著者

千田 二郎 柴田 一郎 段 智久 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.3173-3178, 1997-09-25 (Released:2008-03-28)

参考文献数

8

被引用文献数

1 2

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This study investigates the atomization mechanism of fuel spray dissolved in noncondensable gas, such as N2, CO2. The fuel spray was injected at room temperature and in an atmospheric pressure field through a diesel-hole-type nozzle. In this paper, N2 gas was dissolved into diesel fuel, n-tridecane, under several pressurized conditions using a gas bubbling method in a constant volume vessel. This fuel, with high gas solubility, was injected under several injection pressures using an accumulated injection system designed by the authors. It was found that the dissolved gas separated into gas bubbles like gas cavitation phenomena under the atmospheric field. The change in spray patterns caused by the gas solubility is discussed using photographs of the patterns.

著者

西原 淳夫

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.728, pp.1052-1058, 2007-04-25 (Released:2011-03-03)

参考文献数

15

被引用文献数

1 1

---

An optimization method for fin pitch in naturally cooled heat sinks is described. Because the heat sinks for the power units of electric trains are stacked vertically, lower heat sinks heat upper heat sinks. However the fin pitch of conventional heat sinks is optimized as single heat sink without accounting for the influence of the lower heat sinks. Equations to predict heat dissipation and a rise in exhaust air temperature in the heat sinks, along with an optimization method for the fin pitch are presented. These equations were carried out from a developed profile of velocity and temperature between two plates. A valid range of the Rayleigh number for the equations is shown, and the optimizing process for the fin pitch of stacked heat sinks is described. The experimental results of the rise in fin temperature of triple stacked heat sinks are compared with the calculated results. The heat sink with optimized arrangement of fins shows over 10% improvement in performance compared with the conventional heat sink.

著者

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:03875016)

巻号頁・発行日

vol.65, no.630, pp.505-512, 1999-02-25 (Released:2008-03-28)

参考文献数

18

被引用文献数

2 3

---

Finite difference method in a collocated grid system has the merits of both regular and staggered grid systems, and has mainly been used for steady flow simulations. Recently, some unsteady flows have been simulated by using the collocated grid system. The author pointed out a violation of kinetic energy conservation in the collocated grid system, which is important to unsteady turbulent flow simulations. In this paper, a modified algorithm for improving the conservation property of the collcated grid system is proposed. Van Kan type pressure correction is introduced to minimize the defect. The modified algorithm with fourth order accuracy in space is also proposed. Conservation properties of the numerical algorithms in the collocated grid system are demonstrated on the example of two dimensional periodic inviscid flow simulations. Plane turbulent channel flow simulations are also performed to confirm the reliavility of the modified algorithm.

著者

阿部 裕幸 筒井 康賢 吉識 晴夫

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.567, pp.3388-3392, 1993-11-25 (Released:2008-03-28)

参考文献数

9

被引用文献数

1

---

The Agency of Industrial Science and Technology, Ministry of International Trade and Industry has been researching and developing three types of 300kW ceramic gas turbines since 1988. The turbine blade's Reynolds numbers based on the basic design are predicted to be in the region of l04∼105. In the field of wind turbines, for example, some studies on the characteristics of airfoils at low Reynolds numbers have been carried out. However, it is not yet obvious how the turbulence affects the characteristics of airfoils. This paper describes the experimental results obtained with use of turbulence screens. It is found that laminar seperated flows, in some cases, reattaches to airfoils by raising turbulence intensity of free stream at Reynolds numbers of 0.5×105 and 1×105, and that lift to drag ratios increase further.

著者

一色 尚次

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.452, pp.905-906, 1984-04-24

著者

藤田 和央

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.700, pp.3038-3044, 2004-12-25 (Released:2011-03-03)

参考文献数

7

被引用文献数

3 13

---

The air-breathing ion engine (ABIE) is a new type of electric propulsion system to be used to compensate the aerodynamic drag of the satellite orbiting at extremely low altitudes. To save the propellant mass for a long operation lifetime, it inhales the low-density atmosphere surrounding the satellite and use it as the propellant of ion engines. Since feasibility and performance of the ABIE depend strongly on the compression ratio and the air-intake efficiency, numerical analysis has been performed by means of the direct-simulation Monte-Carlo method to clarify the characteristics of the air-intake performance in highly rarefied flows. Influences of the flight altitude, the aspect-ratio of the air-intake duct, and the angle of attack are investigated.

著者

足立 高弘 合志 洋介 上原 春男

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.68, no.672, pp.2232-2239, 2002-08-25 (Released:2008-03-28)

参考文献数

16

被引用文献数

2 2

---

Transitions and pressure drop characteristics of flow in periodically grooved channel are numerically investigated by using finite difference method. The channels consist of fundamental channel elements which have concave or convex rectangular grooves on the smooth plate. The flow fields are assumed to be two-dimensional and to be periodically fully developed. We have examined the effect of combination of the fundamental channel elements on transitions and pressure drop characteristics. The critical Reynolds numbers where a steady state flow bifurcates to a self-sustained oscillatory flow and the corresponding frequencies are evaluated for the combined channels. It is found that the self-sustained oscillatory flow occurs as a result of Hopf bifurcation. As for the pressure drop characteristics, it is found that the pressure drop for the combined channel which consists of elements with concave and convex grooves takes a middle value between the channel of concave elements and that of convex ones.

著者

内田 浩二 齊藤 弘順 立石 又二

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.71, no.712, pp.3076-3081, 2005-12-25 (Released:2011-03-03)

参考文献数

11

---

This paper revealed the reason of poor self-ignition quality of alcohol spray from the viewpoint of mixture formation considering fuel properties. Ignition characteristics of Ethanol and Diethyl Ether blended fuels were experimentally investigated with changing their blend ratio in order to clear the effects of fuel's physical and thermal properties on ignition. Experimental results and prediction of mixture formation of blended fuels showed that stoichiometric air/fuel ratio (Lth) and latent heat for vaporization (γ) were main parameters on ignition. Alcohol spray becomes lean situation faster than conventional diesel fuel such as Gas oil due to their smaller Lth. On the contrary, temperature rise of alcohol spray up to ignition point is slower than Gas oil caused by their larger γ.This causes poor self-ignition quality of alcohol spray. Namely, it is difficult for an alcohol spray to be a mixture of suitable mixing ratio and temperature for self-ignition at the same time and place.

著者

岡西 直樹 福谷 格 渡部 英一

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.56, no.525, pp.1558-1564, 1990-05-25 (Released:2008-03-28)

参考文献数

4

---

To improve the volumetric efficiency of a crankcase-supercharged 4-stroke cycle engine in the high speed range, rotary disc valves were used at both the inlet and the outlet sides of the crankcase in an investigation of the effects of opening angle and timing of disc valves on the volumetric efficiency. As a result it was found that a volumetric efficiency of 120% was possible over a wide engine speed range of 3000-6000 rpm, which was not poss ble by using the reed valve system.

著者

染矢 聡 吉田 智 李 艶栄 岡本 孝司

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.758, pp.1983-1988, 2009-10-25 (Released:2017-06-09)

参考文献数

7

---

It is known that flying fish perform long-range flight in the air in order to escape from predators such as tuna and swordfish. During the unsteady flight, ground effect enables the flying fish execute to flight for the maximum range and longest time. In this study, it was investigated a basic characteristic of the flow around the flying fish fin in ground effect, in order to understand the flying fish gliding performance quantitatively. The streamwise velocity profiles around the airfoil model were measured by a high time-resolved PIV (particle image velocimetry) in an open loop wind tunnel. A moving ground essential to generate the ground effect was supplied using a rotating disk. Two plates were put in tandem as the test wing model of a pectoral fin and a ventral fin of the flying fish. It was found that decreasing the height of the airfoil model caused a larger difference between the velocity in the suction surface side and that in the pressure surface side of the pectoral fin model.

著者

宗像 鉄雄 永田 眞一

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.74, no.747, pp.2365-2371, 2008-11-25 (Released:2011-03-03)

参考文献数

6

被引用文献数

4 10

---

Sodium acetate trihydrate is considered as the promising thermal energy storage material due to its high melting enthalpy at the melting temperature of 58°C. However, incongruent melting (phase separation) and remarkable supercooling are made difficult to use. In this study, solidification process of the sodium acetate trihydrate from supercooled state was both experimentally and numerically investigated. On the experiment, effects of supercooling and sodium acetate concentration on the crystal growth rate were measured by varying the supercooling temperature (-48K) and the sodium acetate concentration (40-55wt%) and obtained an empirical equation. Further, simplified crystal growth model, which is based on the experimentally obtained crystal growth rate, was also proposed and the heat release process, which is important for the thermal energy storage equipments, was investigated.

著者

伊藤 慎一郎

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.73, no.734, pp.1975-1980, 2007-10-25 (Released:2011-03-03)

参考文献数

7

被引用文献数

2 8

---

A slipstream is a region of reduced pressure or even suction (negative pressure) formed behind an object in downstream. Even in a marathon event, it is possible to use preceding runners as a shield to reduce aerodynamic drag and to carry out physical strength presservation. These preceding runners are called pacemakers, who maintain a lap time of an main runner. In this research, to confirm the effect of pacemakers' slipstream and to find a suitable arrangement of pacemakers, drag of the main runner was measured using 3 component load cells in a wind tunnel. And the factor of drag reduction was studied by grasping the flow field using a smoke tunnel. Numerical calculations were also carried out in a real Reynolds number and compared with experiments concerning drag and flow field.

著者

新井 雅隆 天谷 賢児 長倉 邦仁

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.622, pp.1925-1931, 1998-06-25

被引用文献数

2

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Laser induced fluorescence method was applied for the measurement of NO concentration in the propane and methane diffusion flames. A tunable, narrow band ArF excimer laser was used to excite the D (υ′=0) ←X (υ″=1) band of NO molecule. Emission spectrum of the induced light by a laser beam was measured by a spectroscope. Spectrum of the induced light from the diffusion flame was compared with that of the premixed flame. Although the spectrum had only NO fluorescence components on premixed flame, a lot of strong spectrum components related to the laser induced incandescence of the soot and laser induced breakdown appeared in the spectrum from the diffusion flame. NO fluorescence component was picked out from the emission spectrum with traversing the irradiate position of laser beam in order to obtain the accurate distribution of NO fluorescence on the flame axis. In this paper this method was named as S-LIF method. A planer laser induced fluorescence (P-LIF) method was tried to measure the distribution of NO fluorescence on the flame axis. In the P-LIF method, an interference filter was used to remove the obstructive light component from the LIF image. NO fluorescence distribution measured by P-LIF method was compared with that of S-LIF method. As the result, the P-LIF image qualitatively agreed with the data of S-LIF. It was confirmed that the interference filter did not remove completely the obstructive light components.

著者

畠沢 政保 杉田 洋 小川 孝廣 瀬尾 宜時

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.689, pp.292-299, 2004-01-25 (Released:2011-03-03)

参考文献数

9

被引用文献数

15 31

---

A new type of thermoacoustic sound wave generator driven with the waste heat of a 4 cycle automobile gasoline engine is described. The exhaust-pipe connected sound wave generator, in which the hot heat exchanger is set in the exhaust pipe in order to recover the waste heat of exhaust gas, is proposed. A temperature of 780°C of exhaust gas in the exhaust is observed. In a conventional thermoacoustic sound wave generator, sound waves originate at a temperature of the hot heat exchanger, TH, of 200-300°C and become sufficient at 700°C. It is confirmed that the new generator generates sufficient sound waves and its performance is almost equal to that of the electric heater driven generator at a thermal input of 300 W, which corresponds to slightly more than 1% of the heat quantity of exhaust gas provided under the condition that the number of engine revolutions is 2 600 r.p.m. and that the throttle opening is 35%.

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

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.74, no.746, pp.2132-2137, 2008-10-25

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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

奥 知久 笠木 伸英 鈴木 雄二

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.69, no.686, pp.2313-2320, 2003-10-25 (Released:2008-03-28)

参考文献数

9

被引用文献数

3

---

Micro bare-tube heat exchangers can accomplish high performance and compactness with their simple structure. In general, decreasing characteristic length leads to higher heat transfer area density at the expense of larger pressure drop. The trade-off has been so far optimized by trial and error. In the present study, simulated annealing (SA) is employed to optimize various design parameters of heat exchangers, which composes a multiple-variable highly nonlinear system. Although the heat transfer coefficient and the pressure drop on the air-side make major contribution to the total heat resistence and pumping power, empirical correlations of flow around tube bank can not predict them accurately in the low Reynolds number range, which is characteristic of compact heat exchangers. Hence, we make a series of numerical simulation for heat transfer and pressure drop of flow in the tube bank at various tube spacings and Reynolds numbers, and correlation functions are developed using an artificial neural network. Finally, optimum design is made for three types of micro bare-tube heat exchangers, i. e., heater core and radiator for automobiles, electronic equipement cooling system, and recuperator for micro gas turbine.

著者

田中 道雄 河嶋 敬 磯崎 俊明 竹平 昭暢

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.47, no.421, pp.1681-1690, 1981-09-25

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超音速衝動タービン翼列の設計方法は, 既に, いくつか公表されており, 中でもBoxerらが最初提唱した超音速自由うず流式のものが著名である. しかし, その性能については系統的資料が乏しく, 不明な点が多い. 本研究は, 設計転向角・マッハ数を違えた四種の自由うず流式翼列の二次元翼列実験を行い, 流入マッハ数と背圧による翼列特性の変化, 設計転向角・マッハ数と性能の関係など翼列性能の全般を明らかにした.

著者

藤松 孝裕 廣田 真史 藤田 秀臣 岡田 修 鈴置 純

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.673, pp.2534-2541, 2002-09-25 (Released:2008-03-28)

参考文献数

19

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The deformation of the interface between a water drop and silicone-oil surface impacted by it was examined in detail. Special attention was directed to the influences of the water-drop diameter dL on the deformation of oil surface and on that of the water drop itself after the impact with the oil surface. The drop diameter was varied from 1.9 mm to 4.1 mm. The influences of dL on the shape of oil cavity at its maximum depth and on the drop shape at its maximum spread were observed conspicuously in case of minimum oil viscosity of vT=5 mm2/s. It was also found that both the maximum cavity depth ratio DM/dL and the maximum diametral deformation ratio dM/dL became smaller as dL was increased. These deformation parameters DM/dL and dM/dL could be well correlated with the impact velocity of drop uL for each oil viscosity. Moreover, in Case B, C and D, DM/dL could be correlated by a dimensionless group ReTLWeTL, and dM/dL was correlated by Re2LOh for highly viscous silicone oil of vT ≥ 5 × 103 mm2/s.

著者

平原 裕行 川橋 正昭 荒舘 俊

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.68, no.667, pp.658-665, 2002-03-25

被引用文献数

2

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A numerical simulation technique of creature's flow was proposed on the basis of molecular dynamics method. Creatures, such as humans, fishes, bird and so on, usually move in a cluster or crowd. Features of crowd's behavior were discussed from the point of fluid dynamical view. The motivation of its motion was classified into a several categories due to intelligent level. In the present report, three primitive categories were taken into the consideration. In order to express a suitable individual potential, directional and influence functions were introduced to with a dependency of creature's view angle. Macroscopic quantities of state such as temperature, density, and pressure of the crowd were defined for a local region in the creature flow. An interaction between two intellectual particles and crossing flows between two crowds were simulated and discussed in detail.

著者

古谷 正広 太田 安彦 北口 佳範 大崎 守 村井 美樹 磯貝 鉄也

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.67, no.662, pp.2625-2631, 2001

被引用文献数

3

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Compression ignition of a stoichiometric iso octane/oxygen/argon mixture was observed using a shock tube and a rapid compression machine. Reducing the compression temperature, the activation energy for the shock compression ignition fell suddenly at the critical temperature the ignition delay exceeded around 1 ms. This peculiarity could be seen in the shock compression stoichiometric methane ignition with which mixture absolutely no cool flame low-temperature reactions accompanied. Shock wave diagrams indicated that the ignition was originated not at the end of the tube but to the inside of the tube. It resulted in the smaller activation energies in the lower temperature regions. This phenomenon was not due to the difference of chemical reaction mechanisms. IIigh-speed schlieren observations using another shock tube with visualization windows have allowed us to confirm the peculiarity that the earliest ignition sites were located apart from the tube end and the ignition initiation structure would change depending on the compression temperature.