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葉 啓南, 神本 武征, 小酒 英範, 小堀 繁治
1995 年 61 巻 590 号 p.
3401-3406
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
A new method of quantitative measurement of fuel vapor concentration in transient evaporating sprays is described. TMPD, a fluorescence dopant, was doped in n-tridecane fuel, and the blended fuel was injected into high-temperature and high-pressure nitrogen to form an evaporating spray. A sheet of laser light from a pulsed Nd : YAG laser illuminated a cross section of the evaporated spray to induce a fluorescence emission from TMPD vapor in the spray. The laser-induced fluorescence image taken from a direction perpendicular to the illuminated plane was analyzed based on a detailed calibration concentration conducted at high-temperature and high-pressure conditions and an assumption of the thermal equilibrium state for fuel vapor and nitrogen mixture. The quantitative fuel vapor concentration distribution at an instant in an evaporating spray was thus obtained by the analysis, and its accuracy was proved satisfactory through a comparison of the mass of fuel vapor integrated over the entire spray and the mass of injected fuel.
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城戸 章宏, 上野 正樹, 小川 英之, 宮本 登
1995 年 61 巻 590 号 p.
3407-3413
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
In unsteady gas jets, the influence of gas injection conditions on ambient gas entrainment processes was evaluated by a LIFA (laser-induced fluorescence of ambient gas technique. The influence of injection nozzle diameter, D, the ratio of nozzle length to diameter, L/D, discharge velocity, u
m, kinematic viscosity of the gas jet, ν, specific gravity of the gas jet, ρ
j and of ambient gas, ρ
a was investigated. Experimental results show that the influence of injection conditions on the ambient gas entrainment processes correlates with the influence of both specific gravity ratio, ρ
j/ρ
a, and eddy kinematic viscosity, ν
t, whhch is calculated from the discharge turbulence intensity of jets. The discharge turbulence intensity increases with increase in u
m and with decrease in ρ
j, L/D, and D. The mean jet concentration, C
jm, which was calculated by averaging C
j over the whole jet, can be predicted approximately with only one parameter, (ρ
j/ρ
a)D
2/[(ν+ν
t)Δt].
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小酒 英範, 鈴木 貴雄, 神本 武征
1995 年 61 巻 590 号 p.
3414-3419
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
The turbulent dispersion of particles in an unsteady 2-D particle-laden jet was simulated by a discrete vortex method coupled with a model of gas/particle interaction. A grid system was used to calculate the change in the circulation of the cell, which is caused by drag force on particles in a cell. The change of circulation in a cell was shared by vortices in a cell, and then the circulation of each vortex was corrected. Numerical analysis of a particle-laden jet yielded the distributions of vorticity, fuel concentration and local Sauter mean diameter. These distributions indicated that large particles are centrifuged to the periphery of the spray resulting in an increase of local mean diameter of particles in the peripheral region of the spray.
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大聖 泰弘, 森田 晃司, 斎藤 孟
1995 年 61 巻 590 号 p.
3420-3425
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
An experimental study has been carried out to investigate the effects of supercharging on diesel spray dynamics and combustion characteristics. A rapid compression and expansion machine has been developed to reproduce diesel sprays and combustion. A copper vapor laser is used as a light source to visualize the spray. By synchronizing the laser output to a high speed 16 mm camera, instantaneous photographs of the spray can be taken. It is shown that supercharging can increase air entrainment in the spray and its evaporation. As a result, ignition lag can be reduced while the early part of diffusion combustion is increased.
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小酒 英範, 西垣 隆弘, 原田 伸一, 神本 武征
1995 年 61 巻 590 号 p.
3426-3431
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
Two kinds of planar soot imaging techniques, laser-induced incandescence (LII) and laser-induced scattering (LIS) techniques, were applied simultaneously to an unsteady free spray flame achieved in a rapid compression machine. An analysis of LII and LIS images yielded three qualitative images of soot concentration, size of soot particles, and number density of soot in the flame. These images revealed that the soot is formed mainly in the center region of a flame, resulting in an appearance of a soot cloud with high number density and small particle size in this region. The soot size increases and the number density decreases when soot is conveyed downstream.
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吉川 康雄, 中田 勉, 伊東 輝行, 高木 靖雄, 河崎 照文, 川部 隆平
1995 年 61 巻 590 号 p.
3432-3439
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
A numerical model for film flow analysis was developed in which three-dimensional film flow behavior is treated as two-dimensional flow on curved surfaces, and the three-dimensional curved surfaces are projected onto imaginary flat planes to transform the three-dimensional equations into two-dimensional ones. This model is combined with a gas flow model and a spray model to form a numerical simulation system for analyzing fuel film flow in the intake port of gasoline engines. The qualitative validity of the system was verified by comparison with a fuel film flow formed in the intake port of a real engine.
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浜本 嘉輔, 吉山 定見, 冨田 栄二, 李 興虎
1995 年 61 巻 590 号 p.
3440-3445
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
Cycle-to-cycle fluctuation in combustion of a lean mixture and a nitrogen-diluted mixture in a spark-ignition engine was investigated under the conditions that the fluctuations of mixture strength and charge quantity were very small. Pressure history in the cylinder was measured, and indicated mean effective pressure, rate of heat release and combustion duration were determined. The experiment was carried out under various conditions of engine speed, swirl ratio, equivalence ratio, degree of dilution of intake charge, ignition timing, and spark location. As a result, it was found that the correlation between the duration of early-stage combustion in crank angle θ(00-05) and the indicated mean effective pressure P
mibecomes strong, under the conditions of lean or diluted mixture, but the correlation between the two parameters is not recognized under the condition of a near stoichiometric mixture.
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森吉 泰生
1995 年 61 巻 590 号 p.
3446-3451
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
A prediction model of the cycle-to-cycle variation and turbulence of the in-cylinder flow in reciprocating internal combustion engines that employs a modified k-ε turbulence model is applied to different types of combustion chamber namely ; square-stroke, short-stroke and long-stroke. Also the effect of the engine speed and compression ratio on the flow characteristics is estimated to have new implications for engine design. As a result, both the initial flow field with swirl and/or tumble and the combustion chamber profile are found to affect the cycle-to-cycle variation and turbulence inside the combustion chamber during the compression stroke.
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張 瓏, 植田 隆広, 高月 俊昭, 横田 克彦
1995 年 61 巻 590 号 p.
3452-3457
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
An experimental study investigating cyclic variation of the internal air motion was made in a motor engine having a cup-in-piston combustion chamber. The engine used for this study had a transparent quartz liner and a transparent acryl piston. The continuous wave beam of a 4 watt argon ion laser was formed into a thin light sheet to define the measurement plane. The scattered light from the particles which were supplied to the intake air stream, were recorded by a NAC E-10 high-speed camera and the bulk flow fields inside the combustion chamber were measured at both planes parallel and vertical to the piston crown by means of an image processing technique. This study reveals for the first time the continuous cycle-resolved two-dimensional bulk flow fields inside the combustion chamber around the compression TDC. Also, comparison between cycle-resolved and ensemble-averaged flow patterns showed that ensemble-averaged flow patterns may become artificial ones if there exists a large effect of the cyclic variation. Moreover, by examining the rms of the cyclic variation component and the ratios of the rms to ensemble-averaged velocity with/without swirl conditions, it was found that the ratios of the rms to ensemble-averaged velocity can be used for evaluating the effect of the cyclic variation on the flow fields.
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藤川 武敏, 片岡 匡男, 勝見 則和, 小林 辰夫
1995 年 61 巻 590 号 p.
3458-3463
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
Misfire under light-load conditions in a 2-stroke engine is analyzed. Direct photography and laser-induced fluorescence techniques are used simultaneously in order to visualize flame behavior and fuel mixture distribution. The following are clarified. (1) Misfire is caused not by misignition but by incomplete flame propagation. (2) Fuel mixture distribution on misfire cycles is not severely stratified. (3) Incomplete flame propagation originates from the decrease of flame speed which is caused by a large amount of residual gases.
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城戸 裕之, 黄 樹偉, 田上 公俊, 城戸 秀樹
1995 年 61 巻 590 号 p.
3464-3469
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
The demand for clarifying the structure of non-stoichiometric mixture flames as well as that of stoichiometric mixture flames and the local burning mechanisms in turbulent flame has become urgent to establish the lean-burn technique in internal combustion engines from the viewpoint of environmental protection and energy conservation. In our previous work, a suggestion that the local burning velocity in turbulent flames was changed from the original laminar burning velocity was made based on experiments. However, the mechanism remains unclear. The purpose of this paper is to clarify this molecular behavior in more detail experimentally, and to discuss this mechanism. As a result, it was found that the Lewis number affected the local burning velocity in turbulent flames, and this effect was amplified by preferential diffusion.
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古谷 博秀, 濱 純, 高橋 三餘
1995 年 61 巻 590 号 p.
3470-3476
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
We have carried out experiments on the ignition of hydrogen-oxygen-argon mixtures with an ArF excimer laser as an ignition light source to study the phenomena of ignition and flame growth by using high-speed shadowgraphy and a spectroscopic analyzer, and to evaluate the minimum incident laser energy necessary for ignition under various mixture conditions. A series of shadowgraphs indicated that ignition occurred in the laser focal area. The flame growth speed was greater in the laser axis direction than in the perpendicular direction, and the difference increased with the laser energy. We confirmed that the laser light irradiation induces the ignition and augments the initial flame growth. The results of spectroscopic analysis showed that no strong plasma was generated in the laser focal area. The minimum incident laser energy has a linear relationship with the reciprocal of oxygen partial pressure within the experimental range. These results indicate that the photodissociation of oxygen molecules into oxygen atoms plays an important role in the ignition process.
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畑村 耕一, 人見 光夫, 大江 博海, 小林 尭
1995 年 61 巻 590 号 p.
3477-3483
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
A Miller cycle gasoline engine has been developed by adopting the late intake-valve closing technique and the Lysholm compressor. The effectiveness of the Miller cycle depends on the reduction of compression temperature at TDC. The relation between the compression temperature and the mean effective pressure is discussed in this paper. For the reduction of compression temperature, a supercharger with high adiabatic efficiency at high pressure and an intercooler system with high cooling efficiency are essential. An optimized Lysholm compressor and a twin intercooler system have been developed for this purpose. Furthermore a twin intake system with short independent intake pipes has been adopted to make full use of late intake-valve closing potential since the conventional intake system with inertia supercharging is inadequate. The combined effect of these techniques has realized mean effective pressure 1. 5 times as high as in conventional engines with the same compression ratio of 10.
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森吉 泰生, 室木 巧, 宋 元偉
1995 年 61 巻 590 号 p.
3484-3490
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
The ignition mechanism of a pilot flame in a stratified charge mixture was examined using a model combustion chamber of a Wankel-type rotary engine. Experimental study such as LDV measurement, pressure data analysis, high-speed photography and image analysis provides detailed knowledge concerning the stratified charge combustion, which is complemented by theoretical study of the mixture formation process inside the combustion chamber. Characteristics of the pilot flame as an ignition source and the mixture formation inside the model chamber required for enhanced combustion are determined in this study.
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津江 光洋, 角谷 浩, 角田 敏一
1995 年 61 巻 590 号 p.
3491-3496
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
An experimental and theoretical study was carried out of mixture formation process in the combustion chamber of a gas engine. The planar laser induced fluorescence technique was applied for the measurement of the concentration distribution in the combustion chamber in the case that the fuel is injected continuously in the intake port. The effect of the state of the inlet mixture on the mixture formation process was investigated. The measured results show that the in the case that the fuel and air mixing is insufficient in the intake port, the fuel concentration distribution at the last stage of the intake stroke becomes less uniform. A three dimensional numerical analysis was applied for the prediction of the fuel concentration and velocity distributions. The calculated results also show that the mixture formation process in the combustion chamber is affected by the fuel and air mixing behavior in the intake port.
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Mkilaha S. N. Iddi, 川合 大三郎, 井上 充紀, 成瀬 一郎, 大竹 一友
1995 年 61 巻 590 号 p.
3497-3503
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
Modification has been made to one of the prechambers of a 4-cylinder, IDI diesel engine used to study the combustion process, for the purpose of reducing emissions. With the provisions for optical assessment of the combustion process in the prechamber, the effect of high-pressure gas injection into the prechamber during injection has been carried out. Results of this work indicate that high-pressure gas injection during combustion can affect simultaneous soot and NO
x reduction with a reasonably low amount of emission of other diesel engine pollutants. An optimum chamber type is suggested based on analysis of the effect of air, argon and nitrogen injection.
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武田 好央, 新村 恵一
1995 年 61 巻 590 号 p.
3504-3511
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
This paper shows the test results of a multi-injector diesel engine system which has two side injectors in addition to one center injector. This system provides greater flexibility in the fuel injection rate pattern compared to one with only a single injector. Using this system, injection timing and fuel quantity of each injector can be controlled individually, and injection pressure of center and side injectors can be set differently. The engine test results indicate that the small amount of retarded side injections improved fuel consumption and reduced particulate matter while maintaining low NO
x emissions.
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武田 好央, 新村 恵一
1995 年 61 巻 590 号 p.
3512-3517
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
This paper shows the test results of a multi-injector diesel engine system which has two side injectors in addition to one center injector. This system provides greater flexibility in the fuel injection rate pattern compared to one with only a single injector. Using this system, injection timing and fuel quantity of each injector can be controlled individually. The effects of spatial spray distribution and injection rate pattern on engine performance and emissions were investigated. Spray distribution was changed by the center injector which has two different spray directions. The engine test results indicate that the spray distribution having spray overlap increases smoke emissions. Of the various types of injection rate patterns, six injections per cycle reduces particulate matter.
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石田 正弘, 陳 之立, 植木 弘信, 山田 武
1995 年 61 巻 590 号 p.
3518-3523
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
To reduce the level of exhaust emissions and to improve the ignition characteristics, the effect of pilot injection on combustion was examined experimentally in a turbocharged direct-injection diesel engine, and was analyzed theoretically using a two-zone combustion model. The pilot injection effect was compared with the combustion in the injection without pilot injection and also with the effect of fuel additive as an ignition improver in two kinds of fuel : high-quality fuel having a cetane index of 57 and low-quality fuel having that of 40. It is found that the pilot injection effectively reduces ignition delay at the retarded injection timing, under the low-load condition, and in the case of low-cetane fuel. The ignition delay of the main injection is reduced to about a half of that of the injection without pilot injection by the pilot injection with the short interval between pilot and main injection. The ignition delay of the low-cetane fuel is reduced to that of the high-quality fuel by a small amount of pilot injection, or by adding 1% of the ignition improver.
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石田 正弘, 陳 之立, 植木 弘信, 駱 貴峰
1995 年 61 巻 590 号 p.
3524-3531
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
To reduce the level of exhaust emissions and to improve ignition characteristics, the effect of pilot injection was investigated in a turbocharged direct-injection diesel engine. As a result, it is found that the pilot injection shows some significant effects on reducing the ignition delay and on improving the trade-off relationship between NO
x and fuel consumption. The improvement in the trade-off relationship by pilot injection is observed in both the low-cetane fuel and the high-quality fuel. This simultaneous reduction in NO
x and fuel consumption is caused by a slow rate of pressure rise during the initial combustion which results in a higher mechanical efficiency and a lower cooling loss. In the short interval between pilot and main injection, a small amount of pilot injection is rcommended to reduce both NO
x and fuel consumption without increasing smoke.
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中川 洋, 小田 裕司, 加藤 敏, 中島 政吉
1995 年 61 巻 590 号 p.
3532-3540
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
The experimental and theoretical analyses of fuel spray motion in a side-injection combustion system, which is used to control fuel spray motion with air swirl for dynamic fuel-air mixture formation, were shown in this paper. Experimental studies on the fuel spray motion with air swirl in a constant-volume test rig by means of high-speed photographic observation, and theoretical analyses of fuel spray motion in a combustion chamber using CFD multi-dimensional model, and of fuel velocity, spray motion in a combustion chamber using CFD multi-dimensional model, and of fuel velocity, spray trajectory, and excess air ratio in the fuel spray were carried out. From these studies, important results on the characteristics of fuel spray motion and dispersion in side-injection combustion systems were obtained and the usefulness of CFD multi-dimensional analysis for improving spray dispersion in the combustion chamber was shown.
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石田 正弘, 陳 之立
1995 年 61 巻 590 号 p.
3541-3547
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
The effect of water on NO formation was analyzed theoretically from the point of view of changes in the entrained air rate and specific heat of the burned gas in the combustion chamber. The specific heat was calculated accurately based on the chemical equilibrium composition analysis considering the absolute humidity of the inducted air, the amount of water in the emulsified fuel and the residual gas fraction. It is clarified by the two-zone combustion model analysis that about 20% reduction in NO
x is attained by an increase of only 0. 01 kg/kg in the absolute humidity, and the NO
x reduction due to the water-emulsified fuel is caused by increases in both gas weight and specific heat of the burned gas whereas the entrained air rate is hardly affected by the water in the emulsified fuel.
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田山 経二郎, 土佐 陽三, 永江 禎範, 浦 晟, 石田 正弘, 本村 収
1995 年 61 巻 590 号 p.
3548-3553
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
A newly developed stratified fuel-water-injection system has been tested for NO
x reduction, targeting the future strict restrictions to be set for slow-speed cross-head marine diesel engines. In addition to this system, we have developed anothor possible measure of a direct water injection system. We introduce the details of various test results in comparison to stratified fuel-water-injection system, and also discuss the expected effects on cylinder lubrication of the two different water-injection systems.
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中川 洋, 森 俊一, 遠藤 浩之
1995 年 61 巻 590 号 p.
3554-3560
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
This paper describes the effects of water-emulsified fuel on diesel spray combustion. Theoretical analysis and numerical simulation show that the high momentum of water-emulsified fuel spray per unit mass due to lower calorific value leads to higher air entrainment into spray than in the case of ordinary fuel. The experimental results show that these effects cause a reduction in the temperature of the combustion reacting zone of water-emulsified fuel spray, and a shortened combustion duration, and less formation of soot and nitric oxide in a diesel engine.
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塚原 実, 吉本 康文, 土田 恭博
1995 年 61 巻 590 号 p.
3561-3566
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
We have previously reported that reductions in specific fuel consumption of a diesel engine achieved by using emulsions depended on the base fuel properties, the type of combustion chamber, load conditions, the type of injection, injection timing, and water content. In this paper, the effect of cooling loss on specific fuel consumption was investigated by calculating the cooling loss φw from the gas pressure in the cylinder and the φc obtained from the circulation water flowing through the water jacket of the engine. It was confirmed that compared with water-free fuel, specific fuel consumption of emulsified fuel showed a decrease with decreasing cooling loss φw and φc.
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林 百福, 小倉 勝
1995 年 61 巻 590 号 p.
3567-3572
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
The new concept of attaching a multi-impingement-wall head (MIW head) located in the center of the combustion chamber, to the cylinder head to obtain a three-dimensional diffusing spray for improving the combustion and performance of a DI diesel engine has been investigated. In this paper, we present the effect of combustion chamber geometry on NICS-MH DI diesel engines. Based on the experimental results of engine performance, it was shown that a reentrant combustion chamber with cutouts and projection has better fuel consumption and less harmful exhaust gases (HC, NO
x and smoke) than other NICS-MH engines. Moreover, compared with a DI diesel engine, the reentrant combustion chamber with cutouts and projection also yields decreased densities of harmful exhaust gases.
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林 百福, 小倉 勝
1995 年 61 巻 590 号 p.
3573-3580
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
A three-dimensional diffusing spray using the multi-impingement-wall head (MIW head) has been proposed to form air-fuel mixtures in a single DI diesel engine. In this study, the effect of the width of the MIW head on spray pattern, distribution and engine performance have been investigated. In the fuel spray and engine performance experiments, an optimal width of the MIW head results in the collision of fuel droplets at an advantageous position in the combustion chamber for obtaining a good fuel spray distribution. The minimum BSFC is almost the same value as that of a single DI diesel engine, the HC and smoke densities are reduced and the NO
x density show a tendency to increase under partial load and to decrease under full load. A relatively slow heat-release rate and maximum temperature duration of the MIW head can be obtained by shortening the ignition delay.
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Iman K.REKSOWARDOJO, 北村 融, 小川 英之, 宮本 登, 榎本 良輝
1995 年 61 巻 590 号 p.
3581-3587
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
Diesel combustion and exhaust gas emissions under transient operation (when fuel amounts abruptly increased) were investigated under a wide range of operating conditions by using a newly developed gas sampling system. The relation between gas emissions and piston wall temperatures was also investigated. The results indicated that NO
x, THC and smoke showed transient behavior after the start of acceleration before reaching the steady-state condition. Of the three gases, THC was most affected by piston wall temperature ; its concentration decreased as the wall temperature increased. Criteria cycle numbers, at which gas concentration reached a steady-state value after the start of acceleration, were about 1. 2 times the cycle constant (τ
*) of the piston wall temperature for THC, and 2. 3 times in the case of smoke. A slight increase in NO
x concentrations immediately after the start of acceleration resulted in increased premixed ROHR. This was caused by a temporary increase in ignition lag under increased wall temperatures.
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近久 武美, 藤田 雅也, 村山 正, 登坂 茂
1995 年 61 巻 590 号 p.
3588-3596
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
This paper presents a theory and its experimental validation for air entrainment changes in fuel sprays in DI diesel engines. The theory predicts air entrainment changes for a variety of swirl speeds, numbers of nozzle holes, nozzle diameters, engine speeds, injection speeds and fuel densities. The formulae of the theory are simple nondimensional equations, which are applicable to engines of various sizes. Experiments were performed in order to compare theoretical predictions and experimental results in six different engines varying from 85 to 800 mm in bore. All results showed good agreement with the theoretical predictions for shallow-dish piston engines. Using the theory, it is possible to interpret a variety of combustion phenomena in diesel engines, providing additional understanding of diesel combustion characteristics.
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原 浩昭, 小森谷 晴夫, 岩宮 保雄
1995 年 61 巻 590 号 p.
3597-3602
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
An SI engine test was carried out to elucidate the effect of fuel properties on the engine performance in a lean combustion region. Several combustion characteristics, i. e., the indicated mean effective pressure (IMEP), the cycle variation of IMEP, the combustion duration, the fuel consumption and the indicated thermal efficiency, were demonstrated for four kinds of alternative fuels and regular gasoline with equivalence ratio ranging from 0.56 to 1.0. From the results of this test, we have cofirmed that the fuel composition significantly affected engine combustion under lean-burn conditions. This study has also revealed the effect of fuel properties on exhaust emissions, such as the carbon monoxide (CO), the total hydrocarbon (THC) and the nitrogen oxide (NO
x) amount. The CO emissions did not depend on the fuel types, but the THC emissions and the NO
x emissions were affected by differences between several fuel types in the lean region. In an extremely lean region, however, the NO
x emissions became similar for all fuels.
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林 重信, 澤 則弘, 榎 清, 吉井 秀司
1995 年 61 巻 590 号 p.
3603-3609
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
Methanol fuel has high antiknock characteristics and burns in the lean mixture region, but preignition occurs easily. In this paper, we carried out some experimental investigations for the improvement of performance and emission characteristics, using a supercharged four stroke-cycle methanol SI engine. In the experiment, operating conditions, that is, the boost pressure ratio, ignition timing, compression ratio and excess air ratio, were changed. As a result, we have clarified that if the optimum operating conditions are selected, it is possible to improve both the engine performance and exhaust emission characteristics.
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赤井 泉明, 金 永一, 岩井 信夫, 伊藤 献一
1995 年 61 巻 590 号 p.
3610-3615
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
n this paper, technology to form a high concentration of hydrogen and carbon monoxide, based on partial oxidation of methanol, was investigated for improvement of cold startability of neat methanol S. I. engines. Ignition conditions of a mixture of flammable gas and oxygen, and air dilution ratio necessary to form a flammable mixture were discussed. Test results show that the highest concentration of hydrogen that can be produced at the rich limit of a premixed flame is about 20%. It is essential to maintain the level of hydrogen concentration at 5% or more, and to supply sufficient air to ensure that the oxygen concentration is at least 9% to achieve engine starting.
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中谷 純, 近久 武美, 村山 正
1995 年 61 巻 590 号 p.
3616-3621
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
This paper presents concepts of new combustion analysis methods, and a learning and inference algorithm for the concepts. The analysis methods are based on the following three concepts : (1)constructing a database on the relationships between experimental conditions and combustion characteristics, and predicting combustion performance for a given condition ; (2) extracting the physical relationships among the combustion factors ; (3) enabling deficiencies in measurements and numerical simulations to compensate each other by adjusting uncertain parameters in the simulation to fit the calculated results to the measurement based on learning and inference functions. In the present study, we attempt to develop a new method of inference which enables analysis of nonlinear multi-variable relationships using a limited number of data. A feasibility study of this method showed that good learning and inference performance were achieved using these concepts.
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馬場 直樹, 大澤 克幸, 飯田 清三, 石田 忍
1995 年 61 巻 590 号 p.
3622-3628
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
Transient thermal characteristics of one-brick-type and multibrick-type catalytic converters were investigated by means of experiment and numerical simulation. Flow visualization using the laser-sheet method and temperature measurement using thermocouples was carried out. The experimental results show that the inlet gas velocity distribution of one-brick-type converters is roughly flat, while that inside the multibrick-type is high in the center and becomes flat gradually as the gas passes through each brick. During warm-up, the temperature distribution of the inlet gas has a difference of at least 70°C between the center and inside wall surface. The catalytic converter simulation model considers heat and mass convection, gas-solid heat and mass transfer, heat conduction, chemical reactions and heat loss to the surroundings. The simulation also accounts for flow and temperature distribution of the inlet gas as boundary conditions. The calculations indicate that warm-up characteristics of the multibrick-type are partially superior to the one-brick-type converters, but the percentages of activated volumes are almost the same.
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稲垣 英人, 斎藤 昭則, 村上 元一, 許斐 敏明
1995 年 61 巻 590 号 p.
3629-3635
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
A fluorescence image diagnostic method which uses a filtered Xe-flash lamp and CCD camera has been developed to observe the detailed distribution and behavior of oil film on a piston surface. A light source which has appropriate spectrum characteristics for measurement of thin oil film was employed after theoretical consideration of the absorption spectrum of fluorescent dye and oil with fluorescent dye. A simple correction for results measured on a cylindrical surface and calibration were carried out. The use of this system ensures that distribution and behavior of oil film on the piston skirt and piston rings are quantitatively measured and system has ability for practical use.
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三田 修三, 村上 元一, 野田 卓, 許斐 敏明
1995 年 61 巻 590 号 p.
3636-3643
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
Theoretical analysis of mixed lubrication has been carried out for a piston ring package of an automotive reciprocating engine as a method to elucidate better specifications of rings for reducing friction loss. The starved inlet boundary condition has been employed for oil film of each ring based upon experimental results obtained through scanning laser-induced-fluorescence oil film thickness measurement. By considering starvation, predicted oil film thickness at compression rings was in better agreement with that measured than the former prediction under the fully flooded inlet condition. Film thickness at the 1st compression ring under the full load firing condition was predicted to be smaller than that in motoring, which also agreed with experimental results, due to the different inlet conditions assumed for oil film at the 2nd compression and upper rail of the oil ring under different operating conditions. Predicted oil film thickness was much smaller than that measured at both rails of the oil ring, which seems to be caused mainly by insufficient ability of the spatial analysis of the LIF measurement. Effects of the change of the oil ring surface profile due to tilting during sliding, of viscosity variation and of cylinder bore distortion, were not negligible, but were not considered in the analysis.
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村上 元一, 許斐 敏明, 稲垣 英人, 斉藤 昭則
1995 年 61 巻 590 号 p.
3644-3649
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
A new method using an induced fluorescence technique with a filter-covered Xe-flash lamp and a CCD camera has been developed, by which the 2-dimensional distribution of lubricating oil film thickness between piston and cylinder liner in an operating engine can be measured. The results show that it is possible to estimate the oil film boundary position on the skirt from the oil film thickness distribution. Analysis of the wrist pin offset effect shows that excessive pin offset increases the piston friction force during the compression stroke in motoring, because the piston tilts unfavorably and consequently the oil film on the upper side of the skirt becomes thinner at the antithrust side.
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劉 樹軍, 樋口 二郎, 井小萩 利明, 大場 利三郎
1995 年 61 巻 590 号 p.
3650-3654
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
In order to clarify the effects of cathodic electric current on cavitation erosion, the cavitation noises are systematically measured in vibratory erosion tests. Photographs of the cavitation aspects are taken with a xenon flash lamp of 1 μs exposure time. With increasing cathodic current, bubbles on the specimen surface as well as in the liguid increase, leading to a marked decrease in cavitation noise. Such a decrease in cavitation noise can be accounted for by the absorption of cavitation energy by these bubbles.
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湯 晋ー, 梅景 俊彦
1995 年 61 巻 590 号 p.
3655-3663
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
Turbulence causes collisions between neighboring particles due to random motion, resulting in coagulation of particles. In this study, we measured size distributions of the suspended aerosol particles in a stirred tank using a scanning electron microscope. We also calculated the process of turbulent coagulation using a population balance equation with three different collision rate equations. Of these, Saffman and Turner's collision rate equation [Saffman, P. G. and J. S. Turner, J. Fluid Mech., 1 (1956), 16. ] neglects particle inertia while Abrahamson's one [Abrahamson, J., Chem. Eng. Sci., 30 (1975), 1371. ] neglects correlation between two collision particles. In contrast to them, Yuu's collision rate equation [Yuu, S., AIChE J., 30 (1984), 802. ] takes both effects into account and the calculated size distribution based on it was found to be in good agreement with the experimental results. It is concluded that the particle inertia and the correlation between two collision particles play important roles in turbulent coagulation.
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伊藤 基之, 今尾 茂樹, 徳田 和行
1995 年 61 巻 590 号 p.
3664-3670
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
Turbulent characteristics of a drag-reducing surfactant solution in a two-dimensional channel flow are measured by means of a hot-film anemometer. It is confirmed for the drag-reducing flow that the mean velocity profiles on the semilogarithmic plot are S-shaped at high drag reduction and the ratio of the wall-normal turbulence intensity υ'
rms to the streamwise u'
rms is constant within a region near the wall. At a distance from the wall, the large-amplitude turbulent velocity fluctuations are more intermittent than in the corresponding water flow. The generation of Reynolds shear stress is maximized in a very-low-frequency range of turbulent fluctuations. The energy content of the turbulent fluctuations decreases at the intermediate frequency range.
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米村 茂, 田中 敏嗣, 辻 裕
1995 年 61 巻 590 号 p.
3671-3678
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
Effects of physical properties of particles on the structure of particle clusters are studied numerically. A numerical simulation was made on two-dimensional upward gas-solid flows in a rectangular domain with periodic boundaries. Flow fields of gas and solid are solved simultaneously taking the interaction between both phases into consideration. The flow of the solid phase is obtained by calculating individual particle motions, i. e. by the Lagrangian method, while gas flow is obtained by solving the equations of an inviscid fluid. The direct simulation Monte Carlo (DSMC) method is used to take account of particle-to-particle collisions, and the following results are obtained. The predicted spatial structure of particle clusters is like a strand. There are two typical types of clusters, a V-shaped cluster and an inverse V-shaped one. These patterns are consistent with those obtained from previous experiments. The cluster size increases with increasing particle size. The predicted range of cluster size agreed with that obtained from the experiments of Horio and Kuroki. Furthermore autocorrelations of the concentration distribution are discussed.
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小河原 加久治, 飯田 誠一, 登里 卓也, 足羽 賢治
1995 年 61 巻 590 号 p.
3679-3683
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
Recently, many studies have been conducted on velocimetries by which flow field is measured by following tracer particles with CCD cameras, because noncontact measurements are possible at many positions. However, velocity does not correspond to particle speed unless particle diameters are sufficiently small, and measurement error is expected when the density of the tracer particle is different from that of fluid. Therefore, we propose a technique for estimating velocity using a Kalman filter for the case that tracers do not follow the flow. This estimation method is effective even if uncertainty of the particle diameter exists. It is shown that estimation of particle diameter is also possible. However, when fluid density changes, it becomes necessary to consider follow ability. This study focuses on the development of the method of estimating velocity by following several tracers simultaneously in flow fields. Characteristics of this technique have been numerically examined for a flow field that imitates a reciprocating internal combustion engine, and for a shock wave. We found that this new technique is effective in estimating flow velocities and density even if the tracers do not follow the flow.
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松田 安弘, 邵 長城, 西尾 宏之
1995 年 61 巻 590 号 p.
3684-3690
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
In our previous research, the modified Galerkin method (MGM) was proposed as one of the most efficient methods for one-dimensional, two-dimensional and three-dimensional convection-diffusion equations. In the MGM, the non-symmetric matrixes, which are derived from the convection term in the Galerkin formulation, are not used, and an artificial viscosity is introduced through the error analysis approach to improve its discretization accuracy in both time and space directions. In this study, this MGM is applied for two-dimensional viscous fluid flow analysis, and the driven cavity flow problems are solved up to the Reynolds number of 10 000 using the vorticity-stream function formulation for non-uniform meshes. The results show the effectiveness of our modified Galerkin method.
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大坂 英雄, 望月 信介, 王 凱建
1995 年 61 巻 590 号 p.
3691-3698
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
Conditional averages of longitudinal and normal velocities and of their products have been obtained with the VITA analysis for a centerline development of a boundary layer flow through a gap in an isolated wall-mounted roughness element. All measurements were made for a ratio of roughness height to boundary layer thickness 0. 135 at a Reynolds Number of 3 300, based on obstacle height and free stream velocity. It is inferred that conditional averaged patterns and higher-order moments are significantly affected by the difference of gap size G. In particular, the gap width effect on the peak ratio, mean event frequency and mean consecutive time for both accelerating and decelerating events at X/G=0 is completely contrary to those at X/G=4. The higher-order moments show the reverse tendency at the Y/δ≒0. 14 border.
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福富 純一郎, 中瀬 敬之, 伊澤 昌一郎, 玉置 雅司
1995 年 61 巻 590 号 p.
3699-3705
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
The effects of two parameters, scroll throat width and scroll area distribution, on the performance and the internal flow of a cross-flow fan are investigated experimentally. Moreover, the movement of a vortex in a rotor with the variation of the flow rate and the scroll shape is visualized by the depth-tuft method. The main results are as follows. (1) The ratio of the throat width to the length of rotor exit arc [S
0/(R
1θ
1)] is one of the important parameters which affect the vortex position and the fan efficiency. (2) When the internal vortex moves into the initial part of the scroll and the discharge area of the rotor decreases, the pressure coefficient increases. However, for low flow rate, reverse flow occurs at the suction area of the rotor, and therefore the fan efficiency drops.
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荒谷 眞一, Narayanswami Natraj, 小島 英則, 高山 和喜
1995 年 61 巻 590 号 p.
3706-3711
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
By using double exposure holographic interferometry, supersonic free jets emanating from nozzles which appear in the process of a glass quenching were observed. Three different nozzle shapes for producing tempered glass were tested, and an axisymmetric free jet emanating from a 4-mm-i. d. and 24-mm-long nozzle was numerically simulated by TVD finite difference scheme applied to the Navier-Stokes equations. In the stagnation pressure ranging from approximately 0.5 MPa to 0.6 MPa, good agreement was obtained between interferograms and computations. Complicated structures of free jets were well resolved and a time variation of pressure caused by shock waves in the jets which would affect the process of glass tempering was clarified.
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青木 俊之, 右近 哲哉, 益田 光治, 松尾 一泰
1995 年 61 巻 590 号 p.
3712-3719
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
The response of a shock wave in a Faraday-type MHD generator to small-amplitude pressure disturbances introduced downstream of the shock wave is analyzed with the method of small perturbations. The subsequent shock wave motion is classified as a stable oscillation about the initial steady flow shock position and an unstable oscillation where the shock wave moves upstream of the MHD channel, depending on interaction parameter, channel cross section and load parameter in the upstream of the shock wave. In the case of unstable condition, the Faraday-type MHD generator has a hysteresial characteristics such as the jump behavior of shock wave position and power output.
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眞下 伸也, 仲津 英治, 青木 俊之, 松尾 一泰
1995 年 61 巻 590 号 p.
3720-3727
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
A high-speed train entering a tunnel generates a compression wave ahead of it. The wave is propagated through the tunnel and causes an impulsive noise when it arrives at the tunnel exit. The magnitude of impulsive noise from the tunnel exit is proportional to the maximum time rate of pressure change of the compression wave reaching the exit, according to the aeroacoustic theory. From this point of view, it is important to clarify the formation mechanism and the waveform of the compression wave generated at the entrance of the tunnel. In this paper, the entry compression waves are measured in actual high-speed train/tunnel systems and the results are compared with the theoretical values. Then the formation mechanism of the entry compression waves is clarified.
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坂本 雅彦, 蔦原 道久, 木村 雄吉
1995 年 61 巻 590 号 p.
3728-3734
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
We describe here an experimental study of a new type of nozzle which generates a high-speed two-phase water jet as a propulsion device for aship. In order to investigate performance improvement of this nozzle, two types of the improved device were proposed. The first type has the same structure as that of an axially symmetrical nozzle equipped with propeller and turbine. The second type has a cap of U-shaped cross section in front of the two-dimensional nozzle without bottom. These devices were set in a towing tank, and thrust was measured for various parameters such as air jnjection angle, pressure of injection gas, and towing speed. The thrusts of these two types of device increase as compared with those of the original type. The maximum propulsion efficiency is about 20% at the flow velocity of 1. 5 m/s. It was proven that the two types of actuators improve the performance of this device.
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土屋 敬一, 松坂 知行
1995 年 61 巻 590 号 p.
3735-3740
発行日: 1995/10/25
公開日: 2008/03/28
ジャーナル
フリー
In order to maximize the power generated by wind turbines, we must examine the wind characteristics at the site before constructing a wind park. In such a case, so far we have estimated the expected wind energy obtained at scheduled siting points of wind turbines by using a small number of anemometers installed in a wind park. However, in Japan, a site proposed for a wind park is often in a mountainous and rough complex terrain, and hence, it is difficult to accurately estimate wind resources of all other scheduled siting points with such a small number of anemometers. To cope with this difficulty, a wind tunnel test is usually used. However, in such a complex terrain, it is very difficult to accurately estimate the wind energy production by a wind tunnel test. On the other hand, the WASP code, which was developed by Riso National Laboratory in Denmark, is well known as a good method of estimating wind energy production, but it has not been used in such a complex terrain as that found in Japan. In this work, we applied a wind tunnel test and the WASP code to Tappi Wind Park, and compared the simulation results with actually generated power. As a result, we conclude that the wind tunnel test and the WASP code are useful under the certain condition, but the accuracy of estimation is decreased in a rough complex terrain.
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