著者

岩田 和也 松山 新吾 小島 淳 布目 佳央 川島 秀人 丹野 英幸 水書 稔治

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.62, no.200, pp.94-102, 2020 (Released:2020-06-13)

参考文献数

24

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Japan Aerospace Exploration Agency has now been working to understand detailed morphologies of detonation wave encountered in Rotating Detonation Rocket Engine (RDRE), which is one of the most potential engine concepts for light-weight and compact rocket system, and to investigate how they influence thrust performance and operational stability of the engine. Combustion experiments of an annular RDRE propelled by gaseous methane and oxygen were conducted to measure thrust performance and to visualize detonation propagation and CH*/OH* chemiluminescence, from which specific thrust was revealed close to the theoretical value with stable propagation modes, and without throat contraction. CH* chemiluminescence also indicated deflagrative combustion anchoring at the injection plane, which could partly explain the performance degradation in a configuration with throat. Experimentally observed detonation velocity ranged 45-75 % of Chapman-Jouguet (C-J) velocity, which was partly confirmed to be induced by incomplete mixing from the results of two/three-dimensional simulation employing detailed chemical kinetics. However, numerically predicted velocity was higher by several tens of percentage, indicating potential influence of thermal/viscous loss to the confinement. Overall, physical insight was achieved into non-ideal behavior of detonation including strongly curved wave front induced by incomplete mixing and our findings emphasizes a need for better mixing techniques to achieve more ideal characteristics of detonation.

著者

田中 克己

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.50, no.152, pp.91-99, 2008 (Released:2018-01-26)

参考文献数

26

著者

金野 満 酒井 康行

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.63, no.206, pp.316-323, 2021-11-15 (Released:2022-02-08)

参考文献数

33

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Polyoxymethylene dimethyl ethers are a class of ethers with the molecular structure CH3(-O-CH2)n-O-CH3, called OME for short. Amid a growing global trend for a carbon neutral, OME has attracted the attention as a potential e-fuel for compression ignition engines because it has good ignitability and low-sooting tendency. In this article, the fuel property, the synthesis, the cost, chemical kinetic mechanisms and the effects of OME blends on engine performance are described based on the latest literatures, as well as the research on the spray characteristics made by the authors. The points are as follows: it is not feasible to use neat OME because the cost of OME synthesis is high with the current technology, but to use as diesel fuel additive that can greatly reduce PM emission. Without changing the fuel injection strategy from diesel fuel, the thermal efficiency is penalized with OME blends. The ignition delay and combustion duration decrease with the increasing of OME ratio in the diesel fuel blends. The thermal efficiency could be improved by optimizing the fuel injection parameters.

著者

畑中 修二 薄葉 州

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.60, no.193, pp.181-190, 2018 (Released:2019-02-15)

参考文献数

20

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Japanese fireworks began in the Edo period. And the technology has advanced with the support by the people over time. Currently, Japanese fireworks are highly respected worldwide. I think the reason is that Japanese are creating the clear bright color and sound technology using the characteristics of aluminum powder (Al powder) well. On the other hand, severe accidents such as “mass explosion” which affect almost the entire explosives virtually instantaneously during manufacture and storage of fireworks articles including Al powder had continued until recently. It was similar in overseas. For this reason, investigation and research have been conducted at various levels, such as international, national and industrial levels, and regulations had been also tightened. International regulation on transportation of dangerous goods including fireworks should follow the regulation called "UN Recommendations". By these investigation and researches, the regulations of fireworks were changed dramatically in 2005, and then continued to change. Additionally, ISO standards of fireworks have been developed from 2012 and published in 2017. The transport classification of fireworks should be decided by the flash composition test of UN Recommendation. This flash composition test is composed of two kinds tests, a time pressure test with 0.5g sample and DDT test with 25g one. It became clear by Japanese studies that the time pressure test overestimates due to the scale effect. It seems that the combustion behavior of Al powder at high temperature and high pressure tightly relates to mass explosion, but the actual behavior is unknown now time.

著者

白石 泰介 漆原 友則

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.51, no.155, pp.31-39, 2009 (Released:2018-01-26)

参考文献数

14

被引用文献数

1

著者

小林 秀昭 早川 晃弘

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.61, no.198, pp.277-282, 2019 (Released:2019-11-15)

参考文献数

33

被引用文献数

1

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The Cross-ministerial Strategic Innovation Promotion Program (SIP) “Energy Carriers”, which aims development of hydrogen value chain, was conducted for five years from 2014. Research and development of ammonia combustion played an important role in the project, and significant outcomes related to utilization of ammonia as a carbon-free fuel were produced for gas turbines, internal combustion engines, industrial furnaces, co-firing of pulverized coal combustion, as well as feasibility study of ammonia combustion in large scale power plants. The project introduced renewed interest of ammonia combustion into international combustion community in terms of reducing greenhouse-gas emission from combustion in energy and industrial sectors. Ammonia combustion also has an impact not only on Japanese domestic policy for energy and environment but also on international energy agencies, which influence governments and industries of various nations.

著者

小林 秀昭 早川 晃弘

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.58, no.183, pp.41-48, 2016 (Released:2018-01-26)

参考文献数

27

被引用文献数

6

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Recent advances in the research and development of ammonia combustion are introduced. They are mainly promoted by the Cross-ministerial Strategic Innovation Promotion Program (SIP), “Energy Carrier”. Ammonia is a potential chemical substance not only for a hydrogen energy carrier but also a carbon free fuel. Ammonia also has advantages in terms of storage and transportation because the thermal properties are almost the same as those of propane. The subjects of ammonia combustion research are on low combustion intensity, low radiation intensity, as well as high NOx emission. In this article, recently obtained fundamental ammonia flame characteristics, such as the features of NO formation, laminar burning velocity, Markstein length and reaction enhancement by hydrogen addition are summarized. Flame structures and burnt gas characteristics were experimentally and numerically evaluated. NO mole fraction decreased with an increase in equivalence ratio and it is caused by NHi (i = 2, 1, 0) generated from excess NH3 in the mixture. Laminar burning velocities and Markstein lengths were evaluated from spherically propagating flames up to 0.5 MPa. The maximum value of laminar burning velocity of ammonia/air is less than 7 cm/s and is about 1/5 of that of methane/air flame. 1D flame simulation with detailed reaction mechanisms were also performed and it was showed that the quantitatively predicted laminar burning velocities were inaccurate. The laminar burning velocity exponentially increases with the increase in the hydrogen ratio. On the other hand, the Markstein length varies non-monotonically with with an increase in the hydrogen ratio.

著者

石原 咲子 石井 一洋 片岡 秀文

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.56, no.178, pp.355-363, 2014 (Released:2018-01-26)

参考文献数

18

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For deflagration to detonation transition (DDT), several explanations on initiation have been given. Nevertheless, the knowledge on DDT is still insufficient for predicting where and when detonation occurs. In order to improve the reproducibility, an ethylene oxygen mixture was ignited forcibly by spark discharge behind an incident shock wave near the wall. The process of flame development was visualized by Schlieren imaging and analyzed by drawing several wave element trajectories on the shock waves ahead of the flame. As a result of varying the timing of spark discharge, detonation initiation was promoted as the boundary layer Reynolds number Reign increases. For Reign of more than 5.0 × 106, DDT was caused at 45 ± 10 μs. The processes of flame development were classified as Mode 1 and 2, which denote Reign of less than transition Reynolds number and more than it, respectively. Although the times for detonation initiation were markedly different in Mode 1 and 2, it was found that the both flame developments were similar. The accelerated flame near the wall propagates in upstream direction along the wall, resulting in approaching the shock wave front. This makes the shock stronger by coalescing of numerous compression waves. As the strengthened shock compresses the unburned gas, the flame was more accelerated, so that at the position where the flame front reached the shock front detonation initiation occurred. The difference of flame development between Mode 1 and 2 was observed in the initial stage in particular in the early 20 μs. Detonation initiation was caused at the position where following three conditions were satisfied: (1) A local Mach number reaches 2.4. (2) The flame front approaches and reaches the shock front ahead of it. (3) A concavity is generated on the flame/shock front, compressing the unburned gas coming into the point.

著者

三宮 大弥 鈴木 正太郎

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

pp.2202, (Released:2022-07-20)

参考文献数

5

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Smoldering of a futon, a Japanese style mattress, is significantly affected by the blend ratio of polyester and cotton fibers comprising the wad that is stuffed in the futon; it was found that the smoldering is inhibited when a relatively small amount of polyester fibers is added to the wad. To understand this effect of blend ratio, experiments are conducted in this study with bare wads of cotton and polyester fibers having different blend ratios. A thin wad is laid on a hot plate with the intention of compensating the heat loss and letting the smoldering occur within the visible range in the wad so that the behavior of it can be observed from the surface. A spot of its surface is heated locally with a lamp and the temperature is measured by means of a thermographic camera for detecting the ignition. After it ignites, the smoldering behavior is recorded by a video camera or a microscope. It is found that the average of the ignition delay time increases as the polyester ratio increases, while data scatter widely depending on each sample. All the wad samples containing 25wt.% of polyester ignite just as those of 100wt.% cotton fibers, but the travel distances of the smoldering spread become distinctly shorter. These results indicate that the inhibition of the smoldering with small amount of polyester is originated from not the propensity of ignition but the propensity of smoldering spread. The microscopic observation reveals a vast movement of fibers in the preheating zone, which is caused by the melting and deformation of polyester fibers; such a movement may influence the propensity of the smoldering spread.

著者

金 佑勁

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.62, no.201, pp.228-233, 2020 (Released:2020-09-26)

参考文献数

24

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This paper reviews the features and hazards of large-scale fireball generated by accidental explosions. A catastrophic failure of storage vessel of flammable materials in a fire can lead to a fireball. The estimation of diameter and duration of fireball based on various experiments are discussed. The results calculated by empirical equations agreed reasonably well with the experimental data. The results demonstrated that the size and duration of the fireball depend on the mass of fuel. Additionally, in this article, the experimental investigations on fireball dynamics after rupture of 35 MPa and 70 MPa high-pressure hydrogen tank in a fire are described, and the results were used to validate the development of CFD model.

著者

湯浅 三郎

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.45, no.133, pp.152-163, 2003 (Released:2019-10-24)

参考文献数

57

被引用文献数

3

著者

植田 利久

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.53, no.164, pp.69-77, 2011 (Released:2018-01-26)

参考文献数

20

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Characteristics of flame propagation over combustible hydrates, methane hydrate and natural gas hydrate, in a laminar flat plate boundary layer has been investigated experimentally. The fine powder hydrate is packed in an insulated container and set flush with the bottom wall of the wind tunnel. The free stream velocity (U∞) is varied from 0.4m/s to 1.1m/s. The hydrate is ignited at the downstream end of the container when the surface temperature at the center of the hydrate surface reaches that at the igniton (Ts,ig). Ts,ig is varied from -80℃ to -20℃. The motion of the flame propagation is recorded by a digital video camera. The location of the leading flame edge is measured by using the image of the video camera. Two types of flame propagation are observed. When Ts,ig is low, the flame propagates almost linearly with time with the velocity around 3-4mm/s. In this case, the flame propagation velocity is determined by the dissociation rate of the hydrate. When Ts,ig is relatively high, the periodic flame propagation is observed. The maximum flame propagation velocity reaches around 800mm/s. In this case, the premixed mixture is formed over the hydrate surface because the hydrate can dissociate in the atmospheric condition and the flame propagates in the premixed mixture.

著者

八房 智顕 遠藤 琢磨 滝 史郎

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.47, no.140, pp.90-96, 2005 (Released:2019-10-24)

参考文献数

13

著者

林 謙年 山口 以昌 川村 晋 榊原 信幸 伊藤 和男 岩田 直也

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.55, no.171, pp.21-26, 2013 (Released:2018-01-26)

参考文献数

2

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City gas, which is mainly made from natural gas, has been widely recognized as clean fuel, and its demand is getting higher year by year in Japan. The natural gas is imported in the form of LNG from varied countries. The calorific value of the imported natural gas is usually lower than the Japanese city gas, therefore, gas companies adjust the calorific value of send-out city gas to the regulated value by adding LPG to the natural gas during the process of city gas production. We have developed a new, state-of-the-art, calorific value adjusting system, which operates in wide flow-rate range, more than four (4) times wider than a conventional system does. We report the outline of the newly developed system and its performance confirmed through a pilot-scale test, along with a short description of a typical process of city gas production and conventional methods of calorific value adjustment.

著者

八木 克記

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.48, no.143, pp.111-116, 2006 (Released:2019-10-24)

参考文献数

10

著者

牧野 敦

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.55, no.172, pp.94-109, 2013 (Released:2018-01-26)

参考文献数

38

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Particle combustion of solid carbon in the quiescent atmosphere has been overviewed by use of accomplishment in the aerothermochemical analyses, in which not only the surface C-O2 and C-CO2 reactions but also the gas-phase CO-O2 reaction is taken into account. By virtue of the generalized species-enthalpy coupling functions, close coupling of those reactions has been elucidated. It has been identified that the combustion response in the three limiting situations, such as the Frozen, the Flame-detached and the Flame-attached modes, can be described analytically, by using the generalized coupling functions. Explicit combustion-rate expressions by use of the transfer number in terms of the natural logarithmic term, just like that for droplet combustion, have further been obtained for the combustion response in the limiting situations. In addition, by examining establishment of CO-flame over the carbon particle, it has been confirmed that the combustion rate can fairly be represented by the expression in the Frozen mode when the particle diameter is 100 μm or less. Since this expression is explicit and has fair accuracy, various contributions are anticipated not only qualitatively but also quantitatively. Combustion response in the transient situation has further been examined, from which an existence of the critical size for the particle burn-out has even been derived. A fair degree of agreement in experimental comparisons indicates that the present formulation has captured the essential features of the particle burn-out.

著者

新井 充

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.50, no.152, pp.107-110, 2008

著者

森吉 泰生

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.54, no.170, pp.237-242, 2012 (Released:2018-01-26)

参考文献数

14

被引用文献数

3

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Spark ignition engines are widely used for a small generator as well as a passenger vehicle. The exhaust gas emissions no longer have pollution problem by adopting a combination of three-way catalyst and stoichiometric mixture control, but an improvement of thermal efficiency is an urgent task. To achieve this, an increase of compression ratio and down-sizing with a turbo-charger are solutions. However, employing these methods causes abnormal combustion of such as knocking and pre-ignition that will bring about damages to engine components. In this article, why these phenomena occur and how to solve the issues are briefly mentioned with some author's ideas: since autoignition itself does not lead to a heavy knocking, a quick expansion at early expansion stroke and a spatial temperature distribution of mixture inside the cylinder can control the knocking intensity. As pre-ignition at low engine speed is not well analyzed, this phenomenon must be quantitatively examined.

著者

新井 充

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.50, no.152, pp.107-110, 2008 (Released:2018-01-26)

参考文献数

33

著者

橋本 望 西田 啓之 小沢 靖

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.50, no.153, pp.215-224, 2008 (Released:2018-01-26)

参考文献数

21