著者

増田 糧 河村 清美 永岡 真 増渕 匡彦 小森 啓介

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:18848346)

巻号頁・発行日

vol.78, no.793, pp.1584-1597, 2012 (Released:2012-09-25)

参考文献数

25

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A liquid fuel injection nozzle with a novel fuel atomization strategy which actively utilizes the effect of collapse of cavitation bubbles in a liquid jet is proposed. The nozzle comprises two orifices and an intermediate cavity between the orifices. The role of the upstream first orifice is to generate the cavitation bubbles at both inlet and exit of the orifice. The intermediate cavity is placed to hold the cavitation bubble within it. The role of the downstream second orifice is to mix the cavitation bubbles and liquid fuel, and to inject the mixture into atmosphere. Each size and relative positions of the first orifice, the intermediate cavity and the second orifice were studied using multi-phase computational fluid dynamics. Finally, a poppet type nozzle whose void fraction at the nozzle exit is 0.5 was designed.

著者

有田 隆一 加瀬 篤志 大場 謙吉

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:18848346)

巻号頁・発行日

vol.77, no.775, pp.823-831, 2011 (Released:2011-03-25)

参考文献数

5

被引用文献数

3

---

The purpose of this research is to elucidate the mechanism of aerodynamic force generation and control in flapping flight of a mosquito. In this paper, a tenfold enlarged realistic model of the flapping wing was used to simulate the motion of the mosquito's wing and flow pattern around it. Experiments were conducted using a very low speed wind tunnel to coincide the condition of Reynolds and Strouhal numbers with those of real mosquito. The flow field around the wing model was analyzed by a stereo-PIV system. The aerodynamic forces generated by the model wings were calculated by using a momentum conservation law applied to the flow field. In these experiments, two unsteady ring vortexes around model wings were observed. The magnitude and direction of the jet flow induced by the ring vortex were greatly influenced by the attack angle. It was found that the lift was generated during the down-stroke and the thrust during the up-stroke in the real mosquito's flight.

著者

長谷川 裕晃 大津 里実

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:18848346)

巻号頁・発行日

vol.77, no.783, pp.2049-2057, 2011 (Released:2011-11-25)

参考文献数

20

被引用文献数

1

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The reverse osmosis (RO) method is a method obtaining the fresh water by using semi permeable RO membrane. However, the RO method has to give continuous operation at high pressure in seawater desalination plants. In the present study, in order to improve the efficiency of RO desalination under low pressure conditions, the water treatment system is proposed by using microbubbles in salt water disposal. Microbubbles are very small air bubbles with diameters of the order of less than several tens microns, and our proposed microbuble generator was developed in our previous study. The RO desalination efficiency can be improved by microbubble generation in salt water in contrast to the method with no microbubbles, and the efficiency of desalination is significantly improved by microbubbles with a high electrical potential. The effect of the microbubbles on the rate of osmosis was also investigated by measurements of the electric conductivity and the shrinkage rate of microbubbles. The electrical conductivity of salt water decreases with increasing the electrical property of the gas-water interface (ζ- potential) of microbubbles. Furthermore, microbubbles with a high electrical potential of high number density in salt water can exist in salt water because the rising velocity and the shrinkage rate of microbubbles become smaller with increasing the high electrical potential of microbubbles.

著者

平沼 賢次 川名 優孝 刑部 真弘 木船 弘康 毛利 邦彦 犬飼 和具

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:18848346)

巻号頁・発行日

vol.79, no.799, pp.234-238, 2013 (Released:2013-03-25)

参考文献数

2

被引用文献数

2

---

This paper describes on the energy saving experiment by using the smart meter. In Japan, last summer, the power shortage was concerned and the limited use of electric power had been issued from the government. We constructed display system of the electric power consumption of Tokyo University of Marine Science and Technology (TUMSAT) on the web. This system could provide the average power usage during 10 minutes to promote the energy saving actions of each consumer. From the energy saving experiment in our university, it was found that the display on web was significantly effective to suppress the consumption of electric power without the compulsory cut off.

著者

山田 和豊 喜久田 啓明 古川 雅人 郡司嶋 智 原 靖典

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:18848346)

巻号頁・発行日

vol.79, no.801, pp.900-916, 2013 (Released:2013-05-25)

参考文献数

28

被引用文献数

1 1

---

Flow fields near rotating stall inception in a low-speed axial compressor rotor with two different tip clearances have been investigated by instantaneous measurements of casing wall pressure distributions using 30 high response pressure transducers and by detached eddy simulations (DES) using 120 million grid points. It is found that the stall inception process in the large tip clearance case is dominated by the breakdown of the rotor tip leakage vortex, in contrast to the spike-type stall inception in the small tip clearance case which is dominated by the leading-edge separation near the rotor tip. The vortex breakdown induces the large oscillation of the tip leakage vortex with its unsteady nature, resulting in the low-pressure regions in the instantaneous casing wall pressure field and the high pressure fluctuation region on the pressure side of the adjacent blade tip in the ensemble-averaged casing wall pressure field. The large blockage effect due to the tip leakage vortex breakdown causes the rotating disturbance propagating in the circumferential direction, which can appear and disappear with a slight change in the flow rate.

著者

横山 博史 北宮 克哉 飯田 明由

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:18848346)

巻号頁・発行日

vol.79, no.804, pp.1419-1433, 2013 (Released:2013-08-25)

参考文献数

16

被引用文献数

1 1

---

To clarify the mechanism of acoustic radiation in flows around a cascade of flat plates, fluid structures and acoustic fields were elucidated by direct simulations. The simulations were mainly performed for flows around 5 parallel plates and the separation-to-thickness ratio s/d was 6.0. The freestream velocity was changed from 30 m/sec to 60 m/sec, and the acoustic resonance occurs between plates at the freestream velocity of 44 m/sec. At that velocity, the Reynolds number based on the chord length and the freestream velocity was 8.7×104 and that based on the plate thickness was 5.8×103. Computational results were validated by the experimental results performed in the present research. The computational results showed that large-scale vortices composed of fine-scale vortices are shed in the wakes of the plates independently of the acoustic resonance. When the large-scale vortex is shed from the upper or lower face, an expansion wave is radiated around the downstream edge of the upper or lower face, respectively. The compression wave is radiated around the downstream edge of the opposite face. The simulation for the flow around a single plate was also performed, and the results confirmed the above-mentioned acoustic radiation mechanism. For the flows around a cascade of flat plates, the sheddings of the vortices from neighboring plates are synchronized when the acoustic resonance occurs. It was also clarified that the mode of the synchronization is an anti-phase mode and the standing waves generated between plates are reinforced.

著者

吉住 文太 近藤 靖裕 諸井 隆宏 玉野 真司 森西 洋平

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:18848346)

巻号頁・発行日

vol.79, no.806, pp.2003-2018, 2013 (Released:2013-10-25)

参考文献数

3

被引用文献数

2 2

---

The opening delay of a discharge reed valve for compressors caused by the oil film in the clearance between the reed and the valve seat is investigated. The developed simulation method which couples the reed deformation, the gas flow and the oil film flow is applied to simulate delay times on two types of seats with different contact areas. Three models for cavitaion in the oil film are tested; no-cavitation model, the static cavitation model (Reynolds' condition), and the dynamic cavitaton model in which the bubble expansion is directly simulated. The calculaion through the dynamic cavitation model reproduces well experimental results with regard to the delay time and oil film behaviors of cavitation and blow-by (oil film rupture). The result also shows that the growth of cavitation bubbles occupies the change in the oil film volume and prevents the oil film pressure from falling. The rupture mechanism based on the calculation results is that the increase of the oil film thickness directly causes the oil film pressure recovery leading to the blow-by flow, and both cavitation and the smaller contact area promote the growth of the oil film thickness.

著者

水口 博貴 長山 暁子 鶴田 隆治

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:18848346)

巻号頁・発行日

vol.77, no.781, pp.1826-1833, 2011 (Released:2011-09-25)

参考文献数

20

被引用文献数

1 2

---

A simple theoretical expression for the evaporation/condensation coefficient in equilibrium has been proposed by Nagayama and Tsuruta based on the transition state theory and molecular dynamics simulations in 2003. It is not clear, however, whether this approach can be applied to complex molecules such as n-dodecane with long chain structures. In this study, molecular dynamics (MD) simulations have been performed to investigate the evaporation/condensation coefficients of n-dodecane in equilibrium systems. It is found that the evaporation coefficient of n-dodecane primarily depends on the translational energy and the surface temperature similar to simple molecules like argon and water, while the molecular orientation of long chain n-dodecane has less effect. Also, the MD data of n-dodecane agree well with the theoretical expression based on the transition state theory. We conclude that the evaporation coefficient can be predicted by the translational length ratio of liquid to vapor in general even for the long-chain molecules.

著者

辻村 真治 飯田 雄章 長野 靖尚

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.67, no.659, pp.1762-1769, 2001

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In the Earth's atmosphere, zonal currents with a vertical velocity gradient are induced under the action of rotation and horizontal temperature gradient. These currents satisfying the so-called "thermal wind equation" generate the cyclones and anticyclones through the baroclinic instability, and hence have serious effects on the global circulation. In this study, the generation and development mechanisms of vertical vortices associated with the cyclones and anticyclones are investigated by using direct numerical simulation of the thermal wind. By imposing the stable density stratification in the vertical direction, the effects of the stable stratification and the Reynolds number are studied in detail. As a result, we have found the distinct effects of stable stratification on the anisotropy of the flow field and the generation of the vortical structure. It is also found that the cyclone becomes dominant in comparison to the anticyclone at a relatively low Reynolds number under the weak stable stratification. At a higher Reynolds number, both cyclonic and anticyclonic vortices are enhanced by the nonlinear vortex stretching term, and hence the asymmetry between them becomes negligible. The intensive stable stratification attenuates the nonlinear vortex stretching and contributes to the occurrence of the asymmetry in the vortices even at the higher Reynolds numbers

著者

徳尾 健一郎 有冨 俊亮 臼井 悟史

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:18848346)

巻号頁・発行日

vol.77, no.779, pp.1542-1549, 2011 (Released:2011-07-25)

参考文献数

7

被引用文献数

3 3

---

Direct injection (DI) is becoming increasingly popular among gasoline automotive engines, due to its benefits for fuel consumption and engine output. A key component of a DI system is the fuel pump, which must deliver fuel at much higher pressures than a conventional spark ignition (SI) engine. For a DI fuel pump, maximum fuel flow rate, maximum operation speed, electrical power consumptions and noise are conflicting requirements. This paper describes the development of a compact single-cylinder DI fuel pump which achieves increased fuel flow rates while consuming decreased electrical power and generating less noise, compared to conventional DI fuel pumps currently in the market. This is achieved by the introduction of a new concept for the flow rate control valve, so called normally close valve. The construction of this valve allows it to have smallest air gap between magnetic surfaces at valve open position, which makes it possible to generate high magnetic force with less electrical energy. Moreover, the magnetic force is used for handling hydraulic force, which makes it possible to handle higher flow rate. In addition, the flow rate control valve moves passively by the hydraulic forces, such that the impact noise at valve opening is reduced significantly.

著者

越後 亮三

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.48, no.435, pp.2315-2323, 1982

被引用文献数

9

---

適度の光学的厚さをもつ多孔性の通気性大層を高温の作動ガスが横切って流れるとき大きなエンタルピ落差が生じ, ふく射エネルギに変換され, その主要部が流れの上流方向に伝般する新しい伝熱系に関し理論解析と基礎実験を実施した. 本原理は応用範囲も広く, 工業用路に適用すると設計の基本概念を変革するほどの大きな効果が期待でき, 小型金属加熱炉の実験を行った結果, 60%もの燃費節減ができた.

著者

八束 真一 新山 泰徳 福田 健太郎 鹿園 直毅

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:18848346)

巻号頁・発行日

vol.79, no.808, pp.2859-2872, 2013 (Released:2013-12-25)

参考文献数

8

被引用文献数

2 2

---

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.

著者

新冨 雅仁 牧野 敦 藤井 淳志 荒木 信幸

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.69, no.678, pp.476-481, 2003

被引用文献数

1

---

An experimental study has been conducted in order to elucidate influences of additions of hydrogen and methane on the combustion synthesis of diamond films. Differences between the flat flame and the conical flame are first examined, and it is reconfirmed that the velocity gradient is one of the dominant parameters in the combustion synthesis of diamond films. Additions of hydrogen and/or methane are examined on the growth rates of diamond films, crystal sizes, and morphology. These results are also confirmed by conducting the similar experiments with a welding torch, instead of the flat flame burner. It is found that an addition of hydrogen reduces the growth rate and crystal size, while that of methane enhances those although homogeneity of the diamond films is reduced.

著者

新冨 雅仁 牧野 敦 藤井 淳志 荒木 信幸

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.68, no.675, pp.3136-3143, 2002

被引用文献数

1

---

An experimental study to synthesize diamond films has been conducted under a well-defined flow field to make clear the mechanism of combustion synthesis of diamond films. Using a flat flame burner, the homogeneous diamond films are synthesized on substrates, above which flat, premixed acetylene/hydrogen/oxygen flames are established. The effect of equivalence ratio and velocity gradient is examined on the growth rates of diamond films, crystal sizes, and their morphology. It is found that not only the maximum growth rate but also the maximum crystal size can be obtained when the equivalence ratio is about 2.50, and that the growth rate, crystal size, and/or morphology are nearly the same when the velocity gradient is kept constant. These results are confirmed by a conical flame with a welding torch. In addition, the scratching treatment for the substrates by diamond powder is unnecessary, the maximum growth rate of diamond films can be obtained when the surface roughness is about 0.11 &mu;m, and the nuclei of diamond appear in scratches on the substrates.

著者

奈良 松範

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:18848346)

巻号頁・発行日

vol.78, no.789, pp.1053-1057, 2012 (Released:2012-05-25)

参考文献数

5

被引用文献数

1

---

We researched concerning the new energy technology of producing the hydrogen gases with the organic refuse by using sunlight and phototropic bacteria. Electricity can be generated by supplying the produced hydrogen gases to the fuel cell. Hydrogen production efficiency enough to put it to practical use has not been obtained in the past though a full-scale experiment for the hydrogen production that uses algae and the microorganism that does the photosynthesis has been conducted. That is, the cost performance for practical use is not obtained. We did an experimental research that used the wavelength conversion material of sunlight and the optical reflection material of the aluminum foil as a method for the efficiency gain of the hydrogen production. As a result, the design parameter of the system to produce hydrogen with the waste fluid by using the purple non-sulfur bacteria that carried out photosynthesis was able to be decided. Substrate (The sugar manufacture waste fluid: [Molasses]) dosage in which the highest incidence of hydrogen was obtained was 0.4mg/100kcells*day for the pure culture system. Moreover, the improvement of the hydrogen production efficiency of about 15% was obtained in the maximum with a light wave length conversion net. A design parameter of the biomass hydrogen energy production system and basic data concerning the efficiency gain of the system were able to be obtained from the above-mentioned results.

著者

小笹 俊博 新関 雅俊

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:18848346)

巻号頁・発行日

vol.77, no.781, pp.1834-1843, 2011 (Released:2011-09-25)

参考文献数

10

被引用文献数

2 1

---

In the case of engine bearings, pressure in a cylinder is necessary for the analysis of lubrication. In this study, a cycle simulation of gasoline engines has been developed to predict the pressure in a cylinder under the wide range of engine operation. In the cycle simulation, intake and exhaust processes are included and combustion process is calculated with flame propagation based on burning velocity. The pressure in the cylinder is introduced into the bearing analysis to calculate the load on the bearing in addition to the inertia force. Orbital movement, minimum oil film thickness, and power loss in the bearing are estimated. This method may be useful on an engine design.

著者

平田 勝哉 川北 正寿 飯島 高善 古賀 光泰 紀平 光彦 舟木 治郎

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集B編 (ISSN:18848346)

巻号頁・発行日

vol.77, no.776, pp.1111-1126, 2011 (Released:2011-04-25)

参考文献数

12

被引用文献数

1

---

The aerodynamic characteristics of airfoils have been researched in higher Reynolds-number ranges more than 106, in a historic context closely related with the developments of airplanes and fluid machineries in the last century. However, our knowledge is not enough at low and middle Reynolds-number ranges. So, in the present study, we investigate such basic airfoils as a NACA0015, a flat plate and the flat plates with modified fore-face and after-face geometries at Reynolds number Re < 1.0×105, using two- and three-dimensional computations together with wind-tunnel and water-tank experiments. As a result, we have revealed the effect of the Reynolds number Re upon the minimum drag coefficient CDmin. Besides, we have shown the effects of attack angle α upon various aerodynamic characteristics such as the lift coefficient CL, the drag coefficient CD and the lift-to-drag ratio CL/CD at Re = 1.0×102, discussing those effects on the basis of both near-flow-field information and surface-pressure profiles. Such results suggest the importance of sharp leading edges, which implies the possibility of an inversed NACA0015. Furthermore, concerning the flat-plate airfoil, we investigate the influences of fore-face and after-face geometries upon such effects.

著者

小出 瑞康 関崎 敬広 山田 修一 高橋 勉 白樫 正高

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:18848346)

巻号頁・発行日

vol.77, no.775, pp.702-714, 2011 (Released:2011-03-25)

参考文献数

11

被引用文献数

5 4

---

The target of this research is to develop a micro electric power generator for a low cost small river monitoring device. First, the power generation by VIVs, its efficiency coefficient and the optimum condition of the generator were estimated from energy balance analysis based on the assumption that VIVs can be regarded as a resonance oscillation of a linear system. Second, water tunnel experiments were carried out and it was confirmed that the trailing vortex induced vibration (TVIV) occurs on a cruciform circular-cylinder/strip-plate system over a velocity range about 15 times wider than that of Karman vortex induced vibration (KVIV). Finally, power generation experiments were carried out by utilizing TVIV. The generator circuit consists of coils mounted on the circular cylinder vibrated by TVIV and magnets fixed on rigid supports. The generator is shown to extract energy from the water flow in the same way as a viscous damper over the expected velocity range. Although the efficiency coefficient of TVIV is lower than that of KVIV, it is more appropriate for natural rivers of which flow velocity changes greatly.

著者

村田 香 長倉 清

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:18848346)

巻号頁・発行日

vol.78, no.789, pp.974-978, 2012 (Released:2012-05-25)

参考文献数

5

被引用文献数

1 2

---

It is necessary to understand the vibratory properties of a track and a wheel in order to evaluate the rolling noise. In this paper, focusing on the vibration of a wheel, we measured the accelerance of the corrugated wheel by the impact test. Then accelerometers were temporarily placed on the tire and web of the wheel of a vehicle which runs on a narrow gauge, we have measured the acceleration of the rolling wheel. In addition, we reported the vibratory properties of a wheel with a wheel flat and passing a turnout.

著者

劉 本柱 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

日本機械学会論文集B編 (ISSN:03875016)

巻号頁・発行日

vol.62, no.600, pp.3220-3226, 1996

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The flow induced noise from an expansion cavity-type muffler increases abruptly for some sizes of mufflers and flow velocities. This phenomenon is strongly related to the resonance of the tail pipe and the cavity of the muffler ; therefore, it is called the predominance of resonance&Prime;When the cavity length is increased, the measured resonance frequency shows periodic jumps. The cause of the predominance of resonance is assumed to be the generation of vortex rings with a particular frequency in the cavity. The generation of vortex rings is verified by analyzing fluctuating velocities in the cavity when the predominance of resonance occurs. The phenomenon is induced not only by the tail pipe resonance, but also by the cavity resonance. It is suggested that there exists the feedback phenomenon from the sound to the flow and it is strongly related to the sound pressure level in the cavity.