日本機械学会論文集 B編
Online ISSN : 1884-8346
Print ISSN : 0387-5016
68 巻, 671 号
選択された号の論文の47件中1~47を表示しています
  • 深野 徹
    2002 年 68 巻 671 号 p. 1833
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
  • 藤川 重雄, 深野 徹
    2002 年 68 巻 671 号 p. 1834-1840
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
  • 辻 義之, 野沢 幸司, 関 紘介, 久木田 豊
    2002 年 68 巻 671 号 p. 1841-1848
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Parasitic capillary ripples emerging on the forward face of wind-driven gravity-capillary waves are investigated experimentally. The wave slope angle is measured optically with sufficient time and space to characterize short ripples. The condition of ripple generation and the ripple steepness are correlated with the amplitude, the degree of fore-aft asymmetry, and the maximum local curvature of the underlying gravity-capillary waves. The phase speed of the gravity-capillary waves carrying ripples can be correlated with the characteristic parameter of ripples. These characteristics do not explicity depend on the wind velocity over the waves.
  • 深野 徹, 稲冨 誉也, 松澤 洋平, 吉田 智洋
    2002 年 68 巻 671 号 p. 1849-1856
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Gas-liqudid annular two-phase flow is an important flow pattern in terms of the liquid film dryout at the high quality region in various kinds of heat exchangers. In the past, many investigations on an annular-dispersed flow in horizontal pipelines were conducted, and the behaviors of entrained droplets have been discussed. They, however, focussed only on spatially averaged values of various properties of the droplets. In the present experiment, an isokinetic sampling probe technique was used for the measurement of the droplet flow rate generated from an imitated disturbance wave which constructed by injecting liquid through a slit mounted on the bottom of a horizontal duct. The experimental data on the distribution of entrained droplets and their deposition on the duct wall are presented. As a result, it is clarified that the distribution of the droplet flow rate is not uniform axially and in the direction of height and is actually nonsteady. Furthermore, the correlation of the entrainment fraction proposed by Paleev-Filippovich is superior to that by others.
  • 松村 邦仁, 神永 文人, 齋藤 寛
    2002 年 68 巻 671 号 p. 1857-1863
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    A frictional drag reduction using a specific coating surface (Super Water-Repellent Surface) has been studied. Experiments were carried out by injecting a small amount of air to a rectangular horizontal duct with super water-repellent wall. Three kinds of flow patterns, i.e., bubble, slug and stable air film flow, were defined based on the observation of flow behaviors. It was shown that the friction factors with super water-repellent wall duct were smaller than those of the smooth acrylic wall when the thin air film was formed. The maximum drag reduction ratio was about 32% at Reynolds number around 24000. At higher Reynolds number, the drag reduction ratio decreased due to air film-bubble flow transition occurring.
  • 松村 邦仁, 神永 文人, 齋藤 寛
    2002 年 68 巻 671 号 p. 1864-1870
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Experiments were conducted to investigate the slit width effect on the frictional drag reduction using the Super water repellent surface (SWR) and air injection method. The results showed that the friction factor of slit width 2.0 mm was smaller than that of 0.5 mm at low Reynolds number. It was also observed that the stable plane air film was formed for slit width 2.0 mm. The drag reduction mechanism, considering fluid slip at the air/water interface, was also studied both numerically and theoretically. As a result, the drag reduction by the thin air film was maximally 95% at Re=24×104 was obtained.
  • 長田 孝二, 白尾 龍太郎, 小森 悟
    2002 年 68 巻 671 号 p. 1871-1877
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    The effects of heavy-oil surface contamination on the CO2 transfer across the air-water interface were investigated through laboratory experiments in an oscillating-grid tank. The CO2 transfer velocities across the air-water interface contaminated with heavy-oil were estimated for both tap water and saltwater. The results show that the CO2 transfer volocity across the non-breaking interface for tap water contaminated with heavy-oil is damped to 30% of that for tap water without heavy-oil contamination. The CO2 transfer velocity across the non-breaking interface for 3.5 wt% saltwater (or natural seawater) contaminated with heavy-oil is damped to 46% of that for 3.5 wt% saltwater (or natural seawater) without heavy-oil contamination. The reduction in the CO2 transfer velocity can well be explained by assuming the resistance equivalent for tap water and saltwater to mass transfer due to a thin oil film on the surface. When the interface is intensively broken, the CO2 transfer velocity across the air-water interface contaminated with heavy-oil approaches to that for tap water or saltwater without heavy-oil contamination. The reduction in the CO2 transfer velocity across the air-water interfaces suggests that the effects of the surface contamination should be taken into account in the General Circulation Model (GCM) for estimating the global CO2 budget.
  • 石原 勲, 森 裕典, 松本 亮介
    2002 年 68 巻 671 号 p. 1878-1883
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Authors have being studied natural convection heat transfer of carbon dioxide in the subcritical region and observed condensate flowing along the vertical cylinder. Near the critical point, physical properties of fluids show remarkably different behavior from those for lower pressure region. A very low difference of density between vapor and liquid causes that the buoyancy becomes comparable to the gravity force, so that the flow velocity of condensate decreases. A small value of latent heat makes the amount of condensate very large. These result in a thick layer of the condensate film. On the contrary, as the temperature approaches the critical temperature, the surface tension decreases sharply and becomes zero. This very low value makes the condensate film breakable. As hydrodynamics of the condensate affects condensation heat transfer, based on observing condensate flow and measuring condensate volume, the flow of condensate was classified into four regimes : the smooth laminar flow, wavy flow, wavy flow with sharp crest and wavy flow with scattered droplets.
  • 藤川 重雄, 葉山 眞治, 小谷 正直, 阿部 稔弘, 井奈波 晃
    2002 年 68 巻 671 号 p. 1884-1889
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    A shock tube available in a state from initially normal to high temperatures is made and it is used for the measurement of the growth of a liquid film formed on the endwall surface of the tube in a shock wave reflection region. It is found that the shock tube satisfies requirements for the experiment and the liquid film grows uniformly on the wall surface at an initially high temperature. The condensation coefficient of methanol vapor is determined from the growth of liquid films at initially normal temperatures (286.3 K∼299.6 K) and higher ones (323.3 K∼324.4 K). It is clarified that the condensation coefficient is strongly dependent on both by the ratio of vapor and liquid temperatures and by the ratio of number densities of vapor and saturated vapor at the vapor/liquid interface. For the same temperature and number density ratios, the higher is the liquid temperature, the smaller becomes the condensation coefficient, and it decreases with the increase of the number density ratio.
  • 松本 充弘, 宮本 憲一, 大口 晃司, 金城 友之
    2002 年 68 巻 671 号 p. 1890-1897
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Non-equilibrium molecular dynamics computer simulation was performed to investigate phase change on the surface of a micro-scale vapor bubble in liquid which shrinks under compression. The system consists of Lennard-Jones particles as liquid and vapor, and soft-core particles as non-condensable gas inside the bubble. Without the gas, the bubble rapidly shrinks and completely collapses, after which a bubble reemerges at the same spot. The temperature and the pressure inside the bubble increases as the bubble shrinks, and reaches a maxium at the instant of collapse. In the case where the bubble contains large amount of non-condensable gas, it does not collapse but bounces back when it shrinks to a certain radius. Slight inhomogeneity of temperature and vapor composition inside the bubble is observed, which suggests a heat-up mechanism similar to the shock wave model for a single bubble sonoluminescence. The self-condensation of vapor particles is examined with a correlation function method. The condensation coefficient a on surface of a shrinking bubble without the gas was found to be only slightly larger than that of an equilibrium bubble. For a gas bubble, in contrast, a of a shrinking bubble is smaller than that of an equilibrium bubble.
  • 鶴田 隆治, 長山 暁子
    2002 年 68 巻 671 号 p. 1898-1904
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Molecular dynamics simulations are carried out for two kinds of water molecule potentials, the C-C and the SPC/E models, in order to consider the effect of different water-surface structure on the condensation coefficient. The molecular exchange behavior caused by incident molecules is examined first and we find it has no marked effect on the condensation coefficient in both models. The condensation coefficient of water depends on the translation energy of molecule and the surface temperature as same as the case of simple gas like argon. The value is summarized by a function of the surface-normal component of translation energy and the surface temperature. Also, relations between the surface structure and the condensation coefficient are discussed based on the trasition state theory developed in our former study. The paper shows that the theory can explain the simulation results very well and it is concluded that the translation motion is important compared with the rotational motion even for multi-atomic molecules.
  • 佐藤 大悟, 山本 悟
    2002 年 68 巻 671 号 p. 1905-1910
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Transonic viscous flows around a wing in atmospheric conditions are numerically investigated. Fundamental equations contain conservation laws of mixed gas, water vapor, water liquid, and the number density of nucleus, momentum equations, and the energy equation. Classical condensation theory is used for modeling homogeneous nucleation and nonequilibrium condensation. Heterogeneous nucleation is approximately modeled assuming a constant radius and the constant number density of nucleus. These equations are solved by the fourth-order accurate compact MUSCL TVD scheme and LU-SGS scheme. The effect of condensation to transonic flows around a wing is evaluated by changing atmospheric conditions.
  • 高田 保之, 日高 澄具, 山本 弘志, 中村 匡亨, 増田 正孝, 伊藤 猛宏
    2002 年 68 巻 671 号 p. 1911-1918
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Titanium Dioxide, TiO2, is one of the photocatalysts that has a very unique characteristic. The surface coated with TiO2 exhibits extremely high affinity for water by exposing the surface to ultraviolet ray and the contact angle decreases nearly to zero. On the contrary, the contact angle increases when the surface is shielded from ultraviolet ray. We have developed two types of TiO2 surface by sputtering process. One is the copper surface with TiO2 layer and the other is with TiO2 and SiO2 layer. The contact angle the former varies between 30-84° and the latter varies between 4-13°. We applied these surfaces to control the contact angles with the other thermal properties of the surface being constant. Experiment of droplet evaporation has been performed to manifest the effect of contact angle on the evaporation curves. It is found that the wetting limit temperature increases as the contact angle decreases to 13°, but it decreases again as the contact angle decreases to 4°.
  • 松本 充弘, 若林 英信, 牧野 俊郎
    2002 年 68 巻 671 号 p. 1919-1925
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Non-equilibrium molecular dynamics computer simulation was carried out to investigate a thermal resistance phenomenon at interfaces of Lennard-Jones particle crystals. Inside an FCC crystal, one-dimensional steady thermal energy flow was realized using a pair of temperature-controlled heat-baths. Four types of sharp and flat interfaces between the following crystals were investigated : (i) crystals with different particle masses, (ii) crystals with different interaction parameters, (iii) crystals with various surface interaction parameters, and (iv) crystals with different size parameters. Except for the case (iv), observed temperature profiles have a discontinuity at the interface, from which the temperature gap Tgap is evaluated. Due to the temperature discontinuity, the thermal energy flux is smaller than that through a single crystal without an interface. The observed reduction of the energy flux is larger than that predicted with a simple acoustic model. Interfaces with finite width, or composistion gradient, were also examined.
  • 鯉渕 弘資
    2002 年 68 巻 671 号 p. 1926-1932
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    We discuss the phase transition of shape fluctuations in two models of fluid membranes. The energy functions of the models are assumed to be the linear combination of an area energy and a bending energy. As a result, the models have the membrane elasticity seen in such a lipid bilayer membrane (BLM) in the aqueous solution and in an adsorbed monolayer on the water. The models are also assumed to have the fluidity corresponding to the lateral diffusion well-known experimentally as a molecular motion in such a BLM. The energy functions are discretized on random triangulated networks. The fluidity is realized by the dynamical triangulation in MC, and is visualized by CG. The phase transition of shape fluctuations as well as the main transitons are investigated on the basis of the motions of the molecules in R3.
  • 王 暁亮, 伊藤 基之
    2002 年 68 巻 671 号 p. 1933-1939
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Rayleigh-Taylor instability in a shock tube has been invistigated experimentally. Such instability was produced by accelerating a liquid column down a vertical circular tube employing shock wave impact. In the experiments, water, decane and glycerin solution, were used respectively as the testing fluid to study the instability at the gas/liquid interface. A combination of decane and salt solution was used to study the instability at the liquid/liquid interface. The resulting instability of the gas/liquid interface and the liquid/liquid interface was recorded and later analyzed using high-speed video images. Cavity formation was observed in the middle of the gas/liquid interface soon after the shock wave impact ; bubbles and spikes then developed across the rest of the interfacial plane. Flow visualizations show that surface tension and viscosity greatly affects the instability development. Measurements show that the grouth coefficient of the cavity is about twice of that of the bubbles. The growth coefficient of the bubbles is nearly independent of the Atwood number, while the growth coefficient of spikes is sensitive to the Atwood number.
  • 高橋 克明, 棚橋 隆彦
    2002 年 68 巻 671 号 p. 1940-1947
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    On this paper, fluid analysis scheme is developed which can apply complex shapes easily with triangle mesh and can deal with both compressible flow and incompressible flow accurately and with low memory consumption using adaptive mesh refinement (AMR). To verify the effectiveness of this scheme, problems of shock waves peculiar to compressible flow and vortices peculiar to incompressible flow were analyzed. The results show this scheme can deal with the different properties of fluid compressibility and incompressiblity accurately and AMR plays the great role for efficiency of computation to compressible flow and incompressible flow both.
  • 崎山 幸紀, 高木 周, 松本 洋一郎
    2002 年 68 巻 671 号 p. 1948-1954
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Chemical vapor deposition (CVD) process composes a complex system, where chemical reaction and heat and mass transfer interact with each other. And these macro-scale phenomena are deeply related to micro-scale mechanics. Hence, multi-scale analysis is required to understand these complicated interactions. As the first step of the analysis, we constructed the new site-site potential model of SiH4 molecules by ab initio molecular orbital calculations at MP 2/Aug-cc-pVTZ level. Potential parameters of Si-Si, Si-H and H-H interaction for rigid silane molecules were successfully obtained by the least square method after decomposing the energy into repulsion and dispersion term. Result of molecular dynamics simulation with the new potential model showed that it was good agreement with the experimental viscosity coefficient.
  • 宋 明良, 笹井 浩介, 中島 健
    2002 年 68 巻 671 号 p. 1955-1962
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    In order to certify the possibility of the realization of the New Printing System, an influence to the volume and time of ink transportation by the switching pulse shapes has been numerically approved. The optimized period of the switching pulse for constant ink transportation when switching pulses are repeatedly added has been also approved numerically. The following conclusions can be drawn from the results of this study. Ink transportation can be controlled in 25 pl as minimum through the width of the switching pulses, and constant ink transportation was realized with 0.52 msec of period, so that the possibility of the realization of the high-speed printers could be certified.
  • 伊藤 孝文, 加藤 征三
    2002 年 68 巻 671 号 p. 1963-1971
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Cup-mixing system (Cup-type Vessel mixed by paddle) becomes so dominant system in cup-type beverage vending machines that the optimum design procedure for paddle stirrer geometry, its setting location, its revolutions, etc, is strongly required to be quickly specified for different kind of beverage materials. This work aims first at numerically simulating the stirring flow-fields of cup-type mixing vessel, second characterize the stirring flow phenomena by introducing a new standard measure called fluid exchange frequency, and finally at evaluating the stirring characteristics resulting in the optimum condition. The simulation with the sliding mesh method is carried out of water stirring flow in the cup-type vessel, which is mixed by paddles with a revolution of 900 rpm. Based on the verification of the stirring flow simulation with the flow visualization experiment, the fluid exchanging frequency is proved to be helpful to evaluating the stirring performance locally and entirely.
  • 杉山 和靖, 高木 周, 松本 洋一郎
    2002 年 68 巻 671 号 p. 1972-1980
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Considering the flow around an object, the pressure averaged over its surface is less than the bulk one. In the present study, the depressurization behavior of a circular cylinder is theoretically and numerically investiated at the sufficiently small but non-zero Reynolds number. The dimensionless number "CTDP", which is corresponding to the dimensionless depressurization scaled by the fluid density and the stream velocity, is used to organize the data. The method of matched asymptotic expansions is used to evaluate CTDP expanded by "ε" (=log(8/Re)-γ+1/2)-1). The theoretical result shows that the leading order term of CTDP is ε2 log Re and is affected by the outer field of the expansion. Direct Numerical Simulation (DNS) of a flow around the circular cylinder is carried out in order to verify the present theory. The CTDP at the small Reynolds number (Re≤O(0.1)) obtained by the present theory shows good agreement with that by the DNS. On the other hand, the theoretical CTDP at the higher Reynolds number (Re≥O(1)) remarkably deviates from the value obtained by the DNS because the assumption of the sufficiently small Reynolds number is no more justified.
  • 杉山 和靖, 高木 周, 松本 洋一郎
    2002 年 68 巻 671 号 p. 1981-1989
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    A dimensionless number "CTDP", which corresponds to the dimensionless pressure reduction due to the translational motion of a drop scaled by the fluid density and the translational velocity, is numerically investigated. Sufficiently small but non-zero Reynolds number "Re" cases are investigated in order to verify the theory given in the 1st report. Direct Numerical Simulation (DNS) of a flow around a spherical drop is carried out for various Reynolds numbers and viscosity ratios between interior and exterior fluids of the drop. The effect of the computational domain size on the drag coefficient, CTDP and the velocity profile in the far field is discussed in order to obtain the perturbed components of CTDP by Re with high accuracy and the outer boundary of computational domain is set to be about 1000 bubble raii. The CTDP obtained by the DNS shows good agreement with that by the method of matched asymptotic expansions up to the term of order Re2 log Re shown in the 1st report.
  • 伊藤 隆英, 藤谷 誠, 酒井 康彦
    2002 年 68 巻 671 号 p. 1990-1997
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Two-phase leakage model in consideration of the film thickness on the wall surface has been proposed to improve the estimation accuracy of the leakage in a scroll compressor. The oil adhesion rate was introduced as a parameter which gives the probability that the oil in a compression chamber adheres to the scroll wall surface. In order to obtain the oil adhesion rate computationally, the flow in a scroll compression chamber was simulated by the MAC method which is a kind of non-compressing viscosity flow analysis, and the adhesion position to the wall surface was computed by tracking oil particles in a flow field. The average oil adhesion rate in the seal section was 0.21 by numerical computation. This means that 21% of the oil in a compression chamber adheres to the wall surface. The scroll leakage loss was measured for verification of the two-phase leakage model in two kinds of different suction volumes compressors. The rate of oil adhesion identified from the experiment result was 0.2 to 0.45. Leakage losses by experiments agree with the numerical results within 2% to 4%, so that the effectiveness of the two-phase leakage model were confirmed.
  • 大黒 正敏, 古舘 仁
    2002 年 68 巻 671 号 p. 1998-2005
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    The objective of this study is to promote disintegration of liquid jet by cavitation inside the nozzle. Using cylindrical nozzle, the effects of the nozzle dimensions on the liquid breakup are investigated. When the length-diameter ratio L/D of the nozzle is low, cavitation bubbles are formed inside the nozzle and the breakup of the issuing jet is promoted.
  • 妹尾 茂樹, 鹿野 芳雄
    2002 年 68 巻 671 号 p. 2006-2013
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    A flux-splitting procedure of compressible flow analysis based on steam properties is presented. To compute the high-speed steam flow, a new generalized Roe average is introduced. Density and internal energy per unit volume are selected as thermodynamic independent variables. Pressure and temperature in a superheat region or wetness mass fraction in a wet region are calculated by using steam table. To improve computational efficiency, discretized steam table matrix is made. This table has 201×201 nodes for density and specific internal energy. For the accuracy and continuity of steam properties, the second order Taylor expansion and linear interpolation are used. The computational results of one-dimensional shock tube problem are compared with the theoretical results. These show that this numerical technique is valid both from high pressure region to low pressure region and from superheat region to wet steam region.
  • 山口 隆平, 工藤 奨, 天谷 英昭, 重田 雅也, 早瀬 敏幸
    2002 年 68 巻 671 号 p. 2014-2019
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    The flow structure and the periodical oscillation in the right-angle branch have been experimentally studied in laminar steady flow using laser Doppler velocimeter. The side branch bifurcates at right angle from the trunk, and both upstream and downstream corners at the entrance of the side branch are square edge. The axial and the transverse velocity components have been primarily measured for the trunk 12.2 mm in radius and the side branch 6 mm in radius. In addition, the velocity oscillation has been measured for several radii of side branch, 4, 5, 7, 9 mm. The wall shear stress at the upstream corner takes very large magnitude. The change of wall shear stress around the upstream corner is comparable to that around the flow divider, the downstream corner. Furthermore, it has been clarified that the periodical oscillation of velocity is induced in the side branch and the Strouhal number based on the variables in the side branch is constant in terms of the Reynolds number. Therefore, this periodical oscillation in the side branch is a characteristic flow phenomenon in the right-angle branch.
  • 張 明, 王 宏, 塚本 寛
    2002 年 68 巻 671 号 p. 2020-2027
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Experimental and computational study was developed for unsteady hydrodynamic forces on a diffuser pump impeller excited by the interaction between the impeller and the vaned diffuser with the same number of vanes as impeller. Unsteady flow calculations are made using commercially available CFD software. CFX-TASCflow and 2-D vortex method. Calculated pressure and fluid forces on the impeller show good agreement with measured ones. It has been demonstrated that the fluid forces on the impeller with the same number of vanes as vaned diffuser are smaller comparing with other combination of vane numbers. However, the pressure fluctuations are found to be greater than other cases.
  • 藤井 正史, 大島 修造, 山根 隆一郎
    2002 年 68 巻 671 号 p. 2028-2035
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Molecular dynamics-like simulation of ER fluid flow is carried out to investigate the particle behavior and its influence on the flow between the parallel plates. The flow field is computed with the basic equations of multi-phase flow and the particle behavior with the equation of motion. The main results are as follows ; The long chain like clusters are formed at the center of the flow field, which makes the velocity of the center of the flow field uniform. As a result ER fluid flow changes from the Newtonian flow to the Bingham flow with the plug. The state of the flow depends on Mason number (Mn) and is classified into three patterns in terms of the change in the flow rate and the formation of the particle layer near the electrodes. At high Mn, the layer isn't formed and the flow rate is stable. At medium Mn, the layer is formed and the flow rate fluctuates. At low Mn, the clusters are formed between electrodes, and the fluid flow is stoped.
  • 後藤 邦彰, 渡壁 宏行, 西村 龍夫
    2002 年 68 巻 671 号 p. 2036-2041
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    The effect of orientation of chain-like agglomerated particles on the pressure drop has been studied experimentally by using the electro-rheological fluid. By means of two types of test sections generating the electric fields perpendicular (= cross flow type) and parallel (= parallel flow type) to the flow, increments of pressure drop by the agglomerations were measured. The obtained pressure drop increment by the cross flow type was almost 3 times higher than that by the parallel type when the concentration of particles, fluid Reynolds number and electric field intensity were the same. In order to explain the main cause of the agglomerations orientation, we proposed a model in which the pressure drop induced by the agglomeration is assumed to be equivalent to the energy consumption by the breakage of the chain-like agglomeration in the unit volume. Based on this model, the ratio of the increment of the pressure drop of the cross flow type to that of the parallel flow can be deduced as the ratio of the numbers of agglomerations. The number of the agglomerations was estimated by the force balance between the adhesive force of the particles and the drag force induced by the flow through the fibrous layer. In the force balance, we took into consideration the effect of the orientation of the force. This model could explain the effect qualitatively. This fact implies that the effect of orientation can be considered as the effect on the drag force of fibrous agglomeration layer and the force direction, depending on the agglomerations orientation.
  • 岩本 薫, 鈴木 雄二, 笠木 伸英
    2002 年 68 巻 671 号 p. 2042-2049
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Direct numerical simulation of turbulent channel flow at Reτ=110∼650 is made in order to assess the feedback control algorithms which have been proposed for reducing skin friction. The effectiveness of the existing control schemes is decreased with increasing the Reynolds number from Reτ=110 to 300. It is found, through the Karhunen-Loeve (KL) decomposition of turbulent fluctuations, that the KL modes at 15<y+<30, which correspond to longitudinal vortices and near-wall streaky structures, play a dominant role in the production of turbulence and wall shear stress at Reτ=110. At Reτ=300, however, the KL modes at 30<y+<75 also make appreciable contribution to the wall shear stress generation. The regeneration mechanism of the near-wall vortices is related to the nonlinear interaction between the KL modes at 15<y+<30 and those at 30<y+<75.
  • 細川 茂雄, 冨山 明男
    2002 年 68 巻 671 号 p. 2050-2055
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Most of interface tracking simulations conducted so far have been based on the assumption that the gas velocity is equal to the liquid velocity on gas-liquid interfaces. To the contrary, the theory of jump conditions presented by Ishii and Delhaye implies that an interfacial slip would exist when interfacial entropy generation takes place. In the present study, we therefore measured velocity distributions in the vicinity of a flat gas-liquid interface using an LDV system with a high spatial resolution of about 10 μm to examine whether or not the interface slip exist. To accurately measure the interface position, we utilized a secondary measurement volume formed by beams reflected by the interface. As a result, we could confirm that the interface slip does exist and its magnitude is large where the interfacial shear stress is large, i.e. where a large interfacial momentum transfer takes place.
  • 太田 有, 大田 英輔, 斎藤 純夫
    2002 年 68 巻 671 号 p. 2056-2063
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Active cancellation of noise source of higher-order blade-passing frequency noise, abbreviated to BPF noise, radiated from a centrifugal blower is conducted. The extents of noise sources of 2nd-and 3rd-order BPF components were determined by measuring a cross-correlation function between the data of the acoustic pressure measured at blower inlet and the pressure fluctuation on the scroll surface. The effective noise sources of these higher-order BPF components exist on the volute side surface of scroll relatively apart from the cut off apex, and vary irregularly with operating conditions of the blower. While the noise source of fundamental BPF lies on the vicinity of the cut off apex as usually expected. Oscillating the volute side surface of the cut off, i.e. the effective noise source of higher-order BPF components, directly by piezoelectric actuators, sound pressure level of higher-order BPF components can be reduced more than 15 decibels, and discrete tone disappears completely from power spectra of the blower radiated noise.
  • 渡辺 光徳, 澤田 雅, 大林 哲郎, 井口 昌司
    2002 年 68 巻 671 号 p. 2064-2070
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Recently, the turbo molecular pump that has the ability to pump a large quantity of gas under a low vacuum is required in the field of semiconductor and liquid-crystal device manufacturing. In this study, we propose the method of performance prediction for the turbine blade under a low vacuum, which enables the high throughput pump to be designed. The performance was analyzed by Stokes equation, which govern the low vacuum flow between the turbine blades in small Reynolds number. Experiments were carried out by conventional and optimized blade pumps under a low vacuum, and throughputs were measured. The comparison between the measurements and the predicted values shows that the present method predicts the performance of the turbo molecular pump in the pressure range of under 10 Pa with a sufficient accuracy for practical applications.
  • 冨士原 民雄, 鬼頭 修己
    2002 年 68 巻 671 号 p. 2071-2078
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    A micro-pump using an electroosmotic flow has some advantages over a mechanical pump in smallsizing, easy-controlling and no pulsation. The electroosmotic flow, however, has not been studied much in the field of mechanical engineering and fluid mechanics because the flow is appreciable only in a micro-channel like a capillary not but in a channel used in conventional fluid mechanics. In this study, the relations between the electroosmotic flow rate and a channel size, a pressure gradient and an applied electric field were measured. In addition, the electric current along the electroosmotic flow channel was measured. The electroosmotic flow rate is shown to be proportional to the channel size. There are cases that the electroosmotic flow rate is not proportional to the applied electric field. The flow rate of an electroosmotic flow under the influence of a pressure gradient is linear to the pressure gradient. In the bulk region of the liquid in an electroosmotic flow channel, there is an excess electric charge that contributes to an additional electric current over the conductive current.
  • 伊藤 浩二, 宮崎 大輔, 庄司 正弘
    2002 年 68 巻 671 号 p. 2079-2085
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    The experiment of air-water isothermal two-phase flow in a vertical pipe was conducted by paying attention to the dynamic characteristics of flow pattern and its transition. Differential pressure fluctuation for bubble, slug, churn and annular flow were measured, and nonlinear characteristics of the flow were analyzed through the return maps on which the extreme values of the differential pressure fluctuation were plotted. It is found from the results that the distribution of the data points on the map differs markedly depending on the flow patterns. The characteristics of the flow configurations provide a criterion and a new identification method of flow patterns.
  • 西尾 茂文, 永田 真一, 馬場 史郎
    2002 年 68 巻 671 号 p. 2086-2092
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    The SEMOS-HP (Self-Exiting Mode Oscillating-Flow Heat Pipe) consists of a closed capillary loop meandering between heated and cooled parts. The closed loop is vacuumed and then it is charged with an operating liquid up to a volume fraction. When the temperature difference between the heated and cooled parts is increased beyond a critical value, the operating fluids lining up as liquid columns and vapor plugs along the closed loop starts to oscillate and circulate in the loop. In the present paper, the effects of some system parameters on the heat transport characteristics of the SEMOS-HP were experimentally investigated and the following results were obtained. A vertical SEMOS-HP with R 141 b and 0.8mm in inner diameter can transport sufficient amount of heat. The SEMOS-HP can operate at inclination angles (=0 for the horizontal plain) down to 3 degree. The effective thermal conductivity of SEMOS-HPs is not sensitive to wall material and initial vacuum of the tube. The contribution of sensible heat transport to the total heat transport is not neglibible. Finally, a stop valve effect of liquid columns is presented as one of the mechanisms driving the pulsating flow of the operating fluids.
  • 門出 政則, 劉 維, 有馬 博史, 光武 雄二, HAMMAD Jaffar A.
    2002 年 68 巻 671 号 p. 2093-2097
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    An analytical method has been developed for inverse problem of one- and two-dimensional heat conduction by using Laplace transform technique. For the cases of radical change in a measured temperature and of a triangular shape of temperature change, a proposed function cannot approximate the temperature over the whole range of measured time so that the inverse solution obtained thereby makes its estimation deteriorate. The characteristic of Laplace transform gives this deterioration clear by splitting the whole time into a partial time. The result shows that the estimation of surface temperature and heat flux can be markedly improved on comparison of any existing one.
  • 橋詰 健一, 徳留 篤, 松江 孝博
    2002 年 68 巻 671 号 p. 2098-2105
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Heat transfer characteristics was investigated in liquid-fluidized beds using particle mixtures, which mix homogeneously during fluidization in fluidizing columns. In the experiment, fluidization columns having a diameter of 21, 36 and 56 mm were provided, and water was used as a fluidizing liquid. Tested particles were of glass and ceramics, and their diameter range was from 1.87 mm to 6.98 mm. It was found, that the heat transfer coefficient for particle mixtures can be predicted by an appropriate correlation for single-kind particles, when the mean particle diameter and density are evaluated from volume fraction and from mass fraction, respectively.
  • 三角 利之, 蒲池 雅樹, 北村 健三
    2002 年 68 巻 671 号 p. 2106-2113
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Natural convective flows around a pair of vertical heated plates were investigated both analytically and experimentally. Main concerns are directed to an interaction of thermal plumes arising from the plates and also to its influence on the local heat transfer from the plates. In order to simulate the flow and temperature fields around the plates, full elliptic equations for the momentum and energy transport were solved numerically for the computational domain that encloses the plates. The results showed that the present elliptic analysis well predicts the plume interaction and also the local heat transfer coefficients of the plates. The present results were also compared with those of the conventional parabolic analysis. The results depict that a full elliptic analysis is necessary to obtain accurate local quantities such as the velocity distributions in between the plates and also the local heat transfer coefficients of the plates.
  • 三角 利之, 蒲池 雅樹, 北村 健三
    2002 年 68 巻 671 号 p. 2114-2121
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Natural convective flows of water induced around a horizontal row of vertical heated plates were investigated both analytically and experimentally. In order to analyze the whole flow and temperature fields around the row, full elliptic equations were solved in a large computational domain that encloses the row. Heat transfer and flow visualization experiments were also carried out to ascertain the present analysis. The results showed that the present analysis well predicts the actual flow field and heat transfer from the plates. It was also found that the velocity profiles and flow rates within vertical slots bounded by the plates vary not only with the location of slots in the row but also with the total number of plates. These variations also result in a marked difference in the local and overall heat transfer coefficients of the plates.
  • 丹澤 祥晃, 竹下 恵介, 天野 嘉春, 橋詰 匠
    2002 年 68 巻 671 号 p. 2122-2127
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Dynamic behavior of a directory combined binary turbine system using a mixture of R 134 a and R 123 is investigated experimentally and theoretically. Our previous binary turbine system, which employs steam as the primary working fluid, used R 11 as the secondary working fluid because R 11 has good characteristics as a working fluid in power plants. However, substitute LBMs (Low Boiling temperature Medium) are being developed because of the ozone layer depletion by CFCs (Chloro Fluoro-Carbons). We investigated the system using R 123 in the second stage. Because R 123 is also controlled, in this paper, the steady state characteristics and dynamic behavior of the system using a mixture of R 134 a and R 123 are investigated taking into account the mole fraction of the mixture. In addition to the investigation using the experimental system, the following are clarified using our model : In the steady-state characteristics, there are remarkable differences in pressure based on the thermodynamic properties and in the load allotment of the two turbines. However, in the dynamic characteristics, the effect of the mole fraction could hardly be observed on the response characteristics of the rotating components to the load change.
  • 浅野 等, 藤井 照重, 久角 喜徳, 王 暁, 津田 英毅
    2002 年 68 巻 671 号 p. 2128-2134
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    In the case that an absorption cycle is driven by using waste heat as a heat source, it is efficient for the improvement of exergy efficiency to decrease the temperature in regenerators. In this paper, two methods of decreasing the temperature in high-temperature regenerator of double-effect cycle were evaluated based on the energy and the exergy analysis. Those are parallel flow systems, in which aqueous solution is fed to high-and low-temperature regenerators individually, and hybrid cycle with a steam compressor placed at the exit of a low temperature regenerator in order to decrease the dew point of the low temperature regenerator. As a result, it was shown that performance characteristics of LiBr-water absorption cycle is strongly dependent on the difference of solution concentration between the inlet and the exit of the absorber, the maximum value of COP is obtained at 63 wt% at the inlet of the absorber for all cycles, and the temperature in high-temperature regenerator can be decreased by 14°C for decreasing of 10°C of dew point in low-temperature regenerator without decreasing in COP by utilizing the hybrid system.
  • 中谷 辰爾, 芝 世弐, 笠原 希仁, 荒木 幹也, 尾下 充利, 津江 光洋, 河野 通方
    2002 年 68 巻 671 号 p. 2135-2142
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    This fundamental study on the effect of jet exhaust gas on the stratospheric ozone layer was performed experimentally. The stratospheric condition was simulated using a large vacuum chamber, where the pressure was sustained at 2.67 kPa and an ultraviolet ray source was directed. This condition was defined as a simulated ozone layer. A low-pressure mercury lamp was used as a source of ultraviolet rays. After evacuating the chamber, a certain amount of NO or NO2 was injected into the chamber and was diluted by Air or N2. Then ultraviolet rays started emitting and the evolution of NO and NO2 was observed by LIF measurement. Calculations using properties in the stratosphere were conducted to compare with the experimental results. In addition to that, calculations were performed using properties from the experimental results. As a result of this study, we could determine the tendencies of these reactions in the stratosphere, including NO, NO2 and O3, and make out their mechanisms.
  • 西村 浩一, 店橋 護, 宮内 敏雄
    2002 年 68 巻 671 号 p. 2143-2149
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Prediction method of drag reduction is presented based on the coherent fine scale eddy in turbulence. To estimate the drag reduction efficiency, time scale ratio of drag reducers like surfactants to coherent fine scale eddy is introduced for the near wall turbulence. Key point of this prediction method is the utilization of characteristics of the coherent fine scale eddy in full-developed near wall turbulence before the manipulation of drag reduction. From analysis of DNS data, it is shown that the time scale of the coherent fine scale eddy can be approximated to be 20 η/μrms, 20 νρ/τw0 or 80 νρ/Δp0d. Since the time scale of a drag reducer is considered to be constant under a constant condition, the time scale ratio depends on the time scale of the coherent fine scale eddy. Therefore, the range of drag reduction can be estimated from the characteristics of turbulence before the manipulation of drag reduction. The prediction method is applied for the case of drag reduction by surfactants. The ranges of drag reduction are assembled for different mean velocity and pipe diameter. The effective range for each surfactant mixture is derived and estimation of scale-up effects are shown.
  • 鳥飼 宏之, 松尾 亜紀子, 植田 利久, 溝本 雅彦
    2002 年 68 巻 671 号 p. 2150-2155
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    Stabilizing mechanism of a methane-air edge flame that is a partially premixed flame, is investigated experimentally using the axisymmetric wall jet burner. Measurements of stability limits, flame locations and velocity fields with PIV, and visualization of themal boundary layer around of the edge flame have been performed. As a result, it is found that Peclet number Pe, which is expressed as Pe= Ut× pe/D, where Ut is tangential velocity toward the edge flame, Pe is curvature radius of thermal boundary layer of the edge flame and D is mass diffusivity, shows constant value at stability limits. The Pe physically means the ratio between partially premixing time to form flammable mixing layer and residential time of a fluid element in partially premixing region. Therefore, the result obviously indicates that the edge flame's stability is determined due to the balance between the partially premixing time and the residential time in partially premixed region. Thus, it is clear that a partially premixing, which is absent in a pure premixed flame, is important for stabilizing mechanism of the edge flame in the wall jet.
  • 石田 明男, 佐々木 順也, 久島 寔, 松山 貴史, 川口 明男, NEWMAN Paul
    2002 年 68 巻 671 号 p. 2156-2162
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    The Diesel Dual Fuel (DDF) system is a diesel fuel ignition type natural gas engine, which ignites and burns the mixture of the natural gas with the self-ignition flame of a pilot diesel fuel injected directly into the combustion chamber. This engine with the EGR cooler, VG Turbocharger and Catalytic Converter installed, controlled the supply volume of natural gas and of diesel fuel respectively with the most optimized balance. As a result, It is effective to the thermal efficiency improvement of the engine to maintain an excessive air ratio of the natural gas to be high, and it met stringent stationary internal combustion engine NOχ guidelines such as in the Metropolis of Tokyo or Osaka City etc., while achieved nearly equal thermal efficiency with the base diesel engine.
  • 平澤 茂樹, 鈴木 匡, 円山 重直
    2002 年 68 巻 671 号 p. 2163-2166
    発行日: 2002/07/25
    公開日: 2008/03/28
    ジャーナル フリー
    To unify heat flux on a wafer during rapid thermal processing with lamp heaters, we developed a rapid computation technique to find the optimum conditions for controlling lamp heating rate. Box's method was used to optimize heating rate by repeatedly calculating distributions of heat flux on the wafer by using 3D radiative heat transfer analysis program. Calculation results show that the minimum distribution of heat flux on the wafer is 1.5% at a heat-up condition of 100°C/s and 4-zones control of 16 rod-type lamps. The minimum heat flux on the wafer is 210 W/m2 (so the temperature difference in the wafer is 0.5°C) at a steady state at 1000°C. This minimum heat flux is 1/15 times of that produced by non-controlled heating with the same lamps.
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