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| 1.
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長谷川, 和之 ; 茂木, 俊夫 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Behavior of a spray combustion in a hot air was studied experimentally. A kerosene spray was injected from swirl atomizer into a hot air stream. The air temperature was controlled from room
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temperature to 1 100 K which was higher than the self-ignition temperature of a kerosene spray. Flame shape and temperature distribution were measured to characterize the spray combustion appeared in the hot air stream. Flow state around the spray was visualized by a Schlieren method to analyze the behavior of the air entrainment into the flame. Furthermore, Mie scattering from the spray droplets by irradiation of the laser beam was observed to visualize the spray concentration in a flame. As the result, ignition point was shifted to the upstream side with an increase of air temperature. When the air temperature became higher than 800 K, the blue flame appeared at the bottom portion of the flame. Penetration of the spray became shorter with an increase of air temperature. Spatial distribution of the spray which were not vaporized in a flame was strongly affected by the air temperature.
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| 2.
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廣安, 博之 ; 小田, 晴己 ; 西田, 恵哉 ; 鈴木, 護 ; 吉川, 滋 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />An experimental study on emission formation processes, such as particulate, nitric oxide and total hydrocarbon, in a small D. I. diesel engine was carried out by using a newly developed total
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in-cylinder sampling technique. The sampling method was composed of rapidly opening a blowdown valve attached to the bottom of the piston cavity, and quickly transferring most of the in-cylinder contents into a large sampling chamber below the piston. The sampling experiment gave a history of spatially averaged emission concentrations in the cylinder. The effects of several engine variables on the emission formation processes were investigated.
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| 3.
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松江, 孝博 ; 新井, 雅隆 ; 廣安, 博之
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application/pdf<br />Journal Article<br />Combustion characteristics of a single CWM (Coal-Water-Mixture) droplet placed on a hot surface in a test furnace were investigated. The collapsing load of an ash grain which is formed by the
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combustion of the CWM droplet was also measured to clarify the relationship between the burning temperature and burn-out state of the droplet. Two stage combustion which is usually observed in pulverized coal combustion was observed in the burning sequence of the CWM droplet on the hot surface. The first stage of combustion was due to the burning of flammable gas from the volatile matter in the coal. The second stage was the char combustion of the coal. As the temperature on the hot surface increased, the collapsing load of the ash grain decreased. It reached a minimum load and then increased with an increase of the temperature of the hot surface. It was considered that the combination of the unburned coal at low temperatures and melted ash at high temperatures resulted in the hard grain of ash which had a high collapsing load.
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| 4.
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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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| 5.
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西田, 恵哉 ; 廣安, 博之 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />An experimental study was conducted on the evaporation and combustion phenomena of a single n-dodecane drop in ambient gas pressurized and heated beyond the critical point of fuel, that is,
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supercritical environments produced on a hot wall. The evaporation lifetime in air at the wall temperature below the ignition temperature was found to be shorter than that in nitrogen at the same wall temperature. The end of combustion time in air at ambient pressure below the critical pressure of the fuel was correlated with the evaporation lifetime, and it was maximum in the wall temperature range where the drop showed spheroidal evaporation. As the ambient pressure increased beyond the critical pressure of the fuel, the end of combustion time increased in the wall temperature range around the critical temperature of the fuel, and in other wall temperature ranges, it decreased.
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西田, 恵哉 ; 廣安, 博之 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />An experimental study was conducted on the evaporation and combustion phenomena of a single fuel drop in ambient gas pressurized and heated beyond the critical point of fuel, that is, supercritical
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environments on a hot wall. Several kinds of liquid paraffin such as n-heptane, n-decane, n-dodecane and n-tetradecane were used as the test fuel. The evaporation lifetime in air was found to be shorter than that in nitrogen at the same wall temperature. The difference in the evaporation lifetimes in air and nitrogen environments was greater under higher ambient pressure for the same fuel ; for the same ambient pressure, it was greater under a larger ratio of ambient pressure to critical pressure of the fuel. As ambient pressure increased from subcritical to supercritical pressure, the end of combustion time increased in the wall temperature range around the critical temperature of the fuel, whereas in a wall temperature range higher than the critical temperature of the fuel, it decreased.
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| 7.
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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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| 8.
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松江, 孝博 ; 新井, 雅隆 ; 廣安, 博之
概要:
application/pdf<br />Journal Article<br />A single CWM droplet was suspended in a hot air stream by a fine R-type thermocouple. The surface temperature of this evaporating and burning droplet was measured by a radiation thermometer. The
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emissivity of the CWM droplet surface was kept at around 0.98 until the char combustion of the droplet proceeded to its middle stage. In the later stage of the char combustion, the emissivity decreased gradually to 0.82. Several degrees of temperature difference between the center and the surface of the droplet remained at the dry-up time, even when the diameter of the droplet was reduced to 2mm. The surface temperature at the start of char combustion was 700K when the droplet was exposed in surroundings of less than 900K. However, the surface temperature at the start increased from 700K in surroundings where it's temperature exceeded 900K. When the surroundings were 650K, the surface temperature at the char combustion start was 700K and higher than the surroundings, and the center temperature of the droplet was higher than that of the surface, which suggested that slow exothermic reactions in the droplet were already initiated before the char combustion started.
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| 9.
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ARAI, Masataka ; HIROYASU, Hiroyuki ; NAKAMORI, Kaoru ; NAKASO, Shinji
概要:
application/pdf<br />Journal Article<br />A new combustion system called a jet-mixing-type combustor was designed to obtain a nonluminous blue flame of a kerosene spray. A spray was injected by a conventional-type swirl atomizer into
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the combustor, and combustion air was introduced through a baffle plate with 16 inlet holes. The principle of this combustion method was revealed as a prompt mixing of the air and spray, which was achieved by high-speed air jets. The combustion characteristics such as combustion stability, temperature distribution and exhaust emissions were compared with a conventional swirler-type combustor. NO and THC emissions exhausted from nonluminous kerosene flame were at lower levels than those exhausted from the swirler-type combustor.
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| 10.
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新井, 雅隆 ; 廣安, 博之 ; 中森, 薫 ; 中曽, 伸二
概要:
application/pdf<br />Journal Article<br />A new combustion system called a jet-mixing-type combustor was designed to obtain a nonluminous blue flame of a kerosine spray. A spray was injected by a conventional-type swirl atomizer into
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the combustor and combustion air was introduced through a baffle plate with 16 inlet holes. The principle of this combustion method was revealed as a prompt mixing of the air and the spray, which was achieved by a high-speed air jet. The combustion characteristics such as combustion stability, temperature distribution and exhaust emissions were compared with a conventional swirler-type combustor. NO and THC emission levels exhausted from nonluminous kerosine flame were lower than those exhausted from the swirler-type combustor.
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| 11.
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松江, 孝博 ; 新井, 雅隆 ; 廣安, 博之
概要:
application/pdf<br />Journal Article<br />The evaporation and combustion characteristics of a single coal-water slurry droplet were studied in an elevated temperature environment and in a hot air stream by measuring the
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temperature of a burning droplet and observing its behavior. When the droplet was suspended in an elevated temperature environment, the decomposing combustion, that is, the combustion of an inflammable gas included in the coal, started after the dry-up. The surface reaction, that is, the combustion at the coal surface, followed after that. Thereby, the surface reaction was slightly influenced by the decomposing combustion. When the droplet was suspended in a hot air stream, the decomposing combustion started during the surface reaction process and a blue wake flame was induced. In this case, the spread of the surface reaction region was prevented by a flame of the decomposing combustion.
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| 12.
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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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| 13.
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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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| 14.
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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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| 15.
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中山, 満茂 ; 荻原, 五郎
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application/pdf<br />Journal Article<br />In order to develop the low NO_x combustion system and high performance steam
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generator, several tests had been made. The first, to reduce NO_χ emissions , a new type swirl nozzle has been developed. The feature of this nozzle. The second, the combustion tests with package type boiler have been made. From the experimental investigations, NO_χ emission levels emitted from this combustion chamber the grooved swirl nozzle were 30-40 percent less than that of the conventional hollow-cone type swirl nozzle.
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鈴木, 富雄 ; 中山, 満茂
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application/pdf<br />Journal Article<br />各種燃料の燃焼形態は大別して輝炎, 不輝炎である. 単一燃焼器でこれら火炎が任意に得られる旋回流形式による噴霧燃焼器の試作を示す. 燃焼に関与する諸条件(燃
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料量, 噴霧特性, 空気量など)を同一としたままで, 旋回流の流れ場と噴霧主流との相対位置を選択することによって燃焼を制御, それぞれの燃焼形態での燃焼特性を明らかにした. これらデータは噴霧燃焼のモデリング, あるいは数値計算による予測に利用が期待される.
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