著者

中山 満茂 荻原 五郎

出版者

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.51, no.462, pp.p725-729, 1985-02

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In order to develop the low NO_x combustion system and high performance steam generator, several tests had been made. The first, to reduce NO_χ emissions , a new type swirl nozzle has been developed. The feature of this nozzle. The second, the combustion tests with package type boiler have been made. From the experimental investigations, NO_χ emission levels emitted from this combustion chamber the grooved swirl nozzle were 30-40 percent less than that of the conventional hollow-cone type swirl nozzle.

著者

高橋 陽一 末永 陽介 北野 三千雄 工藤 めぐみ

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.712, pp.3046-3052, 2005

被引用文献数

2

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Response of a cylindrical premixed flame to periodic concentration fluctuation was investigated. The flame was formed in a porous cylinder by percolating the mixture uniformly through the cylinder wall. The burner used here was devised so as to fluctuate the mixture concentration (equivalence ratio) only in the radial direction of the flow (vertically to the cylindrical flame surface) without varying the flow field. With this burner the time variations of burning velocity, burnt gas temperature and flame luminosity were measured for the lean methane-air mixture in the range of fluctuation frequency from 3 Hz to 50 Hz, and the results were examined from the viewpoint of flame curvature effects. The results show that the variation width of the burning velocity of the dynamic flame is larger than that of the static flame corresponding to the concentration fluctuation. Burnt gas temperature and flame luminosity also exhibit similar tendencies. The magnification ratio of the variation width depends on the flame curvature and the large flame curvature makes the flame sustainable even for the mixture leaner than the flammability limit of the static flame.

著者

藤井 照重 太田 淳一 蒋 安衆 木島 和夫 金加 貴史

出版者

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.56, no.527, pp.p2093-2097, 1990-07

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In a system constructed by combining a gas turbine with a generator and an unfired waste-heat-recovery boiler,the exhausted gas becomes the heat input to the boiler and thus,the characteristics of this heat input obviously differ from those of the heat input to a conventional boiler system. To clarify the dynamic characteristics of the unfired waste-heat-recovery boiler,a simple naturalcirculation loop tube was manufactured to simulate an actual boiler. The experiments on dynamic responses with step changes in heat input were carried out for the cold start of about 10℃ and the warm start of 50℃ or 90℃. Dynamic responses such as the drum pressure,the drum water level and the natural-circulation velocity were clarified experimentally.

著者

平石 雅之 蔦原 道久

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.74, no.746, pp.2132-2137, 2008

被引用文献数

2

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We propose the Spectral Lattice Boltzmann Method (SLBM) that is the numerical calculation method of fluids based on the lattice BGK (Bathnagar-Gross-Krook) model discretized with spectral method. Two-dimensional homogeneous isotropic turbulence are simulated by the SLBM. Numerical results agree with another calculation results i.e. the energy spectra proportional to the wave number to -4 and backward cascade of energy is observed. As a result, we obtain the conclusion that homogeneous isotropic turbulence can be simulated by the SLBM, and it is confirmed that this method is useful for numerical simulations of turbulent flows.

著者

稲田 英一 山下 克典 棚橋 隆彦

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.62, no.597, pp.1685-1692, 1996-05-25 (Released:2008-03-28)

参考文献数

11

被引用文献数

1 1

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In the present paper, unsteady natural convection flows of air in a square cavity with differentially heated walls are investigated numerically using the hybrid-GSMAC (generalized and simplified marker and cell) finite-element method. A direct-numerical simulation of two-dimensional turbulence is shown in the present paper without introducing any random forces. The present result at Rα=1.0×108 is compared with the other numerical results. The present result of calculation is in good agreement with that of the others This study allows us to say that the hybrid-GSMAC method suggested by Tanahashi is clarified. In addition, selected frames from an animation generated from the computational results at Rα=1.0×109 show very clearly the formation of large-scale eddies via the following sequence : initial instability, proceeding through transition, and eventually the statistical steady state. Using this method, it is possible to investigate natural convection and heat transfer phenomena at high Rayleigh numbers up to 1010.

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

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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

小垣 哲也 小林 敏雄 谷口 伸行

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.633, pp.1559-1567, 1999-05-25 (Released:2008-03-28)

参考文献数

15

被引用文献数

3 2

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In order to conduct direct numerical simulation (DNS) or large eddy simulation (LES) of turbulent flows in complicated flow geometry, accurate finite difference methods are needed in generalized curvilinear coordinate system. Recently, it was shown that the analytical conservation properties of the set of basic equations are needed to be satisfied properly even in discretized basic equations in order to obtain accurate and stable solutions in simulations of incompressible turbulent flow using finite difference method. The basic equations treated here are the continuity equation, the Navier-Stokes equation and the transport equations of the square values of velocity components and the kinetic energy. In this paper, finite difference schemes in generalized curvilinear coordinate system that are suitable for simulations of incompressible turbulent flow are constructed from relatively simple extension of the proper finite difference schemes derived in equidistant Cartesian coordinate system. The extension of finite difference scheme into generalized curvilinear coordinate system is based on the fact that the analytical conservation properties of the coordinate transformed basic equations for incompressible viscous flows are identical with that in Cartesian coordinates.

著者

中島 求 面田 雄一

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.73, no.734, pp.2010-2017, 2007

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The objective of this study was to develop a simulation method for analysis of body behavior in skydiving freefall and to clarify the most stable body position during the freefall. The details of the developed simulation method were firstly described. Using the simulation method, we conducted an optimizing calculation to maximize an objective function with respect to the stability in the freefall. It was found that the most stable position became arched one. In order to clarify the reason why the most stable position became arched, optimization with respect to a simple shaped object which consists of 20 cylinders was conducted. Then the angle to maximize the restoring moment for each cylinder element was analytically calculated and compared with the optimized angle. From the results, we conclude that the most stable position becomes arched mainly since the restoring moment at each part itself becomes maximum at that angle. We also conclude that the magnitude of the arch in the most stable position is determined by the ratio of the normal and tangential drag coefficients.

著者

日向 滋 桜井 正幸 姫野 修廣 岩出 浩正

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.535, pp.971-976, 1991-03-25 (Released:2008-03-28)

参考文献数

14

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The theoretical study was carried out to clarify the mechanism of bubble formation through a submerged nozzle in upward water flow. On the basis of the experimental results, a model of breakup of the air column in which the surface membrane is oscillating at the top of the nozzle due to the disturbance of flow was proposed. The size of the bubble generated from a nozzle in a stream ranging from Nozzle Reynolds number 1500 to 15000 was determined by applying the theory of the instability of a jet which was first analyzed by Lord Rayleigh. The proposed model is in good agreement with the experimental results.

著者

近江 宗一 井口 学

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.47, no.418, pp.993-1001, 1981-06-25 (Released:2008-03-28)

参考文献数

26

被引用文献数

2 1

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前報における円管内振動流れの速度分布や管摩擦係数に関する実験結果によれば, 振動流れの乱れ生成機構は定常流れのそれと類似している. 本報告では振動流れの乱れ生成領域は定常流れの場合と同じであるとして, 管内にこの領域が完成されたときのレイノルズ数を臨界値としてこれを評価する式を導き, 計算値が測定値とよく一致することを示すとともにバースト現象が起こる臨界周期と定常乱流の平均バースト周期との関係を求めた.

著者

小糸 康志 井村 英昭 望月 正孝 齊藤 祐士 鳥居 修一

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.72, no.714, pp.404-411, 2006-02-25 (Released:2011-03-03)

参考文献数

12

被引用文献数

1

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A “Vapor Chamber” is used as a novel heat spreader to cool high-performance MPUs (micro-processor units). The vapor chamber is placed between small heat sources and a large heat sink. This paper describes the effect of heat source size on the heat transfer characteristics of the vapor chamber. First, by the experiments, the effect of heat source size on the temperature distribution of the vapor chamber is investigated, and the validity of the mathematical model of the vapor chamber is confirmed. Secondly, by the numerical analyses, the effect of heat source size on the thermal resistances inside the vapor chamber is discussed. It is found that the heat source size greatly affects the thermal resistance of the evaporator section inside the vapor chamber. Although the thermal resistance is hardly affected by the heat generation rate and the heat flux of the heat source, it increases as the heat source becomes smaller.

著者

内山 知実 成瀬 正章

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.74, no.742, pp.1324-1331, 2008-06-25 (Released:2011-03-03)

参考文献数

16

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This study proposes a two-dimensional grid-free simulation method for gas-particle two-phase flow. The method is based on a vortex method, in which the vorticity field is discretized by vortex elements. The behavior of vortex element and the particle motion are simultaneously computed by the Lagrangian approach. Four square cells are allocated around each particle. In each cell, the change in the circulation of gas-phase due to the particle motion is calculated, and it is considered through the change in the strength of vortex element. The grid-free method is applied to simulate the particulate jet generated by small glass particles falling from a slit orifice into an unbounded quiescent air. It is shown that the simulated distribution of air velocity is favorably compared with the measurement. It is also confirmed that the entrained air flow rate agrees well with the prediction by an analytical model. These results suggest the validity of the method.

著者

野村 信福 中川 勝文

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.59, no.563, pp.2232-2237, 1993-07-25 (Released:2008-03-28)

参考文献数

23

被引用文献数

3 4

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Ultrasonic enhancement of heat transfer on a narrow surface was measured by changing the width of the surface from 8 to 0.1 mm. Ultrasonic power of 600 W with a frequency of 40 kHz was used. Heat transfer on the narrow surface without ultrasonic vibration was correlated by means of the experimental equation for thin wire. The cavitation intensity was measured by means of the cavitation erosion loss of aluminum foil of 15μm thickness. The effects of acoustic streaming and cavitation were separated by this measurement. Heat transfer by acoustic streaming was predicted through the forced convection. Enhancement by cavitation was explained by the turbulence heat conductivity of the microjets.

著者

野村 信福 中川 勝文

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.59, no.562, pp.2028-2034, 1993-06-25 (Released:2008-03-28)

参考文献数

16

被引用文献数

3 2

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The cavitation intensity and the heat transfer coefficient on the bottom surface of the object, by applying ultrasonic vibration, were measured experimentally. The object faced the ultrasonic generator adhered to the bottom of the water tank. The dimensions of the object were greater than the ultrasonic wavelength. Ultrasonic power of 600 W with a frequency of 40 kHz was used. The cavitation intensity was defined by the erosion loss of aluminum foil, whose thickness was 15 μm, when aluminum foil stuck on the bottom of the object was immersed into water in the ultrasonic field. The result was that the larger the cavitation intensity became, the more the heat transfer coefficient increased. With varying densities of objects, the greater the density was the larger the cavitation intensity.

著者

岡田 昌章 渡部 康一

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.52, no.473, pp.135-143, 1986-01-25 (Released:2008-03-28)

参考文献数

40

被引用文献数

3

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工業上重要な熱物性値である各種フロン系冷媒の表面張力に関する実測情報を収集し、比較・検討することにより各県九社の実測値についてその信頼性を評価した。これらの実測値情報にもとづき、17種類のフロン系冷媒について、広い温度範囲にわたり最も信頼し得ると考えられる表面張力値を与える相関式を、核物質に共通の関数形を用いて作成した。さらに、各温度における表面張力値を、その不確かさとともに数値表としてまとめた。

著者

東野 文男 菊地 英弥

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.49, no.437, pp.115-120, 1983-01-25 (Released:2008-03-28)

参考文献数

2

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気体と液体の二つの相の領域を考え,気体中で発生した爆風が境界面を通して液体中へ伝ぱする問題を波の干渉を考慮して解析した.解析結果はエクスプローデイング・ワイヤによる実験結果と良く一致し,特に水面上の爆発に対する結果を良く説明できた.また,水中へ透過した圧力波の伝ぱ速度は,水面上で最も強く爆風の影響を受け,ある一定時間後に水の音速まで減衰する.

著者

神保 佳典 高比良 裕之 小林 一道 安田 章宏

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.219-229, 2010-02-25 (Released:2017-06-09)

参考文献数

17

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The growth and collapse of a bubble under a floating body are simulated by using the boundary element method with linear elements to predict the damage of ship bodies induced by underwater explosion. The three-dimensional deformation of the bubble, the translation and rotation of the floating body, and the motion of water surface are taken into account in the simulation. It is shown that the bubble deforms three-dimensionally, and the liquid jet threads the bubble due to the interactions among the bubble, the floating body, and the water surface; the directions of the bubble translation and the liquid jet depend on the initial location of the bubble. The Kelvin impulse is found to be useful in evaluating the translational motion of the bubble. Also, the horizontal translational motion of the bubble is much dependent on the rotational motion of a floating body; when the moment of inertia of the floating body is small, the largest horizontal translation is realized between the axis of flotation and the edge of the floating body. It is also shown that there exists an initial horizontal bubble location where the moment of force acting on the floating body has the maximum value.

著者

亀本 喬司

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.75, no.760, pp.2349-2351, 2009-12-25 (Released:2017-06-09)

参考文献数

2

著者

里深 信行

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.718, pp.1385-1387, 2006-06-25 (Released:2011-03-03)

著者

前川 博

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.724, pp.2845-2850, 2006-12-25 (Released:2011-03-03)

参考文献数

20