluate the experimental data of flame length under the various gravity level. From this method the following empirical correlation was proposed : L_f/γ_o=1.72Re^<0.667>Fγ^<0.0846>, where L_f is a flame length, γ_o is a nozzle radius, Re is the Reynolds number based on nozzle radius and Fγ is the Froude number.
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| 44.
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林田, 和宏 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Laser induced fluorescence was applied for the measurement of OH concentration
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in the propane diffusion flames. A tunable, narrow band KrF excimer laser was used to excite the A(ν'=3)←X(ν""=0) band of OH radical. An emission spectrum of the induced light from the flames was measured by a spectroscope. An OH fluorescence component was picked up from the emission spectrum in order to obtain the accurate distribution of OH fluorescence in the flames. We call this method for spectrum-LIF (S-LIF). The spectrum of the induced light from the diffusion flames was compared with that of the premixed flames. Although the spectrum had only OH fluorescence components in the case of premixed flames, high intensity emission from the yellow flame appeared on the LlF image in the case of diffusion flames. To remove the high intensity emission from the LIF image, off resonance image was deducted from the OH resonance image as the background image. Using this deduction method, a planer laser induced fluorescence (P-LIF) was tried to measure the distribution of OH fluorescence. OH fluorescence distribution measured by P-LIF was compared with that of S-LIF. As the result, the P-LIF image qualitatively agreed with the data of S-LIF.
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| 45.
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斉藤, 正浩 ; 荻原, 五郎 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Behavior of spray-to spray impingement, where two spray jets were formed EFI (Electronic Fuel Injection) nozzles and impinged each other, was studied experimentally. This system was
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named MISS EFI. Spray penetration and the Sauter mean diameter of the spray were measured to investigate the effect of spray-to-spray impingement. When the impingement location was set at the vicinity of the nozzles, impingement phenomena became to be jet to jet impingement of the liquid column. In this condition, the penetration became shorter than that of the individual penetration. However, the penetration did not changed after spray-to-spray impingement. From the photographs of jet-to-jet impingement, it was confirmed that the liquid film was formed by the impingement, and then this liquid film disintegrated to small droplets. In the spray-to-spray impingement, on the other hand, the relatively large droplets still existed in the impinged spray, because the two sprays crossed each other without disintegration of the droplets. The photograph of the spray-to-spray impingement showed that the droplet-to-droplet impingement in the spray was rarely observed. Further, the chance of coagulation of the droplets was less observed than the disintegration of the dropled. These behavior of the spray-to-spray impingement agreed with the reduction of the Sauter mean diameter of the impinged spray.
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| 46.
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伊東, 明俊 ; 天谷, 賢児 ; 新井, 雅隆 ; 三舩, 博史
概要:
application/pdf<br />Journal Article<br />This paper experimentally investigates a behavior of a bioconvective pattern under super gravitational fields. Experimental materials are the high density culture media of Tetrahymena. A
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centrifugal force was used to synthesize various super gravity conditions by using a spin tester that can generate 1-12[G]. To realize the decreasing effect of bioconvection pattern size by the increase of synthesized gravity, different lengths of a rotative beam are used to change the rate of Corioli's force and synthesized gravity. The main results are as follows: (1) The size of the convection pattern is reduced by an increase of the synthesized gravity. (2) Under synthesized gravitational field, the stream mode of bioconvection is changed by the Corioli's force. (3) The maximum transition velocity (upward, downward) of Tetrahymana is obtaind with the 2-4[G] condition. (4) The decrease in the size of convection pattern is due to the composite gravity.
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| 47.
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岡本, 雄一郎 ; 荻原, 五郎 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />A six-stroke diesel engine which was proposed by authors had second compression and second combustion strokes which were added on a four-stroke diesel engine. Numerical prediction and experiments
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on six-stroke engine which were carried out previously, showed that a six-stroke diesel engine could reduce NO concentration and shorter ignition delay could be attained in second combustion. Using various fuels on second combustion, it might be possible to improve more the emission characteristics. In this report, Methanol was used in the second combustion to improve the six-stroke engine performance. As the result, NO concentration in the exhaust gas decreased with delaying of the injection timing at second combustion and increased with an increase of the heat allocation ratio of second combustion stroke when the injection timing at first combustion stroke was fixed. Smoke wasn't exhausted at all when Methanol was put into the second combustion stroke. NO concentrations were affected by the heat allocation ratio and related with gas temperature. It was confirmed that the NO concentration of the Diesel fuel-Methanol engine become lower compared with that of the Diesel fuel engine.
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| 48.
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新居, 利洋 ; 斉藤, 正浩 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />This paper reports the suppression of soot emission from acetylene diffusion flame by applying electric field. The effects of applied voltage, polarity and spacing of electrodes on soot emission
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were investigated experimentally. The results showed that the shape of flame changed and the soot emission decreased with increasing the applied voltage. The polarity of applied voltage influenced to the shape of flame and the soot emission. When positive voltage was applied to the nozzle electrode, the flame length became short and the width at the flame tip was spread. And, more than 90% of soot emission was suppressed at over 200 kV/m of the intensity of electric field. The surface temperature of flame increased with increasing the applied voltage. Thus, it was considered that the increase of flame surface temperature promoted the soot oxidation. When negative voltage was applied to the nozzle electrode, on the contrary, only the 70% of soot emission was suppressed, because the flame temperature was comparable to that for non-applied voltage.
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| 49.
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江原, 拓未 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />In the previous paper, the authors clarified that an impingement spray have the slip flow region near the impingement point on the wall. Then, behavior of a diesel spray impinging on an
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inclined wall was modeled to make an empirical formula of impingement spray tip penetration. To introduce a new model of spray growth behavior, uniform velocity penetration of the spray growth behavior in the slip region were framed and included into the traditional formula about the free spray. The momentum conservation theory was applied to the spray of after slipping. The growth behavior of an impingement spray was expressed as the function of wall distance and inclined wall angle. Spray path length calcurated from this formula showed qualititaively well agreement with an actual measurement.
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| 50.
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岡本, 雄一郎 ; 荻原, 五郎 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />A Six-stroke diesel engine was developed and its performance was evaluated. This engine had second compression and second combustion strokes which were added on the four stroke diesel engine.
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To control the fuel injection ratio and injection timings for first and second combustion strokes independently, two fuel pumps were attached to the engine. Effect of the fuel allocation ratio between first and second combustion strokes on the engine performance was investigated. Engine performance of the six stroke diesel engine was compared with that of the four stroke diesel engine which was the base engine of the six stroke engine. As a result, NO concentration in the exhaust gas decreased with a delaying of injection timing at second combustion stroke, but the injection timing at first combustion stroke didn't influence NO concentration. NO concentration decreased with an increase of allocation fuel ratio into the second combustion stroke. A trade-off relation between NO and soot concentration was observed against the change of allocation ratio. From the comparison between six and four stroke engine, it was confirmed that the NO concentration of the six stroke engine becomes lower than that of the four stroke engine.
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| 51.
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江原, 拓未 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />In this paper, behavior of a diesel spray impinging on an inclined wall was experimentally investigated in a pressurized vessel. In order to clarify the wall effect on a diesel spray
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structure, a relative angle of the inclined wall to the spray axis was varied. Spray penetration along the wall was observed optically and compared with that of a free spray. To observe an internal structure of the spray, it was visualized by a YAG laser sheet light and its tomographic image was captured on a film. The photo-image on a film was taken into an image analyzing computer using a high resolved image scanner. High density ridges in the tomographic image were extracted to clarify the internal structure of an impingement spray. Further, the growth characteristics of impingement spray was observed by a high speed photograph. To evaluate various spray motion quantitatively, a spray path penetration which described a development of a spray tip along the wall was used. As the result, the slip flow region of spray was found near the impingement point on the wall. It seemed that the injected fuel does not make a mixture and slipped on the wall surface in this slip region. The length of this region was measured in various impingement wall condition.
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| 52.
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新井, 雅隆
概要:
application/pdf<br />Journal Article
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| 53.
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新井, 雅隆 ; 天谷, 賢児 ; 長倉, 邦仁
概要:
application/pdf<br />Journal Article<br />Laser induced fluorescence method was applied for the measurement of NO concen
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tration in the propane and methane diffusion flames. A tunable, narrow band ArF excimer laser was used to excite the D (υ′=0) ←X (υ″=1) band of NO molecule. Emission spectrum of the induced light by a laser beam was measured by a spectroscope. Spectrum of the induced light from the diffusion flame was compared with that of the premixed flame. Although the spectrum had only NO fluorescence components on premixed flame, a lot of strong spectrum components related to the laser induced incandescence of the soot and laser induced breakdown appeared in the spectrum from the diffusion flame. NO fluorescence component was picked out from the emission spectrum with traversing the irradiate position of laser beam in order to obtain the accurate distribution of NO fluorescence on the flame axis. In this paper this method was named as S-LIF method. A planer laser induced fluorescence (P-LIF) method was tried to measure the distribution of NO fluorescence on the flame axis. In the P-LIF method, an interference filter was used to remove the obstructive light component from the LIF image. NO fluorescence distribution measured by P-LIF method was compared with that of S-LIF method. As the result, the P-LIF image qualitatively agreed with the data of S-LIF. It was confirmed that the interference filter did not remove completely the obstructive light components.
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| 54.
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廣安, 博之 ; 小田, 晴己 ; 西田, 恵哉 ; 鈴木, 護 ; 吉川, 滋 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />An experimental study on emission formation processes, such as particulate, nitric oxide and total hydrocarbon, in a small D. I. diesel engine was carried out by using a newly developed total
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in-cylinder sampling technique. The sampling method was composed of rapidly opening a blowdown valve attached to the bottom of the piston cavity, and quickly transferring most of the in-cylinder contents into a large sampling chamber below the piston. The sampling experiment gave a history of spatially averaged emission concentrations in the cylinder. The effects of several engine variables on the emission formation processes were investigated.
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| 55.
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松江, 孝博 ; 新井, 雅隆 ; 廣安, 博之
概要:
application/pdf<br />Journal Article<br />Combustion characteristics of a single CWM (Coal-Water-Mixture) droplet placed on a hot surface in a test furnace were investigated. The collapsing load of an ash grain which is formed by the
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combustion of the CWM droplet was also measured to clarify the relationship between the burning temperature and burn-out state of the droplet. Two stage combustion which is usually observed in pulverized coal combustion was observed in the burning sequence of the CWM droplet on the hot surface. The first stage of combustion was due to the burning of flammable gas from the volatile matter in the coal. The second stage was the char combustion of the coal. As the temperature on the hot surface increased, the collapsing load of the ash grain decreased. It reached a minimum load and then increased with an increase of the temperature of the hot surface. It was considered that the combination of the unburned coal at low temperatures and melted ash at high temperatures resulted in the hard grain of ash which had a high collapsing load.
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| 56.
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江原, 拓未 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />In this paper, behaviors of diesel spray injected along a wall were experimentally investigated. In order to clarify the wall effect on spray structure, the geometry of the wall and its
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relative position to the spray axis were varied. Structures of spray injected into a high-pressure atmosphere were recorded by high-speed photographs. Results shows that the asymmetrically large vortexes in the spray were induced by the wall effect, and the spray penetrating along the wall was deviated to the wall surface. This phenomenon is called the Coanda effect in the field of fluid dynamics. The growth orientation of spray was defined by image analysis. Maldistribution ratio of spray area was defined for the quantitative estimation of the spray deviation behavior. The spray deviating conditions such as the geometry of the wall and its relative position to the spray axis were fined.
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| 57.
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天谷, 賢児 ; 張, 峰 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />The performance of a six stroke diesel engine which has been proposed by the authors was experimentally investigated using a cyclical rapid-compression-expansion machine. The ignition delay and the
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maximum heat release rate in the first and second combustion processes were measured under the various conditions of wall temperature of the engine cylinder. An optical fiber probe connected to a photo sensor was installed into a combustion chamber to measure the ignition delay and to obtain the luminosity of soot exidation in the second compression process. The experimental data were compared with the numerical predictions from the 1st report. As a result, the soot oxidation phenomenon in the second compression process was numerically and experimentally confirmed. It was clarified that the experimental data of the wall temperature effect on ignition delay qualitatively agreed with the numerical prediction.
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| 58.
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新井, 雅隆 ; 井田, 祐一 ; 天谷, 賢児
概要:
application/pdf<br />Journal Article<br />The performance of a six-stroke diesel engine which has been proposed by the authers was numerically predicted using a phenomenological model developed in the previous study. Concentrations of nitric
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oxide and soot are calculated from the simple phenomeno
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| 59.
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新井, 雅隆 ; 天谷, 賢児
概要:
application/pdf<br />Journal Article<br />Droplet evaporation on a hot surface under super-gravitational fields was experimentally inves tigated. A test chamber attached to the end of a rotating arm was constructed to produce the
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quasi-super-gravitational fields. A hot surface, droplet-forming equipment and a video camera for measuring the lifetime of a droplet were installed in a test chamber. Lifetime curves of water, n-decane and benzene were measured under the gravity of G = 1 to 12. As a result, it was found that an increase of the gravitational acceleration led to the decrease of lifetime near the Leidenfrost point.
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| 60.
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新井, 雅隆 ; 井田, 祐一 ; 天谷, 賢児
概要:
application/pdf<br />Journal Article<br />The performance of a 6-stroke diesel engine was numerically analyzed by means of a simple thermodynamical model. Since the 6-stroke diesel engine proposed in this report has two combustion
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processes in one cycle, it will offer new methods of the Combustion Control which could not be attained in an ordinary 4-stroke diesel engine. For example, the second combustion stroke provides the oxidation process of the soot that formed in the first combustion stroke. With this method, the in-cylinder gas temperature related to the NO_x and soot formation in the combustion processes was predicted. It was confirmed that under various conditions, the maximum gas temperature of the 6-stroke diesel engine was lower than that of the 4-stroke engine. Furthermore, a 6-stroke low-heat-rejection diesel engine was analyzed. It was predicted that in comparison with the temperature in an ordinary 4-stroke engine, a higher thermal efficiency would be attained with a lower in-cylinder gas temperature.
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| 61.
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西田, 恵哉 ; 廣安, 博之 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />An experimental study was conducted on the evaporation and combustion phenomena of a single n-dodecane drop in ambient gas pressurized and heated beyond the critical point of fuel, that is,
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supercritical environments produced on a hot wall. The evaporation lifetime in air at the wall temperature below the ignition temperature was found to be shorter than that in nitrogen at the same wall temperature. The end of combustion time in air at ambient pressure below the critical pressure of the fuel was correlated with the evaporation lifetime, and it was maximum in the wall temperature range where the drop showed spheroidal evaporation. As the ambient pressure increased beyond the critical pressure of the fuel, the end of combustion time increased in the wall temperature range around the critical temperature of the fuel, and in other wall temperature ranges, it decreased.
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| 62.
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西田, 恵哉 ; 廣安, 博之 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />An experimental study was conducted on the evaporation and combustion phenomena of a single fuel drop in ambient gas pressurized and heated beyond the critical point of fuel, that is, supercritical
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environments on a hot wall. Several kinds of liquid paraffin such as n-heptane, n-decane, n-dodecane and n-tetradecane were used as the test fuel. The evaporation lifetime in air was found to be shorter than that in nitrogen at the same wall temperature. The difference in the evaporation lifetimes in air and nitrogen environments was greater under higher ambient pressure for the same fuel ; for the same ambient pressure, it was greater under a larger ratio of ambient pressure to critical pressure of the fuel. As ambient pressure increased from subcritical to supercritical pressure, the end of combustion time increased in the wall temperature range around the critical temperature of the fuel, whereas in a wall temperature range higher than the critical temperature of the fuel, it decreased.
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| 63.
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小田, 哲也 ; 廣安, 博之 ; 新井, 雅隆 ; 西田, 恵哉
概要:
application/pdf<br />Journal Article<br />To elucidate the atomization process of a liquid jet across a high-speed airstream, the spray shape, the mass flow rate per unit area and the Sauter mean diameter were measured. Under an
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airstream velocity of 140m/s or 70m/s and injection velocity of 10m/s, 20m/s or 40m/s, the Sauter mean diameter and the maximum liquid mass flow rate per unit area in the spray hardly changed with the liquid injection velocity. However, with increasing air velocity, the Sauter mean diameter decreased and the maximum liquid mass flow rate per unit area increased. Rearranged spatial distribution of the liquid mass flow rate per unit area in a horizontal direction agreed with the profile by the Gauss's function. An equation for width of spray was obtained from the photographic results.
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| 64.
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小田, 哲也 ; 廣安, 博之 ; 新井, 雅隆 ; 西田, 恵哉
概要:
application/pdf<br />Journal Article<br />To elucidate the atomization process of a liquid jet across a high-speed airstream, the spatial distribution of liquid, drop diameter and drop trajectory were calculated. In this model, a
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liquid column is not incorporated. Drops ejected from the injector have the same velocity V_l but different drop diameters, which are defined by the volume distribution of drop size. The ejected drop is broken up by the airstream. Calculated spatial distribution of liquid agrees well with measured spatial distribution of liquid. The trend of the calculated drop diameters agreed well with the trend of the measured Sauter mean diameter. The drop diameter decreases rapidly, near the injector especially along the outer line of the spray.
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| 65.
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松江, 孝博 ; 新井, 雅隆 ; 廣安, 博之
概要:
application/pdf<br />Journal Article<br />A single CWM droplet was suspended in a hot air stream by a fine R-type thermocouple. The surface temperature of this evaporating and burning droplet was measured by a radiation thermometer. The
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emissivity of the CWM droplet surface was kept at around 0.98 until the char combustion of the droplet proceeded to its middle stage. In the later stage of the char combustion, the emissivity decreased gradually to 0.82. Several degrees of temperature difference between the center and the surface of the droplet remained at the dry-up time, even when the diameter of the droplet was reduced to 2mm. The surface temperature at the start of char combustion was 700K when the droplet was exposed in surroundings of less than 900K. However, the surface temperature at the start increased from 700K in surroundings where it's temperature exceeded 900K. When the surroundings were 650K, the surface temperature at the char combustion start was 700K and higher than the surroundings, and the center temperature of the droplet was higher than that of the surface, which suggested that slow exothermic reactions in the droplet were already initiated before the char combustion started.
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| 66.
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吉田, 肇 ; 新井, 雅隆 ; 廣安, 博之 ; 横谷, 昌道
概要:
application/pdf<br />Journal Article<br />High speed schlieren movies were taken for detailed observation of the physical structure of flames propagating in propane-air mixtures containing kerosene spray. Effects of an overall
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equivalence ratio and a mixture ratio of propane/kerosene to the total fuel on the structure were examined. Fractal analysis of the flame structure was also attempted. As a result, two typical flame structures were observed, into which flame structures were classified according to propane concentration. One consisted of droplets ignited successively, the other consisted of flame front propagating in the interdroplet propane-air mixture. In the latter, flame front had fractal character and its fractal dimension increased and decreased with the flame propagation velocity.
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| 67.
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新井, 雅隆 ; Saito, Kozo ; Altenkirch, Robert A.
概要:
application/pdf<br />Journal Article<br />An experimental investigation of the boilover phenomenon for a liquid burning above a water sublayer indicates that boilover occurs when the boiling point temperature of a pure fuel is more than
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that of the water. In this situation, the fuel temperature near the fuel-water interface is somewhat limited by the presence of the boiling water and cannot reach the fuel boiling point. The boilover behavior of multicomponent fuels is similar to that of pure fuels. The temperature measurements at the onset of boilover for multicomponent fuels show that a fixed amount of superheat, 10K, exists in the water sublayer near the fuel-water interface. Onset time of water boiling was measured and compared with an estimated value that was derived by a simple analysis of unsteady conductive heat transfer.
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| 68.
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松江, 孝博 ; 新井, 雅隆 ; 廣安, 博之
概要:
application/pdf<br />Journal Article<br />The evaporation and combustion characteristics of a small CWM droplet were analyzed on a hot surface in a test furnace. The minimum temperatures for decomposing combustion caused by the
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volatile matter of the coal and char combustion rise with a decrease of the initial diameter of the droplet. Droplets with diameters below about 1.3mm show different combustion characteristics from the larger droplets. From the photographic observation of the final state of the burned CWM droplet, the cracked shell and popcorn states were noted on the agglomerated surface of the ash. These symptoms appeared more clearly when the initial diameter of the droplet was larger than 1.3mm. The contraction ratio of the diameter in the dried-up state decreases correspondingly with the decrease in the initial diameter of the droplet.
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| 69.
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新井, 雅隆 ; 廣安, 博之 ; 中森, 薫 ; 中曽, 伸二
概要:
application/pdf<br />Journal Article<br />A new combustion system called a jet-mixing-type combustor was designed to obtain a nonluminous blue flame of a kerosine spray. A spray was injected by a conventional-type swirl atomizer into
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the combustor and combustion air was introduced through a baffle plate with 16 inlet holes. The principle of this combustion method was revealed as a prompt mixing of the air and the spray, which was achieved by a high-speed air jet. The combustion characteristics such as combustion stability, temperature distribution and exhaust emissions were compared with a conventional swirler-type combustor. NO and THC emission levels exhausted from nonluminous kerosine flame were lower than those exhausted from the swirler-type combustor.
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| 70.
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松江, 孝博 ; 新井, 雅隆 ; 廣安, 博之
概要:
application/pdf<br />Journal Article<br />The evaporation and combustion characteristics of a single coal-water slurry droplet were studied in an elevated temperature environment and in a hot air stream by measuring the
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temperature of a burning droplet and observing its behavior. When the droplet was suspended in an elevated temperature environment, the decomposing combustion, that is, the combustion of an inflammable gas included in the coal, started after the dry-up. The surface reaction, that is, the combustion at the coal surface, followed after that. Thereby, the surface reaction was slightly influenced by the decomposing combustion. When the droplet was suspended in a hot air stream, the decomposing combustion started during the surface reaction process and a blue wake flame was induced. In this case, the spread of the surface reaction region was prevented by a flame of the decomposing combustion.
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| 71.
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吉田, 肇 ; 新井, 雅隆 ; 廣安, 博之
概要:
application/pdf<br />Journal Article<br />Ignition characteristics of a propane-air mixture that contains kerosene spray were studied to understand the ignition behavior of an evaporating gasoline spray injected into a cylinder of a
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direct injection stratified charge (DISC) engine. Ignition probability as a function of an overall equivalence ratio, a mixture ratio of propane/kerosene to the total fuel and spark energy, was measured under atmospheric conditions. Adding a small amount of kerosene spray to a lean propane-air mixture improved the ignition probability of the mixture. A lean propane-air mixture had the suitable mixture ratio of kerosene spray for ignition. The results obtained here will give basic information about the ignition behavior of an evaporating gasoline spray, because a propane-air mixture containing a kerosene spray would simulate various evaporating stages of a gasoline spray.
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| 72.
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吉田, 肇 ; 新井, 雅隆 ; 廣安, 博之
概要:
application/pdf<br />Journal Article<br />The process of flame development in a spark-ignited propane-air mixture that contained kerosene spray was observed by a high-speed VTR. Flame areas were measured on the VTR and the process of flame
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development was shown as a change of flame area versus time from ignition. Propagation delay, which means a period between spark ignition and the start of rapid flame development, was defined. Effects of an overall equivalence ratio, a mixture ratio of propane/kerosene to the total fuel and spark energy on the propagation delay and development rate of a flame were studied. Each lean propane-air mixture had a suitable value of the mixture ratio of kerosene spray for the minimum propagation delay and maximum development rate of a flame. When the mixture ratio of propane to the total fuel was low, the propagation delay decreased as the spark energy increased.
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| 73.
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清水, 正則 ; 新井, 雅隆 ; 廣安, 博之
概要:
application/pdf<br />Journal Article<br />In order to elucidate the disintegrating mechanisms of a diesel spray, the breakup length was measured by an electric resistance method. A reattachment distance of separated liquid flow
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in a nozzle and a spray were observed photographically. The mechanism of the two disintegrating processes of the jet was investigated by separating an ambient effect from a disturbed effect of the nozzle. The atomizing mechanism of the jet was governed by both the initial disturbance due to the nozzle geometry and an interfacial force between the jet and the environment. If a strong disturbance was given to the internal flow in a nozzle, the jet would be broken up into a spray flow.
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| 74.
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新井, 雅隆 ; 斎藤, 孝三 ; Altenkrich, R.A ; Evans, D.D.
概要:
application/pdf<br />Journal Article<br />Under certain circumstances, the water on which a burning pool of liquid fuel is supported may begin to boil. The bubble of water vapor that is released and escapes through the fuel surface
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tends to chenge the temperature distribution in the fuel layer and sometimes to atomize the fuel which results in a boilover of the burning liquid fuel. A pool fire system, in which the burning surface of the fuel was fed into the flame so that a boiling water sublayer could be oberved, was designed to invstigate the effect of water sublayer on the burning phenomena of the liquid fuel layer. Data obtained incrude temperature and mass loss history of the liquid fuel and water, flame hight, and irradiance from the flame. Results show that when boiling occurs, the temperature gradient across the fuel layer vanishes, the temperature level of the fuel decreases, and the burning rate of the fuel decreases. Because water-vapor bubbles released from the fuel-water interface stir the fuel layer as they pass upward through it.
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