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
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.67, no.662, pp.2625-2631, 2001-10-25

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
上宇都 幸一 越後 亮三 長谷川 修
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.45, no.390, pp.261-269, 1979-03-01

繊維媒体領域に外部から一様な平行光が入射する場合の媒体中でのふく射輸送を積分方程式法によって解析し、入射ふく射束分布、ふく射熱流束分布を明らかにしたが、とくに入射ふく射束分布については、散乱のアルベドが大きい領域で、ピークが形成されることを示した。また精度のよい指数積分核近似法を提示した。さらに本体系のふく射減衰関数はBickley-Naylor関数で表示できることを示し、二、三の積分公式を導いた。
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

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
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

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
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

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
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

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
大平 哲也 池田 裕二 中島 健
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.60, no.574, pp.2223-2228, 1994-06-25
被引用文献数
1

Cyclic variations of CO and CO_2 emission were investigated in relation to in-cylinder pressure in a small two-stroke engine. High-speed exhaust gas sampling of 200 Hz was carried out at the exhaust port. The results obtained show that the time resolution of gas sampling was insufficient to account for the cycle-resolved fluctuations observed, but was sufficient to show cyclic variation of emissions. The concentrations of CO and CO_2 were measured with regard to the in-cylinder pressure and IMEP. The misfiring effect was examined from the time variations of CO and CO_2 concentrations. The cyclic variation of the ratio of CO to CO_2 and IMEP showed the same periodic pattern under light load condition.
著者
富山 明男 宋 明良 南川 久人 坂口 忠司
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.57, no.539, pp.2167-2173, 1991-07-25
被引用文献数
6

In order to examine the feasibility of direct simulation of bubbly flows, the applicability of the VOF (volume of fluid) method to the analyses of a single rising bubble was examined in this study. Calculated bubble shapes and terminal velocities under wide ranges of Eotvos number and Morton number were compared with the experimental data summarized by Grace et al. Except for the cases when bubble shapes are spherical-cap and skirted, the VOF method could predict them well by assigning only eight cells to the bubble diameter. Hence, it was confirmed that some modification of this method will enable us to simulate bubbly flows directly under a wide-range of flow conditions. Moreover, the relation between a bubble shape and velocity distribution was examined within the ranges in which the VOF method is valid. It was found that the secondary vortex appearing in wobbling bubbles induces the velocity component normal to the bubble interface, and this velocity is one of the causes of the wobbling shape of the bubble.
著者
小川 信夫 牧 博司 黒田 健嗣
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.59, no.566, pp.2975-2981, 1993-10-25
被引用文献数
1

Control of turbulent jets has applications in the manufacturing industry. It has been reported that it is possible to control the jet structure by a pure tone. However, in pure-tone-excited jets, the detailed characteristics of the flow fields are unknown. In this paper, a jet excited by a pure tone radiated from the direction perpendicular to the axis is addressed. A woofer was set downstream near the nozzle. As a result, we found that the cross section of the jet was distorted elliptically in shape. It was clarified that the distorted cross section depended on frequency and sound pressure level of the excitation. This phenomenon is very useful to control jet flows, since it can change the characteristics of the flows. We attempted to clarify the mechanism of elliptical distortion of the jet cross section, assuming the mixing region of the jet was organized into many vortex rings in a time-averaged domain.
著者
中嶋 智也 木田 輝彦
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.61, no.592, pp.4257-4262, 1995-12-25

A vortex method is used to simulate several flow fields, such as high Reynolds number flows around bluff bodies, jet flows, and the backward-facing step flows. This method has some advantages : it does not require construction of a complex mesh, the algorithm is simple, numerical viscosity is not inherently included, and numerical results agree well with experimental and other numerical results. However, a few models, which do not satisfy the solenoidal condition, have been used in three-dimensional flow problems. The aims of the present paper are to derive a basic equation concerning the vortex method from the three-dimensional Navier-Stokes equations and to determine the relationship between the vortex method and the Navier-Stokes equations. The basic equation is derived as a simple integral form of the vorticity ; the present equation shown that the evolution of vorticity field is obtained by taking the sum of the two effects : stretching of vorticity and viscosity, which are obtained individually. The solenoidal condition is also discussed in detail the initial approximate vorticity field must be solenoidal.
著者
沖 良篤 酒田 威志 内山 直樹 佐々木 隆 三友 俊輝
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.672, pp.2269-2276, 2002-08-25
被引用文献数
1

In high-Reynolds number flow problems, very fine and stretched grids are generally required to resolve accurately thin boundary layers developed along the body surface and so the application of the tetrahedral unstructured grids has several difficulties in computational efficiency and solution accuracy. One promising approach is to use a hybrid unstructured grid technique for the boundary layers; prism, pyramid, tent and tetrahedron. In this paper, the hybrid unstructured grid technique is incorporated into a CFD-based design system, CASPER. To validate the present CFD codes, we carried out the Reynolds-Averaged Navier-Stokes simulations of a military aircraft configuration such as an F-16A in both subsonic and supersonic regions. On wing surface pressure coefficient distributions, longitudinal, lateral and directional forces and moments, the present computed results are quantitatively compared to the wind-tunnel testing data, the Euler computed and the multi-block structured N-S computed results.
著者
梅宮 弘道 大高 敏男
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.56, no.532, pp.3860-3868, 1990-12-25
被引用文献数
3

A theoretical analysis of a snow-melt road has been performed using a method of imaging line sources. The results showed that: (1) The snow-melt road proposed in this report is assumed to be a uniform concrete road which has a deep heat storage zone 2.9m under the road. (2) The heat loss through the road shoulder can be eliminated by a thermal insulator buried in the shoulder 50cm deep. (3) The power of the proposed type of heat storage is far superior to the standard one. Over 5 days, the surface heat flux of this road is larger than the standard one. (4) The optimal relation between the pitch, the depth of the buried heat transfer pipes and the temperature of water used are shown in the figures. A thermal design process is proposed.
著者
羽鳥 彰一 宮内 敏雄
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.58, no.546, pp.463-470, 1992-02-25

The SMAC method was improved by modifying the treatment of boundary conditions on free boundaries to simulate fluid flows with complicated free boudaries. This new method was applied to liquid flows in a tray-type distillation column, and the flow conditions for different locations of inlet flow were investigated. Good agreements were obtained between simulated results and experimental ones as to the liquid surface levels. The mechanism of downcomer flooding was also investigated and the following conclusions were obtained. The location of the inlet flow affects the condition of the main flow under the downcomer. In the case of the inlet flow falling down along the downcomer surface, the velocity of the main flow under the downcomer is not sufficiently recovered from the deceleration caused by the collision with the bottom. In this case, the downcomer disturbs the main flow and causes downcomer flooding at a large flow rate.
著者
島田 邦雄 藤田 豊久 岡 英夫 赤上 陽一 神山 新一
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.67, no.664, pp.3034-3040, 2001-12-25
被引用文献数
25

We propose a new smart or intelligent fluid which reacts upon a magnetic field. It is a magnetic compound fluid (MCF). We measured the relation of shear stress to shear rate with a rotating rheometer as its hydrodynamic characteristics and the complex magnetic permeability at heigh frequency range as its magnetic characteristics. The hydrodynamic characteristics can be varied qualitatively and quantitatively by the direction of the applying magnetic field, the type of a rotating body in the rheometer and the compound rate of the iron and the magnetite particles. The magnetic characteristics can be varied by the the compound rate of the iron and the magnetite particles. Also, the MCF is expectable for engineering applications with using a magnetic field.
著者
横山 孝男 梅宮 弘道 寺岡 達夫 渡部 英男 桂木 公平 笠原 敬介
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.46, no.402, pp.322-330, 1980-02-25
被引用文献数
7

日本のような温帯性気候では夏は猛暑に冬は豪雪に悩むところが多いが,本研究では夏野猛暑(冬の酷寒)を地下水に託し井戸より人工かん養し大地の断熱性と帯水層の大熱溶量性により季節的に畜熱し冬季暖房・消雪(夏季冷房)に結びつけるものである.本論では野外実験と数値解析により夏季かん養温度の40%を冬季まで蓄積可能なことを明らかにし熱汚染を防止し,効果的な季節的畜熱を行うための適正井戸間隔を提示するものである.
著者
安ヶ平 和一 塚田 享彦 庵原 昭夫
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.69, no.677, pp.75-81, 2003-01-25
被引用文献数
3

For a hydroelectric power station utilizing the osmotic pressure generated between pure water and sea water, a performance prediction method was proposed in considering the concentration polarization on the flow parallel to the membrane surface. The analysis was one-dimensional and was based on equations of concentration polarization, water permeate flux, salt permeate flux, mass conservations both of water and salt, and energy conservation. From prescribed equations, the salt concentrations at the flow core and in the neighborhood of membrane surface, permeate flux, core flow velocity and also core pressure were numerically analyzed. From the analysis, the hydroelectric power performance was calculated and compared with one in case of non-concentration polarization. The result showed that the polarization lowered the performance. Based on the present analysis, the ability of electric power extracted from main rivers in Japan was estimated. It showed that the total electric power equal to the several nuclear power stations of 1 000 MW class was possible.
著者
土田 潤 伊東 聰 藤澤 智光 矢川 元基
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.69, no.678, pp.280-285, 2003-02-25

The sounding mechanism in air-reed instruments is investigated based on the computational fluid dynamics. While previous studies have assumed a sound source based on acoustic theory, the authors attempt in the present study to elucidate exactly the source of sound as an essential factor defining the timbre of musical instruments. To deal with the large computational grids required to capture minute changes in pressure, the Hitachi SR 8000 massively parallel supercomputer is employed for computation. The computational results are consistent with Brown's experimental equation, and new frequency component revealed only in this three-dimensional analysis is identified, attributed to the harmonics of the air jet.
著者
中島 求 面田 雄一
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.73, no.734, pp.2010-2017, 2007-10-25
被引用文献数
1

The objective of this study was to develop a simulation method for analysis of body behavior in skydiving freefall and to clarify the most stable body position during the freefall. The details of the developed simulation method were firstly described. Using the simulation method, we conducted an optimizing calculation to maximize an objective function with respect to the stability in the freefall. It was found that the most stable position became arched one. In order to clarify the reason why the most stable position became arched, optimization with respect to a simple shaped object which consists of 20 cylinders was conducted. Then the angle to maximize the restoring moment for each cylinder element was analytically calculated and compared with the optimized angle. From the results, we conclude that the most stable position becomes arched mainly since the restoring moment at each part itself becomes maximum at that angle. We also conclude that the magnitude of the arch in the most stable position is determined by the ratio of the normal and tangential drag coefficients.