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

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

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

佐藤 久雄 千島 美智男 細川 成之

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 = Transactions of the Japan Society of Mechanical Engineers. B (ISSN:03875016)

巻号頁・発行日

vol.72, no.718, pp.1456-1464, 2006-06-25

参考文献数

5

被引用文献数

1

---

In order to increase the safety and reliability of ropeway systems, it is extremely important to improve windproof performance of carriers since the excessive swing of the carrier by wind may lead to a serious accident such as a collision with the columns. As the first step of studying improvement of windproof performance of ropeway carriers, this paper presents analysis results of accidents due to wind and results of wind tunnel experiments of real carriers. Analysis results of accidents clarified features of ropeway accidents due to wind. Results of wind tunnel experiments showed aerodynamic characteristics of two typical monocable carriers.

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

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

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.

著者

段 智久 高岸 佐代 大石 直己 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.62, no.597, pp.2079-2085, 1996-05-25 (Released:2008-03-28)

参考文献数

15

被引用文献数

7 8

---

In the experiments presented here, a single diesel spray of n-tridecane was injected for a certain duration through a hole-type nozzle (ln/dn=1.1mm / 0.2mm) into a quiescent high pressure atmosphere at room temperature. We used the same amounts of fuel injection for each injection pressure and the same ambient gas density field for all injection experiments including tests of the effect of changing the ambient gas. The macroscopic spray structures were observed by instantaneous photography and using a high-speed video camera system. Furthermore, the microscopic structure was observed by means of laser light-scattering photography, fuel droplet distribution was measured using the laser light-sheet of a pulsed Nd-YAG laser, and the mean diameter of the drop was obtained through image processing by the laser extinction method. This study revealed that the diesel spray consisted of a number of large vortices, which was considered to be the coherent structure. With high ambient gas viscosity, the fuel droplet became smaller. It was also found that a large vortex existed at the tip of the spray.