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| 1.
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橋本, 健 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Six-stroke diesel engine proposed here has six processes in one cycle, i.e. intaka, 1st compression, 1st combustion, 2nd compression, 2nd combustion and exhaust. By the effect of direct EGR in the
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2nd combustion process, NO concentration could be expected to decrease. However, by a weak mixing in the 2nd combustion process, much soot was exhausted and NO concentration was hardly decreased compared with the conventional four-stroke diesel engine. To improve the fuel/air mixing at the 2nd combustion process, high pressure injection with common rail system was applied to the engine. As the result, NO concentration was increased owing to the increase of premixed combustion of 1st combustion process, although soot was reduced. Therefore, the 1st injection timing was extremely advanced to control the 1st combustion process. It changed 1st combustion process into HCCI-like combustion, and NO concentration was greatly decreased. Moreover, soot was reduced with no increase of NO concentration in the 2nd combustion process. As the result, trade-off curve of NO and soot was improved compared with the conventional four-stroke diesel engine. But CO concentration was increased.
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| 2.
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ARAI, Masataka ; AMAGAI, Kenji ; NAKAJI, Takayuki ; HAYASHI, Shinji
概要:
application/pdf<br />Journal Article<br />Particulate matter (PM) emission exhausted from diesel engine should be reduced to keep the clean air environment. PM emission was considered that it consisted of coarse and
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aggregate particles, and nuclei-mode particles of which diameter was less than 50nm. However the detail characteristics about these particles of the PM were still unknown and they were needed for more physically accurate measurement and more effective reduction of exhaust PM emission. In this study, the size distributions of solid particles in PM emission were reported. PMs in the tail-pipe emission were sampled from three type diesel engines. Sampled PM was chemically treated to separate the solid carbon fraction from other fractions such as soluble organic fraction (SOF). The electron microscopic and optical-manual size measurement procedures were used to determine the size distribution of primary particles those were formed through coagulation process from nuclei-mode particles and consisted in aggregate particles. The centrifugal sedimentation method was applied to measure the Stokes diameter of dry-soot. Aerodynamic diameters of nano and aggregate particles were measured with scanning mobility particle sizer (SMPS). The peak aggregate diameters detected by SMPS were fallen in the same size regime as the Stokes diameter of dry-soot. Both of primary and Stokes diameters of dry-soot decreased with increases of engine speed and excess air ratio. Also, the effects of fuel properties and engine types on primary and aggregate particle diameters were discussed.
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| 3.
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新井, 雅隆 ; 天谷, 賢児 ; 長瀧, 翼 ; 沖田, 秀樹
概要:
application/pdf<br />Journal Article<br />Ignition and combustion characteristics of diesel spray impinging on an inclined wall were experimentally investigated. Ignition position and appearance position of the
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luminous flame kernel were stereoscopically observed using a two-way fiber optical system. Flat impingement wall was fixed in a high temperature, high pressure combustion chamber. Inclined angle of the flat wall was set at 30 degees or right angle against the center axis of the injection spray. Distance from nozzle tip to the impingement point on the wall was set at 50mm. Effect of ambient temperature on ignition position was investigated. As the result, ignition positions were observed near the spray periphery in the both cases of 30 degrees and right angle impingements. However, the luminous flame appeared near the wall surface at downword side of inclined wall because the fuel rich region was formed around the downword side of spray impingement point.
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| 4.
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牧野, 利昭 ; 田辺, 秀明 ; 藤田, 健史 ; 加藤, 聰 ; 大西, 繁
概要:
application/pdf<br />Journal Article<br />An impinging distribution spray combustion system, named OSKA, was applied to a small direct injection diesel engine in order to reduce the wall quenching originated emittants, e. g. SOF and
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THC. Experimentation was carried out using a single cylinder eng
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| 5.
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高, 炅男 ; 樅山, 智裕 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Diesel spray impinged normally on a flat wall was investigated. Spray tip penetration and spray volumes of before and after impingement were measured on high speed photographs of the sprays
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which were injected by a single shot injection system into a high pressure chamber of cold state. The effects of the spray tip penetration, spray volume, entrainment mass and air-fuel ratio were discussed on the sprays of before and after impingement. The volume of the post-impingement spray was calculated using axi-symmetrical model. It was greatly affected by the distance between the injection nozzle and the wall. When the impingement distance was shorter than the break-up length of the original spray, the entrainment mass as well as the volume of post-impingement spray was the larger than that of the original spray at the same inspection time. To calculate the average spray concentration of after impingement spray, the fuel film stuck on the wall was measured. The average air-fuel ratio of the impingement spray increased faster than the free spray because the spray concentration in a space decreased by the fuel stuck on the wall.
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| 6.
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岩崎, 浩二 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Combustion characteristics and engine performances of a swirl-chamber type IDI diesel engine using two-stage injection were experimentally investigated. The injection timing and fuel allocation ratio
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between first and second injections were widely varied. Heat release rate was analyzed to evaluate the combustion phenomena in the engine. As the result, ignition delay period for two-stage injection became longer than that for single-stage injection when the amount of fuel in the first stage injection was small. However, when the amount of fuel in the first injection was large, there was no difference of ignition delay period between two-stage injection and single-stage injection. NO and Smoke emissions and fuel consumption were improved by two-stage injection when ingition delay period became long.
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| 7.
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岩崎, 浩二 ; 荻原, 五郎 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Combustion characteristics and engine performances of a two-stage injection DI diesel engine were experimentally investigated. Two-stage injection was achieved by using two injection pumps.
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Injection timing and fuel allocation ratio between first and second injection were widely controlled. Engine performance of a two-stage injection diesel engine was compared with that of a single injection diesel engine with early timing injection. The heat release rate was analyzed to understand the combustion phenomena in a two-stage injection diesel engine. As a result, NO emission of two-stage injeciton diesel engine was improved when the first injection timing is early. The various pattern of heat release rate appeared with the change of a fuel allocation ratio. It was greatly affected by the first injection spray impinged on the cylinder wall or the piston top. The trade-off tendency between NO and smoke was influenced by the fuel allocation ratio of sub-injection pump was high.
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| 8.
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周, 斌 ; Machacon, H.T.C. ; 志賀, 聖一 ; 譚, 達明 ; 柄澤, 隆夫 ; 小保方, 富夫 ; 中村, 寿雄
概要:
application/pdf<br />Journal Article<br />In this study a neural network prediction method that can be used in predicting engine behavior is proposed. Using data from a series of characteristic experiments, this method eliminates
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the need for complicated mathematical calculations used in prediction models. To test this method exhaust emissions and engine performance data from intake gas composition variation experiments were taken and compared with the predicted data from this network. The method has been tested and found effective in predicting engine exhaust emissions and engine performance. This technique can be a valuable tool in engine research.
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| 9.
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岡本, 雄一郎 ; 荻原, 五郎 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />A six-stroke diesel engine which was proposed by authors had second compression and second combustion strokes which were added on a four-stroke diesel engine. Numerical prediction and experiments
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on six-stroke engine which were carried out previously, showed that a six-stroke diesel engine could reduce NO concentration and shorter ignition delay could be attained in second combustion. Using various fuels on second combustion, it might be possible to improve more the emission characteristics. In this report, Methanol was used in the second combustion to improve the six-stroke engine performance. As the result, NO concentration in the exhaust gas decreased with delaying of the injection timing at second combustion and increased with an increase of the heat allocation ratio of second combustion stroke when the injection timing at first combustion stroke was fixed. Smoke wasn't exhausted at all when Methanol was put into the second combustion stroke. NO concentrations were affected by the heat allocation ratio and related with gas temperature. It was confirmed that the NO concentration of the Diesel fuel-Methanol engine become lower compared with that of the Diesel fuel engine.
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| 10.
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江原, 拓未 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />In the previous paper, the authors clarified that an impingement spray have the slip flow region near the impingement point on the wall. Then, behavior of a diesel spray impinging on an
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inclined wall was modeled to make an empirical formula of impingement spray tip penetration. To introduce a new model of spray growth behavior, uniform velocity penetration of the spray growth behavior in the slip region were framed and included into the traditional formula about the free spray. The momentum conservation theory was applied to the spray of after slipping. The growth behavior of an impingement spray was expressed as the function of wall distance and inclined wall angle. Spray path length calcurated from this formula showed qualititaively well agreement with an actual measurement.
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| 11.
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岡本, 雄一郎 ; 荻原, 五郎 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />A Six-stroke diesel engine was developed and its performance was evaluated. This engine had second compression and second combustion strokes which were added on the four stroke diesel engine.
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To control the fuel injection ratio and injection timings for first and second combustion strokes independently, two fuel pumps were attached to the engine. Effect of the fuel allocation ratio between first and second combustion strokes on the engine performance was investigated. Engine performance of the six stroke diesel engine was compared with that of the four stroke diesel engine which was the base engine of the six stroke engine. As a result, NO concentration in the exhaust gas decreased with a delaying of injection timing at second combustion stroke, but the injection timing at first combustion stroke didn't influence NO concentration. NO concentration decreased with an increase of allocation fuel ratio into the second combustion stroke. A trade-off relation between NO and soot concentration was observed against the change of allocation ratio. From the comparison between six and four stroke engine, it was confirmed that the NO concentration of the six stroke engine becomes lower than that of the four stroke engine.
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| 12.
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江原, 拓未 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />In this paper, behavior of a diesel spray impinging on an inclined wall was experimentally investigated in a pressurized vessel. In order to clarify the wall effect on a diesel spray
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structure, a relative angle of the inclined wall to the spray axis was varied. Spray penetration along the wall was observed optically and compared with that of a free spray. To observe an internal structure of the spray, it was visualized by a YAG laser sheet light and its tomographic image was captured on a film. The photo-image on a film was taken into an image analyzing computer using a high resolved image scanner. High density ridges in the tomographic image were extracted to clarify the internal structure of an impingement spray. Further, the growth characteristics of impingement spray was observed by a high speed photograph. To evaluate various spray motion quantitatively, a spray path penetration which described a development of a spray tip along the wall was used. As the result, the slip flow region of spray was found near the impingement point on the wall. It seemed that the injected fuel does not make a mixture and slipped on the wall surface in this slip region. The length of this region was measured in various impingement wall condition.
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| 13.
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TAKEDA, Chikashi ; OHTA, Yuji ; ISHIMA, Tsuneaki ; ISHII, Kiyoshi ; OBOKATA, Tomio
概要:
application/pdf<br />Journal Article<br />In order to measure flow velocity in the swirl and radial directions of a cylinder of an engine in practical use by means of a laser Doppler anemometer(LDA)through a small measuring window on the
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cylinder head, a back scattering fringe mode LDA is used. This LDA, however, can not be used to measure the velocity component in the axial direction of the cylinder. A single incidence-beam reference-mode LDA is developed to measure the velocity component along the optical axis of the LDA and is applied to measure the fluctuating flow velocity in the axial direction of the cylinder. Ensemble-averaged mean velocity and fluctuation intensity of the velocity as measured using the LDA show good agreement with those measured using the conventional fringe-mode LDA. Based on these results, it can be concluded that the reference-mode LDA is applicable to measurements of the flow velocity in the axial direction of the cylinder through the amall window on the cylinder head.
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| 14.
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江原, 拓未 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />In this paper, behaviors of diesel spray injected along a wall were experimentally investigated. In order to clarify the wall effect on spray structure, the geometry of the wall and its
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relative position to the spray axis were varied. Structures of spray injected into a high-pressure atmosphere were recorded by high-speed photographs. Results shows that the asymmetrically large vortexes in the spray were induced by the wall effect, and the spray penetrating along the wall was deviated to the wall surface. This phenomenon is called the Coanda effect in the field of fluid dynamics. The growth orientation of spray was defined by image analysis. Maldistribution ratio of spray area was defined for the quantitative estimation of the spray deviation behavior. The spray deviating conditions such as the geometry of the wall and its relative position to the spray axis were fined.
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| 15.
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天谷, 賢児 ; 張, 峰 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />The performance of a six stroke diesel engine which has been proposed by the authors was experimentally investigated using a cyclical rapid-compression-expansion machine. The ignition delay and the
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maximum heat release rate in the first and second combustion processes were measured under the various conditions of wall temperature of the engine cylinder. An optical fiber probe connected to a photo sensor was installed into a combustion chamber to measure the ignition delay and to obtain the luminosity of soot exidation in the second compression process. The experimental data were compared with the numerical predictions from the 1st report. As a result, the soot oxidation phenomenon in the second compression process was numerically and experimentally confirmed. It was clarified that the experimental data of the wall temperature effect on ignition delay qualitatively agreed with the numerical prediction.
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| 16.
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新井, 雅隆 ; 井田, 祐一 ; 天谷, 賢児
概要:
application/pdf<br />Journal Article<br />The performance of a six-stroke diesel engine which has been proposed by the authers was numerically predicted using a phenomenological model developed in the previous study. Concentrations of nitric
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oxide and soot are calculated from the simple phenomeno
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| 17.
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武田, 親士 ; 太田, 祐司 ; 石間, 経章 ; 石井, 清 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />In order to measure flow velocity in the swirl and radial directions of a cylinder of an engine in practical use by means of a laser Doppler anemometer (LDA) through a small measuring window on
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the cylinder head, a back-scattering fringe mode LDA is used. It, however, could not measure the velocity component in the axial direction of the cylinder. The single incidence-beam reference-mode LDA is developed to measure the velocity component along the optical axis of the LDA and applied to measure the fluctuating flow velocity in the axial direction of the cylinder. Ensemble-averaged mean velocity and fluctuation intensity of the velocity as measured by the LDA show good agreement with those measured by the conventional fringe-mode LDA. Based on these results, it can be concluded the reference-mode LDA is applicable to measurements of the flow velocity in the axial direction of the cylinder through the small window on the cylinder head.
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| 18.
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高橋, 秀夫 ; 柳沢, 洋樹 ; 志賀, 聖一 ; 柄沢, 隆夫 ; 中村, 壽雄
概要:
application/pdf<br />Journal Article<br />The atomization behavior of an intermittent fuel spray from a diesel nozzle was clearly observed by means of shadowgraphy using an image-converting camera with the framing rate of 10^5
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f.p.s. and an image-intensified CCD camera with high-speed gating. A rather wide range of valve-opening pressure (5 to 70 MPa) was covered, and simultaneous measurement of the injection pressure inside the nozzle sac was also attempted to clarify the atomization mechanisms at its very early stage of injection. At the beginning of injection, the emergence of a liquid column was observed. Initially, it has almost the same diameter as the nozzle hole and then spreads radially, forming the spray angle in the vicinity of the nozzle exit. The timing of this spray-angle formation becomes earlier with the increase in valve opening pressure, even if the pressure inside the nozzle sac at this moment does not vary. This pressure approximately corresponds to that of the transition region in an atomization regime of a steady jet.
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| 19.
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高橋, 秀夫 ; 柳沢, 洋樹 ; 志賀, 聖一 ; 柄沢, 隆夫 ; 中村, 壽雄
概要:
application/pdf<br />Journal Article<br />The development of a high-pressure diesel spray in its very early stage is examined through enlarged shadowgraphs in both atmospheric and pressurized conditions. A rather wide range of valve
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opening pressure was covered to clarify the mechanisms of the initial stage of development. At 0.3 ms after the start of injection, there is a region where the tip penetration is insensitive to the ambient pressure and it becomes shorter with the increase in valve opening pressure. This characteristic feature of the spray formation process is related to the eddy motion generated in the spray. The transition of the atomization regime from a wavy jet to a fully developed spray is also shown, and it is suggested that the pressure history in the nozzle sac is closely related to this phenomenon.
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| 20.
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新井, 雅隆 ; 井田, 祐一 ; 天谷, 賢児
概要:
application/pdf<br />Journal Article<br />The performance of a 6-stroke diesel engine was numerically analyzed by means of a simple thermodynamical model. Since the 6-stroke diesel engine proposed in this report has two combustion
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processes in one cycle, it will offer new methods of the Combustion Control which could not be attained in an ordinary 4-stroke diesel engine. For example, the second combustion stroke provides the oxidation process of the soot that formed in the first combustion stroke. With this method, the in-cylinder gas temperature related to the NO_x and soot formation in the combustion processes was predicted. It was confirmed that under various conditions, the maximum gas temperature of the 6-stroke diesel engine was lower than that of the 4-stroke engine. Furthermore, a 6-stroke low-heat-rejection diesel engine was analyzed. It was predicted that in comparison with the temperature in an ordinary 4-stroke engine, a higher thermal efficiency would be attained with a lower in-cylinder gas temperature.
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| 21.
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吉津, 文嗣 ; 中山, 満茂
概要:
application/pdf<br />Journal Article<br />A new type of pilot injector for low emission combustion in DI diesel engine has been developed by applying the authors' creative conception which are an active control of the time-dependent
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spray penetration and an appropriate radial distribution of local Sauter Mean Diameter during the ignition lag. The concept was realized in the new-type pilot injector where the opening pressure of the second stage (main injection) was higher than that of the first stage (pilot injection). In this paper, the new spray concept and the relationship between the design factors of the Dodge Plunger set in the injector and the fundamental injection characteristics were made clear.
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| 22.
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小保方, 富夫 ; 橋本, 徹 ; 五十木, 慎一 ; 柄沢, 隆夫 ; 志賀, 聖一 ; 倉林, 俊雄
概要:
application/pdf<br />Journal Article<br />The swirl and axial components of gas velocity in the disk-type combustion cha
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mber of a firing engine were measured by an LDA. The engine was operated under the conditions of a speed of 1500rpm, η_υ=0.5, φ=1.4 and ignition timing of 30°BTDC. The gas velocities at 9 points on a diameter at midheight of the combustion chamber were analyzed by the cycle-resolved method. The bulk (mean) velocity was determined by the frequency discrimination method with the cut-off frequency of 667Hz. The flame propagation pattern was detected by ionization probes set at 17 points on the piston. It has been observed that, in the case of fired operation, the turbulence intensity is higher, the integral length and micro length scales are longer and the swirl flow is weaker and is eccentrically shifted compared with the case of motored operation. These results show that it should be noted that there are remarkable differences in the gas flow between motored operation and fired opeation.
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| 23.
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TABATA, Michihiko ; FUJII, Hiroshi ; ARAI, Masataka ; HIROYASU, Hiroyuki
概要:
application/pdf<br />Journal Article<br />The Sauter mean diameter and size distribution of a diesel spray in a vaporizing process were studied to obtain detailed information of the diameter change of the spray in an
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elevated-temperature and-pressure environment. In this study, direct photographs of the diffracted light from particles or spray drops were taken using a pulsed laser and analyzed directly. The mean particle size could be measured even if the diffracted light from particles passed through a high-ambient-temperature and-pressure environment. The liquids used for studying a vaporizing diesel spray were diesel fuel and n-heptane. The Sauter mean diameter increased to a maximum, then decreased with a further increase of the ambient temperature. The change of the Sauter mean diameter was different for different fuel evaporation rates. The increase of the Sauter mean diameter of n-heptane spray occurred at a lower ambient temperature condition than did that for the diesel spray.
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| 24.
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吉田, 肇 ; 新井, 雅隆 ; 廣安, 博之 ; 横谷, 昌道
概要:
application/pdf<br />Journal Article<br />High speed schlieren movies were taken for detailed observation of the physical structure of flames propagating in propane-air mixtures containing kerosene spray. Effects of an overall
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equivalence ratio and a mixture ratio of propane/kerosene to the total fuel on the structure were examined. Fractal analysis of the flame structure was also attempted. As a result, two typical flame structures were observed, into which flame structures were classified according to propane concentration. One consisted of droplets ignited successively, the other consisted of flame front propagating in the interdroplet propane-air mixture. In the latter, flame front had fractal character and its fractal dimension increased and decreased with the flame propagation velocity.
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| 25.
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志賀, 聖一 ; Heywood, John B ; Chun, Kwang M
概要:
application/pdf<br />Journal Article<br />This study aims to clarify the importance of chamber wall temperature in the knocking characteristics of a spark-ignition engine. To vary the chamber wall temperature, two procedures were
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used, one is to change the coolant temperature and the other is to raise the exhaust valve surface temperature by substituting a ceramic surface layer for the original steel layer. Although the coolant temperature change had no influence on the flame propagation process, it fairly affected the knocking process, such as mean knock intensity and mean knock occurrence timing. This is caused by both the change of bulk mixture temperature of the end gas and the temperature uniformity within the end gas region. Cycle-by-cycle based knocking behaviour can also be influenced by the coolant temperature, which is considered to be based on the temperature uniformity in the whole chamber region. Exhaust valve surface temperature change did not affect any knocking characteristics. It suggests the importance of the wall temperature in the end gas region.
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| 26.
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吉田, 肇 ; 新井, 雅隆 ; 廣安, 博之
概要:
application/pdf<br />Journal Article<br />Ignition characteristics of a propane-air mixture that contains kerosene spray were studied to understand the ignition behavior of an evaporating gasoline spray injected into a cylinder of a
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direct injection stratified charge (DISC) engine. Ignition probability as a function of an overall equivalence ratio, a mixture ratio of propane/kerosene to the total fuel and spark energy, was measured under atmospheric conditions. Adding a small amount of kerosene spray to a lean propane-air mixture improved the ignition probability of the mixture. A lean propane-air mixture had the suitable mixture ratio of kerosene spray for ignition. The results obtained here will give basic information about the ignition behavior of an evaporating gasoline spray, because a propane-air mixture containing a kerosene spray would simulate various evaporating stages of a gasoline spray.
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| 27.
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吉田, 肇 ; 新井, 雅隆 ; 廣安, 博之
概要:
application/pdf<br />Journal Article<br />The process of flame development in a spark-ignited propane-air mixture that contained kerosene spray was observed by a high-speed VTR. Flame areas were measured on the VTR and the process of flame
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development was shown as a change of flame area versus time from ignition. Propagation delay, which means a period between spark ignition and the start of rapid flame development, was defined. Effects of an overall equivalence ratio, a mixture ratio of propane/kerosene to the total fuel and spark energy on the propagation delay and development rate of a flame were studied. Each lean propane-air mixture had a suitable value of the mixture ratio of kerosene spray for the minimum propagation delay and maximum development rate of a flame. When the mixture ratio of propane to the total fuel was low, the propagation delay decreased as the spark energy increased.
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| 28.
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清水, 正則 ; 新井, 雅隆 ; 廣安, 博之
概要:
application/pdf<br />Journal Article<br />In order to elucidate the disintegrating mechanisms of a diesel spray, the breakup length was measured by an electric resistance method. A reattachment distance of separated liquid flow
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in a nozzle and a spray were observed photographically. The mechanism of the two disintegrating processes of the jet was investigated by separating an ambient effect from a disturbed effect of the nozzle. The atomizing mechanism of the jet was governed by both the initial disturbance due to the nozzle geometry and an interfacial force between the jet and the environment. If a strong disturbance was given to the internal flow in a nozzle, the jet would be broken up into a spray flow.
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| 29.
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高橋, 秀夫 ; 志賀, 聖一 ; 小柴, 英俊 ; 柄沢, 隆夫 ; 倉林, 俊雄
概要:
application/pdf<br />Journal Article<br />The purpose of this study is to clarify the characteristics of diesel spray with higher and unsteady injection pressure under an elevated pressure condition and an elevated pressure and
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temperature condition. A Bosch-type injection system and a rapid compression machine were used. The behavior of the spray until 2 ms after the beginning of injection, which corresponds to the period of the ignition delay of most diesel engines, was observed by high-speed photography. Under the less evaporating condition, the spray penetrations of higher and normal injection pressure are almost the same, whereas, under the evaporating condition, those penetrations are not the same. Thus, the penetration of the normal injection pressure is affected by the ambient temperature, while the penetration of the higher injection pressure is little affected by the evaporation. The same tendency was observed in the behavior of spray cone angle development. It is also shown that the spray generates small eddies and the spray pattern is affected by the growth and dissipation of those eddies.
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| 30.
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高橋, 秀夫 ; 志賀, 聖一 ; 柄沢, 隆夫 ; 倉林, 俊雄
概要:
application/pdf<br />Journal Article<br />A rapid-compression machine is developed for fundamental studies of diesel combustion. Low-pressure compressed air and a stainless-steel membrane are employed to drive the piston. This is
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similar to the principle of a shock tube and is quite simple compared with other machines. The combustion chamber has a 120 mm bore and is 20 mm in depth. These dimensions were determined to avoid the impingement of the spray within 2ms, which seems to be a typical ignition delay period. Compression time and polytropic exponent are about 38ms and 1.30, respectively. High-speed photographs were taken to observe the spray development for both evaporating and non evaporating spray, and the effect of evaporation could be shown clearly. A combustion test was also carried out, and a pressure rise due to combustion was recognized. Thus, it is shown that this machine has sufficient performance for the study of diesel combustion. A simple simulation technique to design the machine is also presented and its availability is verified.
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| 31.
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小保方, 富夫 ; 柄沢, 隆夫 ; 倉林, 俊雄
概要:
application/pdf<br />Journal Article<br />The bulk velocity and turbulence of air swirl flow in the dish type combustion
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chamber of a motored engine were measured by an LDA. The LDA was modified with optical finers for easy operation and was improved to form a smaller measuring space 0.29 mm in length. The engine was operated at a speed of 1 000 rpm. The gas velocity at a mid section of the combustion chamber was analyzed by the stationary time average method. The radial distribution of mean swirl flow and turbulence characteristics such as turbulence intensity (u'), integral time and spacial scale (L_t, L) and micro time and spatial acale (λ_t, λ) were obtained, and time depending properties of such flow data were investigated. It has been revealed that the mean swirl velocity and swirl ratio almost agree with those of previous reports, but u' is higher and scales of turblence are lower than the data given by the hot-wire anemometer.
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| 32.
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小保方, 富夫 ; 花田, 尚喜 ; 桑原, 秀樹 ; 倉林, 俊雄
概要:
application/pdf<br />Journal Article<br />The velocity and turbulence in two-dimensional wedge type engine combustion chambers are measured by a laser Doppler anemometer (LDA) with an optical fiber transmitting system under motored
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and firing conditions. The engine is operated at a speed of 2 500 rpm with propane-air mixtures changing the combustion chamber setting direction to the cylinder, here named normal ""N"" and reverse ""R"" combustion chambers. The preliminary experiment indicates that the flame propagating velocity near the slant ceiling and the indicated mean effective pressure are of a higher level at the R chamber than at the N chamber. The mean velocity U^^-, fluctuation intensity u' and integral time scale of turbulent L_t in both chambers are derived through the stationary time averaged analysis of the measured velocities, and each is compared between both chambers. The results have showed that the flow patterns in both chambers are different and the mean value of the U^^- of the R chamber at the spark timing is large than the other by about 70%. However there is little difference at u' and L_t in both chambers.
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| 33.
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柄沢, 隆夫 ; 川口, 暁生 ; 志賀, 聖一 ; 倉林, 俊雄
概要:
application/pdf<br />Journal Article<br />This paper presents an experimental study being aimed at revealing the ignition assistance effect of a hot surface in an alcohol-fueled diesel engine and its mechanism. A single shot of spray was
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injected into a motored diesel engine. Ignition lag was measured and was split into two regimes, physical lag and chemical lag, by applying a statistical technique presented by S. Kumagai. High-speed direct photographs were also taken. The dependence of those ignition lags were classified into three regions on their Arrhenius plots. In lower hot-surface temperatures, the ignition lags decrease exponentially with increasing the hot-surface temperature. In higher temperature regions, the ignition lags tend to have constant values, passing through the transient region. By combining the high-speed photographs, it is suggested that the hot surface does not initiate flame propagation, but supplies heat to assist the spontaneous ignition as the assistance mechanism.
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| 34.
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長屋, 幸助
概要:
application/pdf<br />Journal Article<br />An analytical method and a result for obtaining dynamic stresses in the valve-spring of a driven valve system of internal combustion engines are presented with a consideration of the end
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effects. To treat the complex dynamic behavior due to cam rotation with complex profile, this paper applies a combination method of the transfer matrix, the Laplace transform and the Fourier series expansion procedures. Numerical calculations have been carried out for a sample case of general valve-springs, and the numerical results for the dynamic stresses have been obtained in the case of a spring excited by the driven valve system.
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| 35.
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小保方, 富夫 ; 花田, 尚喜 ; 倉林, 俊雄
概要:
application/pdf<br />Journal Article<br />The intensity and structure of turbulence in a flame front may be changed by expansion flow due to combustion. Therefore the velocity and turbulence in a combustion chamber of a spark
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ignition engine are measured by mans of a laser Doppler anemometer with fiber-optic pick-up under firing conditions. The engine is operated at a speed of 2500 rpm with propane-air mixtures. Data acquisition window width affects the turbulence intensity (u') and integral time scale of turbulence (Lt) of the analysis. In the experiment, a short (0.67 ms) and long (4 ms) window are selected and compared with each other. In the combustion period, twice the intensity of u' and an increase of 40 % in Lt are observed in the case of short window analysis. A stronger u' and larger Lt are observed in the long window analysis and it is shown that the Lt expands laterally during the compression stroke and vertically during the expansion stroke.
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| 36.
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長屋, 幸助
概要:
application/pdf<br />Journal Article<br />This paper presents a method for solving the dynamic response problems of a driven valve system of internal combustion engines. In this system there is a hysteresis behavior between the
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restoring force and the deflection for the locker arm. To treat this nonlinearity, the rigidity of each section is assumed to be the one of a partly linear spring. For the valve trains, the cam profile is complex in general. For treating a general cam profile, this paper applies a combination method of the Fourier expansion and the Laplace transform methods given by the author. Numerical calculations have been carried out for a sample problem of high speed driven valve trains, and the jump and the bounce phenomena are discussed in detail.
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| 37.
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志賀, 聖一 ; 柄沢, 隆夫 ; 倉林, 俊雄
概要:
application/pdf<br />Journal Article<br />To predict the shape of a flame in a vessel is one of very important problems in the field of combustion. But it is difficult because the shape is strongly influenced by the flow which is affected
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not only by the surrounding walls but also by the expansion of gas due to combustion. The mechanism of formation of a wedge shaped flame in a constant volume combustion chamber has longtime been a target of many researchers since Ellis pointed it out in 1928. Several hypotheses have been proposed but they do not clearly present a complete mechanism. Modern techniques of measurement are giving new data about the combustion gases. In this report, a two dimensional LDV and some other measuring techniques are used to check the hypotheses mentioned above, and a new idea on the mechanism of formation of a wedge shaped flame is proposed.
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| 38.
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小保方, 富夫 ; 花田, 尚喜 ; 倉林, 俊雄
概要:
application/pdf<br />Journal Article<br />To improve the adaptability of LDA (laser Doppler anemometer) for measuring velocities in an engine, an optical fiber system composed of a couple of single mode, polarization-preserving
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optical fibers has been made to transmit the incident beams. Though the total transmitting efficiency of this optical system is about 24 %, it has been confirmed that a fiber-optic LDA system with a 25 mW He-Ne laser is applicable to the real-time measurement of gas velocity in the combustion chamber of a small-sized two-stroke spark ignition engine. The ensemble-averaged mean velocities obtained by using this optical system show that the gas velocity rapidly decreases just before the flame front arrival and suddenly increases after passing of the flame. It is also shown that a new bulk flow is generated in the chamber by the gas expansion due to combustion.
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| 39.
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志賀, 聖一 ; 江原, 秀治 ; 柄沢, 隆夫 ; 倉林, 俊雄
概要:
application/pdf<br />Journal Article<br />This paper presents one of the studies which aim to reveal the capability of controlling diesel combustion by exhaust gas recirculation (EGR). In a previous paper, the effect of EGR on soot emission
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was examined, and it was shown that soot emission is suppressed under the condition that the mass fraction burned by spontaneous (pre-mixed) combustion is increased. In a present paper, diesel knock intensity is defined as a sound pressure distributed over 1-1.5kHz, and the effect of EGR on the diesel knock intensity is examined. The diesel knock intensity is remarkably reduced by EGR under the same operating condition as soot emission is reduced by EGR. By calculating the heat release rate based on the indicated pressure diagram, it was suggested that a reduction of knock intensity originates from the reduced reaction rate in the spontaneous ignition. The quantitative relationship between the diesel knock intensity and the maximum rate of pressure rise is also presented.
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| 40.
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志賀, 聖一 ; 江原, 秀治 ; 柄沢, 隆夫 ; 倉林, 俊雄
概要:
application/pdf<br />Journal Article<br />In previous paper, it was suggested the effect of exhaust gas recirculation (EGR) on the diesel knock is relevant to the reaction rate of spontaneous ignition which occurs at the initial stage of
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diesel combustion. In a present study, this suggestion is verified by measuring the ignition lag and separating it into physical and chemical lags by applying the statistical technique presented by S. Kumagai. Under the operating condition used in this study, the physical lag is rather longer than the chemical lag and hardly changes with an increase in EGR ratio. On the other hand, the chemical lag is considerably affected by EGR. Though the dependent behaviour of the chemical lag on EGR is not simple, it is clearly shown that the tendency of chemical lag versus EGR ratio is quite the reverse of that of the diesel knock intensity. This means that the diesel knock intensity with EGR is dominated by the reaction rate of spontaneous ignition.
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| 41.
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志賀, 聖一 ; 江原, 秀治 ; 柄沢, 隆夫 ; 倉林, 俊雄
概要:
application/pdf<br />Journal Article<br />By using a direct injection diesel engine, the effect of exhaust gas recirculation (EGR) on soot emission was investigated. It was revealed that EGR had both effects of soot promotion and
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suppression. Soot emission was suppressed when the premixed (initial rapid) combustion fraction of the two combustion patterns was increased, which was accomplished by throttling the intake valve equipped the engine or advancing the injection timing. It was also suggested that the effect of EGR on soot emission should not ascribe only the physical or thermal properties of the inert gases within the exhaust gas, but some chemical properties of CO_2. Because it was shown that only CO_2 had the effect of soot suppression under some conditions.
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| 42.
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志賀, 聖一 ; 河野, 通方 ; 飯沼, 一男
概要:
application/pdf<br />Journal Article<br />火花点火可能な急速圧縮機によってノックを再現し,得られた指圧線図から求めた圧力振動振幅によってノック強さを定義した.このノック強さに影響する重要な要因として
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火炎伝ばによる燃焼質量割合が存在すること,また圧縮比,当量比の影響などを明らかにした.円筒形燃焼室においてノック強さが大きく変動するのは,ガス振動モードの節線位置が試行ごとに変化するためであることが2種の実験手法によって確認された.
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| 43.
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志賀, 聖一 ; 河野, 通方 ; 飯沼, 一男
概要:
application/pdf<br />Journal Article<br />急速圧縮機において再現した火花点火機関のノックを,直接およびシュリーレンの高速度撮影によって観察した結果,以下の知見が得られた.すべての混合気が自発点火する
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ときのガス振動の発生は,熱炎発生の不均一性による.自発点火における2段点火の1段めは局部的熱炎発生によるものではなく冷炎によるものである.火炎伝ぱをともなう場合の末端ガスの点火現象は,すべての混合気が自発点火する場合の点火過程と同等である.
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| 44.
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小保方, 富夫 ; 松尾, 典孝 ; 平野, 嘉男
概要:
application/pdf<br />Journal Article<br />ピストン・リード弁付きクランク室圧縮形二サイクル機関の流れをレーザ流速計で実時間測定した.その結果,交換窓や回転窓の使用が不可欠であることがわかった.また,
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実機の吸気流および排気流は駆動と発火時によりかなり異なったパターンを示すが,掃気流ではあまり差異はない.さらに機関を一連の管系におきかえ,特性曲線法を用いたシミュレーションで求めた駆動と発火時の各管内流は実測値とよく一致した.
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| 45.
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小保方, 富夫 ; 浅沼, 強
概要:
application/pdf<br />Journal Article<br />火花点火機関の低公害・省エネルギ燃焼を実現するために燃焼室内のガス流動が利用されている. このガス流動を発火運転中までも含めて実測するためのレーザ流速計シス
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テムを完成させ, ±80m/s以上の変動流や強いサイクル変動のある燃焼流と実時間で測定した. 副室からのトーチ噴流に及ぼす副室容積, ノズル径, 当量比, 回転数の影響を調べ, トーチ開口割合が大きいと複数の噴流, 逆流があるなど, 流速計の実機適用の可能性を示した.
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