著者

吉田 英生 石部 英臣 吉冨 聡 齋藤 元浩 松井 裕樹 江川 猛 岩井 裕 坪田 宏之 桑原 健雄 金丸 一宏

出版者

The Japan Society of Mechanical Engineers

雑誌

日本機械学会論文集 B編 (ISSN:03875016)

巻号頁・発行日

vol.72, no.722, pp.2562-2569, 2006

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A hybrid bearing effectively stabilized by water evaporation from ultra-fine porous medium is proposed and its basic characteristics are clarified by numerical simulation and experiment. The proposed bearing aims to be applied to MGT (Micro Gas Turbine) and has mainly three advantages suitable for application to MGT. The first is the stability improved by water evaporation from ultra-fine porous medium. The second is the effective lubrication by liquid water at the start and stop of the journal rotation. The third is the cooling effect on the high-temperature journal due to water evaporation. A fundamental experiment from water lubrication to vapor lubrication via transition state has been carried out. The experiment indicated the potential of vapor lubrication and confirmed the stable start-up at water lubrication.

著者

須賀 一彦 Timothy J. CRAFT Hector IACOVIDES

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.71, no.711, pp.2725-2733, 2005-11-25 (Released:2011-03-03)

参考文献数

21

被引用文献数

1

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This paper reports the development of a refined wall-function strategy for the modelling of turbulent flows over smooth and rough surfaces. In order to include the effects of fine-grain surface roughness, the present study extends a more fundamental work on the development of advanced wall functions of general applicability. The presently proposed model is validated through comparisons with data available for internal flows through channels, pipes and for external flows over flat plates with both smooth and rough surfaces. Then, its further validation in separating flows over a sand dune and a sand-roughened ramp as well as a smooth ramp is discussed. The validation results suggest that the presently proposed form is successfully applicable to a wide range of attached and separated turbulent flows over smooth and fine-grain rough surfaces.

著者

田中 正暁 佐郷 ひろみ 岩本 幸治 江原 真司 小野 綾子 村上 貴裕 早川 教

出版者

The Japan Society of Mechanical Engineers

雑誌

日本機械学会論文集 B編 (ISSN:03875016)

巻号頁・発行日

vol.78, no.792, pp.1392-1396, 2012

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A study on flow induced vibration in the primary cooling system of Japan Sodium cooled Fast Reactor (JSFR) consisting of large diameter pipe and pipe elbow with short curvature radius ("short-elbow") has been conducted. Flow-induced vibration in the short-elbow is an important issue in design study of JSFR, because it may affect to structural integrity of the pipe. In this paper, unsteady flow characteristics in the JSFR short-elbow pipe related to the large-scale eddy motion were estimated based on knowledge from existing studies for curved pipes and scaled water experiments and numerical simulations for the JSFR hot-leg piping.

著者

池田 博和 松浦 文生 越塚 誠一 岡 芳明

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.64, no.624, pp.2431-2437, 1998-08-25 (Released:2008-03-28)

参考文献数

13

被引用文献数

2 7

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Fragmentation of liquid metal takes place as basic processes of vapor explosions. This leads to rapid evaporation on the stretched interface. To date, a number of models explaining the fragmentation mechanisms have been proposed. However, few evidence has been obtained from the experiment because the phenomena are rapid. In Moving Particle Semi-implicit (MPS) method, grids are not necessary so that fluid fragmentation as well as multi-fluid thermal hydraulics can be analyzed. A numerical model of evaporation is developed for the present study. Impingement of water jets on a liquid metal pool is analyzed using the MPS method to investigate two typical models explaining the fragmentation mechanisms : Kim-Corradini and Ciccarelli-Frost models. Penetration of the water jet, which is assumed in Kim-Corradini model, is not observed in the calculation results. A filament of the liquid metal is observed between two water jets as assumed in Ciccarelli-Frost model. The filament appears when the jet density is smaller than the pool density, while the penetration appears when the jet density is hypotheticaly larger. The usual combinations of densities in vapor explosions are in the region of Ciccarelli-Frost model.

著者

佐藤 智明

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.76, no.762, pp.359-361, 2010-02-25 (Released:2017-06-09)

参考文献数

1

被引用文献数

1

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In this paper, as a new application of Stirling cycle, it is proposed to apply the Stirling cycle to heat speaker which amplifies sound vibration by means of the thermal energy. The heat speaker is composed of a pressure vessel whose capacity is variable, a displacer to which a voice coil is attached, a vibration board attached to the pressure vessel and a permanent magnet placed around the vessel. The displacer with voice coil is vibrated by the magnetic force which is generated by electric current of sound signal flowing in the voice coil. The vibrating displacer makes the air come and go between the hot side and the cold side in the pressure vessel. The air temperature goes up and down, and then the pressure follows it. The capacity of the vessel repeats expansion and shrinkage by the pressure change of the air. The moving vessel vibrates the vibration board and it yields the sound.

著者

千田 二郎 錦織 環 北條 義之 塚本 時弘 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.578, pp.3551-3555, 1994-10-25 (Released:2008-03-28)

参考文献数

13

被引用文献数

3

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In this study, the influence of the flash boiling phenomenon on the fuel spray characteristics was in vestigated using both experiments and model analysis. Pure liquid fuel of n-Pentane or n-Hexane is injected into a vessel under quiescent gaseous atmosphere at room temperature through a pintle-type injector. Fuel sprays are observed by taking photographs for variation of ambient back pressure. In particular, changes in spray characteristics with back pressure are examined in detail. The results show that the saturated vapor pressure of fuel is the most significant factor and the spray characteristics can be varied with the pressure difference between the back pressure and saturated vapor pressure. Furthermore, flow field of the fuel inside the nozzle is estimated with regard to bubble initiation inside the film flow.

著者

千田 二郎 山田 耕司 藤本 元 三木 英雄

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.53, no.485, pp.176-182, 1987-01-25 (Released:2008-03-28)

参考文献数

19

被引用文献数

1 2

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The purpose of this paper is to obtain fundamental information concerning the heat transfer process and breakup behavior characteristics of individual small droplets impinging upon a hot surface. A uniform sized water droplet array at room temperature under atmospheric pressure was produced by the vibratory method to impinge upon a heated flat copper surface. And then, heat transfer from a surface to the droplets is assessed by a transient technique. Further, the deformation and the breakup behavior owing to the impingement of the droplet is observed by means of a drum camera recording high-speed microscopic photographs. Heat transfer effectiveness in a low temperature range of less than 125°C decreases as droplet impingement frequency increases because of interference between the impinging droplet and the remaining liquid film on a surface. It is possible that heat transfer per droplet is transfermed into a heat transfer coefficient by use of droplet residence time and film contact area on a surface. And Variations in the heat transfor coefficient for a droplet array with surface temperature are measured by difference calculus of the one dimensional unsteady heat conduction equation.

著者

佐藤 泰生 佐田富 道雄 堀田 圭之助 中里 見正夫 世古口 言彦

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.46, no.409, pp.1790-1796, 1980-09-25 (Released:2008-03-28)

参考文献数

8

被引用文献数

1 2

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第1報で提案した管内気ほう流の運動量と熱輸送の理論を実験値をもとに検討した.運動量輸送に関しては液相速度分布と摩擦圧力損失,熱輸送に関しては液相温度分布と熱伝達係数のそれぞれについて予測値と実験値を比較した結果,いずれもよい一致がみられ,理論の妥当性が確かめられた.本理論により摩擦圧力損失と熱伝達係数の断面ボイド率分布への依存性が定量的に明らかになった.

著者

佐藤 泰生 佐田富 道雄 川原 顕磨呂 朝倉 信次

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.57, no.538, pp.1979-1984, 1991-06-25 (Released:2008-03-28)

参考文献数

10

被引用文献数

2 2

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The purpose of this work is to propose an experimental method of a two-dimensional (2-D) two-phase gas-liquid flow. A test channel in which a nearly 2-D, uniform two-phase flow can occur was made. This channel was a vertical, narrow gap space made up of two large concentric pipes. A two-phase air-water flow around a body mounted in the channel was recorded consecutively by a high-speed TV camera, and its void fraction distribution was determined using image processing. Several results for flows around a flat plate, and flows along a straight wall and flows between parallel walls were obtained.

著者

古川 徹 世古口 言彦

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.52, no.473, pp.199-207, 1986-01-25 (Released:2008-03-28)

参考文献数

13

被引用文献数

1

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環状流路内を垂直に上昇する空気-水系二相流の相分布に関する調査を行った。実験には半径比の異なる3種類の環状流路を用いた。まず,環状流路における流動様式について述べ,次いで,断面内ボイド率分布を提示し,流路幅が及ぼす影響について論ずる。調査の対象とした流動様式は気泡流,スラグ流,フロス流およびフロス流領域に近い環状流である。最後に断面平均ボイド率の整理式を導出した結果について報告する。

著者

白羽 陸宏 藤井 健一 原田 英一 野添 浚平 平尾 元亮

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.57, no.542, pp.3513-3519, 1991-10-25 (Released:2008-03-28)

参考文献数

11

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The slag flow rate and heat flux through a combustor wall were measured in a 24 T/D pilot plant of a coal partial combustor, which is one kind of slagging cyclone combustor. Results of computer analysis on the slag behaviour and the heat transfer were compared with good agreement to the test results. The computer model predicted the following characteristics. (1) The slag flow rate showed rapid increase or sudden decrease when combustion conditions were changed. (2) The effects of various factors were evaluated, including the firing rate, combustor stoichiometry, ash content, flux additive, air preheat temperature, enriched oxygen concentration, refractory thickness, cooling-wall temperature and the reactivity of coals.

著者

木村 俊哉 川崎 聡 島垣 満 内海 政春 後藤 公成

出版者

The Japan Society of Mechanical Engineers

雑誌

日本機械学会論文集 B編 (ISSN:03875016)

巻号頁・発行日

vol.78, no.787, pp.576-587, 2012

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CFD simulations were performed for the leakage flow in the gap between the casing and the shroud of a centrifugal impeller. The effects of swirl brakes equipped in the casing on the leakage flow were numerically investigated. The leakage flow swirling due to impeller rotation was trapped inside swirl brakes and interacted with the walls of the swirl brake, generating a very complex flow and a vortex structure inside. By the interaction with swirl brakes, the leakage flow rapidly lost its angular momentum mainly in the outer region of the swirl brake. The loss of swirl resulted in a decrease of the pressure difference in the radial direction due to the centrifugal force effect. The radial distribution of pressure in the gap between the casing and the shroud was largely modified, and thus the axial thrust force on the impeller was changed as well. The thrust balance of the impeller can be adjusted by an appropriate design of swirl brakes and the instability of rotating shaft can be reduced by decreasing the swirl of the leakage flow.

著者

西 義久 木下 泉 西村 聡

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.70, no.691, pp.715-722, 2004-03-25 (Released:2011-03-03)

参考文献数

17

被引用文献数

2

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The experiments about the gas lift pump in lead-bismuth eutectic are performed with risers of three kinds of diameters [φ 69.3 mm (SD case), φ 106.3mm (MD case), φ 155.2mm (LD case)]. The main results are as follows : (1) The coefficient of the drift flux model was derived from the experimental results. (2) The LBE flow rate obtained from the design method based on water/gas system with the relation of the drift flux model corresponds to the experimental results obtained in the MD and the SD cases. It is considered that the evaluation method can be used for the LBE gas lift pump in a small diameter riser. (3) In the LD, the design method excessively evaluates the lead-bismuth circulating flow rate. It thought that the circulation head will not occur in the experimental loop. The following factors are considered to be the causes of this the three-dimensional behavior of bubbles becomes significant, and the local descending flow is generated in the riser when the riser diameter increases.

著者

武田 好央 中込 恵一 新村 恵一

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.2887-2894, 1996-07-25 (Released:2008-03-28)

参考文献数

6

被引用文献数

5 8 8

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There is a gradient of fuel concentration in the spray of conventional direct-injection diesel engines. Therefore, a region of stoichiometric mixture ratio exists in the injected spray and a high concentration of NOχ is produced. In this study, fuel injection timing was widely advanced to promote the mixing of fuel and air. Using this injection method, the engine could be driven with premixed lean diesel combustion (PREDIC), and NOχ emissions were greatly reduced. To avoid the fuel spray contacting the cylinder liner, the fuel was injected by two side injectors simultaneously. The two sprays from the side injectors collided with each other and remained in the center region of the cylinder. Thus mixing of fuel and air was promoted by a long ignition delay period. In the case of conventional injection methods, NOχ could not be reduced to under 400ppm (λ=2.7). In contrast, in the case of PREDIC, NOχ emissions were reduced to as low as 20ppm (λ=2.7).

著者

西野 耕一 笠木 伸英 平田 賢 佐田 豊

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.55, no.510, pp.404-412, 1989-02-25 (Released:2008-03-28)

参考文献数

13

被引用文献数

6 8

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A technique for measuring instantaneous, three-dimensional velocity components in liquid flows was developed using digital image processing system. This system consists of three TV cameras, a digital image processor, a stroboscope, a laser disk recorder and a 16-bit microcomputer. The three-dimensional displacements of fine particles suspended in the liquid are tracked by the TV cameras and recorded on the laser disk recorder. The recorded image data is later replayed and sent to the image processor, and the three-dimensional velocity field is automatically calculated on the microcomputer. Uncertainty intervals associated with the present technique are systematically evaluated. An unsteady laminar Couette flow between two concentric cylinders, of which the outer cylinder starts to rotate impulsively, is measured by the present technique. The instantaneous velocity profiles measured show good agreement with the analytical solutions within the experimental uncertainty, and thus, the present technique is proven to be applicable to the measurement of unsteady flow. The decay of turbulence generated in a stirred water tank is also measured in good agreement with the theoretical prediction.

著者

篠原 俊夫 松浦 祐太郎

出版者

The Japan Society of Mechanical Engineers

雑誌

日本機械学会論文集 B編 (ISSN:03875016)

巻号頁・発行日

vol.46, no.406, pp.1065-1073, 1980

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軸流タービンの内部効率向上のため,損失の大きなブレード先端部および根本部の流れについて翼列実験およびモデルタービン実験を行い,主流と損失流れとの相互関係を明らかにした.そして,翼先端および翼根本での反動度を買えた新しいフローパターンを考え,これをノズルをねじることにより実験して,従来系との比較実験を行った.その結果1%以上のタービン効率の上昇を確認した.

著者

北川 石英 山本 和明 村井 祐一

出版者

The Japan Society of Mechanical Engineers

雑誌

日本機械学会論文集 B編 (ISSN:03875016)

巻号頁・発行日

vol.78, no.793, pp.1539-1549, 2012

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This paper describes effects of microbubble injection on natural convection heat transfer from a vertical heated plate in water. Thermocouples are used for the temperature measurement and an image processing technique is used for obtaining the bubble diameter, the bubble velocity and the bubble layer thickness. The working fluid used is tap water, and hydrogen bubbles generated by electrolysis of the water are used as the microbubbles. For a constant bubble flow rate and a constant wall heat flux, in the laminar and transition regions, the heat transfer coefficient is significantly increased by the microbubble injection (The ratio of the heat transfer coefficient with bubble injection to that without injection is 1.6-2.0 in both regions). The heat transfer enhancement in the laminar region results from both the forced-convection and mixing effects due to microbubble injection. On the other hand, the heat transfer enhancement in the transition region is mainly affected by acceleration of the transition to turbulence due to microbubble injection.

著者

大橋 博志 門脇 敏

出版者

The Japan Society of Mechanical Engineers

雑誌

日本機械学会論文集 B編 (ISSN:03875016)

巻号頁・発行日

vol.79, no.802, pp.1185-1185, 2013

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3件の誤植がありましたので訂正いたします.

著者

西村 正治 糟谷 秀太郎 後藤 知伸

出版者

The Japan Society of Mechanical Engineers

雑誌

日本機械学会論文集 B編 (ISSN:03875016)

巻号頁・発行日

vol.78, no.789, pp.949-953, 2012

被引用文献数

1

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Light wall structures with high sound insulation performance are desired to be developed for houses and fuselage of vehicles. In this paper, a new light sound insulation structure is proposed. It is constructed with light inflated membrane bound by hard wire nets. By impedance tube tests, the proposed structures were proved to have not only high but also adjustable sound insulation performance by tuning the inside air pressure, which means stiffening the membranes. This structure can also construct a light sound insulation panel with high sound insulation performance by being inserted between light double walls.

著者

大西 領 高橋 桂子 小森 悟

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.72, no.722, pp.2441-2448, 2006-10-25 (Released:2011-08-16)

参考文献数

21

被引用文献数

1 1

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The collision frequency of inertia particles in turbulent flows is governed by a wide range of scales of flow motion. Recent studies have shown that large-scale energetic eddies dominate the relative velocity between two colliding particles (the turbulent transport effect), whereas small-scale dissipative eddies can enhance the collision frequency significantly by inducing local non-uniform particle distribution (the accumulation effect). In this study, we have developed an integrated collision kernel model, which takes into account both the turbulence effects and can predict collision frequencies at arbitrary Reynolds numbers and particle inertia. In addition, we have implemented the developed collision kernel model into a large-eddy simulation (LES). We have performed our developed LES for particle collision growth in an isotropic evolving turbulence. A direct numerical simulation (DNS) for the same system has also been done. Comparison between our LES and DNS predictions has confirmed that our LES can predict the particle collision growth in the turbulent flow.