著者

篠原 俊夫 松浦 祐太郎

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.406, pp.1065-1073, 1980-06-25

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軸流タービンの内部効率向上のため,損失の大きなブレード先端部および根本部の流れについて翼列実験およびモデルタービン実験を行い,主流と損失流れとの相互関係を明らかにした.そして,翼先端および翼根本での反動度を買えた新しいフローパターンを考え,これをノズルをねじることにより実験して,従来系との比較実験を行った.その結果1%以上のタービン効率の上昇を確認した.

著者

辻本 聡一郎 神田 誠 国友 孟

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.48, no.427, pp.545-553, 1982-03-29

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低温機器の構造材料として重要なA1およびA1合金の垂直反射率を室温では0.4μmから20μmの波長域で,室温から16Kまでは2.6μmから20μmで測定し,実測値を説明できるモデルの検討を行った.従来の異常表皮効果理論ではその温度依存性を説明することができず,表面の微小凹凸,格子欠陥による伝導電子の付加的な散乱を考慮して求めた緩和時間をDrudeの式に導入する新しいモデルにより,うまく説明できることがわかった.

著者

牧野 俊郎 若林 英信

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.76, no.769, pp.1406-1411, 2010-09-25

被引用文献数

2

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This paper discusses the Kirchhoff's law on thermal radiation. The logic of derivation of the law is reconsidered, first. Then, spectra of normal emittance ε_N and normal incidence hemispherical reflectance R_<NH> are measured on surfaces whose microstructure changes in a non-equilibrium experimental system to examine the validity of the complementary relation between ε_N and R_<NH>, which is the suggestion of the Kirchhoff's law. As the results of the examination, it is illustrated experimentally on a variety of surfaces that the complementary relation is valid within an experimental uncertainty. Provided this conclusion is admitted, the followings are suggested. If a surface is designed so that it does not reflect a narrow spectral region of radiation to any direction and reflects the other spectral regions of radiation much over the hemisphere, then the surface can be a new spectrally-functional emitter of radiation. It is also suggested that thermal radiation emitted at a surface is considered as the emission of plane waves at the surface rather than as the emission of spherical waves by electric dipoles.

著者

吉田 篤正 国友 孟

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.453, pp.1444-1450, 1984-05-24

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In order to make clear the thermal structure of the atmosphere in urban area, one-dimensional numerical simulation is performed. Paticular attention is paid to the effects of condition of the earth surface, aerosol and artificial heat release. The results indicate that the temperature in urban area is generally higher than that in rural one and that the inversion layer near the earth surface in the urban area disappears at night in the winter season due to surface roughness and artificial heat.The considerable difference is formed in temperature in rural and urban areas for several hours before and after sunset. Aerosol has much effect in the daytime and the maximum effect of the diameter is found in the case when the diameter nearly equal to the wavelength of the visible light.

著者

竹森 利和 中島 健 庄司 祐子

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.584, pp.1513-1520, 1995-04-25

被引用文献数

22 1

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We have developed a fundamental model of the human thermal system (AVA model) for the prediction of thermal comfort. The distinguishing feature of this model is a more precise description of heat transfer by blood flow (i. e., it includes arteriovenous anastomoses (AVA) of the extremities and a dual vascular network) than conventional models of human thermal systems. The following results were obtained : (1) The experimental verification under three different steady thermal conditions (22℃, 28℃ and 34℃) and an unsteady thermal condition (28. 1℃+ 47. 1℃+ 28. 3℃) suggests that the AVA model can simulate body temperature profiles well. (2) The visualized results of the model predictions demonstrate that the calculated tissue temperature and blood temperature distributions are physiologically plausible.

著者

石原 勲 村上 巧 南 秀一

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.63, no.614, pp.3370-3374, 1997-10-25

被引用文献数

1

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Optical interferometers, such as the Mach-Zehnder interferometer, have often been used to measure the temperature of transparent fluids. In this paper, we utilize a Moire interferometer in which a conventional interferometer is combined with the Moire technique. By applying a fringe scanning technique to this Moire interferometer, a new fringe analytical system is obtained and the fringe analysis is automated with the aid of a personal computer. The temperature field of the air around a vertical heated plate under natural convection is measured and compared with the theoretical solution. The temperature measured using this system is in good agreement with the theoretical one. It is verified that this optical system is applicable for measuring the temperature of transparent fluids.

著者

伊與田 浩志 西村 伸也 野邑 奉弘

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.66, no.650, pp.2681-2688, 2000-10-25

被引用文献数

7 1

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For clarification of the mechanism of heat and mass transfer in the early stages of superheated steam drying which accompanies condensation and evaporation, we had done both the experiments and the simple calculation for a semiinfinite heat transfer model. And we found the existence of "reverse point" at which neither condensation nor evaporation occurs in the early stage of superheated steam drying. In this report, in order to investigate the physical reason of the reverse point and its change according to the shapes of heat transfer model, similar analytical and experimental methods were applied for both a spherical and a large slab heat transfer models. As a result, restoration time changes in the range of 3.2〜10times the reverse time with changes of scale, heat transfer rate and initial temperature of the heat transfer models.

著者

山口 義幸 浅古 豊 Faghri Mohammad

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.63, no.610, pp.2119-2126, 1997-06-25

被引用文献数

2

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Combined heat transfer characteristics are obtained numerically for three-dimensional natural convection and thermal radiation in a long and wide vertical porous layer with a hexagonal honeycemb core. The porous layer is assumed to be both homogeneous and isotropic. The pure Darcy law for the fluid flow and Rosseland's approximation for the radiation are employed. The numerical methodology is based on an algebraic coordinate transformation technique and the transformed governing equations are solved using the SIMPLE algorithm. The effect of radiation on the heat transfer characteristics is investigated in a wide range of radiation numbers and emprerature ratios, for two Darcy-Rayleigh number values (Ra^*=100,1000), and for a fixed aspect ratio of H/L=1. The results are presented in the form of combined and convection heat transfer coefficients, and are compared with the corresponding values for pure natural convection.

著者

山田 純 一宮 浩一

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.63, no.616, pp.4036-4042, 1997-12-25

被引用文献数

1

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This study deals with gas sensible heat-radiative energy exchange in fibrous media used for a system of energy recovery from high temperature exhaust gas from an industrial plant. The effects of fiber diameter, orientation, medium thickness and the fiber radiative characteristics on the recovered energy have been numerically investigated. The results show that, if the heat transfer coefficients between the fibers and the gas are assumed to be those of circular cylinders in a cross-flow, the gas sensible heat can be exchanged to radiative energy and recovered by use of a medium with fibers less than 500μm in diameter under the present calculation conditions. The results also show the value of the absorption index of the fiber material required for efficient energy recovery.

著者

平野 昌宏 宮内 敏雄 高比良 嘉一

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.52, no.480, pp.3043-3051, 1986-08-25

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This study aims at establishing a heat transfer analysis of non-gray gas in a flow system. An integro-differential equation of energy conservation is established for the laminar channel flow of non-gray gas, which includes the multi-band feature of radiative gas. The numerical analysis was conducted and the results are compared with the results obtained from the analysis based on the conventional gray gas assumption. From the comparison of these results, it is made clear that the radiative heat flux q_r obtained from the gray analysis is greater than that of the non-gray analysis, and convective heat flux q_c is vice versa. By comparing the divergence of radiative heat flux and temperature profile, it is made clear that the gray gas analysis estimates excessively small absorption of radiation in the cold region near the heat absorbing surfaces. This results in the large q_r and small q_c compared with the non-gray analysis.

著者

清水 幸丸 鈴木 利明 鈴木 邦仁 清川 寛

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.63, no.616, pp.3921-3927, 1997-12-25

被引用文献数

3

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Sport science progresses step by step in the world. This work is a challenge to develop the athlete woman swimming suit with low fluid drag. To begin with, the fluid drag of the woman swimming suit is very small. It is very difficult to measure the several percent difference in the fluid drag of the swimming suit. Special experimental apparatus is developed to measure the fluid drag, precisely. It can successfully measure the fluid drag of athlete woman swimming suits at the precision 1〜2%. As a result, the cloth with low fluid drag is found. It is worked water repellent into every other stripe on the cloth. The cloth is woven of thin threads (polyester 80% and polyurethane 20%). Also, the relationship between fluid drag for the model body and the water depth from the water surface to the model body is investigated in details.

著者

齋藤 武雄 山田 昇

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.63, no.609, pp.1783-1790, 1997-05-25

被引用文献数

5

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In most cities, it is becoming evident that the increase in energy consumption is causing environmental problems, including a temperature rise in the urban atmosphere (an urban heat island) and air pollution. The present paper reports on the results of a three-dimensional computer simulation of the urban heat island in the Tokyo metropolitan area, as well as moisture migration. The three-dimensional governing equations for the urban atmospheric boundary layer were formulated by virtue of the vorticity-velocity vector potential method. Particular attention was focused on the representation of a buoyancy term in the equation of motion in the vertical direction, thereby describing the cross-over effect and stratified inversion layer near the ground surface. According to a recent computer simulation for urban warming in the Tokyo metro area in 2031,the maximum ambient temperature in the evening (18 : 00) at Otemachi will exceed 42℃. In contrast to the interior thermal comfort in residential and office buildings, the urban outdoor comfort is strongly affected by intense thermal radiation coming from the surface of the structures, as well as solar radiation. Motivated by the above facts, we propose a new standard effective temperature index (USET^*), which is applicable to urban comfort. By using this comfort index, assessment of the urban environment is made for both presentday Tokyo and Tokyo around 2030. Furthermore, it is suggested that a comprehensive urban environmental index (UEI). which includes pollutants and ultraviolet rays, is adopted for the future urban environment.

著者

山田 昇 長谷川 豊 円山 重直

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.748, pp.2615-2620, 2008-12-25

被引用文献数

1

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This paper describes the numerical simulation results of radiative heat transfer between the human body and an urban street canyon (building walls, pavement, and the sky) in the presence of participating non-gray gas mixtures consist of H_2O and CO_2. The ambient temperature of typical summer condition and the concentration of gas mixtures in summer Tokyo were assumed, and parallel infinite plane model and simple urban street canyon model were used. The results show that the participating gas significantly affects the infrared radiation field in urban street canyon. The radiation flux emitted by the participating gas is approximately 35% of the total incident radiation flux to the human body surface. This causes a homogenization of the infrared radiation field. Gas radiation plays an important role in the heat transfer between human and environment under hot and humid summer condition.

著者

松本 尚之 山本 靖人 西田 迪雄

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.62, no.600, pp.3058-3063, 1996-08-25

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This paper describes numerical results of a thermal and chemical nonequilibrium plume of high-temperature air. The gas is expanded from an orifice into low-density stationary air as a free jet. The gas considered here is high-temperature air composed of N_2, O_2, N, O, NO, NO^+and e^-, and translational-rotational and vibrational-electron temperatures are treated in a two-temperature model. In addition to this model, a six-temperature model using a multi-vibrational temperature model is adopted. The governing equations for computation are axisymmetric Navier-Stokes equations coupled with species vibrational energy, electron energy and species mass conservation equations. The equations have been numerically solved using the second-order upwind TVD scheme of the Harten-Yee type.

著者

新井 隆景 遠藤 彰 永田 晴紀 杉山 弘 森田 修至

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.63, no.614, pp.3318-3324, 1997-10-25

被引用文献数

7 1

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Supersonic combustion using a catalytic combustion in a cold supersonic flow field was investigated in a square duct with a backward-facing step. The free stream Mech number was M_m=1.81. Hydrogen was injected transversely behind a backward-facing step into a cold air free stream. Using a catalyst in a cold supersonic turbulent mixing layer, it was found that hydrogen reacted stably to oxygen in the air flow. The relationship between the heat release due to catalytic combustion and supersonic flow properties, which influence the supersonic combustion, was clarified experimentally. The spatial distribution of heat release generated by catalytic combustion in the supersonic turbulent mixing layer is discussed. It was found that the heat release due to the catalytic combustion had a maximum at the outer edge of the mixing layer.

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

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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

長野 靖尚 服部 博文 宮澤 純 稲垣 賢一郎

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.70, no.696, pp.1911-1918, 2004-08-25

被引用文献数

1

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It is well known that the turbulence energy is overpredicted by the k-ε model at the stagnation point. This problem causes inadequate predictions of flow field. In particular, since the wind-power energy is proportional to wind velocity cubed, it is crucial to predict a correct profile of wind in selecting the best site for a wind-power plant. The effects of the ground are often neglected owing to the very large length scale of the real environment. However, the complex terrain affects a profile of wind near the ground. Therefore, we have to consider the ground effects to obtain an exact profile of wind near the ground. In this study, to evaluate the performance of a low-Reynolds-number type turbulence model for flows on a complex terrain, we carried out a simulation of a flow around various complex terrain. From evaluation, we have improved the model introducing the time scale based on the velocity gradient parameter. The proposed model is evaluated in four complex turbulent flows, i.e., forward-facing step, two-dimensional block, two-dimensional hill and three-dimensional block flows. The proposed model indicates good agreement with the experimental data.

著者

北川 石英 山本 和明 村井 祐一

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.78, no.793, pp.1539-1549, 2012

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This paper describes effects of microbubble injection on natural convection heat transfer from a vertical heated plate in water. Thermocouples are used for the temperature measurement and an image processing technique is used for obtaining the bubble diameter, the bubble velocity and the bubble layer thickness. The working fluid used is tap water, and hydrogen bubbles generated by electrolysis of the water are used as the microbubbles. For a constant bubble flow rate and a constant wall heat flux, in the laminar and transition regions, the heat transfer coefficient is significantly increased by the microbubble injection (The ratio of the heat transfer coefficient with bubble injection to that without injection is 1.6-2.0 in both regions). The heat transfer enhancement in the laminar region results from both the forced-convection and mixing effects due to microbubble injection. On the other hand, the heat transfer enhancement in the transition region is mainly affected by acceleration of the transition to turbulence due to microbubble injection.

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

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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

武田 好央 中込 恵一 新村 恵一

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.62, no.599, pp.2887-2894, 1996-07-25

被引用文献数

48

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There is a gradient of fuel concentration in the spray of conventional direct-injection diesel engines. Therefore, a region of stoichiometric mixture ratio exists in the injected spray and a high concentration of NO_χ is produced. In this study, fuel injection timing was widely advanced to promote the mixing of fuel and air. Using this injection method, the engine could be driven with premixed lean diesel combustion (PREDIC), and NO_χ emissions were greatly reduced. To avoid the fuel spray contacting the cylinder liner, the fuel was injected by two side injectors simultaneously. The two sprays from the side injectors collided with each other and remained in the center region of the cylinder. Thus mixing of fuel and air was promoted by a long ignition delay period. In the case of conventional injection methods, NO_χ could not be reduced to under 400ppm (λ=2.7). In contrast, in the case of PREDIC, NO_χ emissions were reduced to as low as 20ppm (λ=2.7).