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Kenichi SHIMIZU, Takahiro KOSEKI, Shinichi TAMURA, Kota SHINDO, Kazuno ...
Article type: Article
Session ID: 2117
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Preservation of the global environment and diversification of energy sources have become pressing issues in recent years, and there have been demands for the reduction of nitrogen oxides (NOx) and particulate matter (PM) that are the principal causes of air pollution in the exhaust gas of diesel engines. In this research, therefore, DME was supplied to a test diesel engine at a point 600 mm upstream of the intake port, and the premixed mixture was burned in an HCCI process. The resultant flame light was extracted from the combustion chamber and analyzed to determine the combustion characteristics.
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Masato IKEMOTO, Yuichiro KOJIMA, Susumu SATO, Norimasa IIDA
Article type: Article
Session ID: 2118
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Homogeneous Charge Compression Ignition (HCCI) engine is supposed to achieve high thermal efficiency and low emissions. In this study, a new closed loop control system for HCCI engines is suggested to make it practical application. Amount of internal EGR, amount of external EGR and mass of input fuel are used as control factors. And an HCCI engine running on Di-Methyl Ether (DME), which applies the system, is developed. This paper shows the effectiveness of the system confirmed by experimental result and some governing equations. In the result, in-cylinder gas temperature needs to be controlled strictly and the constructed control system is totally available.
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Atsushi SAKAI, Hiroyuki TAKEYAMA, Hideyuki OGAWA, Noboru MIYAMOTO
Article type: Article
Session ID: 2119
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Decreasing the compression ratio improves thermal efficiency in a premixed charge compression ignition engine for the range of investigated octane numbers due to improvement in the degree of constant volume combustion and decreased cooling loss as the ignition timing approached TDC. The indicated thermal efficiency with different octane numbers is almost unchanged if the compression ratio is optimized. The thermal efficiency benefits of lower compression ratios decreased with higher homogeneity achieved by advancing the injection timing at due to a corresponding deterioration in combustion efficiency.
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Toshio SHUDO, Takehiro TAKAHASHI
Article type: Article
Session ID: 2120
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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One of the authors has proposed an HCCI combustion engine system that was fueled with dimethyl ether (DME) with a high cetane number and methanol-reformed gas (MRG) with a high anti-knock property in the previous research. In the system, both DME and MRG are to be produced from methanol by onboard-reformers utilizing the exhaust-heat from the engine. High overall thermal-efficiency has been achieved over a wide operable-range by both the lean HCCI combustion and the waste-heat recovery. While the MRG used in the research was the thermally decomposed methanol, methanol can be reformed to various compositions of hydrogen, carbon monoxide and carbon dioxide. This research aims to find the optimum MRG composition for the system in terms of the ignition control and the overall thermal efficiency.
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Satoshi KETADANI, Kegngo KUMANO, Norimasa IIDA
Article type: Article
Session ID: 2121
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Homogeneous charge compression ignition combustion is auto ignition of homogeneous intake gas. But in the HCCI engine, there are inhomogeneity of fuel distribution, temperature, and gas composition that are produced by residual gas, flow, and heat transfer on the wall. In this study, the effect of fuel distribution in the intake gas was investigated with Rapid Compression Machine. In the result, inhomogeneity of fuel distribution caused spatial and temporal dispersion of luminescence. And in the condition of nonexistence of residual gas and flow, overall luminescence intensity was same.
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Mitsuhiro NAKAJIMA, Akihiko AZETSU
Article type: Article
Session ID: 2122
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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The effect of injection rate modulation on the spatial dispersion of fuel droplets and inner structure of fuel spray were investigated by high-speed sectional photographs of fuel spray. To obtain the injection modulation, an electronically controllable fuel injection system developed at this laboratory was used. Through the experiments ranging from OHz to 6.5kHz of modulation frequency, it was confirmed that the shape of spray with injection rate modulation became pulse like one from a specific modulation frequency. It is considered that the pulse like spray is the result of the catching up motion of the high velocity droplets crowd.
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Chihiro WAKABAYSHI, Kenji AMAGAI, Masahiro SAITO, Masataka ARAI
Article type: Article
Session ID: 2123
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Diesel sprays impinged on a flat wall and an extruded column surface were investigated experimentally. The purpose of this study is to clarify the effect of diameter of extruded wall on spray growth behavior after impingement. High-pressure injection system was used for the spray formation. The sequential photographs of spray growth were taken by a high-speed drum camera. Spray volume after wall impingement was derived from the photographs. The result showed that the spray shape after the impingement was remarkably changed by the effect of extruded column. Also, it was found that there was the optimum diameter of the extruded column for increasing of spray volume.
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Tsubasa NAGATAKI, Masataka ARAI, Kenji AMAGAI, [in Japanese]
Article type: Article
Session ID: 2124
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Ignition and combustion characteristics of diesel spray impinging on a flat wall were experimentally investigated. Ignition position and appearance position of the luminous flame kernel were stereoscopically observed using a two-way fiber optical system. Distance from nozzle tip to impingement point on the wall was set at 50mm and ambient temperature was varied from 653K to 793K. Effect of ambient temperature on ignition position was investigated. As the result, ignition positions were observed near the spray periphery. However, the luminous flame appeared near the impingement wall because the fuel rich region was formed near the wall.
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Sadahiro AKIBA, Keiya NISHIDA, Shinsuke NOMURA
Article type: Article
Session ID: 2125
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Influences of split injection on combustion and emission characteristics of a D.I. Diesel engine were investigated. A ratio of amount of fuel injected between two injection pulses were varied under the total injection period kept constant. The concentration distributions of the vapor and liquid phases in the splitting fuel spray injected into a high-pressure and high-temperature vessel were measured by means of the Laser Absorption Scattering (LAS) technique. The mixture properties obtained by the LAS measurements were correlated with the engine experiment. The results indicate the possibility that the split injection could reduce NO_x without an increase in BSFC and with a slight increase in the smoke emission.
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Yasutaka KITAMURA, Ali MOHAMMADI, Takuji ISHIYAMA
Article type: Article
Session ID: 2126
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Effects of injection parameters on combustion characteristics of n-heptane spray and nitrogen oxides NOx concentration under the supercharged conditions were investigated using a constant volume vessel. History of NOx formation during combustion was clarified using a total gas-sampling device. The results show that increasing ambient pressure enhances the spray combustion and offers higher heat release rate. Elevating ambient pressure also promotes NOx formation. In addition, NOx formation is significantly affected by injection parameters.
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Hiroyuki YAMADA, Masataka YOSHII, Atsumu TEZAKI
Article type: Article
Session ID: 2127
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Effects of fuel reformation prior to load, on ignition timing in the HCCI process with DME (Dimethyl ether) has been studied by numerical integration of a DME detailed kinetic mechanism. HCHO was found to be most effective to retard ignition among major reformation products. By 6% addition of HCHO to DME, ignition timing is retarded by 25 degree CA. In addition, it is possible to estimate the effect to fuel consumption in cool flame stage, using simplified formula of low temperature oxidation which was applied for methanol addition in our former study. HCHO can be produced in fuel by keeping DME for 0.3 sec under 900K, avoiding the production of H_2 and CO.
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Takayuki Yamada, kenji Miyashita, Masataka Arai, Tomoyasu Aihara
Article type: Article
Session ID: 2128
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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In present study, aggregation processes of Polycyclic Aromatic Hydrocarbons (PAH) are numerically simulated by Molecular Dynamics (MD) to clarify the formation of Particulate Matter (PM) in exhaust gas of diesel engine. Aggregation kinetics of Benzene, Naphtalene, Anthracene molecules and their mixture at ensemble of constant temperature ant volume are studied. Fraction of transformation of the aggregation is quantified by internal energy change and is analyzed by Avrami formula. The aggregation rate of Benzene increases with molar fraction of Anthracene. Similar quantity of exponent of Avrami formula for every molecules show that the aggregation occurs under same phase transformation mechanism.
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Masahiro Furutani, Masanori Takasawa, Nursuhana Bt Alauddin, Yasuhiko ...
Article type: Article
Session ID: 2129
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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The formation of polycyclic aromatic hydrocarbons (PAHs) and ion has been studied on the laminar, diethyl-ether/air premixed low-temperature flames under atmospheric pressure and the equivalence ratio ranging from 3.0 to 6.0, to obtain an advanced knowledge of soot formation processes. A flat-burner is enclosed by a concentric quatz tube to prevent infiltration of surrounding air. Ion formation is recognized to be related to soot precursor formation. The ion current has been measured using an ionization gap. A liquid chromatograph with a fluorescence detector was applied to separate and determine PAHs contained in specimens sampled from low-temperature flames. PAHs was obtained by microwave extraction of soluble organic fraction (SOF) on silica glass filters. It is indicated a possibility that the ion is generated from the exited oxygen molecules and acetylene generation due to the interrelation between ion current and light emission. It has also been found that the PAHs first appears during the cool flame period.
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Terunao Kawai, Rahman Md. Montajir, Yuichi Goto, Matsuo Odaka
Article type: Article
Session ID: 2130
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Fluctuation in the measurement result of nano-particles is a common problem with recent available instruments. Therefore thermal conditioning of the sampling gas before measurement using the so-called Thermo-Conditioner was proposed in order to restrain the fluctuation in nano-particle measurement. The prime objective of this thermo-conditioner is to vaporize the volatile fraction by re-heating the diluted gas to a certain temperature and cooling down again to room temperature. As the result measurement fluctuation due to volatile fractions can be avoided. However, it is a newly developed device and the performance of this device is yet to be understood sufficiently. In this study we have attempted to clarify the effect of thermo-conditioner on the nano-particle measurement. It was found that the nuclei-mode particles are significantly influenced by the thermal conditioning temperature. Thermal conditioning at a temperature of over 300℃ was found to be optimum. Thermo-conditioner can completely vaporize the volatile fraction formed due to cold dilution in the full dilution tunnel. But it cannot vaporize all the nuclei-mode particles those exist in the raw exhaust gas.
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Takayuki SAITO, Takayuki NAKAJI, Masataka ARAI
Article type: Article
Session ID: 2131
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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A large amount of participate matter (PM) is emitted from a diesel engine. A feasibility study was carried out whether the PM from diesel engine can be applied as a new technology of carbon black manufacturing. As the first step of this study, the components of PM such as SOF, soot, sulfate and PM diameter were measured by means of an exhaust gas analyzer and a scanning mobility particle sizer (SMPS), respectively. The diameter distribution and total discharge of PM could be controlled by changing excess air ratio, number of revolutions and fuel additives.
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Ryosuke NAGATA, Hayato MATSUNAGA, Koji YOSHIDA, Hideo SYOJI
Article type: Article
Session ID: 2133
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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This paper presents the results of experiments conducted with a 2-cycle engine that was the world's first such engine to comply with the 2000 California emissions regulations for small off-road engine adopted by the U.S. state of California in 2000. This engine is fitted with two scavenging passage that runs around the crankcase and space of between piston and inside of the crankcase before the scavenging port. The aim of this research was to investigate how changes in the quantity of heat transferred to the fresh air as a result of varying the width of the scavenging passage would affect the state of combustion and exhaust gas composition. An ion prove was fitted to the center and end zone of the combustion chamber in order to detect the state of combustion.
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Tsuyoshi SUZUKI, Takashi SASAGAWA, Akihiro KAKISHIMA, Koji YOSHIDA, Hi ...
Article type: Article
Session ID: 2134
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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This study attempted to elucidate combustion conditions in a progression from normal combustion to knocking by analyzing the light emission intensity that occurred during this transition. With the aim of understanding the combustion states involved, the light emission intensity was measured at two positions-the center zone and the end zone of the combustion chamber. Light emission spectroscopy was applied to examine preflame reactions that are observed prior to autoignition in the combustion process of hydrocarbon fuels.This experiment reports on the result of the light emission behavior at various ignition timings.
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Hironobu KOGA, Setsuri Yoshinaga, Masahiro SAITO, Masataka ARAI
Article type: Article
Session ID: 2135
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Effects of H_2O, CO_2, CH_4 and C_2H_4 existing in automotive exhaust gas on NO_x removal using a DC corona discharge were investigated experimentally. A simulated gas was used in this experiment. N_2/O_2/NO system was basis of the simulated gas. The effect of coexisting gas on NO_x removal was investigated by adding each coexisting gases to the N_2/O_2/NO mixture. In case of H_2O or C_2H_4 addition, 90% NO_x reduction was achieved in negative corona discharge with low energy density. When negative corona discharge applied to the simulated exhaust gas (N2/O2/NO/H_2O/CO_2/C_2H_4), more than 90% DeNO_x was achieved. However, more CO, HNO_3, O_3 and N_2O was formed with increasing the energy density. It was found that the optimum energy density of DeNO_x using corona discharge for simulated gas was about 250 J/L in this experiment.
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Tadashi NOTO, Tadashi MURAYAMA, Yasuhiro FUJIWARA, Shigeru TOSAKA
Article type: Article
Session ID: 2136
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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The use of ethanol as a reducing agent on a silver-base catalyst in the presence of oxygen has a strong reductive effect on NOx emitted from a diesel engine. However, it is possible that nitrous oxide (N_2O) will be formed without reduction of NOx to nitrogen. In this study, an experimental NOx reduction apparatus was constructed, and model experiments on NOx reduction with atmosphere and catalyst temperature simulating those in actual exhaust gas were carried out. Furthermore, the correlations of NOx reduction rate with amount of N_2O produced as well as with ethanol decomposition and oxidized components were investigated. The results showed that N_2O is produced during the process in which acetaldehyde is formed from ethanol.
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Hiroshi TAKAGI, Keiji KONISHI
Article type: Article
Session ID: 2137
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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This paper described the characteristics of a turbocharged diesel engine for automobile driven under various suction temperature and pressure. Inlet temperature to engine were changed by electric heater consist of coil fin heat exchanger up to 30〜180℃. The experiments were carried out on partial load and engine speed from 1000 to 1800 rpm at 2/3 engine control lever position and the power and combustion characteristics were compared with 6 kinds of temperature range. As a results, the following are clarified. Power output and specific fuel consumption is improved remarkably as increasing engine speed.
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Yusuke NAKAHIRA, Takashi OZAWA, Hidekatsu TSUTSUMI, Masahiro ONODERA, ...
Article type: Article
Session ID: 2138
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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In order to increase the brake thermal efficiency and reduce NOx emissions of an industrial diesel engine, a direct injection (DI) combustion system, which consists of a combustion chamber with a high compression ratio and a fuel injection system with a high injection pressure, was installed in a 6 cylinders engine with 102 mm bore and 130 mm stroke, and it was tested to investigate its potential and fundamental characteristics. The high compression ratio was proven to become advantageous on the point of the brake thermal efficiency and NOx emissions. The high injection pressure by means of small nozzle hole diameter promoted the diffused combustion and reduced smoke emission under the high compression ratio and the retard of fuel injection timing.
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Ryota SHIBAMOTO, Naoto MORITA, Eiji GODA, Yoshiyuki KIDOGUCHI, Kei MIW ...
Article type: Article
Session ID: 2139
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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High turbulence combustion is effective to reduce paniculate emissions from a DI diesel engine. This study employed EGR for the chamber to obtain further NOx reduction. Results show that, when EGR ratio increases for the chamber, NOx is reduced with less deterioration of particulate emissions than a standard toroidal chamber. CO_2 gas, which is one of main components of EGR gas, reduces gas temperature, leading to low NOx emission. In the case of CO_2 dilution of intake air, both NOx and particulate emissions are reduced compared with generally EGR or N_2 dilution. CO_2 dilution restrains initial combustion due to lower gas temperature just after ignition, which promotes fuel-air mixing at early stage of initial combustion. Promoted mixing reduces the formation of rich and high temperature mixture, resulting in lower soot generation. Air charge raises gas temperature and makes CO_2 dilution effective in the wider range of dilution ratio.
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Shingo KIDO, Hajime SHIMIZU, Hideyuki OGAWA, Noboru MIYAMOTO
Article type: Article
Session ID: 2140
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Simultaneous reduction in soot and NOx can be realized without significant deterioration of engine performance with ultra high EGR to create a low oxygen concentration combustion environment for loads of up to 0.45 MPa IMEP. While decreasing the oxygen content to 12% actually increases smoke emission, a further reduction of oxygen can decrease smoke, and smoke-free operation becomes possible at 9% oxygen. With low oxygen combustion, ISF of particulate matter decreases while SAF increases. Although the combustion efficiency suffers remarkably from the reduced oxygen content, the indicated thermal efficiency does not significantly deteriorate because of the decreased cooling loss with low combustion temperature.
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Yuzo AOYGI, Hideaki OSADA, Masahiro MISAWA, Tomoaki HIROSAWA, Matsuo O ...
Article type: Article
Session ID: 2141
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Diesel Engines have an advantage in CO_2 emission, however NOx and PM (Participate Matter) need to be reduced. EGR is an effective technique of emission reduction. This experimental study of emission reduction looks into cooled EGR effects by using high-boosted single cylinder engine. Boost-pressure sets just as 6-cylinder turbo diesel engine then extends until 351.3kPa. There are slight little influences on Engine performance by EGR. NOx reduction of 80% was achieved by 30% EGR ratio at wide range load of the engine. EGR is also practical to decrease PM emission under the condition of high air excess ratio and low smoke.
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Masahiro MISAWA, Yuzo AOYAGI, Masayuki KOBAYASHI, Matsuo ODAKA, Yuichi ...
Article type: Article
Session ID: 2142
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Recently the heavy duty diesel engines have adopted the direct fuel injection combined with high injection pressure, the high boost turbo charger and the EGR, which is well known as a means to reduce the emissions effectively. The experiment has been done under the conditions of intake air quantity up to 4 times of naturally aspirated (NA) engine, 250MPa injection pressure and 70% EGR ratio. In these conditions the exhaust emissions such as NOx and smoke are effectively decreased.
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Morio SUMIMOTO, Isao Kimura, Tadonori AZUMA
Article type: Article
Session ID: 2201
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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This paper firstly describes outline of a new technology for semi-permanent use of engine oil without oil change and without waste oil, as well as some results of its practical use. Secondly, the paper reports that engine wear is remarkably decreased if lubricating oil (LO) and fuel oil (FO), or either of them are kept clean. Lastly, assumption of LO optimum contamination is discussed and field data of nearly no wear of engines are presented.
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Tatsumi KITAHARA, Masaru OTSUBO, Daisuke NAKAHARA
Article type: Article
Session ID: 2202
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Experiments were carried out to clarify the load carrying capacity of the crosshead bearing with taper geometry modified oil-grooves for large two-stroke diesel engines. A decrease in the clearance ratio is effective in enhancing squeeze action on the entirety of the bearing pads, and thereby improving load carrying capacity. When the clearance ratio becomes too low, however, the ability to form a thick oil film is degraded, causing the load carrying capacity to decrease. Incorporating a taper geometry on both sides of the oil-grooves promotes a thicker oil film. Thus a significant improvement in the load carrying capacity can be expected. The maximum load carrying capacity is achieved by the taper geometry of a subtended length of 5 degrees and a taper angle of 0.1 degree.
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Hirotsugu HAYASHI, Makoto KOBAYASHI
Article type: Article
Session ID: 2203
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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In this paper, a simultaneous analysis and eight approximate analyses are proposed for piston pin boss bearings, connecting small and big end bearings, and main bearings. Bearing performance such as journal orbits of these bearings are calculated by these nine analyses and compared. Approximate analyses for connecting rod big end bearings and piston pin bearings are established.
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Hidekazu SUZUKI, Noriaki KADOI, Tatsumi OHBAYASHI, Yasukazu BABA
Article type: Article
Session ID: 2204
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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The barrel form at the lower end of the piston skirt greatly affects piston slap noise in the case of gasoline engines. In order to clarify this mechanism, the distribution and thickness of oil film on the piston skirt was visualized and observed with a sapphire cylinder. In addition, the piston secondary motion was calculated by simulation model which can consider the stiffness and profile of the skirt. The results indicated that the barrel form had a large impact on the distribution and thickness of oil film on the skirt, but little impact on the piston motion. It was also found that piston slap noise reduction was caused by the damping effect of oil film distribution.
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Oki SATO, Takayuki AIHARA, Masaaki TAKIGUCHI
Article type: Article
Session ID: 2205
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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This study was aimed at the improvement of piston lubrication of the diesel engine by means of the DLC coating for the piston skirt and the rings. For this purpose, piston frictions measured by floating liner method in between the DLC coating and conventional coating were compared. As the results, it was confirmed that the DLC coating for the skirt and rings deteriorate the state of piston lubrication against the conventional cast iron cylinder and that their state of lubrications were improved when the DLC coated cylinder was used.
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Masaaki KUBO, Kaori ARAI, Takashi ARAKI, Shuji KIMURA
Article type: Article
Session ID: 2206
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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This paper proposes a hypothesis concerning the mechanism causing asymmetrical sprays from sac-less nozzles used for direct-injection diesel engines. The mechanism was deduced by using 3-dimensional numerical simulation techniques. It has been thought by many researchers that the eccentricity of the needle under a low lift condition causes the flow inside the nozzle to vary, resulting in an asymmetrical spray. However, the reason why such eccentricity occurs has yet to be clarified. In this study, the cause of needle eccentricity was investigated by using 3-dimensional fluid analysis techniques to calculate the force acting on the needle and a probable mechanism of asymmetrical sprays is proposed on the basis of the results.
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Takayuki FUYUTO, Ryo MASUDA, Makoto NAGAOKA, Eberhard von BERG, Reinha ...
Article type: Article
Session ID: 2207
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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A series calculation methodology from injector nozzle flow to in-cylinder mixture formation in diesel engine was developed and evaluated in this study. In this approach, an Eulerian three-fluid model was used to calculate cavitating nozzle flow inside the injector, and spatial distributions of velocity, turbulent energy, void fraction, etc. at the nozzle orifice exit were outputted. These output data were transferred to in-cylinder spray calculation, in which a primary break-up model was applied to the Lagrangian Discrete Droplet Model. The calculation results of high speed / high load condition were compared with the in-cylinder observation results. It was confirmed that this series calculation approach showed better good agreement on spray penetration and shape of fuel mixture.
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Daisuke Kawano, Yuichi Goto, Matsuo Odaka, Jiro Senda
Article type: Article
Session ID: 2208
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Alternative fuels, such as gaseous fuels and oxygenated fuels etc., have been used to achieve low exhaust emissions in recent years. In general, most of these alternative fuels have high volatility, and flash-boiling takes place easily in the fuel spray. It is been known that the flashing is a favorable mechanism for atomizing liquid fuels. However, flash-boiling process in a engine is hardly studied. In this study, the sub models for flash-boiling spray of multicomponent fuel which take account for properties, vaporization process, bubble nucleation, growth and disruption in multicomponent fuel droplet were added to KIVA3V. The flashing spray characteristics from numerical simulation qualitatively showed good agreement with the experimental results. In addition, it was confirmed that flash-boiling effectively accelerated the atomization and vaporization of fuel droplets.
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Hiroshi MIYAGAWA, Yoshihiro NOMURA
Article type: Article
Session ID: 2209
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Effect of flame stretch on laminar burning velocity was investigated by calculating outwardly propagating process of spherical flame. When flame is stretched, the flame temperature is different from adiabatic flame temperature. That causes the change of burning velocity from that of unstretched planar flame. It was confirmed that this relation was expressed by using Karlovitz number and Markstein number. Further analysis indicated that Markstein number did not depend on temperature and pressure, but equivalence ratio. In case of n-C_7H_<16>, C_3H_8, Markstein number of rich mixture is fairly lower than that of lean mixture, while it is slightly higher in case of CH_4.
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Tie LI, Keiya NISHIDA, Yuyin ZHANG
Article type: Article
Session ID: 2210
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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The mixture characteristics of DI gasoline spray by split injection were studied by using the Laser Absorption Scattering (LAS) technique. P-xyline was injected into a high temperature and pressure constant volume vessel to simulate gasoline sprays. Base on the comparison of the mixture characteristics between the single and double pulsed sprays, the following possible benefits of the split injection to stratified charge of DI gasoline engine were found: 1) high density liquid droplets piling up at the leading edge of the spray can be avoided, and subsequently the reduction of spray tip penetration; 2) the "over lean" (equivalence ratio less 0.7) can be reduced. These results are believed to contribute to reduction of DI gasoline engine-out smoke and HC emissions.
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Tuyoshi ONOE, Keiya NISHIDA, Tie LI
Article type: Article
Session ID: 2211
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Measurement of the droplet and ambient air velocities in and around a D.I. gasoline spray was made by combining the laser induced fluorescence (LIF) and the particle image velocimetry (PIV) techniques. A fuel spray was injected into the fluorescent tracer clouds dispersed by D.I. gasoline injector and illuminated by an Nd:YAG laser light sheet (wave length:532nm). Only the fluorescent tracer cloud image was captured using a long pass optical filter and a CCD camera, being discriminated from the fuel spray image. In order to clarify the mechanism behind the effect of the split-injection, the spray-induced ambient gas motion was investigated by the LIF-PIV technique.
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Hidemasa KOSAKA, Hiroshi KAWANABE, Yusuke NAITO, Takuji ISHIYAMA, Masa ...
Article type: Article
Session ID: 2212
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Entraining flow of high-speed unsteady fuel jet was successfully measured by means of particle image Velocimetry (PIV). Entrainment rate was estimated based on the integration of obtained velocity along the jet boundary, and the effect of fuel density (natural gas and hydrogen), injection pressure and ambient pressure was investigated. It was shown that large-scale vortex motion around jet tip makes a large contribution to the entrainment and the jet tip penetration increases with injection pressure. For hydrogen jet, the jet tip penetration and jet angle are larger than those of natural gas jet, however, the amount of air entrained air is approximately equal.
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Yuki MIMURA, Yoshiyuki KIDOGUCHI, Kei MIWA, Ali MOHAMMADI
Article type: Article
Session ID: 2213
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Effects of ambient temperature and injection pressure on evaporating process and droplet behavior of diesel spray was investigated by using a magnified nano-spark photography method and a rapid compression machine. Spray tip penetration becomes short with increasing ambient temperature. When ambient temperature rises up to 950K, penetration of liquid core becomes short. Magnified photographs reveal the detailed structure of evaporating spray. Droplets begin to evaporate near middle stream region of the spray. Some droplets fly while evaporating, and the droplets leave streamline at the back. The evaporation is promoted by injection pressure. Under the condition of high injection pressure, observed droplet size is small and the spray evaporation progresses strongly due to introducing high temperature ambient gas. Consequently, high-pressure injection produces wide gas phase region near the spray tip.
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Kenji HOSHI, Hiroto KUSAKA, Akihiro KIDO, Hideyuki OGAWA, Noboru MIYAM ...
Article type: Article
Session ID: 2214
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Atomic emission obtained by irradiating liquid-gas mixtures with a focused high-energy laser was measured to quantify local concentration and vapor fraction. Equivalence ratio can be quantified from the ratio of peak emission intensities of the fuel-borne hydrogen and the nitrogen in the ambient gas.The FWHM of the hydrogen emission peak yields the fuel vapor fraction. This research demonstrates the applicability of this method to high pressure, liquid-gas mixtures, such as diesel fuel sprays.
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Toshihiro MORIOKA, Yoshiya TERAO, Masaki TAKAMOTO, Rai ITO, Jun-ichiro ...
Article type: Article
Session ID: 2215
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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A new test mode which includes transient mode operation of engines is considered to be necessary at the pattern approval test for the recent regulation, considering actual driving pattern of a diesel vehicle in a city, which frequently accelerates and decelerates at various traffic conditions. The flowrate of exhaust gas can be estimated from the flowrates of air and fuel into the engine for the steady test mode. However, as a result of adopting the transient mode operation, the direct measurement of the exhaust gas flowrate is needed to divide the exhaust gas at a constant ratio into the dilution tunnel. The purposes of the present study are to develop the ultrasonic flowmeter measuring directly the exhaust gas flowrate. Several types of ultrasonic sensors taking account of both heat resistance and heat radiation are fabricated, and temperature effect on these sensor is experimentally examined.
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Hideto INAGAKI, Shuichi KUBO, Teruaki KONDO
Article type: Article
Session ID: 2216
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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To analyze in-cylinder soot formation process, we have newly developed a fast gas sampling valve. The valve is directly actuated by piezo electric device and it achieves the minimum opening duration of about 0.2 ms. The other features, to avoid the growth or the coagulation of the captured soot, the valve has ability which dilutes the sampled gas by nitrogen at the tip of the valve. There was a point in the settlement of the dilution rate to make the analysis succeed. We have applied the valve to our homogeneous-charge-compression-ignition engine, and measured the changes of particle size distribution by using a scanning-mobility-particle-sizer. The measured results clearly show the soot formation process from the soot precursor appearance to the coagulation of them.
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Kunihiko SAITO, Junya TANAKA, Koji KOREMATSU
Article type: Article
Session ID: 2217
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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The increase in nitrogen oxides has been pointed out in the first cycle of the spark ignition engines. The new test equipment is developed in order to clarify this fact. The combustion gas in the first cycle is introduced in the chamber where argon gas filled with, by means of the fast sampling valve installed in exhaust pipe. Nitrogen oxides in the combustion gas chemically frozen in argon gas are measured by the NOx analyzer. It is shown that the data of nitrogen oxides are rational and that this new measuring technique is effective.
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Yoshinori YAMASAKI, Atsumu TEZAKI
Article type: Article
Session ID: 2218
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Fluorescence lifetime of formaldehyde excited at 352nm A-X 4^1_0 band was measured as a function of pressure of bath gas: He, N_2, O_2, CO_2, and CH_3OCH_3 (DME). Temperature dependence of lifetime between room temperature and 375K was also examined. In this study we proposed "two-step decay model", which successfully reproduced the non-linear pressure dependence of the inverse lifetime. This model assumes that the optically excited formaldehyde undergoes a reversible collision transfer to a state of higher spontaneous decay rate along with direct collisional and spontaneous deactivation pathways. It was confirmed that the lifetime in a bath gas mixture can be reproduced by this model with the rate constants individually obtained as linear combinations of the bath gas contributions. The temperature dependence is expressed by giving activation energies for the constants in this model formula.
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Hiroyuki MORI, Yohei KAWAUCHI, Tetsuya AIZAWA, Hidenori KOSAKA
Article type: Article
Session ID: 2219
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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The purpose of this study is to investigate the mechanism of heat loss in DI diesel engines via two-dimensional thermography of the combustion chamber wall using laser-induced phosphorescence from a thermographic phosphor. The present paper reports the results of preliminary measurements of instantaneous temperature distribution on a quartz glass plate coated with a thermographic phosphor (La_2O_2S:Eu) heated by an atmospheric jet burner flame. The phosphor-coated glass plate was irradiated by a 355nm Nd:YAG laser pulse and the laser-induced phosphorescence at 620 nm was imaged by a CCD camera. The temperature distribution was obtained from the pixel-by-pixel ratio of phosphorescence intensities at room temperature and the measured temperature.
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Toshiaki KITAGAWA, Yukihide NAGANO
Article type: Article
Session ID: 2220
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Cellularity of the propagating spherical laminar flames induced by the flame instability was studied for methane and propane-air mixtures at the equivalence ratios from 0.8 to 1.3 and the initial pressure from 0.10 to 0.50MPa. The Markstein number was employed to quantify the effects of the equivalence ratio and the pressure of the mixture on the cellularity due to the flame instability. The critical Peclet number, or the critical flame radius normalized by the flame thickness, at which the cells are created over the entire laminar flame surface, decreased with decreasing the equivalence ratio for the methane mixture and decreased with increasing the equivalence ratio for the propane mixture. It decreased with increasing the initial pressure at all the equivalence ratios. It decreased as the Markstein number decreased. The flame was no longer stabilized by the flame stretch at the large Peclet number though the positive flame stretch will restrain the Darrieus-Landau flame instability. Especially with the negative Markstein number, the flame was unstable even at the small Peclet number.
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Takashi SUZUKI, Yasufumi OGURI, Keisuke UCHIDA, Masatake YOSHIDA, Tama ...
Article type: Article
Session ID: 2221
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Measuring precise in-cylinder pressure traces of internal combustion engines is an important factor for estimating their performances. It is known that the actual pressure readings measured with piezoelectric pressure transducers have various forms of error. This paper is devoted to a study of compensation methods for reducing the errors caused by thermal shock. Numerical analysis was carried out for the error to derive the equations of error compensation using the actual pressure data. The results indicate that the error is corrected quite well with the obtained equations.
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Masao YOSHIDA, Soichi ISHIHARA, Yoshio MURAKAMI, Kohei NAKASHIMA, Masa ...
Article type: Article
Session ID: 2223
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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An air coded engine with a firmed cylinder may have reeidiial heat between the fins. In oader to rediioe the residiid heat, the baffle plates were installed between the fins. The teinperature in the cylinder and on the surface of the fins was measured at various air speeds in the wind tunnel The eflects of positions of the baffle plate to the cylinder on fin temperature were examined. Results indicated that when the position of the baffle plate was set so that it was easy for the air to flow between the fins, the heat transfer from the fin was higher and the fin temperature was more uniform in circumference.
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Mitsuharu SHIWA, Weiying CHENG, Ryouich KUME, Yukihiko HORII
Article type: Article
Session ID: 2301
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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An AC magnetic testing method with a small coaxial probe was proposed to evaluate the PWHT temperature of the low alloy steel welded joints and the creep damage of the simulated HAZ specimens nondestructively. A normalized 3rd harmonic intensity of the detected signals could be used to identify the PWHT temperature after applying PWHT. Test results of creep damage measurement showed that a hysteresis was sensitive both to the microstructure change by aging and to the damage by applied stress. In order to evaluate creep damage, stress-induced damage (SID) parameter was proposed to remove aging factor of materials from HL. Creep void were observed by scanning electron microscope (SEM) for all creep damage samples of SID value under 0.8.
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Takashi KASUYA, Takeshi OKUYAMA, Hisashi ENDO, Tetsuya UCHIMOTO, Toshi ...
Article type: Article
Session ID: 2302
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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This paper discusses the capability of Eddy Current Monitoring (ECM) system as a in-situ evaluation method of crack propagation in a Boiling Water Reactor (BWR) environment. The ECM experiment with the eddy current probes on the outer surface of a large-scale pipe specimen, demonstrates the capability to monitor the propagation of cracks introduced from the inner surface of the specimen in a simulated BWR environment. The numerical simulation of eddy current signals shows that the experimental signals can explain the crack propagation. This provides that the ECM system is an effective method to evaluate the crack growth quantitatively.
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Yoshikazu YOKONO, Susumu RYUUOU, Shoutai KANEKAWA
Article type: Article
Session ID: 2303
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Eddy current testing with magnetic saturation was investigated to detect and evaluate corrosion in ferromagnetic steel piping. Advantages of the technique shown as follows were obtained through this investigation. (1) Local corrosion can be detected with high detectability. (2) Testing speed is much higher comparing with any other NDT methods such as ultrasonic testing (UT). (3) Inner and outer flaw can be identified using analysis of signal phase in specific frequency. (4) Mapping of corrosion distribution can be displayed with probe scanning.
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