著者

中野 晋 内田 剛 石ヶ森 勲 菅原 敏 新田 慶治

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.64, no.617, pp.107-114, 1998-01-25

参考文献数

9

---

It is necessary to develop a small positive pressure control system for the closed ecology experiment facilities because of the needs to prevent contamination from the atmosphere and to protect against over differential pressure loading. In the present study, a numerical analysis method was developed to calculate the quantity of state of the closed module which is fitted with rubber buffers for the small positive pressure control system. Experiments to examine the pressure change of the closed module caused by rapid temperature control of an air conditioner were carried out at Biosphere-J. Comparison of calculated and experimental results showed that the present dynamic simulation is suited to estimating the quantity of state of the closed module.

著者

草野 茂之 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.630, pp.804-811, 1999-02-25

参考文献数

10

被引用文献数

2

---

In this study, new models on the new droplet evaporation taking account of the droplet surface temperature related to the modified Spalding model, on the ambient temperature and the mass fraction at the infinite-point was proposed and incorporated into KIVA-II code. These models were compared and reviewed with the droplet evaporation model of KIVA-II original code in relation to the standard Spalding model. As a results, it is found that the calculated results of droplet evaporation by new model agree well with actual phenomena.

著者

劉 本柱 三上 真人 小嶋 直哉

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.600, pp.3220-3226, 1996-08-25

参考文献数

11

被引用文献数

2

---

The flow induced noise from an expansion cavity-type muffler increases abruptly for some sizes of mufflers and flow velocities. This phenomenon is strongly related to the resonance of the tail pipe and the cavity of the muffler ; therefore, it is called the predominance of resonance゛When the cavity length is increased, the measured resonance frequency shows periodic jumps. The cause of the predominance of resonance is assumed to be the generation of vortex rings with a particular frequency in the cavity. The generation of vortex rings is verified by analyzing fluctuating velocities in the cavity when the predominance of resonance occurs. The phenomenon is induced not only by the tail pipe resonance, but also by the cavity resonance. It is suggested that there exists the feedback phenomenon from the sound to the flow and it is strongly related to the sound pressure level in the cavity.

著者

三上 真人 加藤 秀輝 佐藤 順一 河野 通方

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.582, pp.731-737, 1995-02-25

参考文献数

16

被引用文献数

1

---

The effect of gravity on fuel droplets burning interactively has been studied experimentally. Experiments on two droplets aligned horizontally were conducted both in normal gravity and in microgravity. Results show that in normal gravity, oxygen starvation between the flames is not as severe as in microgravity. Natural convection, which supplies oxygen to the flame, is stronger at a smaller initial separation distance when two flames exist separately. The instantaneous burning rate for the same normalized droplet diameter has a maximum in normal gravity when the initial separation distance is changed and decreases monotonically in microgravity with decreasing initial separation distance, except for the initial period of burning. Thus, the effect of gravity, which decreases the burning lifetime, is greatest at a certain initial separation distance.

著者

近藤 卓 飯尾 秀一 昼間 勝 古濱 庄一

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.63, no.610, pp.2209-2214, 1997-06-25

参考文献数

4

被引用文献数

1

---

In order to facilitate practical application of hydrogen fueled engines with external mixture formations. it is necessary to determine the cause of backfire and to identify appropriate countermeasures. It has been found in our study that one of the causes of backfire is attributed to the electric discharge which occurs after the ignition of the spark plug when the pressure in the cylinder becomes low enough to discharge the electric charge remaining in the ignition system. The electric charge in the plug cable remains much longer when hydrogen is used as the fuel than when gasoline is used. In other words, the number of ions produced from hydrogen-air combustion after the ignition of the spark plug is less than that from gasoline-air combustion, so it is difficult for the ion current to flow out through the gap of the spark plug. It has been found in our experiments that backfire takes place when the electric discharge occurs during the intake stroke and that engine operation could be performed up to an excess air ratio of λ=1 without any backfire at a low engine speed when the ignition system was modified such that no electric charge remained in the spark plug cable.

著者

松野 善之 小玉 恭弘

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.66, no.645, pp.1380-1383, 2000-05-25

参考文献数

6

---

Viscosity of magnetic fluid changes when an interaction angle between magnetic field and flow vorticity changes. The test shows that viscosity becomes maximum when they cross perpendicularly and becomes minimum when they are parallel. These phenomena were studied theoretically by M. I. Shliomis and W. F. Hall. This paper describes an analysis of the relation between viscosity and the interaction angle from test results and the comparison between that and the theory.

著者

楊 基明 目黒 俊勝 小野寺 収 高山 和喜

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.591, pp.4031-4038, 1995-11-25

参考文献数

9

---

In the previous paper, the design and performance of a diaphragmless shock tube which could generate, with a higher degree of repeatability, weak shock waves up to shock Mach number of 1.2 were reported. In the present paper, an experimental improvement of the facility, by which the pressure difference between the driver chamber and the driven channel can be increased to about 4 times higher than the previous system, was achieved so that the attainable shock Mach number was extended to M_s=1.6 at the initial atmospheric pressure. Higher shock Mach number up to 3 can also be readily obtained by decreasing the pressure in the driven channel. A numerical simulation and a theoretical analysis were perfomed in order to clarify the characteristics of this diaphragmess shock tube. Although the numerical simulation revealed that the flow near the rubber membrane is very complicated, however, with the help of simplified one-dimensional model, in which the varying cross-section is taken into account, shock Mach numbers achievable in this shock tube were well predicted as a function of the pressure ratio between the high-pressure chamber and low-pressure channel. Good agreement was obtained between the experimental results and theoretical prediction.

著者

李 輝 野崎 勉

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.1810-1818, 1996-05-25

参考文献数

8

被引用文献数

2

---

A new cross-correlation method, which is called a wavelet cross-correlation analysis and expresses the statistical cross-correlation of any signal in terms of period and time delay, is proposed and its main properties are presented. By analyzing two typical signals, the cross-correlations of components with different periods can be detected, and it is shown that wavelet cross-correlation can overcome the limitations of classical cross-correlation. As a practical application to the field of fluid mechanics, wavelet cross-correlation is employed to analyze cross-correlation relationships between χ-components of the fluctuation velocities at two points on opposite sides of the centerline and along the centerline of a plane turbulent jet in terms of period and time delay. From the distributions of the wavelet cross-correlation coefficient, similar structures of motions with various scales are shown, and the successive branching of vortex structures is observed. The period of vortex and apparent flapping motions can be easily determined in terms of period and time delay.

著者

藤田 恭伸 アレクサンダー ロペス

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.588, pp.3044-3051, 1995-08-25

被引用文献数

3

---

Experimental data of liquid and vapor flows of R 113 for Re=5000〜400000 were obtained for both a plain tube and snugly fitted twisted tape insert tubes. No evidence of tape fin effects was found in the heat transfer characteristics of a stainless steel tape insert when compared to a Teflon tape insert. For twist ratios γ = 5.9, 10.0 and 16.0, improvements in heat transfer of up to 35% were observed. Based on a simple consideration of the heat transfer enhancement mechanisms of twisted tape inserts, a Dittus and Boelter-type correlation for a plain tube was modified to include twisted tape effects. For such a case, use of available plain-tube data was recommended to maximize the accuracy of the proposed correlation. The trade-off between pressure loss and heat transfer enhancement was considered before determining the overall desirability of twisted tape inserts.

著者

菅 牧子 河村 哲也 岩津 玲磨

出版者

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.629, pp.108-115, 1999-01

参考文献数

16

---

The natural convection with large temperature difference is computed numerically using the Low-Mach-Number approximation with temperature dependent viscosity and thermal conductivity. In this study staggered grid system is used in order to hold down the numerical oscillation. Firstly, steady laminar natural convection above a horizontal heat source is simulated in order to validate the simulation method. The result is in good agreement with the analytical solution. Secondly, two dimentional flow field driven by two parallel heat sources is computed. This boundary condition may be regarded as a model situation of the big fire covering both sides of a wide straight road. At the same time, it is interesting to investigate interactions between two thermal plumes. The numerical results disclosed different flow behavior when the imposed temperature of the heat sources is changed and the rest of the governing system parameters are varied.

著者

服部 篤 岡田 昌志 Kang Chaedong

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.67, no.662, pp.2533-2540, 2001-10-25

参考文献数

8

被引用文献数

1

---

A water fine particle suspension with a uniform initial temperature and various initial concentration distributions in a rectangular vessel was heated from a vertical wall and cooled from the opposing vertical wall. The particle made of SiO_2 had a narrow size distribution (mean diameter of 2.96μm, standard deviation of 0.023μm). In order to observe phenomena of the natural convection, the temperature distribution, local particle concentration of the suspension and position of first interface were measured under various temperature differences between the opposing vertical walls. To make the influence of initial particle concentration on the phenomena clear, natural convection of suspension with three patterns of concentration, i.e. a naturally or artificially formed gradient, or non-gradient, was investigated. The pattern of formation of layers was classified by Grashof number. Moreover, to make the influence of initial depth of suspension clear, the suspensions with three initial depths, 50,100 or 160mm, were examined.