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

---

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

---

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

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

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

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

武藤 昌也 坪倉 誠 大島 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:18848346)

巻号頁・発行日

vol.77, no.775, pp.781-792, 2011 (Released:2011-03-25)

参考文献数

14

被引用文献数

1

---

Flow characteristics and fluid force on a sphere rotating along with axis perpendicular to mean air flow were investigated using Large Eddy Simulation (LES) at two different Reynolds numbers Rep of 1.0×104 and 2.0×105. As a result of simulation, opposite flow characteristics around the sphere and displacement of the separation point were visualized depending on the Reynolds number even though rotation speed according to the Reynolds number is the same. When the sphere rotates at some specific rotation velocity and at Rep = 1.0×104, flow characteristics agree with the flow field explained in the Magnus effect. While sphere rotates at the same rotation velocity while increasing Rep to 2.0×105, separation point moves in opposite direction and wake appears in the different direction. The reason of the negative Magnus force was discussed in terms of the boundary layer transition on the surface.

著者

寺島 修 伊澤 精一郎 稲澤 歩 福西 祐

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.773, pp.56-65, 2011 (Released:2011-01-25)

参考文献数

19

被引用文献数

4 2

---

The streamwise interface of an isolated turbulent region in a laminar flat plate boundary layer is investigated by performing a wind tunnel experiment. In the experiment, bimorph-type piezoceramic actuators are used to generate a trapezoidal-shaped turbulent region that has a wide interface in the spanwise direction. With the use of the piezoceramic actuators, the interference of the spanwise interface with the streamwise interface of the turbulent region is eliminated. Therefore, the streamwise interface can be considered as an independent interface. The experimental results show that the rms value of the velocity fluctuation and the turbulent fluctuation rapidly changes at the leading edge of the turbulent region. On the other hand, the rms value of the velocity fluctuation remains high after the turbulent fluctuation disappears at the trailing edge of the turbulent region. It is also shown that the traveling speed of the trailing edge of the turbulent region is faster than the ensemble-averaged streamwise velocity at the trailing edge of the turbulent region near the wall (η≤1.3). In addition, the velocity profile at the trailing edge of the turbulent region indicates the existence of the acceleration of the turbulent fluid near the wall. From the above results, it is found that the inverse transition occurs at the trailing edge of the turbulent region near the wall due to the acceleration of the turbulent fluid.

著者

大橋 博志 門脇 敏

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.477-481, 2013 (Released:2013-03-25)

参考文献数

8

被引用文献数

1 1

---

To investigate the front shape and fluctuation of cellular flames on a flat burner, we treated CH4/Air mixtures and two types of CH4/O2/CO2 mixtures. We obtained the front shape of cellular flames, i.e. the cell width and cell depth, by the planar laser-induced fluorescence of CH radicals (CH-PLIF) and measured the light emission to clarify the characteristics of fluctuation of premixed flames. As the flow rate of methane decreased, the cell width and cell depth became larger, and the size of attractors increased. Compared with CH4/Air mixtures, cellular fronts were observed at large flow rates of methane in CH4/O2/CO2 mixtures, and the trajectory of attractors was complicated. These were because of high intensity of diffusive-thermal instability resulting from the replacement of N2 with CO2.

著者

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

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.2873-2884, 2013 (Released:2013-12-25)

参考文献数

15

被引用文献数

2 2

---

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.

著者

川島 豪 星 絢也

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.984-987, 2012 (Released:2012-05-25)

参考文献数

3

被引用文献数

1 1

---

It is necessary to examine what kind of vibration and swinging is comfortable, in order to develop the comfortable human-machine interface using vibration or swinging. This study is focusing on the fluctuation in the period on the rhythm produced by the human; especially the stroke interval of the air stick is examined. The air stick is a simple version of the devil stick which is a kind of street performance. First, the portable measuring system of the stroke interval is developed by sticking two strain gauges on each hand stick and putting a wired battery driven strain amplifier and a portable data recorder in a knapsack which the performer wears. Then, the fluctuation is measured and the power spectrum is examined. As the result, it is clarified that the power spectrum shows the downward-sloping tendency in the low frequency range, and it shows the relation of about 1/f averagely.