著者

千田 二郎 柴田 一郎 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.63, no.613, pp.3179-3186, 1997-09-25 (Released:2008-03-28)

参考文献数

20

---

In this paper, propose a new fuel injection system using diesel fuel dissolved in liquefied CO2. The system has the capability of reducing both NOx and soot simultaneously. This concept strives to improve the atomization of fuel spray by flash boiling liquefied CO2 gas. Moreover, it is possible to control the combustion system, for instance, and internal EGR effect is produced by the separated CO2 gas. In this paper, the characteristics of diesel spray of the fuel dissolved with liquefied CO2 were investigated using several optical measurements and the variance of CO2 molar fraction, ambient pressure and ambient density under room-temperature conditions. The spray characteristics were revealed using analysis in chemical thermodynamics. The atomization and dispersion of a free spray composed of fuel dissolved in liquefied CO2 are much better than those of normal diesel fuel oil, due to the flash boiling process in the relatively low pressure field.

著者

川野 大輔 千田 二郎 和田 好充 藤本 元 石井 素 鈴木 央一 後藤 雄一 小高 松男

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.696, pp.2213-2219, 2004-08-25 (Released:2011-03-03)

参考文献数

20

被引用文献数

1

---

Original KIVA code cannot take account for the spray and combustion processes of multicomponent fuels. Therefore, it is necessary to produce the sub-models for multicomponent fuel using KIVA code. In this study, the modeling of detailed physical properties and evaporation process for multicomponent fuel was conducted. In addition, the effects of fuel composition in multicomponent fuel on vapor distribution, spray tip penetration, vapor mass and evaporation rate, and sauter mean diameter were numerically investigated by using KIVA 3 V code with this multicomponent fuel spray model. From the numerical results, the spray characteristics of multicomponent fuel varied with a change in mixing fraction in multicomponent fuel. Especially, the evaporation of multicomponent fuel was not necessarily improved, even if much amount of high volatility fuel was mixed in the multicomponent fuel.

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.3556-3562, 1994-10-25 (Released:2008-03-28)

参考文献数

23

被引用文献数

2 4

---

This paper presents the model analysis of atomization and vaporization process in a flash boiling spray based on the experimental results. Two kinds of liquid fuel, n-Pentane and n-Hexane, are injected into quiescent gaseous atmosphere at room temperature with low pressure through a pintle-type injector. Then, in flash boiling spray region where the back pressure is below the saturated vapor pressure of fuel, the bubble nucleation process due to flash boiling is modeled by the nucleation rate equation. Furthermore, fuel vaporization process is assessed by considering bubble growth calculations of vapor cavitation phenomena and fuel evaporation due to heat transfer process. Accordingly, we could estimate quantitatively the transient changes in bubble diameter and vapor mass fraction inside the spray for each back pressure condition.

著者

千田 二郎 浅井 崇胤 川口 文悟 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.632, pp.1459-1466, 1999-04-25 (Released:2008-03-28)

参考文献数

15

---

The new injection system by using mixed fuel dissolved with liquefied CO2 was proposed in this paper. Liquefied CO2 was mixed into n-tridecane under pressurized state in order to promote the spray atomization and evaporation due to the effect of the flash boiling phenomena in fuel injection, and to control the combustion process due to the effect of internal EGR effect of CO2 gas. Therefore, the simultaneous reduction of soot and NOx cas be achieved effectively by use of this injection system. In this paper, the characteristics of diesel fuel spray dissolved with liquefied CO2 were investigated quantitatively by means of several optical measurements. And the spray characteristics were revealed by the analysis of chemical thermodynamics. As a result, the atomization of this fuel is promoted due to the flash boiling much more than n-tridecane as the reference of the normal fuel and the spray structure is highly diHerent from that of the normal fuel.Moreover, thenumerical analysis for the atomization and the vaporization process wan carried out based on the flash boiling spray models.

著者

千田 二郎 檜垣 智大 高橋 秀和 高木 靖雄 足立 正之 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.640, pp.4106-4112, 1999-12-25 (Released:2008-03-28)

参考文献数

12

被引用文献数

2 1

---

In previous multi-dimensional modeling on spray dynamics and vapor formation, single component fuel with pure substrance has been analyzed to assess the mixture formation process. Then it shold be expected that the evaporation process could be performed for the multi-component fuel such as actual Gasoline and Diesel gas oil. In this study, vapor liquid equilibrium prediction was conducted for multi component fuels such as 3 and 10 components mixed solution with ideal solution analysis and non ideal solution analysis. And the computation of distillation characteristics was conducted for the steady state fuel conditions to understand the evaporation process. As a result, calculated distillation characteristics is consistent well with experiment results. Further the vapor concentration was measured for the analysis of the binary fuel spray using IR absorption measurement method.

著者

栗原 昇 寺尾 吉哉 中尾 晨一 高本 正樹

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.637, pp.3029-3034, 1999-09-25 (Released:2008-03-28)

参考文献数

10

被引用文献数

3

---

A calibrator of laser Doppler velocimeters (LDVs) has been developed as the measurement standard of flow velocity. This calibrator has a rotor with single fine wire and generates various velocities from the rotation. To minimize the influence of wire deformation, the orbit diameter in movement was measured with an interferometer as the distance of a rotor traversing. A measurement control volume of tested LDV was used to detect the wire orbit position. The calibration factor of tested LDV was decided as a ratio of wire velocity to the average frequency of the Doppler burst signal. In this paper, the uncertainty of LDV calibration with this calibrator was analyzed and unknown sources were quantified by the experiment. The maximum uncertainty source was pitching of the carriage table, which would be reduced by remodeling of the devices. The combined standard uncertainty of the calibration was about 100 ppm in the velocity range of 2 to 30 m/.

著者

林 義裕 若林 千裕 古畑 朋彦 新井 雅隆

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 B編 (ISSN:03875016)

巻号頁・発行日

vol.72, no.716, pp.1021-1028, 2006-04-25 (Released:2011-03-03)

参考文献数

31

---

Mixture formation of diesel spray impinged on an extruded surface, which was a top of cylindrical column, was investigated experimentally. A diesel spray was impinged vertically to the extruded surface. The behaviors of impinged spray were observed using a high-speed drum camera. A spray volume was estimated from the photographs. Effect of cylindrical column diameter on spray behavior was investigated. Adhering fuel was measured by a primitive “wiping by paper and mass measuring” method under various conditions. Air-fuel ratio in spray was calculated from spray volume and adhering fuel. As the result, the behavior of diesel spray impinged on an extruded column was strongly influenced by the diameter of the extruded column. From the measured results, it is clear that the air-fuel ratio in spray in the extruded column diameter of 45 mm was larger than those in the other columns.

著者

藤田 尚毅 永倉 喜一郎 角掛 繁

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.486, pp.654-658, 1987-02-25 (Released:2008-03-28)

参考文献数

8

---

In this paper, we give an account of the studies of gas oil-water-methanol stable emulsified fuel, and the influence of this fuel on pre-combustion type 4-cycle diesel engine performance. By selecting a suitable surfactant and exposing the emulsion to surpersonic waves, the authors succeeded in preparing a stabilized gas oil-water-methanol emulsion. By making use of this emulsified fuel, NOx concentration and smoke in the exhaust gas from the diesel engine were decreased. In the test range, the influence of the water in the emulsion on the engine performance was greater than that of methanol. Moreover, we investigated the influence of a change in the fuel injection timing.

著者

中川 洋 森 俊一 遠藤 浩之

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.61, no.590, pp.3554-3560, 1995-10-25 (Released:2008-03-28)

参考文献数

10

被引用文献数

1 1

---

This paper describes the effects of water-emulsified fuel on diesel spray combustion. Theoretical analysis and numerical simulation show that the high momentum of water-emulsified fuel spray per unit mass due to lower calorific value leads to higher air entrainment into spray than in the case of ordinary fuel. The experimental results show that these effects cause a reduction in the temperature of the combustion reacting zone of water-emulsified fuel spray, and a shortened combustion duration, and less formation of soot and nitric oxide in a diesel engine.

著者

神本 武征 高橋 浩 小林 治樹 松岡 信

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.440, pp.901-908, 1983-04-25 (Released:2008-03-28)

参考文献数

15

被引用文献数

2

---

急速圧縮装置を用いて平面に衝突するディーゼル火災の対流熱伝達に関する実験を行った.衝突面の熱流束は,通常の等温ガス噴流の衝突の場合と異なり,よどみ点から半径方向にほぼ一定に分布する.これは,よどみ点から半径方向に減少する熱伝達率と,半径方向に向かって燃焼が進行するにつれて増加する熱落差とが相殺し合う結果と解釈される.衝突面への熱損失率は熱発生率の約10%であり,両者の時間経過曲線は良く似ている.

著者

李 世文 榎本 良輝 神本 武征 小堀 繁治 吉川 英樹

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.63, no.609, pp.1814-1819, 1997-05-25 (Released:2008-03-28)

参考文献数

14

被引用文献数

3 3

---

Combusting and evaporating diesel sprays, impinging on the wall of a square combustion chamber were obtained in a rapid compression machine. The temperature fluctuations at many locations on the impinging wall surface were measured using thin-film thermocouples, and the local heat fluxes were calculated from temperature history records. The motion of the impinging flames was photographed from two directions using a high speed camera, through optical windows attached to the square chamber. It was shown that the local heat flux increases as the fuel injection pressure and the ambient density increase, and is approximately proportional to 0.6-1.0th power of the injection velocity. However, it decreases downstream from the stagnation point. The ratios of the local heat fluxes between the combusting and evaporating sprays estimated using a two-zone model for the characteristic temperature were found to be close to the measured values.

著者

深野 徹 功能 郁生

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.494, pp.3034-3037, 1987-10-25 (Released:2008-03-28)

参考文献数

3

被引用文献数

1 2

---

It is believed that a helmholtz resonator is a good device for reducing the noise level of a discrete frequency noise, and that the frequency of the resonator can be estimated by a simple theoretical formula. Actually, however, we cannot deny the possibility of an unexpected increase in the noise level due to the resonance between a traveling tone and the resonator. Also, there are few papers which treat of the actual design method of a resonator, especially the dimension of a resonator in relation to the size of a main duct conveying a tone to be reduced. In the present experiment, the theoretically estimated frequency is examined ad to whether its noise level is reduced at that frequency by the resonator or not. The experimental data which are useful for designing a resonator with an optimum geometry are also presented.

著者

児玉 和也 戸田 和之 山本 誠

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.2894-2900, 2006-12-25 (Released:2011-03-03)

参考文献数

8

被引用文献数

1 1

---

With improving a computer hardware and CFD software, the problems treated in industries tend to be more complex, physically and geometrically. The turbulent flow with strong unsteadiness is one of physically complex examples. Since Large Eddy Simulation (LES) is still too time-consuming, a great number of unsteady Reynolds-Averaged Navier-Stokes (RANS) computations have been employed in such engineering applications. However, the applicability of RANS to unsteady flows has not been clear. In the present study, RANS computations for two-dimensional turbulent flow with periodic perturbation over a backward-facing step are performed to verify the performance of a low-Reynolds-number type k-ε turbulence model. Visualizing and investigating the temporal change of the flow pattern and the instantaneous term-by-term budget of the governing equations, it is clarified that the RANS computation can reproduce the unsteady nature satisfactorily, and why the RANS model captures the unsteady turbulent flow reasonably.

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

参考文献数

2

著者

新宅 博文 多田羅 晋生 川野 聡恭

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.745, pp.1942-1950, 2008-09-25 (Released:2011-03-03)

参考文献数

21

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In this study, we demonstrate the small droplet transportation on vertical parallel electrodes using electrowetting and the interfacial oscillation. The transportation of water droplets, which can be applied to the droplet-based biochemical devices, is performed by applying ac voltage that ranges from 0 to 100 Vpp and from 20 to 100 Hz. The characteristic of the transportation is observed by the use of a high speed camera, and the effects of the interfacial oscillation and the dynamical contact angle on the droplet motion are investigated in detail. The experimental results show that the vertical velocity of the droplet can be controlled by changing the amplitude and frequency of applied ac voltage. In addition, the dynamics of the droplet is estimated theoretically considering the interfacial tension force due to the dynamical contact angle and the gravitational force. The predicted force and displacement of the droplet agree well with the experimental values obtained from the high speed observation of the droplet motion.

著者

須藤 誠一 菅 康彦 矢野 哲也 露木 浩二

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.736, pp.2440-2449, 2007-12-25 (Released:2011-03-03)

参考文献数

22

---

The swimming behavior of small aquatic insects was analyzed by a digital high speed camera system. The test aquatic insects were some kinds of water beetles. It was found that the average thrust force of water beetles arises from the drag difference between the power stroke and the recovery stroke in beating movement of their hindlegs. A swimming mechanism based on the kinematic analysis of water beetle swimming was designed and produced. A swimming mechanism was composed of polystyrene foam resin body, permanent magnet, and polyethyleneterephthalate film fin. A swimming mechanism was driven by the magnetic torque acting on the permanent magnet in the alternating magnetic field. Locomotion characteristics of a swimming mechanism were studied. It was found that the swimming velocity of the mechanism depends on the frequency of alternating magnetic field. The flow field around a swimming mechanism was visualized by slow shutter speed photograph. Experimental data are useful to design of micro swimming robot.

著者

滝 史郎 小川 勇治

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:03875016)

巻号頁・発行日

vol.55, no.516, pp.2508-2516, 1989-08-25 (Released:2008-03-28)

参考文献数

10

---

Small scale experiments of unconfined fuel vapor cloud explosions are carried out for various masses of fuel (2.9-25.2 g of iso-butane), and compared with the results obtained by the numerical analysis based o the spherically expanding piston model, where the volume of the piston is expressed by a simple function of time. A self-consistent scaling law of the unconfined fuel vapor cloud explosion is found. The size and the duration of the fireball, and the peak overpressure generated by the explosion of M kg of hydrocarbon fuels, are approximated as follows, although the dispersions in experiments are large. The maximum diameter of the fireball Dmax≒5.5 M1/3 [m]. The duration of the fireball tb≒1.6 M1/6 [s] ; and the peak overpressure of the blast Δpmax≒1.6×103 M2/3r-1 [Pa], or Δpmax/p0≒5.7×10-3M1/3(r/r*)-1, where p0 is the initial pressure and r/r* is the so-called scaled distance. These relations are in good agreement not only with the present experiments but also with the existing experiments for both larger and smaller fuel vapor cloud explosions.

著者

遠藤 剛

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.58, no.550, pp.2003-2009, 1992

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This paper reports on flows around two-dimensional elliptic wings which are linearly arranged above a flat plate. To solve two-dimensional time-dependent incompressible Navier-Stokes equations which use a body-fitted curvilinear coordinate system, a numerical solution method has been developed, and the method has been applied to the flows around 25% thickness elliptic wing cascades slanted at an angle of attack 15°at a Reynolds number of 1.6×10<SUP>3</SUP>. Those wings are linearly arranged at an equal distance above a flat plate. This paper presents a number of numerical solutions for streamlines, vorticity profiles, lift, drag and pressure distributions. The lift and the drag almost regularly fluctuate with time, and the flow rates through each passage also regularly fluctuate. The present studies have been conducted as basic research into the mechanism of blowing snow off a road.

著者

佐味 弘之 高野 孝義 谷沢 清岳 吉富 和宣 伊東 聰智 宮崎 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:03875016)

巻号頁・発行日

vol.69, no.678, pp.512-520, 2003-02-25 (Released:2008-03-28)

参考文献数

14

---

The ignition phenomena of diesel fuel spray injected into a constant volume vessel with medium injection pressure were investigated. Results show that ignition occurs at a certain point near the surface of spray liquid column before breakup where activation reaction is advanced one step ahead of others and the impingement plate assists surface ignition. From these results was deduced the following concept that fuel vaporized from the liquid surface begins to be activated when the velocity gradient at the liquid column surface decreases to a certain level, leading to ignition. The blowing-off limited ignition model was proposed from this concept. Based on the functional relation between various factors and the ignition delay derived from this model, the ignition delay date were well arranged into an experimental formula. Next, ignition investigation was carried out using a bottom-viewed single cylinder engine, revealing that the effects of many factors including EGR rate related to O2 concentration can be analyzed comprehensively based on the above model.

著者

鈴木 正己 荒川 忠一

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.604, pp.4135-4141, 1996-12-25 (Released:2008-03-28)

参考文献数

9

被引用文献数

1

---

The numerical methods for analyzing a fixed terminator type of wave energy conversion device are described under the condition that the linear water wave theory is applicable. Two methods are proposed in order to calculate the device characteristics of an air chamber. One uses the flow rate and the gage pressure in the air chamber directly, because the interaction between the oscillating water column and the turbine is found to be controlled only by the flow rate and the pressure drop through the turbine in this system. The other method uses the equation of the floating body motion in a manner similar to the equivalent floating body approximation. The relations between these two methods are also examined. The hydrodynamic performance with frequency from zero to infinity is required in the simulation of irregular waves. However, resonances occur when the air chamber breadth is equal to an integral multiple of a half wavelength. Therefore the impulse response function is modified in order to eliminate the effects of the resonance frequency. Finally, it is confirmed that these solutions give good agreement with the experimental data.