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 14

---

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

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

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

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

---

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

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

---

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.

著者

飯田 明由 小久保 あゆみ 塚本 裕一 本田 拓 横山 博史 貴島 敬 加藤 千幸

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.73, no.732, pp.1637-1646, 2007-08-25 (Released:2011-03-03)

参考文献数

10

被引用文献数

4 1 7

---

The aim of this investigation is to understand the generation mechanism of aero-acoustic feedback noise radiated from rear-view mirrors. In order to clarify the relationship between the velocity fluctuation and radiated noise, correlation in terms of aerodynamic noise and velocity fluctuations were measured in a low-noise wind tunnel. The experimental results showed that noise level of the tonal-noise depended on the ratio of the height of the bump to the thickness of the boundary layer. Strong tonal-noise was generated when the height of the bump was almost equal to 40% of the height of the boundary layer. The tonal-noise level also depended on the length between the trailing-edge of the bump and the edge of rear-view mirror. The frequency of the tonal noise can be calculated by modified Rossiter equation. The tonal-noise was disappeared in the case of the bump was placed at separated boundary layer. It revealed that the seed of the tonal noise was small disturbances generated by the bump on the surface of the rear-view mirror.

著者

森西 洋平 福井 岳人

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.759, pp.2163-2172, 2009

参考文献数

19

被引用文献数

2

---

A non-segregated numerical algorithm is proposed for unsteady incompressible flow simulations with the fully discrete fully conservative finite difference scheme. The fully conservative finite difference scheme is useful for the numerical simulations of unsteady turbulent flow because of its stability and reliability. However, a large system of nonlinear discrete equations should be solved for the fully (spatio-temporal) discrete fully conservative scheme. In this study, the Jacobian-Free Newton-Krylov (JFNK) method with the GMRES(m) method as a Krylov iterative solver is introduced as a non-linear solver in the non-segregated numerical algorithm. A couple of preconditionings to the Krylov iterative method are tested and a new effective physical-based preconditioning is proposed. Numerical tests on the DNS of turbulent channel flow demonstrate the availability of the present method. Then, the DNS of backward facing step flow is carried out for an example of a stiff problem in which the streamwise grid spacings are locally fine.

著者

坂倉 圭 山本 悟

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.709, pp.2213-2217, 2005-09-25 (Released:2011-03-03)

参考文献数

12

---

The preconditioned flux-splitting method developed by our group is applied to the computation of two-dimensional natural convections. This method is based on the Roe's flux-difference splitting, the LU-SGS scheme, and the preconditioning method. In the present study, the natural convection in a cavity at Ra=103-106 were calculated by the present method, and the numerical results are compared with the benchmark results already reported by Davis, Okanaga and Chenoweth. Finally, the reliability and the limitation of the present preconditioning method applied to the convection problems are discussed in detail.

著者

須藤 浩三 高見 敏弘 矢野 賢司

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.58, no.548, pp.1015-1021, 1992-04-25 (Released:2008-03-28)

参考文献数

10

被引用文献数

7 4

---

An experimental study has been carried out for the turbulnt flow through a circular-sectioned 90°bend of a curvature radius ratio of 4.0 with inlet and outlet straight pipes attached. Three components of mean and fluctuating velocities were measured by the technique of rotating a probe with an inclined hot wire under a Reynolds number of 60000. The flow patterns of main and secondary streams, and Reynolds stress distributions in pipe sections are illustrated with figures, and explanations are added on the process of phenomena in the streamwise direction.

著者

山田 敏郎 可児 弘毅 生田 耕治

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.47, no.415, pp.450-460, 1981-03-25 (Released:2008-03-28)

参考文献数

19

---

衝撃超高圧力研究用に超高速飛しょう体発射装置(二段式軽ガス銃)が試作され, その性能の数値解析が試みられた. 試作装置により16.4gの飛しょう体が3.57km/sまで加速・発射された. 発射実験結果と性能解析の予想値との良い一致により, 解析法の妥当性が確かめられた. 性能解析により, 試作装置は9.5gの飛しょう体が5km/sまで加速できることおよび発射速度支配因子のうち, 特に装薬量と飛しょう体質量の影響が大であることなどが明らかにされた.

著者

新井 隆景 橋本 弘之

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.51, no.465, pp.1624-1630, 1985-05-25 (Released:2008-03-28)

参考文献数

7

---

Helical surface instability of a cylindrical liquid jet in a cocurrent uniform gas stream were investigated theoretically and experimentally. The results of the linear instability theory showed that a nonaxisymmetric wave disturbance could grow enough for a large relative velocity between the liquid jet and the gas stream. When the relative velocity became larger than a specified value, the shape of the liquid jet changed from "axisymmetric mode". The helical disturbance on the liquid surface over the downward liquid column and broke up into droplets. For the frequency of the helical disturbance, the theoretical results agreed well with the experimental results. It was also found that the relation of the helical disturbances to the fluid Flow conditions.

著者

田部井 勝稲 白井 紘行

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:03875016)

巻号頁・発行日

vol.55, no.512, pp.1030-1034, 1989-04-25 (Released:2008-03-28)

参考文献数

8

---

A numerical method is presented for inverting the moire data which represent integral light deflection to internal temperature and /or density distributions. The method is applicable to both symmetrical and asymmetrical flow field. The inverting method is constructed on the basis of the Maldonado-Olsen series representation which was developed for the inversion of an integral intensity fields. The validity and accuracy of the present method have been demonstrated by using a mathematical model with a density function of a truncated pyramid type.

著者

武田 克彦 武田 秀幸 森谷 信次 棚澤 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.70, no.689, pp.279-285, 2004-01-25 (Released:2011-03-03)

参考文献数

7

---

A feasibility study was made on the application of the waste edible oil-ethyl ester fuel to diesel engines. The waste edible oil methyl ester fuel is known as the fuel which emits clean exhaust gas. however, the waste edible oil ethyl ester fuel has not been investigated elsewhere. We prepared the waste edible oil ethyl ester fuel, and tried to apply it to diesel engines. In the experiment described in this paper, the waste edible oil-ethyl ester fuels with 30, 35 and 40% in weight of the ethyl alcohol were prepared in order to decide the amount of the alcohol. The lower calorific value, density, surface tension and kinematic viscosity of the waste edible oil-ethyl ester fuels were measured. It was found that the thermophysical properties of the waste edible oil-ethyl ester fuels are lower than the waste edible oil. In addition, the ignition temperature and the ignition time were measured and found that the ignitionability was improved by the esterification and all ethyl ester fuels are almost the same. Finally the waste edible oil-ethyl ester fuel was burned in a conventional 273-cc diesel engine. Although the specific fuel consumption was a little higher, the smoke scale and NOx in the exhaust gas were lower than the gas oil. Especially, the smoke scale of EE40 (made from 40% in weight of the ethyl alcohol) was reduced drastically, and it was less than half of the gas oil.

著者

高岸 佐代 高橋 知宏 段 智久 千田 二郎 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.65, no.631, pp.1128-1133, 1999-03-25 (Released:2008-03-28)

参考文献数

9

被引用文献数

2 1

---

The characteristics of combustion process in internal combustion engines are affected by mixing process between the injected fuel and the ambient gas. Therefore, it is necessary to understand the flow field in diesel fuel sprays. In this study, a single spray was injected into a quiescent atmosphere with room temperature at high pressure through a single hole nozzle for simplification. To discuss the flow field in diesel sprays, structure of the spray was visualized by laser light sheet method. And, it was revealed that the vortex structure inside the spray affects the classification of droplet particles by taking microscopic photographs of the droplets with high resolution film. And applying PIV method into the spray photography, both the formation of meandering structure of the spray mainstream and the ambient gas entrainment process are clarified.