- 著者
- Takashi SAIKA Mitsuhiro NAKAMURA Tetsuo NOHARA Shinji ISHIMATSU
- 出版者
- 社団法人 日本機械学会
- 雑誌
- JSME International Journal Series B Fluids and Thermal Engineering (ISSN:13408054)
- 巻号頁・発行日
- vol.49, no.1, pp.78-83, 2006 (Released:2006-08-15)
- 参考文献数
- 14
- 被引用文献数
- 10 18
Carbon-free fuel is effective in preventing global warming. Hydrogen has no carbon and can be made also from nuclear energy or reproducible energies other than fossil fuels. However, hydrogen lacks portability because of its difficulty in liquefying, but ammonia can easily be liquefied at a room temperature and dissociated into high-content hydrogen and nitrogen using a suitable catalyst. An ammonia dissociation system for fuel cells is proposed in this paper. The residual ammonia by 13ppm or more in the dissociated gas (H2+ N2) causes a decrease in the output of fuel cells. To separate residual ammonia, it should be sent to an ammonia separator and then to an ammonia distiller. In the experiment, the authors examine the concentrations of ammonia after dissociation at various temperatures, pressures and space velocities. The ammonia separator uses the fact that ammonia dissolves well in water. Then the ammonia water is distilled in the distiller. Thereby, the authors have proposed an ammonia circulation system that is a clean energy system.
- 著者
- Tie LI Keiya NISHIDA Yuyin ZHANG Tuyoshi ONOE Hiroyuki HIROYAU
- 出版者
- 社団法人 日本機械学会
- 雑誌
- JSME International Journal Series B Fluids and Thermal Engineering (ISSN:13408054)
- 巻号頁・発行日
- vol.48, no.4, pp.687-694, 2005 (Released:2006-05-15)
- 参考文献数
- 9
- 被引用文献数
- 5 19
The effect of split injection on the mixture characteristics of DISI (Direct Injection Spark Ignition) engines was investigated firstly by the Laser Absorption Scattering (LAS) technique. Through splitting the fuel injection process, two possible benefits were found: 1) High density liquid droplets piling up at the leading edge of the spray can be circumvented, subsequently the reduction of the spray tip penetration; 2) The quantity of “over lean” (φv<0.7, φv: equivalence ratio of vapor) mixture in the spray can be significantly reduced. These are believed to contribute to the reduction of the engine-out smoke and HC emissions. In order to clarify the mechanism behind the effect of the split injection, the spray-induced ambient air motion was investigated by the LIF-PIV technique. The strong ambient air entrainment into the tail region of the spray and a counter-vortex structure were found in both the single and split injections. In the case of the single injection, the spray develops in extending its length, subsequently a larger volume results and thus it is diluted to “over lean” by the ambient air entrainment. In contrast, in the case of split injection, the second spray is injected into the tail region of the first spray and its evaporation is promoted by the ambient air motion induced by the first spray. Hence the replenishment of the liquid fuel into the leading edge of the first spray is reduced. As a consequence, the high density liquid droplets piling up at the leading edge is avoided. Furthermore, a more compact spray results so that the ambient air motion plays a positive role on evaporating the spray into “more combustible” (0.7<φv<1.3). This is especially true in the tail region of the spray and the region where the counter-vortex motion is occurring.
- 著者
- Yuyin ZHANG Keiya NISHIDA Takuo YOSHIZAKI
- 出版者
- 社団法人 日本機械学会
- 雑誌
- JSME International Journal Series B Fluids and Thermal Engineering (ISSN:13408054)
- 巻号頁・発行日
- vol.46, no.1, pp.100-108, 2003 (Released:2004-06-25)
- 参考文献数
- 17
- 被引用文献数
- 2 10
Recent experimental studies have shown that with split injection strategy, the soot and NOx emissions from a diesel engine can be reduced significantly in comparison with a conventional non-split injection. To understand the mechanism of emissions reduction, it is essential to clarify the process of mixture formation in the diesel spray. For characterizing the droplets and vapor concentration distributions inside a fuel spray, a dual-wavelength laser absorption-scattering technique (LAS) was developed by using the 2nd harmonic (532nm) and the 4th harmonic (266nm) of an Nd: YAG laser and using dimethylnaphthalene as a test fuel. By applying the ultraviolet-visible LAS imaging technique, the distributions of droplets and vapor concentrations in the spray, which was injected into a high-temperature and high-pressure nitrogen ambient in a constant volume vessel by a common-rail diesel injection system, were measured and quantitatively analyzed. The effect of injection mass ratio of double-pulse injections on distributions of equivalence ratios of vapor and droplets in the sprays was examined.
- 著者
- Kazunori HASE Nobutoshi YAMAZAKI
- 出版者
- 社団法人 日本機械学会
- 雑誌
- JSME International Journal Series C Mechanical Systems, Machine Elements and Manufacturing (ISSN:13447653)
- 巻号頁・発行日
- vol.45, no.4, pp.1040-1050, 2002 (Released:2004-06-25)
- 参考文献数
- 33
- 被引用文献数
- 19 51
A model having a three-dimensional entire-body structure and consisting of both the neuronal system and the musculo-skeletal system was proposed to precisely simulate human walking motion. The dynamics of the human body was represented by a 14-rigid-link system and 60 muscular models. The neuronal system was represented by three sub-systems: the rhythm generator system consisting of 32 neural oscillators, the sensory feedback system, and the peripheral system expressed by static optimization. Unknown neuronal parameters were adjusted by a numerical search method using the evaluative criterion for locomotion that was defined by a hybrid between the locomotive energy efficiency and the smoothness of the muscular tensions. The model could successfully generate continuous and three-dimensional walking patterns and stabilized walking against mechanical perturbation. The walking pattern was more stable than that of the model based on dynamic optimization, and more precise than that of the previous model based on a similar neuronal system.
- 著者
- Jiro SENDA Takatsugu ASAI Bungo KAWAGUCHI Hajime FUJIMOTO
- 出版者
- 社団法人 日本機械学会
- 雑誌
- JSME International Journal Series B Fluids and Thermal Engineering (ISSN:13408054)
- 巻号頁・発行日
- vol.43, no.3, pp.503-510, 2000-08-15 (Released:2008-02-18)
- 参考文献数
- 14
- 被引用文献数
- 5 11
A new injection system using mixed fuel dissolved with liquefied CO2 is proposed in this paper. Liquefied CO2 is mixed with n-Tridecane under pressure in order to promote spray atomization and evaporation due to the effect of the flash boiling phenomenon during fuel injection, and to control the combustion process due to the effect of the internal exhaust gas recirculation (EGR) effct of CO2 gas. Therefore, a simultaneous recduction of soot and NOx is achieved effectively using this injection system. In this study, the characteristics of diesel fuel spray dissolved with liquefied CO2 are investigated quantitatively by several optical measurements. The spray characteristics are revealed by analyzing the chemical thermodynamics. As a result, it is determined that atomization of this fuel is promoted by flash boiling much more than in n-Tridecane, which is normal reference fuel, and the spray structure is considerably different from that of the normal fuel. Moreover, the numerical analysis of atomization and vaporization processes are carried out, based on the flash boiling spray model.
- 著者
- 伊東 繁 一宮 和彦 山本 友和
- 出版者
- 社団法人 日本機械学会
- 雑誌
- 日本機械学会九州支部講演論文集
- 巻号頁・発行日
- vol.2001, pp.99-100, 2001
いま地球環境の保全問題が、官民を通じて真剣に論じられ、多様な対策が講じられている。なかでも近年深刻な問題である大量廃棄物については、近年様々な努力により、その排出量は抑制されているが、依然多量である。大量消費社会が生み出すこうした資源の大量消費が避けられないならば、できるだけリサイクルしやすくする消費者の知恵と、分別・排出された廃棄物を生かす企業の知恵があいまって、限りある資源の徹底した有効利用を目指し、資源採集→加工生産→回収→再資源化→再加工生産→再消費という、いわば資源循環型の社会を推進していかなければならない。 日々大量に排出される廃棄物のなかでも、ガラスびんは洗浄後再び使われるリターナブルびんと、破砕され『カレット』というびん原料になるワンウェイびんに分かれている。しかし、リターナルびんが99%再利用されているのに比べ、ワンウェイびんのカレット利用率は65%にとどまっている。この低い利用率の原因は様々あるが、その一つに生成コストが上げられる。 そこで本研究では新たなカレット生成法として水中衝撃波を利用した方法について模索した。通常は大規模な粉砕機によりカレットを生成するが、水中衝撃波を使用すると設備コストが低いことが利点として挙げられる。そこで水中衝撃波によってできるカレットの粒径等のデータを得ることができたので、その結果について中心に報告する。
- 著者
- Takahisa YAMAMOTO Koshi MITACHI Takashi SUZUKI
- 出版者
- 社団法人 日本機械学会
- 雑誌
- JSME International Journal Series B Fluids and Thermal Engineering (ISSN:13408054)
- 巻号頁・発行日
- vol.48, no.3, pp.610-617, 2005 (Released:2006-02-15)
- 参考文献数
- 13
- 被引用文献数
- 16 23
The Molten Salt Reactor (MSR) is a thermal neutron reactor with graphite moderation and operates on the thorium-uranium fuel cycle. The feature of the MSR is that fuel salt flows inside the reactor during the nuclear fission reaction. In the previous study, the authors developed numerical model with which to simulate the effects of fuel salt flow on the reactor characteristics. In this study, we apply the model to the steady-state analysis of a small MSR system and estimate the effects of fuel flow. The model consists of two-group neutron diffusion equations for fast and thermal neutron fluxes, transport equations for six-group delayed neutron precursors and energy conservation equations for fuel salt and the graphite moderator. The following results are obtained: (1) in the rated operation condition, the peaks of the neutron fluxes slightly move toward the bottom from the center of the reactor and the delayed neutron precursors are significantly carried by the fuel salt flow, and (2) the extension of residence time in the external-loop system and the rise of the fuel inflow temperature show weak negative reactivity effects, which decrease the neutron multiplication factor of the small MSR system.
- 著者
- Taketoshi NOJIMA Kazuya SAITO
- 出版者
- 社団法人 日本機械学会
- 雑誌
- JSME International Journal Series A Solid Mechanics and Material Engineering (ISSN:13447912)
- 巻号頁・発行日
- vol.49, no.1, pp.38-42, 2006 (Released:2006-07-15)
- 参考文献数
- 6
- 被引用文献数
- 12 65 22
By folding a thin flat sheet with periodically set slits or punched out portions into the third dimension, ultra-lightweight strong and functional core models are newly devised. The basic idea of this modeling arises from the application of origami technique to engineering. Based on the space filling models, fundamental flat cores and skew type sponge cores have been newly developed. By applying these models, such modified core models as curved cores and 3D honeycomb core are newly devised.
- 著者
- Joel HANSSON Masayuki TAKANO Tadao TAKIGAMI Takahiro TOMIOKA Yasufumi SUZUKI
- 出版者
- 社団法人 日本機械学会
- 雑誌
- JSME International Journal Series C Mechanical Systems, Machine Elements and Manufacturing (ISSN:13447653)
- 巻号頁・発行日
- vol.47, no.2, pp.451-456, 2004 (Released:2005-01-25)
- 参考文献数
- 9
- 被引用文献数
- 3 18
A new method for improving riding comfort by reducing vertical flexural vibrations in railway car bodies using piezoelectric elements is studied in this paper. Piezoelectric elements are attached on the car body in order to convert vibration energy to electrical energy, which can be dissipated in a shunt circuit. Assuming the car body as an elastically supported Bernoulli-Euler beam, theoretical analysis and numerical simulations are carried out. The numerical results are supplemented by experiments on a 1:5 scale model of a Shinkansen vehicle. Both numerical and experimental results indicate that the method yields significant vibration suppression with only a small amount of added weight. Two types of shunt circuits; a single-mode circuit and a multi-mode circuit are studied.