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岡井, 敬一 ; 小野, 豊 ; 森上, 修 ; 芝, 世弐 ; 荒木, 幹也 ; 野村, 浩司 ; 志賀, 聖一 ; 津江, 光洋 ; 河野, 通方
概要:
application/pdf<br />Journal Article<br />Experimental investigation was conducted on two droplet-array combustion of methanol and methanol/dodecanol mixture fuels in microgravity. For methanol, effects of ambient pressure and
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droplet spacing were examined. Results show that the droplet lifetime decreases with increasing spacing at relatively low pressure and the droplet lifetime becomes independent of spacing at higher-subcritical and supercritical pressures. For methanol/dodecanol mixture, effects of pressure, fuel composition were investigated in terms of occurence of disruption. Disruption of droplet during combustion was demonstrated both for single droplet and droplet pairs.
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| 2.
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志賀, 聖一 ; 八木, 静夫 ; 盛田, 宗宏 ; 松本, 隆 ; 柄沢, 隆夫 ; 中村, 寿雄
概要:
application/pdf<br />Journal Article<br />In this paper we present the first stage of a study on the effect of early-closing of intake-valve on the engine performance in a spark-ignition engine. A four-valve single-cylinder engine was
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used with several values of expansion ratio and a half early-closing intake cam. The half early closing leads to almost a half of the volumetric efficiency and the BMEP for all cases of the expansion ratio. It can realize an improvement of about 7% in thermal efficiency under WOT,and about 4% under partial load of BMEP=0.2 MPa. These beneficial results are considered to be mainly caused by the effect of the more-expansion. The ratio of expansion to compression ratios was estimated to be around. 1.4 on the basis of motoring pressure analyses. Under the early-closing condition, an increase in the residual gas fraction was suggested and verified by a heat release analysis using a two-zone combustion model.
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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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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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| 5.
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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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柄沢, 隆夫 ; 志賀, 聖一 ; 倉林, 俊雄
概要:
application/pdf<br />Journal Article<br />This paper presents the experimental study on the phenomena of evaporation and
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ignition of the fuel-droplet impinged upon a hot surface. The experiment was made on the seven kinds of fuel. It was revealed that cool flame is generated in η-Heptane and diethyl-Ether at a surface temperature range which is 300-400 K below that of hot flame generation. The surface temperatures at which the cool and hot flames were generated were measured by applying a statistic method. Their delay times were also measured and then divided into physical and chemical delays by applying the statistic technique which was presented by S.Kumagai et al. Based upon these investigations, the natures of both the cool and hot flames were clarified and the difference between the surface temperature of hot flame generation and the ignition temperatures measured by using the crucible method was discussed.
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