著者

段 智久 大石 直己 千田 二郎 藤本 元

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 B編 (ISSN:03875016)

巻号頁・発行日

vol.60, no.577, pp.3192-3197, 1994-09-25 (Released:2008-03-28)

参考文献数

4

被引用文献数

1 6

---

In the experiments presented, a single diesel spray of n-tridecane was injected for a certain duration through a hole-type nozzle into a quiescent atmosphere at room temperature at high pressure. The experimental variables were nozzle hole dimensions such as the hole diameter dn, the hole length ln and the hole offset between the nozzle axis and the hole axis, and the nozzle needle lift, in order to assess the turbulent flow field inside the nozzle, and the other was the back pressure, in order to examine the effect of the ambient gas properties, especially its kinematic viscosity. The macroscopic spray structures were observed by using instantaneous photography and a high-speed video camera system. Furthermore, the microscopic structure was observed by meant of scattering photography of fuel droplets taken by the laser light sheet of a pulsed ruby laser, and the quantitative 2-D image of fuel concentration in the cross section of the spray containing its central axis was obtained by the image processing. From the experiments, the variation in the spray cone angle with the needle lift is promoted by the turbulence in the sac volume, and spray angle is closely related to the ambient kinematic vincosity.

著者

段 智久 赤松 浩

出版者

神戸大学

雑誌

基盤研究(C)

巻号頁・発行日

2020-04-01

---

地球温暖化の要因となるGHG(CO2、CH4など)を排出する熱機関において、それらの排出量を低減させることが環境保全の観点からも必要である。その手法として、燃料燃焼を促進させる効果のあるプラズマを熱機関の燃焼室内部で生成させて作用させることを試みる。レトロフィットで試作するガス燃料を利用する二元燃料エンジンシステムを用いて、プラズマのガス燃焼促進効果を検証して、本手法の有効性を明らかにする。

著者

段 智久

出版者

公益社団法人 日本マリンエンジニアリング学会

雑誌

マリンエンジニアリング (ISSN:13461427)

巻号頁・発行日

vol.51, no.3, pp.307-314, 2016-05-01 (Released:2017-05-01)

参考文献数

34

被引用文献数

2 4

著者

段 智久 松村 千里 岡村 秀雄

出版者

神戸大学

雑誌

基盤研究(B)

巻号頁・発行日

2017-04-01

---

本研究では、木タールや舶用重質油などねばりけの高い物質が燃える状態をよくするためにジメチルエーテルという物質を液化させて混合し、混合燃料として使用することを試みた。その結果、微小な残留物が多く残る木タールは、ある程度運転は可能であるが、長時間運転が困難であるという結果となった。また二種類の物質を連続的に混合しながら供給できるシステムを構築した。液体と液体の混合送油は、その実用性を確認できたが、揮発性の高い液体と液体の混合については十分な試験が行えておらず、今後の継続的な課題としたい。

著者

段 智久

出版者

公益社団法人 日本マリンエンジニアリング学会

雑誌

マリンエンジニアリング (ISSN:13461427)

巻号頁・発行日

vol.47, no.1, pp.51-58, 2012-01-01 (Released:2013-10-26)

参考文献数

42

被引用文献数

2

著者

段 智久

出版者

同志社大学

雑誌

特別研究員奨励費

巻号頁・発行日

1998

著者

段 智久

出版者

公益社団法人 日本マリンエンジニアリング学会

雑誌

マリンエンジニアリング (ISSN:13461427)

巻号頁・発行日

vol.54, no.3, pp.350-357, 2019-05-01 (Released:2019-05-30)

参考文献数

7

著者

三原 悠 浅野 一朗 段 智久 岡村 秀雄 松村 千里 羽賀 雄紀 中坪 良平

出版者

公益社団法人 日本マリンエンジニアリング学会

雑誌

マリンエンジニアリング (ISSN:13461427)

巻号頁・発行日

vol.56, no.3, pp.473-483, 2021-05-01 (Released:2021-06-02)

参考文献数

29

---

As a way to improve the combustion characteristics of wood tar which is highly viscous and flame retardant, the authors blended it with liquefied dimethyl ether (DME), which can improve fuel fluidity, ignitability and spray atomization. Moreover, heavy fuel oil (bunker-c oil) was added to increase the heating value of this fuel sample. The sample, which has the blending ratio of 35 % wood tar, 30% DME and 35% bunker-c by weight, was used in a combustion test with a three-cylinder in-direct injection diesel engine. Additionally, the authors also investigated particulate matter (PM) produced after burning four samples that mixed liquefied DME with flame retardant fuels in the same engine to analyze its environmental and biological impacts. The four samples prepared for the experiment were (1) 70% distillate oil (bunker-a) and 30% DME; (2) 85% bunker-c and 15% DME; (3) 70% bunker-c and 30% DME; (4) 35 % bunker-c, 30% DME and 35% wood tar.  The results of the engine test suggested the possibility that wood tar could become more combustible by optimizing the flow rate of fuel and the blend ratio of liquefied DME and bunker-c. In the (4) case, PM showed no high mutagenic potentials and there were lower concentrations of such inorganic substances as vanadium and nickel. Polycyclic aromatic hydrocarbons (PAHs) concentrations in PM decreased by blending liquefied DME with bunker-c, whereas did not decrease for the wood tar.

著者

千田 二郎 柴田 一郎 段 智久 藤本 元

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 B編 (ISSN:03875016)

巻号頁・発行日

vol.63, no.613, pp.3173-3178, 1997-09-25 (Released:2008-03-28)

参考文献数

8

被引用文献数

1 2

---

This study investigates the atomization mechanism of fuel spray dissolved in noncondensable gas, such as N2, CO2. The fuel spray was injected at room temperature and in an atmospheric pressure field through a diesel-hole-type nozzle. In this paper, N2 gas was dissolved into diesel fuel, n-tridecane, under several pressurized conditions using a gas bubbling method in a constant volume vessel. This fuel, with high gas solubility, was injected under several injection pressures using an accumulated injection system designed by the authors. It was found that the dissolved gas separated into gas bubbles like gas cavitation phenomena under the atmospheric field. The change in spray patterns caused by the gas solubility is discussed using photographs of the patterns.

著者

段 智久

出版者

公益社団法人 日本マリンエンジニアリング学会

雑誌

マリンエンジニアリング (ISSN:13461427)

巻号頁・発行日

vol.54, no.2, pp.281-282, 2019-03-01 (Released:2019-03-29)

参考文献数

4

著者

段 智久 橋本 正孝 浅野 一郎 奥村 哲平 鈴木 直樹

出版者

公益社団法人 日本マリンエンジニアリング学会

雑誌

マリンエンジニアリング (ISSN:13461427)

巻号頁・発行日

vol.44, no.2, pp.322-327, 2009 (Released:2012-04-20)

参考文献数

9

被引用文献数

3 3

---

DME is the simplest ether and consists of oxygen and methyl. Because of its chemical and physical properties it is thought that DME could be one of the candidates as an alternative fuel in the internal combustion engine. The authors have been investigating the combustion characteristics of the mixed fuel comprising of Dimethyl ether and Marine Diesel Oil (JIS A-heavy oil). In the experiments, DME is mixed at the liquefied state with MDO inside a high pressure fuel tank pressured with nitrogen gas. Fuel supply lines are replaced with pressure resistant tubes, and the mixed fuel is supplied to the small direct injection diesel engine. We obtained the effect on the fuel injection characteristics to the mixed fuel combustion, in the diesel engine. The two different fuel injection rates are obtained by changing the injection nozzle opening pressure, that for the relatively lower case (9.0MPa) and higher (24.0MPa). The fuel injection pressure histories and the combustion characteristics, such as the combustion pressure and the exhaust emission, are examined for both the injection conditions. The average injection pressure increased with increased engine load in the lower nozzle opening pressure case. Whilst it is almost constant with the higher nozzle opening pressure case. It was concluded that ignition delay could be shortened by DME mixing. And NOx emissions were reduced in the higher engine load case, and with mixing DME for both nozzle opening pressure cases.

著者

橋本 正孝 段 智久 浅野 一朗 大谷 友人

出版者

公益社団法人 日本マリンエンジニアリング学会

雑誌

マリンエンジニアリング (ISSN:13461427)

巻号頁・発行日

vol.44, no.3, pp.456-462, 2009 (Released:2012-06-02)

参考文献数

3

被引用文献数

2 2

---

Palm oil is being seriously looked at as one of the alternative fuels to fossil fuels, this being due to the aspect of vegetable oils and the so called carbon neutral state. However, at room temperature, the viscosity of palm oil is too high to apply as a fuel for the internal combustion engine. In this study, pure palm oil is mixed with fossil fuels, this in order to reduce the viscosity. In the experiment palm oil was blended with gas oil and then marine diesel oil, by weight ratio, and the kinematic viscosity of the mixed fuels were measured. In the cases of 20% palm oil used, and 50%, was found to be useable without any heating of the fuels. Engine performances, such as cylinder pressure histories and exhaust emissions, were examined with a pre-combustion chamber type diesel engine. We discovered that a palm oil blended fuel shows earlier ignition and shorter combustion period than gas oil or marine diesel oil. NOx emissions show a lower concentration for all palm blended cases, and the reduction ratio is proportional to the palm mixing amount. From these results, we can suggest that palm oil could be used for the diesel engine by mixing with the fossil fuels without heating the fuels.

著者

段 智久 橋本 正孝 浅野 一朗 中村 卓朗

出版者

The Japan Institute of Marine Engineering

雑誌

マリンエンジニアリング (ISSN:13461427)

巻号頁・発行日

vol.41, no.3, pp.438-443, 2006-05-01 (Released:2010-05-31)

参考文献数

6

被引用文献数

1

---

Dimethyl Ether (DME) was mixed with waste vegetable oil to improve combustion and exhaust emissions in a high speed diesel engine. Past research has shown that the properties of DME, such as lower boiling point and higher cetane number, would affect atomization process and combustion progress of DME/Marine diesel oil blending fuel. In this study, the effect of mixing DME with waste vegetable oil was investigated by using the 4-stroke single cylinder direct injection diesel engine. The combustion pressure history, injection pressure, exhaust gas emissions were measured in variation with mixing ratio of DME and engine load. The emissions of smoke and nitrogen oxide were found to reduce with increase in mixing ratio of DME.

著者

段 智久 橋本 正孝 浅野 一朗 山縣 正史

出版者

The Japan Institute of Marine Engineering

雑誌

マリンエンジニアリング (ISSN:13461427)

巻号頁・発行日

vol.39, no.6, pp.409-414, 2004-06-01 (Released:2010-05-31)

参考文献数

2

---

We improved the system of a high-speed single-acting 4-stroke diesel engine to allow it run on a mixed fuel comprised of A-heavy oil and DME (Di-Methl Ether), fuel components that discharge no soot, no SOx, and little NOx in combustion. The combustion pressure, rate of heat release, exhaust gas components, and other conditions were measured in experiments using diesel oil, A-heavy oil, and the mixed fuel comprised of DME and A-heavy oil.As a result, the ignition timing was earliest with diesel oil, median with the mixed fuel, and latest with A-heavy oil. Mixed fuel discharged a slightly reduced level of NOx. Overall, results indicated that the engine would require further improvements before long-term operation became possible.

著者

高岸 佐代 高橋 知宏 段 智久 千田 二郎 藤本 元

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 B編 (ISSN:03875016)

巻号頁・発行日

vol.65, no.631, pp.1128-1133, 1999-03-25 (Released:2008-03-28)

参考文献数

9

被引用文献数

2 1

---

The characteristics of combustion process in internal combustion engines are affected by mixing process between the injected fuel and the ambient gas. Therefore, it is necessary to understand the flow field in diesel fuel sprays. In this study, a single spray was injected into a quiescent atmosphere with room temperature at high pressure through a single hole nozzle for simplification. To discuss the flow field in diesel sprays, structure of the spray was visualized by laser light sheet method. And, it was revealed that the vortex structure inside the spray affects the classification of droplet particles by taking microscopic photographs of the droplets with high resolution film. And applying PIV method into the spray photography, both the formation of meandering structure of the spray mainstream and the ambient gas entrainment process are clarified.

著者

段 智久 高岸 佐代 大石 直己 千田 二郎 藤本 元

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 B編 (ISSN:03875016)

巻号頁・発行日

vol.62, no.597, pp.2079-2085, 1996-05-25 (Released:2008-03-28)

参考文献数

15

被引用文献数

7 8

---

In the experiments presented here, a single diesel spray of n-tridecane was injected for a certain duration through a hole-type nozzle (ln/dn=1.1mm / 0.2mm) into a quiescent high pressure atmosphere at room temperature. We used the same amounts of fuel injection for each injection pressure and the same ambient gas density field for all injection experiments including tests of the effect of changing the ambient gas. The macroscopic spray structures were observed by instantaneous photography and using a high-speed video camera system. Furthermore, the microscopic structure was observed by means of laser light-scattering photography, fuel droplet distribution was measured using the laser light-sheet of a pulsed Nd-YAG laser, and the mean diameter of the drop was obtained through image processing by the laser extinction method. This study revealed that the diesel spray consisted of a number of large vortices, which was considered to be the coherent structure. With high ambient gas viscosity, the fuel droplet became smaller. It was also found that a large vortex existed at the tip of the spray.

著者

段 智久 高岸 佐代 大石 直己 千田 二郎 藤本 元

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 B編 (ISSN:03875016)

巻号頁・発行日

vol.62, no.599, pp.2867-2873, 1996-07-25 (Released:2008-03-28)

参考文献数

14

被引用文献数

2 5

---

This study deals with the effect of the viscosity of the ambient gas on the atomization process of a diesel spray. The liquid fuel is injected through a single-hole nozzle (ln/dn=0.75 mm/0.25 mm)with the injection differential pressure of 16.2 MPa inside a constant-volume vessel under a high-pressure field at room temperature. In practical combustion chambers of diesel engines, the viscosity of the ambient gas varies mainly with its temperature. In this experiment, various gases (CO2, N2, Ar, Ne, and Ar+Ne) were utilized for the ambient atmosphere in order to change the ambient gas viscosity. The vaporization of fuel drops was negligible. This study, revealed that the higher the viscosity, the more the spray spreads in the radial direction, thus the spray angle increased and tip penetration decreased. The droplets became smaller and were distributed in the inner region of the cold-state diesel spray under high ambient viscosity conditions. Further more, it was found that processes of ligament formation in the liquid jet and initial atomization were affected by kinematic viscosity ratio between the liquid fuel and ambient gas, and the spray dispersion and mixing process in the downstream region was affected only by the ambient gas kinematic viscosity.

著者

三原 悠 浅野 一朗 段 智久 岡村 秀雄 松村 千里 羽賀 雄紀 中坪 良平

出版者

公益社団法人 日本マリンエンジニアリング学会

雑誌

マリンエンジニアリング (ISSN:13461427)

巻号頁・発行日

vol.56, no.3, pp.473-483, 2021

---

<p>  As a way to improve the combustion characteristics of wood tar which is highly viscous and flame retardant, the authors blended it with liquefied dimethyl ether (DME), which can improve fuel fluidity, ignitability and spray atomization. Moreover, heavy fuel oil (bunker-c oil) was added to increase the heating value of this fuel sample. The sample, which has the blending ratio of 35 % wood tar, 30% DME and 35% bunker-c by weight, was used in a combustion test with a three-cylinder in-direct injection diesel engine. Additionally, the authors also investigated particulate matter (PM) produced after burning four samples that mixed liquefied DME with flame retardant fuels in the same engine to analyze its environmental and biological impacts. The four samples prepared for the experiment were (1) 70% distillate oil (bunker-a) and 30% DME; (2) 85% bunker-c and 15% DME; (3) 70% bunker-c and 30% DME; (4) 35 % bunker-c, 30% DME and 35% wood tar.</p><p>  The results of the engine test suggested the possibility that wood tar could become more combustible by optimizing the flow rate of fuel and the blend ratio of liquefied DME and bunker-c. In the (4) case, PM showed no high mutagenic potentials and there were lower concentrations of such inorganic substances as vanadium and nickel. Polycyclic aromatic hydrocarbons (PAHs) concentrations in PM decreased by blending liquefied DME with bunker-c, whereas did not decrease for the wood tar.</p>

著者

草野 茂之 段 智久 千田 二郎 藤本 元

出版者

一般社団法人日本機械学会

雑誌

日本機械学会論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.65, no.630, pp.804-811, 1999-02-25

参考文献数

10

被引用文献数

2

---

In this study, new models on the new droplet evaporation taking account of the droplet surface temperature related to the modified Spalding model, on the ambient temperature and the mass fraction at the infinite-point was proposed and incorporated into KIVA-II code. These models were compared and reviewed with the droplet evaporation model of KIVA-II original code in relation to the standard Spalding model. As a results, it is found that the calculated results of droplet evaporation by new model agree well with actual phenomena.

著者

草野 茂之 段 智久 千田 二郎 藤本 元

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 B編 (ISSN:03875016)

巻号頁・発行日

vol.65, no.630, pp.804-811, 1999-02-25 (Released:2008-03-28)

参考文献数

10

被引用文献数

3 4

---

In this study, new models on the new droplet evaporation taking account of the droplet surface temperature related to the modified Spalding model, on the ambient temperature and the mass fraction at the infinite-point was proposed and incorporated into KIVA-II code. These models were compared and reviewed with the droplet evaporation model of KIVA-II original code in relation to the standard Spalding model. As a results, it is found that the calculated results of droplet evaporation by new model agree well with actual phenomena.