著者

金 由澤 田中 和博 山田 五代治 松本 洋一郎

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.66, no.644, pp.1126-1131, 2000-04-25

被引用文献数

1

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It is reported recently that the pump head deterioration near the best efficiency point, from single-phase flow to the choke due to air entrainment became less in a screw-type centrifugal pump than in a general centrifugal pump. Moreover, at a narrow tip clearance, the pump head became partially higher in two-phase flow than that in single-phase flow. However, the internal pressure fluctuations on this pump due to air entrainment have not been studied yet. For that reason, we have examined the influences of void fraction, flow coefficient and impeller tip clearance on pressure fluctuations in the casing. At narrow tip clearance, the pump head increment in two-phase flow mainly depends on the pressure increasing in the volute casing. And the void fraction became larger, the influence of tip clearance on pressure distribution became less. Moreover, we have observed the internal flow patterns by using a stroboscope and a halogen sheet light. Then, we have investigated the influences of flow coefficient on air-water two-phase pump performance.

著者

鷲尾 誠一 高橋 智 上山 恭平 番匠谷 勝之 菊井 翔太郎

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.72, no.723, pp.2710-2716, 2006-11-25

被引用文献数

1

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A new idea has been proposed to deaerate liquid flowing in a channel on an on-line basis, utilizing a near-vacuum cavity formed on the wall downstream of the point of separation in most vigorous cavitation. The idea has been materialized such a concrete method as connecting a vacuum pump to the cavity formed in a cylindrical constriction and sucking out gas coming out successively from the surrounding liquid. When the method was tested in a hydraulic unit with 25 L of oil in the tank, the gas solubility in the oil was lowered by 40% in 30 minutes. The two experimental factors such as a flow rate through the constriction and air dissolution from atmosphere were examined in the same test unit in terms of their effects on the method's capacity, showing that a larger flow rate results in a better deaseration capacity and a float covering the free surface of oil in a tank works to improve the capacity by preventing air dissolution into the oil. When the critical flow rate at which an incipient cavity emerged on the entrance edge of the cylindrical constriction was measured for oils with different air solubilities, it turned out a 60% reduction of gas solubility increased it by 33%. Moreover oil cloudy with cavitation bubbles after a start of deaeration became more and more translucent as the deaeration proceeded.

著者

劉 本柱 岡 智弘 三上 真人 小嶋 直哉

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.63, no.611, pp.2500-2506, 1997-07-25

被引用文献数

1

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Predominant resonance can occur in flow-induced noise from an expansion-cavity-type muffler for particular combinations of muffler configuration and flow velocity. This phenomenon is caused by self-excited oscillation based on the feedback response from acoustic resonances of the muffler to shear flow. Usually, the sound pressure level is much higher when predominance of tail pipe resonance rather than cavity resonance occurs. The predominance of tail pipe resonance is shown to be strongly influenced by both the frequency characteristics of acoustic amplification of the tail pipe and the frequency of velocity fluctuation with a certain phase criterion. The predominance phenomena can be generalized using a new dimensionless independent variable, (L/l')(1/M), where L, l' and M are cavity length, acoustically equivalent tail pipe length and Mach number in the tail pipe, respectively.

著者

三宅 裕 藤井 貴広 范 秦寅

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.73, no.729, pp.1167-1174, 2007-05-25

被引用文献数

2

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A model for an irregularly indented rough surface has been proposed by the authors in which tall peaks are picked up and represented by hemispheres having equal volume to corresponding peak. In practical application, drag of a hemisphere is substituted by plane shear stress on a flat plate. This simplified model surface is used to simulate flow over the original rough surface. The model requires drag of a hemisphere on a flat plate. In this work, unique drag formula which is simple and acceptably accurate in balance with the compactness of the model, is investigated by numerical simulations. The formula for a hemisphere on a flat plate is deduced on the basis of simulations by RANS, of channel flows having periodically arranged hemispheres on both plates. Obtained formula is confirmed to compare reasonably to those realized by hemispheres of different size in different ambient situation, in a rough wall channel flow, though drag largely scatters. The form is applied also to pipe flows having periodic hemispheres on the wall and is found to reproduce measured friction, satisfactorily. Although the proposed idea must be examined farther carfully and should be improved in details, promising step has been set up to make proposed model a useful method in practical application.

著者

辻 裕 森川 敬信 蝶野 成臣 井前 弘幸 吉川 敏和

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.50, no.458, pp.2378-2385, 1984-10-25

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まず,受圧板の直径がカプセル本体の直径よりも大きい実用カプセルに対応する流体抵抗式を導いた.つづいて,加速区間におけるカプセルの走行を,送風機の性能曲線およびバイパスからの空気流出を考慮し,運動方程式に基づいて解析した.さらに,終端を閉鎖した管路にカプセルを突入させ,空気の圧縮性を利用して停止させる場合についても運動を計算した.以上の結果,計算値が実験値に満足に一致することが確認された.

著者

奥井 健一 三上 房男 山根 隆一郎

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.57, no.538, pp.1973-1978, 1991-06-25

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The flow around two semi-infinite circular cylinders of the same diameter in the tandem arrangement at various spacings on a flat plate has been investigated experimentally. The cylinders were aligned with the axis normal to both the flat plate and the free stream. The time-mean surface pressures on the cylinders and the frequency of the vortex shedding in the direction of the cylinder axis were measured. The flow patterns on the cylinder were visualized using an oil-film technique and the flow visualization around the cylinders was performed by the liquid-parafine-mist technique. The flow patterns near the end of the cylinder were essentially different from two-dimensional flow. The flow passing along the end surface of the upstream cylinder became oscillating flow at the frequency lower than that of Karman vortex.

著者

平田 勝哉 清水 康介 福原 憲典 山内 一樹 川口 大輔 舟木 治郎

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.75, no.749, pp.28-39, 2009-01-25

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In this study, we deal with the tumbling, which is rotating motion with the axis perpendicular to the falling direction. Our purpose is to reveal the fundamental aerodynamic characteristics of the tumbling, experimentally. Regarding a test plate, we consider a prism with a rectangular cross section with a depth-to-width ratio λ of 0.3. The results are as follows. The reduced terminal rotating rate Ω^*, the lift coefficient C_L, the drag coefficient C_D and the lift-to-drag ratio C_L/C_D are independent of the aspect ratio AR, when AR is greater than 10. As the inertia momen ratio I^* increases from zero to 50, Ω^*, C_L and C_D increase. However, Ω^*, C_L and C_D become almost constant, at I^* greater than 50. We propose the empirical formulae to predict them. At low I^*, the tumbling shows a dominant periodicity of 360deg.

著者

益田 重明 児山 秀晴 有賀 一郎

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.p81-90, 1983-01

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固定軸のまわりに一定角速度で回転する乱流せん断流を,レイノルズ平均法を用いて予測する際に必要な乱流モデルについて検討した.モデル定数が回転に依存しないことを主眼として,レイノルズ応力方程式の高レイノルズ数モデルを導き,回転流路内の二次元乱流境界層における実結果と比較した.その結果,回転場での経験則を全く用いずに,平均場および乱流場に対する回転の効果を正しく予測することができることが示された.

著者

伊藤 基之 山田 豊 西岡 潔

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.51, no.462, pp.452-460, 1985-02-25

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容器内で回転する円板に沿う流れの遷移現象を明らかにするため,回転円板と容器壁とのすきま内における時間平均速度分布および速度変動強さを種々のレイノルズ数について測定した.そして,回転円板付近の流れは容器壁側に比べて著しく安定で乱流に遷移しにくいことや,すきまの広い場合の回転円坂上境界層の遷移過程は局所レイノルズ数のみによって支配されることなどが明らかにされた.

著者

川上 幸作

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.488, pp.p1131-1135, 1987-04

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In the previous paper, the pressure Loss coefficient of branching rapidly increased when the flow ratio in a cross pipe was in a certain zone. In this experiment, the author observed the flow condition in a cross pipe by using a hydrogen bubble method. As a result of this experiment, it is made clear that the condition of the pressure loss is closely related to the formative mechanism of a vortex and setting a straightening vane in a grade crossing section of a cross pipe restrains the rapid increase of the pressure loss. This paper reports about these phenomena.

著者

織田 剛 満田 正彦 山極 伊知郎 田中 俊光 名倉 隆雄 大石 峰生

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.64, no.620, pp.1127-1134, 1998-04-25

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Two-dimensional axi-symmetric Euler equations are solved in order to simulate the compression wave induced by a high-speed train entering a tunnel or a tunnel entrance hood. Pressure and pressure gradient histories at the tunnel entrance obtained from the calculation are compared with experimental results. It can be found that calculated results and experimental results are well corresponding each other. The effect of the cross-sectional area of the tunnel entrance hood is numerically investigated by this calculation method. Then, propagation of the compression wave along the tunnel is one-dimensionally calculated by a double mesh method which induces little numerical diffusion.

著者

城田 農 真田 俊之 荒田 康弘 渡部 正夫 亀田 正治

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.73, no.726, pp.467-473, 2007-02-25

被引用文献数

3

---

The mechanism of a bubble production method using controlled gas pressure fluctuation, originally developed by Kariyasaki and Osaka [Trans. JSME, Series B, Vol.68, No.674, (2002)1, is further investigated using high-speed photography. We found out more appropriate pressure fluctuation than that of Kariyasaki and Osaka in producing single bubble. The radius of bubbles can be varied from about 0.3 to 0.8 mm with extremely small standard deviation of less than 1μm. Shrinking motion of a capillary bridge connecting a bubble and a nozzle was observed in detail. Force balance on a growing bubble which is based on a spherical bubble formation model is also estimated. As a result, we reveal that when gas pressure is decreased the capillary bridge is sucked down into a nozzle and upward added mass force is applied on a bubble, both of which cause the detachment of a bubble from a nozzle.

著者

中別府 修 土方 邦夫 CHANDRACHOOD Madhavi LAI Jie MAJUMDAR Arun

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.62, no.593, pp.284-290, 1996-01-25

被引用文献数

5

---

A new technique, which uses the Atomic Force Microscope (AFM) coupled with a micro-thermocouple cantilever, for measurement of microscale temperature profile has been developed. Topological and thermal images of any solid sample can be obtained simultaneously by this technique. Using a handmade thin-wire thermocouple and a thin-film thermocouple deposited on a commercially available Si_3N_4 cantilever, some working small electric devices were measured in both air and vacuum. Since heat conduction through the air between the sample and the probe was dominant in air, clear but distorted thermal images were obtained. In vacuum, heat transfer through the contact point between them was so small that a signal to noise ration was low and the conventional signal amplifying technique was not helpful. The Lock-in technique was employed to detect such small signals and finally, a true temperature image of sample surface was acquired. Also, the thermal environment surrounding the cantilever in the AFM is discussed in this paper.

著者

一宮 浩市 武田 哲明 植村 拓也 範国 哲也

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.72, no.723, pp.2747-2752, 2006-11-25

被引用文献数

1

---

This paper describes the heat transfer and flow characteristics of a heat exchanger tube filled with a high porous material. Fine copper wire (diameter: 0.5mm) was inserted in a circular tube dominated by thermal conduction and forced convection. The porosity was from 0.98 to 1.0. Working fluid was air. Hydraulic equivalent diameter was cited as the characteristic length in Nusselt number and Reynolds number. Nusselt number and friction factor were expressed as functions of Reynolds number and porosity. Thermal performance was evaluated by the ratio of Nusselt number with and without a high porous material and the entropy generation. It was recognized that the high porous material was effective in low Reynolds number and the Reynolds number which minimized the entropy generation, existed.

著者

野田 信雄 池上 康之

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.69, no.680, pp.901-908, 2003-04-25

被引用文献数

4

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The purpose of this paper is to explain the optimum extraction condition of Uehara cycle under Ocean Thermal Energy Conversion (OTEC). We studied about the optimum condition of extraction which makes cycle efficiency highest, because cycle efficiency depends on condition of extraction. And we studied about influence of the performance of the regenerator to the cycle efficiency.

著者

飯田 嘉宏 筒井 健太郎

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.55, no.509, pp.194-199, 1989-01-25

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The effect of ultrasonic wave application on film boiling heat transfer is investigated. A series of heat-transfer experiments are carried out using a fine heater made of a 0.20-mm-dia. horizontal platinum wire, which is immersed in saturated ethyl alcohol and exposed to a 28 kHz ultrasonic wave. The heat-transfer coefficient increases with the increase of power supplied to a ferrite-type vibrator and it is doubled for the maximum in this experimental condition. The minimum heat-flux point is also improved. At a lower degree of superheat than the MHF line, nucleate boiling and film boiling coexist separately along the platinum wire with a high reproducibility. The film boiling configuration is also observed through photograpty. Under a high intensity of ultrasonic wave, many tiny bubbled begin to generate and the shapes of large bubble becomes rather irregular.

著者

西尾 茂文 坂口 和貴

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.53, no.490, pp.1781-1787, 1987-06-25

被引用文献数

1

---

This paper presents experimental results on the real value of the minimum-heat-flux (MHF) -point temperature for subcooled pool boiling of water from a horizontal cylinder and an advanced form of the correlation for subcooled film-boiling heat-transfer proposed in the previous paper. First, experiments to observe the collapse process of film boiling were conducted by using a high speed video. The experimental results show that the collapse mode is classified into the propagative collapse with a precursory local-collapse and the coherent collapse. Second, the propagation velocity of collapse front and the mean surface temperature upon the local collapse followed by the propagative collapse were measured. The experimental results show that, for higher propagation-velocities, the MHF-point temperature decreases and approaches the value upon coherent collapse which has only a slight dependence on liquid subcooling. Finally, an advanced form of the correlation for subcooled film-boiling heat-transfer reported in the previous paper is proposed. This equation is in good agreement with the present data of of water at subatmospheric pressures and the existing data of liquid sodium and freon R-11 at atmospheric pressure and pressurized water.

著者

三階 春夫 西田 秀夫

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.49, no.441, pp.1000-1009, 1983-05-25

被引用文献数

3

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遠心圧縮機の各要素の流れに基づく損失をモデル化し,流れと損失との関係を実験で得られた実数などを含んだ形で数式化して,要素間の相互作用を無視して積み重ねることにより性能を予測する方法を述べた.特に,従来の方式に比べて,せばまり率を導入して理論揚程や流れ角度の精度向上を計るとともに,不完全ガスを含む各種ガスに適用できる.また,計算例により本性能予測法を実際に適用する場合の問題点を検討した.

著者

佐藤 桂司 林田 和宏 天谷 賢児 新井 雅隆

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.70, no.692, pp.1051-1057, 2004-04-25

被引用文献数

12

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In this paper, separation of laser-induced fluorescence (LIF) due to PAHs and incandescence (LII) due to soot by time-resolved measurement was demonstrated for the propane diffusion flame. Laser-induced fluorescence method for the measurement of polycyclic aromatic hydrocarbons (PAHs) in diffusion flame was developed. A KrF excimer laser was used for excite the PAHs. Strong laser-induced incandescence due to soot was appeared with fluorescence signal due to PAHs. In order to separate the signals into LII and the PAHs-LIF detected from diffusion flame, time-resolved measurement was carried out. A pico-second gate CCD camera with a image intensifier was used taking a time-resolved image. From the two different images, which were taken at different time-delay, PAHs-LIF and LII were obtained. Intensity distributions of PAHs-LIF and LII were measured on the flame axis. Overlap region of the LIF and LII was observed around the onset position of the yellow flame. In this region, LIF intensity decreased and LII intensity increased along the flow direction. It seemed that this region was transition region from the PAHs to soot and was attributed the presence of soot precursor.

著者

大八木 重治 落合 辰夫 吉橋 照夫 針谷 安男

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.54, no.508, pp.3559-3564, 1988-12-25

被引用文献数

7

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Detonation cell size has been measured in a mixture of hydrogen with oxygen over wide ranges of equivalence ratio and subatmosheric initial pressure. The experiments have been carried out in a cylindrical tube of diameter 30 mm and the cell size has been determined by using the sooted plate technique. The data of the cell size at subatomospheric pressures have indicated that it is proportional to p_0^<-1.2>, where p_0 is an initial pressure of the mixtures. Values at the atmospheric pressure have been obtained by extrapolating the obtained subatmosheric values of the cell size, and have been plotted against the equivalence ratio and compared with calculated induction zone length by Westbrook. The fact that the cell size is directly proportional to the induction zone length has been verified for the oxyhydrogen mixture over the range of the equivalence ratio tested. The proportionality factor for this mixture has been found to be 23.3, while that for hydrogen/air mixtures had been found by Knystautas et al. to be 52.2. The critical initiation energies etimated from the cell size data obtained here by utilizing the theoretical model proposed by Lee have been found to be in good agreement with measured critical initiation energies by the critical tube diameter method of Matsui and Lee.