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日本機械学会論文集 B編の検索結果

もしかして: 日本機械学会論文集 b編  日本機械学会論文集 b編 英語 

固体高分子形燃料電池における壁面傾斜マイクログルーブを用いたガス拡散層からガスチャネルへの排水性向上 CiNiiでみる

著者名:
岡部 晃  宇高 義郎 

抄録:
Polymer electrolyte fuel cell (PEFC) is expected to be used with the power sources for the automobile and the cogeneration power source for home and so forth. At the cathode-side of a PEFC, oxygen is transported as the reactant gas from gas channel through gas diffusion layer (GDL) to the catalyst layer. However, the large quantity of moisture is generated under the situation of the high power generation. Since, as a result, the moisture blocks transporting oxygen, the cell voltage falls off drastically. The objective of this study is to improve the management of moisture from GDL in gas channels of separator for PEFC. The oblique micro-grooves are manufactured inside gas channel walls. Water from GDL is discharged through the micro-grooves to upper-side of gas channel by surface tension and shearing force generated by air flow. Velocity of water flowing in the micro-grooves was measured by using the laser induced fluorescence method. It was confirmed experimentally that micro-grooves manufactured inside gas channel worked properly, that is, water discharge from GDL to upper-side of channel was succeeded. The water velocity and effective length of micro-grooves to remove water from GDL surface increased with the decrease in inclination angle θ of micro-grooves in this experimental range of θ=20~40°. It was shown that the effective length of approximately 200mm, which was overall length of experimental apparatus, was attained.

出版年月日:
2013 , 
巻:
79 , 
号:
805 , 
ページ:
1866-1874 , 
ISSN:
0387-5016

ビームダウン式太陽集光装置の集光部のための熱流束計測(無冷却式薄膜型熱流束計の開発) CiNiiでみる

著者名:
長瀬 慶紀  友松 重樹  河村 隆介 

抄録:
Concentrated Solar Power, or CSP, is a system that concentrates and converts sunlight into thermal energy by tracking the sun. University of Miyazaki set up a beam-down solar concentrator, one of CSPs, on August 2012. Gardon gauge is a heat flux sensor which is generally used for measuring the heat flux on the light condensing part of CSP. Gardon gauge needs a water-cooling system, and it is impossible to measure heat flux on the sunlight condensing part where equipment is running. In this study, the thin-film heat flux sensor which can measure the heat flux by non-cooling during the equipment operation was developed. Furthermore the calibration system for the heat flux sensor was developed, and the advantages of the sensor were confirmed.

出版年月日:
2013 , 
巻:
79 , 
号:
805 , 
ページ:
1858-1865 , 
ISSN:
0387-5016

経路積分セントロイド分子動力学法による水素の量子性がp-V-T関係に与える影響の解析 CiNiiでみる

著者名:
永島 浩樹  津田 伸一  坪井 伸幸  越 光男  林 光一  徳増 崇 

抄録:
In this paper, we conducted analysis of p-V-T relation of cryogenic hydrogen using classical Molecular Dynamics (MD) and path integral Centroid MD (CMD) method to understand an effect of quantum nature of hydrogen molecules. We performed NVE constant MD simulation across a wide density-temperature region to obtain an Equation Of State (EOS). Simulation results were compared with experimental data. As a result, it was confirmed that classical MD cannot reproduce the experimental data at the high density region. On the other hand, CMD well reproduces the thermodynamic properties of liquid hydrogen. Moreover, it was clarified that taking the quantum effect into account makes repulsion force larger and the potential well smaller. Because of this mechanism, the intermolecular interaction of hydrogen diminishes and the virial pressure increases.

出版年月日:
2013 , 
巻:
79 , 
号:
805 , 
ページ:
1848-1857 , 
ISSN:
0387-5016

初期燃焼速度に着目した最小点火エネルギーの当量比依存性に関する研究 CiNiiでみる

著者名:
村瀬 英一  森上 修  橋本 英樹  松崎 伊生 

抄録:
Spark ignition of premixed gases was experimentally studied. Minimum ignition energy and initial burning velocity, which is a burning velocity at an initial stage of flame propagation, were measured and their dependences on equivalence ratio were discussed. Minimum ignition energy takes a minimum value when equivalence ratio is around 0.9 for methane/air mixtures, and around 1.5 for n-butane/air mixtures, which corresponds with the study of Lewis and von Elbe. A shadowgraph technique was used to observe the growth of the flame kernels. A burning velocity was measured from the images of the flame kernel, and initial burning velocity was defined as a burning velocity at the moment when the equivalent radius of the flame kernel is approximately 3.0mm. Initial burning velocity takes a maximum value when equivalence ratio is around 0.9 for methane/air mixtures, and around 1.5 for n-butane/air mixtures, while laminar burning velocity of well-grown flame takes a maximum value when equivalence ratio is around 1.1 for both mixtures as known well. This is caused by the curvature of flame surface at the initial stage. It is suggested that the equivalence-ratio dependence of minimum ignition energy is derived from that of initial burning velocity.

出版年月日:
2013 , 
巻:
79 , 
号:
805 , 
ページ:
1839-1847 , 
ISSN:
0387-5016

微量ミスト付加による後向きステップ下流域の伝熱促進(第2報; ミストを含む伝熱流動挙動の特性) CiNiiでみる

著者名:
宮藤 義孝  瀬名波 出  比嘉 正樹  加藤 純郎  川平 卓音  松田 昇一 

抄録:
The aim of this study is to clarify the characteristics of the heat transfer enhancement in the downstream region of a backward-facing step flow using a small amount of mist. The effects of the diameter and the amount of mist upon the heat transfer enhancement were investigated analytically and experimentally. The images of the flow field and the behavior of the mist were taken using a high-speed video camera. The distributions of spatial temperature and the heat transfer coefficient were measured. The evaporation position of the mist in the main flow was calculated with the changing parameters of the relative humidity and the particle diameter of the mist. The results of the visualization experiment and the theoretical calculation revealed that the mist almost evaporated in a relatively small region of the channel. The experimental results show that the heat transfer coefficient becomes maximum near the reattachment position irrespective of the amount of mist, and that the maximum and the average Nusselt numbers increase linearly as the amount of mist increases.

出版年月日:
2013 , 
巻:
79 , 
号:
805 , 
ページ:
1827-1838 , 
ISSN:
0387-5016

微量ミスト付加による後向きステップ下流域の伝熱促進(第1報; 伝熱促進効果の検討) CiNiiでみる

著者名:
瀬名波 出  宮藤 義孝  加藤 純郎  比嘉 正樹  屋我 実 

抄録:
A Mist flow, an air flow with mixed water droplets, is suitable for rapid cooling by the latent heat of vaporizing water droplets. The technique using a small amount of fine mist is promising to partially cool the local region. The air flow which contains fine mist promotes heat transfer in some area. The cooled air by means of the evaporating mist augments the heat transfer on the duct wall. All the mist evaporates, and does not remain in the air flow. Therefore, this technique can be useful as well as the usual single phase air flow with heat transfer enhancement of a forced convection. This paper attempts to figure out how the heat transfer coefficient in the mist flow is affected by Reynolds number and heat flux on the duct wall. Experiments of heat transfer enhancement using the mist flow were carried out. It was found that the heat transfer coefficient increases when the mist is added, Reynolds number becomes larger and the added heat flux becomes smaller. The experimental results show that this technique is very promising to heat transfer enhancement.

出版年月日:
2013 , 
巻:
79 , 
号:
805 , 
ページ:
1816-1826 , 
ISSN:
0387-5016

非偏心回転式容積形内燃機関の研究(機関構成・原理と作動特性) CiNiiでみる

著者名:
石野 洋二郎  手嶋 啓介  藤井 博之  山本 優作  齋木 悠 

抄録:
A novel rotational internal combustion engine has been investigated in this study. No eccentric rotational component is used in this engine, resulting in vibration-free operation. The engine consists of rotor casing and two types of rotor; cycloid rotor and trochoid rotor. The shape of the cycloid rotor is characterized by epicycloid surface, and the trochoid rotor also superior-epitrochoid surface. In this paper, first, the typical configuration was shown. Next, a procedure for designing the rotors were described in detail. Furthermore the design drawing and appearance of the prototype engine were given. Its cyclic behavior, the time variations of the chamber volume and the estimated pressure were also indicated. Additionally the flame behavior in the working volume of the prototype engine driven in motoring condition, was presented. Finally the compactness and S/V ratio of the engine was investigated.

出版年月日:
2013 , 
巻:
79 , 
号:
805 , 
ページ:
1805-1815 , 
ISSN:
0387-5016

三重相反境界要素法による不均質材料の三次元定常熱伝導解析 CiNiiでみる

著者名:
落合 芳博 

抄録:
Homogeneous heat conduction analysis can be easily solved by means of the boundary-element method. However, domain integrals are generally necessary to solve the heat conduction problem in non-homogeneous and functionally gradient materials. This paper shows that the three-dimensional heat conduction problem in non-homogeneous and the functionally gradient materials can be solved approximately without a domain integral by the triple-reciprocity boundary element method. In this method, the distribution of domain effects is interpolated by integral equations. In this paper, heat conduction analysis is carried out for laminated materials and a particle-dispersed composite as special cases of functionally gradient materials. The same triple-reciprocity method is used for the analysis of functionally gradient materials, the laminated materials and the particle-dispersed composite. A new computer program is developed and applied to several problems.

出版年月日:
2013 , 
巻:
79 , 
号:
805 , 
ページ:
1793-1804 , 
ISSN:
0387-5016

遠心ブロワ用スリットディフューザの高効率低騒音化に関する研究 CiNiiでみる

著者名:
本多 武史  坂上 誠二  杉村 和之  馮 益祥  荒巻 森一朗  速水 洋 

抄録:
In order to improve the efficiency and decrease the noise level of centrifugal blowers at the same time, we have developed a “slit diffuser” which has a slit structure that connects the flow passages of neighboring diffuser vanes. We investigated the influence of slit structure in terms of performance, internal flow field, as well as noise level. We obtained the following conclusions. Compared with non-slitted diffusers, for the diffusers with slits, the stagnation area generated from the diffusers decreases near the slits and there is less diversion of the mainstream flow. Owing to the flow that goes through the slits from the pressure side to the suction side, the stagnation inside the diffuser is improved and the adiabatic efficiency increases by 0.8%. Compared with non-slitted diffusers, it is possible with slit diffusers to reduce the blade-passing frequency noise and to suppress the acoustic resonance.

出版年月日:
2013 , 
巻:
79 , 
号:
805 , 
ページ:
1784-1792 , 
ISSN:
0387-5016

ノンパラメトリック感度解析を用いた産業車両におけるエンジンルームの熱管理手法 CiNiiでみる

著者名:
中川 修一  桃瀬 一成  池島 薫 

抄録:
Thermal management of industrial vehicles is severe due to heavy load and low traveling speed under operation. And amount of noise exposure tends to increase compared to passenger cars because the industrial vehicles often stay in an area for a long time. Speed-up of a cooling fan and enlarging open area on an engine compartment enhance cooling performance but noise exposure rises. Therefore means to satisfy both of the thermal management and the low noise are required in design of industrial vehicles. In this study, non-parametric sensitivity analysis has been applied to an engine compartment of an agricultural tractor to obtain sensitivity on design variables to coolant temperature. The non-parametric sensitivity analysis has brought in less computational load compared to conventional parametric approach regarding the engine compartment design.

出版年月日:
2013 , 
巻:
79 , 
号:
805 , 
ページ:
1774-1783 , 
ISSN:
0387-5016

ダクト内バックステップ流れの再付着特性 CiNiiでみる

著者名:
巣山 頌文  吉田 拓生  稲岡 恭二  千田 衞 

抄録:
Spatial distributions of flow reattachment position on the bottom wall downstream of a backward-facing step in a duct have been measured by 2D PIV method. Investigations have been done for changing the flow Reynolds number, ranging from steady (Re=200) to unsteady (Re=1000) flow regimes for the stepped duct having an aspect ratio of 16 and expansion ratio of 2. It was found that non-uniform spanwise distribution of the reattachment length was observed in each case. Within the steady state, the reattachment length shows a unique distribution in the spanwise direction being protruded like a tongue over a channel, that is, having the maximum at the center of the duct but the minimum near the side wall. Its short length near the side wall reaches only 60% of that of the center of the duct. Generally, the reattachment length increases rapidly as the Reynolds number is increased and has the maximum at the center of the duct at Re=400. It should be noted that in this paper, as the Reynolds number is further increased Re>400, the reattachment length conversely decreases due to the flow unsteadiness occurring near the center of the duct. This flow unsteadiness expands to the side wall with the further increase of the Reynolds number, therefore, it makes the spanwise distribution of the flow reattachment position more complicated.

出版年月日:
2013 , 
巻:
79 , 
号:
805 , 
ページ:
1764-1773 , 
ISSN:
0387-5016

正方形角柱群内乱流のLESによる体積平均乱流輸送方程式の考察 CiNiiでみる

著者名:
桑田 祐丞  須賀 一彦 

抄録:
To understand the mechanism of the turbulence transport in porous media, large eddy simulations have been performed by a multiple-relaxation time lattice Boltzmann method. The porous media presently considered are square rod arrays. Changing the square rod size, five different cases of the porous media are analysed. Using the simulation data, the budget terms of the volume averaged Reynolds stress equations are investigated in detail. It is found that the behaviour of the production, redistribution and dissipation terms drastically changes when the porosity of the porous media becomes higher than 0.75. When the porosity becomes higher, it is observed that a perturbation by the Kármán vortex shedding propagates in the whole domain. This perturbation is the source of the the cross-streamwise component of the Reynolds stress. It is confirmed that there is a relation between the porous characteristic scales and the turbulent length scale and one of the production terms of the transport equation of the volume averaged Reynolds stress can be modelled by the Darcy-Forchheimer form.

出版年月日:
2013 , 
巻:
79 , 
号:
805 , 
ページ:
1752-1763 , 
ISSN:
0387-5016

溝つき円柱の抗力低減に関する研究 CiNiiでみる

著者名:
山岸 陽一  木村 茂雄  沖 眞 

抄録:
In the flow around a circular cylinder, a sudden decrease in the drag force occurs at a high Reynolds number, but the same phenomenon occurs at a lower Reynolds number in the case where there exist grooves or roughness on the circular cylinder surface. In previous study of authors, in order to investigate the effect of the depth and number of grooves on a circular cylinder for both arc and triangular grooves, the drag coefficient, pressure, turbulence intensity and velocity distribution were measured. Moreover, the flow around circular cylinders was analyzed by applying the RNG k-ε turbulent model. From these studies, it was found that in order to reduce a drag in a wide range of Reynolds number, the depth and number of grooves is increased and the circular cylinder surface is made to change to a turbulent boundary layer in a low Reynolds number. Furthermore, it was clarified that in order to prevent generating of a separating bubble, capacity of groove is made small and separation is retarded. In this paper, new shape of grooves was developed on the basis of the factor of above-mentioned drag reduction. As a result, the separation point of the circular cylinder with grooves of curved sectional shape shifts to the most downstream side and the drag coefficient becomes the smallest.

出版年月日:
2013 , 
巻:
79 , 
号:
805 , 
ページ:
1742-1751 , 
ISSN:
0387-5016

訂正:圧縮機の吐出用リード弁における開き遅れ挙動の計算(弁変形-ガス流れ-油膜流れ連成計算のためのモデル化)[日本機械学会論文集B編,Vol. 79 (2013), No. 806, pp. 1985-2002] CiNiiでみる

著者名:
吉住 文太  近藤 靖裕  諸井 隆宏  玉野 真司  森西 洋平 

抄録:
1995 ページの式(51)に誤植がありましたので訂正いたします.

出版年月日:
2013 , 
巻:
79 , 
号:
808 , 
ページ:
2885-2885 , 
ISSN:
0387-5016

水蒸気改質器による高次炭化水素からの水素製造 CiNiiでみる

著者名:
平田 勝哉  中森 真志  谷川 和哉  片岡 福太郎  藤本 泰貴  篠木 俊雄  谷川 博哉  舟木 治郎 

抄録:
The authors develop a small and simple steam-reforming reactor in a home-use size for n-dodecane as a heavy-hydrocarbons fuel. Under such a well-controlled condition by a thermal diffuser as the reactor satisfies two target-temperature criteria, the authors measure the inside-temperature profile and the hydrogen molar fraction (concentration) CH2, together with the molar fractions CCH4, CCO and CCO2 of other main gas components such as CH4, CO and CO2, respectively, using a gas chromatograph. In addition, the authors conduct theoretical calculations based on the thermal-equilibrium theory, and reveal CH2, CCH4, CCO and CCO2, as well as experiments. As a result, the authors successfully achieve suitable inside-temperature profiles. The steam-reforming reaction becomes more active at the position where temperature T > 800 K. The effects of the steam-to-carbon molar ratio S/C upon CH2, CCH4, CCO and CCO2 are shown, experimentally and theoretically. The experimental results agree well with the theoretical ones. Besides, carbon balance and conversion ratio show high accuracy in experiments.

出版年月日:
2013 , 
巻:
79 , 
号:
808 , 
ページ:
2873-2884 , 
ISSN:
0387-5016

液体ピストン蒸気エンジン(液体ピストン蒸気エンジンの動作解析と性能評価) CiNiiでみる

著者名:
八束 真一  新山 泰徳  福田 健太郎  鹿園 直毅 

抄録:
A novel liquid-piston steam engine which can achieve high efficiency at low temperature region of T < 300 °C as well as high reliability and low cost is developed. In this study, a numerical simulation tool for designing the liquid-piston steam engine is developed and experimentally verified. In this study, nucleate boiling and thin film evaporation are both considered in the model. It is verified that sensitive heat transport and simultaneous occurrence of evaporation and condensation are the major causes of losses. It is expected that higher efficiency can be achieved if whole liquid which is introduced in the heating section is totally vaporized.

出版年月日:
2013 , 
巻:
79 , 
号:
808 , 
ページ:
2859-2872 , 
ISSN:
0387-5016

高レイノルズ数チャンネル乱流場の内層における乱流熱流束の高プラントル数効果に関する考察 CiNiiでみる

著者名:
猿渡 祥悟  山本 義暢 

抄録:
Prandtl number (Pr) effects on characteristics of the thermal boundary layer were investigated by means of Direct Numerical Simulations (DNS) in high-Reynolds number turbulent channel flows. The molecular Pr conditions were changed from 0.71 to 25.0, and the Reynolds number based on the friction velocity and channel half-width was kept to 1000 in all cases. In the thermal conduction sub-layer and logarithmic layer, despite difference of Pr, Joint probability density function (JPDF) profiles of the wall-normal turbulent heat flux were shown good agreements with JPDF profiles of the Reynolds shear stress. On the other hand, in the peak wall-normal height of streamwise velocity intensities, JPDF profiles of wall-normal turbulent heat flux were influenced on Pr. In fact, the temperature fluctuations increase with increase of Pr at this wall-normal position. This is caused from high-Pr effects such as the difference between velocityand thermal boundary thicknesses and low-thermal conductivity.

出版年月日:
2013 , 
巻:
79 , 
号:
808 , 
ページ:
2846-2858 , 
ISSN:
0387-5016

自然エネルギーの変動抑制に利用するガスエンジンの排気特性とコスト評価 CiNiiでみる

著者名:
見並 克俊  山崎 由大  金子 成彦 

抄録:
To utilize photovoltaic power generation (PV), the compensation for power fluctuation is necessary since the fluctuation has a bad influence on electric power system. Therefore, micro grid using several kinds of distributed generation is considered to be a good solution. For this reason, studies on batteries have been done in particular, due to the high output responsiveness. However, the power generation cost of batteries is higher than other distributed generation such as gas engines, which have not been studied enough from the viewpoint of distributed generation to compensate for renewable energy. In this paper, the feasibility of gas engines to compensate for the PV fluctuation is investigated from the point of view of exhaust gas NOx and power cost by simulation. As a result, the amount of NOx increases as the output of the gas engine fluctuates, but this increase on NOx hardly has a problem in micro grid. As for power cost, it can be decreased by combining battery and a few kinds of gas engines efficiently. In conclusion, it can be said that gas engines are able to play an important role in micro grid as distributed generation.

出版年月日:
2013 , 
巻:
79 , 
号:
808 , 
ページ:
2836-2845 , 
ISSN:
0387-5016

揺動式水蒸気圧縮機における気液二相圧縮過程の解析と実験 CiNiiでみる

著者名:
菱木 翼  中村 宗平  天野 嘉春  日野 俊之 

抄録:
The steam compressors have been developed, in large capacities, which have been applied for special VRC (Vapor Re-Compression) process. However, it seems to have a considerable ripple effect on the various purposes if the small size and high performance steam compressors are practically available. The Vapor Compression and Condensation (VCC) system is a heat pump cycle utilizing water as a working fluid. In the process, it should be negative pressure at the inlet of the compressor to prevent the leakage of volatile substances to the atmosphere. It causes higher degrees of superheat of the steam at the discharge. In this paper, the authors introduced two-phase compression process to reduce the superheat and reduction of the compression work. The thermal model of the process which is based on a heat transfer model between droplets and vapor is proposed. In addition, an experimental set-up, which employs a unique reciprocating compressor, is built in order to validate the model. Effect of two-phase compression of the steam is reported by comparing calculation results based on two types of models, conventional and proposed one, with experimental results. It shows that results of both of the models matched the experimental results well.

出版年月日:
2013 , 
巻:
79 , 
号:
808 , 
ページ:
2826-2835 , 
ISSN:
0387-5016

気体収束爆轟駆動の水中衝撃波による微生物処理に関する研究 CiNiiでみる

著者名:
宇田川 洋一  鈴木 実 

抄録:
Ballast water is used to stabilize an empty ship on the open sea. It often contains various microorganisms such as plankton and bacteria, and causes serious damage to aquatic ecosystems when it is discharged. Ultra-high pressure underwater shock waves were applied to treat those microorganisms. The imploding detonation of propane-oxygen mixture was used to generate the underwater shock waves in a sample holder having an inner diameter of 10.9 mm. We investigated the imploding detonation wave in approximately hemisphere-shaped combustion chamber having maximum inner diameter of 60 mm and generated underwater shock waves of 100 MPa. As microorganisms of the high pressure treatment experiments Artemia salina, Heterosigma akashiwo and Coliform group were used. We could completely treat Artemia salina and Coliform group by 5 shots and Heterosigma akashiwo by 1 shot of the underwater shock wave that maximum pressure was about 100 MPa.

出版年月日:
2013 , 
巻:
79 , 
号:
808 , 
ページ:
2818-2825 , 
ISSN:
0387-5016