日本機械学会論文集 B編
Online ISSN : 1884-8346
Print ISSN : 0387-5016
59 巻, 568 号
選択された号の論文の55件中1~50を表示しています
  • 五十嵐 保, 伊藤 真一郎
    1993 年 59 巻 568 号 p. 3701-3707
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    Experimental studies on drag reduction of a square prism were conducted. To control the flow around a square prism, a small vortex shedder was set up upstream of the prism. The side of the prism, D, was 30 mm and the Reynolds number was Re=3.2×104. The diameter of the rod used as the vortex shedder, d, ranged from 1 to 6 mm, and the space between the prism and the rod, G, was varied. The results obtained are as follows. The critical space GC, is given as GC=D+4.5d, where vortex shedding from the rod disappears. The Strouhal number of the prism decreases at G>GC and increases at G≤GC. In the range of 0.1≤d/D≤0.2, drag of the prism decreases about 50% at G>GC and 70% at G≤GC.
  • 中西 裕二, 亀本 喬司
    1993 年 59 巻 568 号 p. 3708-3713
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    The vortex method has been applied to simulation of unsteady separated flow at a high Reynolds number. In the two-dimensional vortex method, unsteady pressure distribution over the surface of a body and fluid force are easily calculated from either the unsteady Bernoulli equation or the Blasius theorem expanded for unsteady flow. However, it is a crucial point that the estimation of the pressure distribution in the flow field compared to over the surface is rather difficult. Although, three-dimensional flow has recently been calculated by the vortex method, the above-mentioned methods for calculation of the pressure distribution are not applicable to three-dimensional flow. In this study, a simple method for solving Poisson's equation for pressure by the boundary element method is proposed in order to estimate the pressure distribution in the two-and three-dimensional vortex method. The pressure distributions around a circular cylinder and a sphere calculated with the proposed method are in good agreement with those obtained with the unsteady Bernoulli equation.
  • 祖山 均, 山内 由章, 佐藤 一教, 井小萩 利明, 大場 利三郎, 大島 亮一郎
    1993 年 59 巻 568 号 p. 3714-3719
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    This paper aims to clarify peculiar phenomena arising around a ultra high-speed submerged water jet accompanied by very severe cavitation. By means of a flow visualization technique with a xenon flash light, three kinds of water jets are carefully observed, and the spatial distributions of cavitation-pressure pulses around the jets are also measured with pressure-sensitive film. The effects of the working pressure and the shape of nozzles are clarified systematically. Thus, the characteristics and the structures of ultra high-speed cavitating submerged water jets are clearly shown.
  • 田部井 勝稲, 白井 紘行, 高草木 文雄
    1993 年 59 巻 568 号 p. 3720-3725
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    Emission experiments on cavitation bubbles in water were performed with circular orifice flows. The region emitting faint light due to the bubbles was visualized with the combined method of photon counting and computerized tomography. Emission data obtained from outer-side observation were inverted into internal intensity distributions by means of the modified Abel transformation in which the light-quenching effect by cavitation bubbles was taken into account. It was observed that, under the condition of large pressure difference before and behind the orifice, a large number of photons were emitted from the region downstream of the cavitation flows, and the emission intensity was strongly dependent upon the pressure difference. The effect of an addition of a small amount of luminol to water was examined to demonstrate the effectiveness of the present method.
  • 西村 龍夫
    1993 年 59 巻 568 号 p. 3726-3733
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    Oscillatory How in a two-dimensional symmetric wavy-walled channel is studied by means of a finite element method over wide ranges of How parameters of the Reynolds and Strouhal numbers. Two-dimensional numerical computations show the variations of How separation and wall shear stress with time. The fluid motion is found to be most unstable in the limited Strouhal number range of 0.02-0.03 as the Reynolds number increases. That is, time and spatial periodicities of the How are not established. Steady streaming induced by oscillatory motion is also examined, and the vortex strength for the steady streaming has a peak at this Strouhal number range, independent of the Reynolds number.
  • 辻野 智二, 島 章, 酒井 宏之
    1993 年 59 巻 568 号 p. 3734-3738
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    The clarification of the dissolving processes of oxygen bubbles in blood is important as a fundamental study on the development of an oxygenator. In this work, the combination of the equation of motion for a bubble in blood subjected to a pulsating pressure and the equation of oxygen diffusion is numerically calculated. Consequently, the effects of the pressure oscillation on the dissolution of oxygen bubbles in blood are elucidated. It is found that the bubbles in blood subjected to pulsating pressure shrink with the radial oscillation, and that bubble dissolution times are short. The oxygen diffusion in blood is promoted due to the effect of pressure pulsation.
  • 橋本 成広, 笹田 直
    1993 年 59 巻 568 号 p. 3739-3742
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    A clot test under a uniform shear field in vitro has been designed, which utilizes a concave-convex cone system. A sample of beagle blood was sheared between a stationary convex cone and a rotating concave cone. Evaluation of clot growth was derived from the clotting ratio, which was calculated from the rate of increase of frictional torque between the two cones. The results show that clot grows smaller with increase of shear rate in the range from l00 to 500 s-1.
  • ?崎 展, 清水 宏文, 辻本 良信, 吉田 義樹, 北川 晃一
    1993 年 59 巻 568 号 p. 3743-3748
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    The internal flow of a cross flow fan (CFF) is complex. Therefore, the design method for a CFF has not yet been established. In our CFF study, the authors measured the internal flow by particle tracking velocimetry using an experimental apparatus for water flow visualization. The pathline images photographed with a digital still camera were analyzed by the computer program developed by one of the authors to obtain velocity distributions. This measuring method was applicable to this study. The measured results were discussed from several points of view and useful information on the internal flow of the CFF was obtained.
  • 森北 博巳, 菱田 公一, 前田 昌信
    1993 年 59 巻 568 号 p. 3749-3755
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    A new instrument for evaluating the equivalent diameter and velocity of nonspherical particles was developed. The technique is based on the diffraction light intensity method where the light scattered in the forward direction is insensitive to the particle shape but is related to the projected area of the scatterer. A calibration curve between diameter and scattered intensity was determined by a computer simulation using Fraunhofer diffraction theory and the geometrical optics method. Signal processing had been performed with transient recorders and a digital signal processor, working with a personal computer. Various types of irregularly shaped particles, such as cooper, aluminum oxide, glass, polyethylene and stainless steal with diameters ranging from 20 to 200 μm have been examined. The reference diameter of these particles was evaluated by a microscope with an image processing system. Measured size distribution coincided significantly with the reference data, with uncertainty bands of + 10 μm, -0 μm in average diameter.
  • 牧 博司, 小川 信夫, 西村 宏貴
    1993 年 59 巻 568 号 p. 3756-3761
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    There have been many investigations which deal with the large-scale fluctuation existing in the flow fields of the developed region of a two-dimensional free jet. However most of them have been made using a jet which has a top-hat velocity profile at the nozzle exit. The objective of the present investigation is to compare the characteristics of large-scale structures existing in two types of flow of the two-dimensional free jet, where the exit velocity profile is the "top-hat" type or "fully developed" type. We also studied the flow fields of a two-dimensional impinging jet. First, it was elucidated that the large-scale fluctuation also existed in the flow field of a fully developed jet. Dimensionless frequency in the initial region of the large-permaneny hyphon scale fluctuation obtained from x-direction data was proportional to the dimensionless distance to the power of - 1/3, and that obtained from y-direction data, to the power of - 2/3, instead of the power of - 3/2 obtained in the developed region of the two-dimensional free jet. Second, it was ascertained that the same kind of large-scale fluctuation as in the flow field of the developed region of the two-dimensional free jet also existed in the flow field of the two-dimensional impining jet.
  • 佐藤 彰, 小池 和雄, 小山 正, 神山 新一
    1993 年 59 巻 568 号 p. 3762-3766
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    Experimental study is carried out to clarify the local concentration of magnetic particles in a magnetic fluid plug in a nonuniform magnetic field. The intensity and the phase differences of the He-Ne laser beam which transmits the magnetic fluid within a duct of rectangular cross section are measured. The polarization angles of polarizer and analyzer are set to the directions of magnetic flux at each measured point. Also, the relationship between the phase difference of the transmitted light and the concentration of the magnetic particles is determined using the magnetic fluid film which has a small area and the same thickness as the plug. This relationship is used to estimate the local concentration of magnetic particles at each measured point in the plug. It is clarified that the region with higher concentration of magnetic particles is formed near the magnetic pole pieces and it is enlarged with magnetic flux density.
  • 望月 信介, 伊澤 明峰, 大坂 英雄
    1993 年 59 巻 568 号 p. 3767-3775
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    The large-eddy structure of a d-type rongh wall boundary layer manipulated with longitudinal thin ribs for turbulent drag reduction has been investigated experimentally in terms of a dynamical equation for a two-point velocity correlation uA uB. Two-point double velocity correlation functions involved in the production terms were measured in order to focus on the role of the large eddies on the turbulent production process. Some noticeable features of the two-point velocity correlation functions show that the well-known hairpin eddy or streamwise rotating vortices predominantly affect the production terms. In the boundary layer manipulated with the longitudinal thin ribs, the magnitude of the two-point velocity correlation functions is reduced only in a relatively small spatial distance of 0.1δ, which is comparable to Taylor's micro length scale in the present turbulent field. This reduction of the two-point velocity correlation is seen throghout the layer.
  • 三栖 功, 斎田 暢三
    1993 年 59 巻 568 号 p. 3776-3780
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    The variable-interval time averaging (VITA) tchnique is applied to detect bursts in the turbulent boundary layer at favorable pressure gradients generated by a two-dimensional asymmetric contraction. Three averaging periods based on (1) the Eulerian micro-time scale, (2) the inner time scale and (3) the outer time scale are used to obtain conditionally averaged streamwise velocities with the VITA technique. The first of these scales is derived from the auto-correlation of the streamwise-fluctuating velocity component, and the second and third scales are obtained from the inner and the outer variables of boundary layers, respectively. Results of experiments show that when the Eulerian micro-time scale at Y+=15 is used as the averaging period in the VITA technique, the conditional averages at Y+=15 are similar and independent of the pressure gradient. On the other hand when the averaging periods based on the inner or the outer time scales are used, the conditional averages become irregular as the pressure gradient decreases.
  • 杉山 均, 秋山 光庸, 松本 将師, 古沢 新平, 平田 賢
    1993 年 59 巻 568 号 p. 3781-3788
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    A numerical analysis has been performed for fully developed turbulent flow in a rectangular duct of aspect ratio 2:1, one of whose long-side walls was roughened. In calculation, an algebraic stress model was adopted in order to predict Reynolds stresses precisely. Calculated results were compared with the experimental data available. The present method can predict well a large eddy caused by anisotropic turbulence in a half-cross-section, and a small eddy is observed in the upper wall corner region. The experimental result of streamwise vorticity shows the existence of the predicted small eddy. Calculated results of normal stresses and turbulent energy are in good agreement with the experimental data. Furthermore, the evaluated terms of streamwise vorticity suggest that the turbulent stress terms of u22- u23 and u2u3 are dominant ones, being of opposite sign and much larger than the convection terms.
  • 佐野 健一, 平野 廣和, 池ノ内 昌弘, 小野 純二
    1993 年 59 巻 568 号 p. 3789-3794
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    Aerodynamic force and moment acting on a body moving in a tube, where the blockage ratio is high and close to unity, play critical roles for the stability and performance of the tube-body system, such as a transportation system by a capsule, a high-speed train in a tunnel or a microgravity experiment facility consisting of a freely falling capsule and a braking tube. A series of preliminary experiments is carried out to determine the flow field confined by the tube inner wall and the body surface boundaries, using models of 18 mm in diameter having a blockage ratio 0.81 and the pressure difference 0.26 MPa between the upstream and downstream stations. The flow around the spindle-shaped body can be treated as an inviscid compressible fluid taking into account the boundary layer effect. The inclination of the body produced such a remarkable increase of the lateral force as has never been found for the body in an open-air flow condition.
  • 岡 憲治, 野崎 孝仁, 伊藤 英覚
    1993 年 59 巻 568 号 p. 3795-3803
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    The loss coefficients and the power-loss coefficients for sharp-edged combining tees with the area ratios of 11.44 and 17.72 are determined experimentally. Based on the least squares analyses of the experimental data of both the present authors and previous investigators, empirical equations of loss coefficients for combining tees are proposed. The effects of both the area ratio and the radius of curvature of the wall at the joining edge on loss coefficients are taken into account in deriving the equations. The comparison of the proposed equations with the experimental data shows that the proposed equations can be used to reliably estimate the energy losses at combining tees.
  • 福原 稔, 野崎 勉, 岩坪 貢, 有水 博
    1993 年 59 巻 568 号 p. 3804-3808
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    Drag reduction of the pipe flow using flexible tubes was experimentally examined in comparison with that using rigid tube. The coefficient of friction in the flexible tube is smaller than that in the rigid tube even if the variation of the cross section accompanied with the flow in the flexible tube is considered. The thinner the flexible tube and the larger the Reynolds number, the larger the rate of decrease of the coefficient of friction. In the case of the thinnest flexible tubes, it becomes about 22% at Re=3.0×104. These results are related to the power spectrum distribution of the pressure fluctuation.
  • 南部 健一, 蕨岡 一郎
    1993 年 59 巻 568 号 p. 3809-3816
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    Argon plasma in a DC magnetron sputtering apparatus with a practical magnet system is analyzed by simulating the motion and collision of electrons and ions. The effects of the pressure and the magnetic field on the erosion distribution of the target are examined in detail. It is found that not only the strength but also the form of the magnetic field has a great effect on the erosion distribution.
  • 福元 裕彦, 南部 健一
    1993 年 59 巻 568 号 p. 3817-3822
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    MCDS (Monte-Carlo direct simulation) has been recognized as the most powerful numerical method for analyzing rarefied gas flows. A new efficient method applicable to three-dimensional rarefied flows with complex geometry is proposed; a complex flow field is divided into a network of arbitrary cells used in FEM (finite-element method). The results show that the computing time for the present method using an arbitrary cell system is, at most, 1.5 times that for the method employing a regular cell system. The latter is not applicable to complex geometries. It is shown that the present method is useful for simulating three-dimensional rarefied flows with complex geometry.
  • 棚橋 隆彦, 沖 良篤
    1993 年 59 巻 568 号 p. 3823-3830
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    In this paper, we present a new hybrid-streamline-upwind finite-element method, which is based on the finite analytic method developed in the field of the finite difference method. In order to obtain an optimal shape function, we introduce an adjoint differential operator to the differential operator for a steady advection-diffusion equation. The shape functions which satisfy these differential operators are mutually dual. One of them interpolates accurately the functions appearing in convection-dominated flows, the other becomes a hybrid-streamline-upwind weight function. Furthermore, we define a discrete del operator for the reduction of memory storage in the computer. As a result, we achieve simplicity of formulation and high-speed calculation of the finite-element method.
  • 金元 敏明, 赤松 弘隆, 松永 茂徳, 塚本 寛
    1993 年 59 巻 568 号 p. 3831-3837
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    Flow structure around a guide vane, installed in a diffuser of a mixed flow pump with low specific speed, was investigated experimentally. The secondary flow along the hub wall, which is caused by the vane camber and runs toward the suction side of the vane, changes to run upstream near the suction surface of the vane. Its flow unites with another secondary flow along the suction surface, which is caused by the meridian curvature and runs toward the hub wall, to form the strong vortex on the hub wall near the suction surface. This vortex induces the downstream flow along the suction surface to run toward the casing wall. This flow also unites with the flow from the leading edge along the suction surface to form another vortex on the suction surface near the casing wall. These vortices induce a circulating flow on the cross section in the downstream passage, and markedly affect the turning angle of the guide vane.
  • 石井 博, 柏原 康成
    1993 年 59 巻 568 号 p. 3838-3845
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    In this paper, the effects of various parameters on the inception and post-stall characteristics of surge and rotating stall in axial compressors are investigated, using a numerical model for multiblade-row compressors. The parameters described in this paper are the shape of total pressure-loss and deviation characteristics, IGV (Inlet Guide Vane) outlet flow angle, inlet flow distortion, and bleeding. It is found that there exist two types of rotating stall differing in magnitude, that inlet distortion and deterioration in compressor performance reduce the inception margin of unstable behavior, and that an optimal bleeding exists which can optimize the inception margin of unstable behavior. The usefulness of the present model is examined through numerical investigation. The validity of the model is also discussed by comparison with test results in a 3-stage compressor.
  • 松内 一雄, 平山 茂
    1993 年 59 巻 568 号 p. 3846-3853
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    To suppress the noise generated from an axial-flow fan, active control was adopted for the pressure fluctuation in the stage. The main part of noise, which oscillates at the blade passing frequency, is caused by rotor-stator interaction. Our main aim is to clarify whether the noise is controllable in principle by manipulation of the pressure fluctuation in the stage. Two types of control systems with two loudspeakers were investigated. One is the "mode replacing" method that changes the traveling mode with blade passing frequency into a damping mode in the stage. The other is the "sound absorbing" method by which the energy of pressure fluctuation is absorbed by loudspeakers. It is found that both these noise reduction systems are effective in controlling the noise.
  • 横溝 利男, 太田 元一
    1993 年 59 巻 568 号 p. 3854-3860
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    This paper is focused on the improvement of the performance of the Savonius rotor. For this purpose, the flow inside and outside the rotor is observed by means of a flow visualization method. The behavior of the vortices shed from both sides of the rotor is measured by means of hot-wire flow velocity meters. From these experimental results, it was found that the formation manners of these two vortices are different. One of the vortices is formed from the shear flow between the blade tip and the outside flow of the rotor and is directly shed into the wake. The other vortex is formed on the back surface of the advanced blade. This vortex rotates with the blade and is shed from the blade after rotating about 400 degrees. The strength of the vortex can be controlled by the slit in the blade. The optimum position of the slit is 120 degrees, at which the power coefficient is increased about 150 % as compared with the original rotor performance at u/U =1.09.
  • 佐藤 雄二
    1993 年 59 巻 568 号 p. 3861-3863
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    Experimental study to verify some of head-loss factors for pipe entrances has been carried out. Head loss factor for sharp edged entrance of circular pipe is published as 3.0∼1.3 on JSME Mechanical Engineer's Handbook since 1937. On the basis of experimental results, the auther presume above-cited figures to be groundless ones. The study covers oblique pipe entrances.
  • 河合 秀治, 長谷川 裕夫, 盛田 幸治, 吉川 邦夫, 塩田 進
    1993 年 59 巻 568 号 p. 3864-3870
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    For the measurements of the fraction of seed metal (potassium or cesium) in a closed-cycle MHD (CCMHD) power generation system, the reduced absorption coefficients of the 4p-4s line of potassium (766.5 nm) and the 6p-6s line of cesium (852.1 nm) have been determined experimentally for K-Ar, K-He, Cs-Ar and Cs-He mixtures under the condition of the CCMHD working gas. The column density of the alkali metal was measured using the modified hook method which is not affected by the profile and width of the absorption coefficient. The emissivity of the blue wing of the line was obtained by the emission spectrum. From the reduced absorption coefficient, the number density of the seed metal can be measured by monitoring the change of absorption at a fixed wavelength in the wing of the line.
  • 刑部 真弘, 李 越
    1993 年 59 巻 568 号 p. 3871-3876
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    Entrainment behavior from a stagnant lower fluid to a turbulent upper fluid in vessels of different sizes was studied experimentally and theoretically. The turbulent energy in the upper fluid was supplied by an injection and extraction flow. The turbulent intensity in the upper fluid was proportional to the injection and extraction velocity at the nozzle. The previous study proved that the entrainment velocity was inversely proportional to a Richardson number Ri* less than l00. In the present study, the depression of the entrainment was observed at Ri* of l00∼ 200. This behavior could be predicted with the turbulent energy balance between the energy released from the energy-containing eddy and the energy consumed by entrainment and dissipation.
  • 小林 伸和, 小竹 進
    1993 年 59 巻 568 号 p. 3877-3882
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    Effects of clusters on film condensation of molecular beam of gas and metal vapors were studied experimentally. Molecular cluster beams of CO2, titanium and indium vapors made by an electron beam gun are condensed on the surface of a quartz plate of film thickness meter. With the TOF method using two choppers, clusters are selected in size depending on the difference of flight time of molecules. Results show that the molecular beams including clusters (dimers) tend to enhance the growth rate of film thickness, that is, clusters have higher sticking probabilities than monomers.
  • 中里見 正夫, 清水 英男, 落合 積, 世古口 言彦
    1993 年 59 巻 568 号 p. 3883-3890
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    The purpose of this study is to investigate the pressure effects on the flow regime transitions in vertical gas-liquid two-phase flow. The following five flow conditions were tested to examine the effects of system pressure; the flow conditions in the transitional area in which the plug flow changes to huge wave flow; the flow conditions of the central gas core in the tube; the flow conditions in the area where the liquid slug disappears; the flow conditions in the transitional area in which the bubble flow changes to plug flow; and the flow conditions in the transitional area in which the time averaged wall shear stress changes from the negative to the positive value. New correlations to predict the flow conditions for the five above-mentioned flow conditions are presented. System pressures tested, range from 0.3 to 20 MPa.
  • 高森 和英, 湊 明彦
    1993 年 59 巻 568 号 p. 3891-3898
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    A multidimensional analysis code for two-phase flow using a two-fluid model was improved by taking into consideration the condensation heat transfer, film thickness, and film velocity, in order to develop an evaluation method for two-phase flow and heat transfer in a feed-water heater. The following results were obtained by a two-dimensional analysis of a feed-water heater for a power plant. (1) In the model, the film flowed downward in laminar flow due to gravity, with droplet entrainment and deposition. For evaluation of the film thickness, Fujii's equation was used in order to account for forced convection of steam flow. (2) Based on the former experimental data, the droplet deposition coefficient and droplet entrainment rate of liquid film were determined. When the ratio at which the liquid film directly flowed from an upper heat transfer tube to a lower heat transfer tube was 0.7, the calculated total heat transfer rate agreed with the measured value of 130 MW. (3) At the upper region of a heat transfer tube bundle where film thickness was thin, and at the outer region of a heat transfer tube bundle where steam velocity was high, the heat transfer rate was large.
  • 土田 一, 相場 眞也
    1993 年 59 巻 568 号 p. 3899-3905
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    An experimental investigation of boiling heat transfer of saturated R11 has been conducted with a horizontal cylinder which is 20 mm in diameter and 50 mm in length, and is enclosed by concentric outer tubes. These outer tubes have two holes which are 3 mm in width and 60 mm long. The clearance (c) between these tubes ranged from 0.15 mm to ∞ and heat flux (q) from 600 to 1.5×105 W/m2. Heat transfer characteristics are demonstrated and discussed in this report. The main results obtained are summarized as follows: (1) The heat transfer coefficient a increases with decreasing c in the ranges of c=0.35 mm to 0.75 mm and q=0.4×104 to 5×104 W/m2. (2) The critical heat flux qc decreases with decreasing c when c≤0.75 mm.
  • 落合 芳博, 石田 良平
    1993 年 59 巻 568 号 p. 3906-3912
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    This paper proposes a boundary element method for analysis of transient heat conduction problems in orthotropic bodies. The time-dependent fundamental solution is used for the formulation of the boundary integral equation. First, the time-dependent fundamental solution of an orthotropic body is obtained using Fourier transform and Laplace transform. In order to solve this boundary integral equation for the case with heat generation or initial temperature, the domain integral is necessary. In this paper we also show that these problems can be solved approximately without the domain integral. This method can also be applied to thermal problems with complicated heat generation, and for general heat generation, the domain must be divided into small areas, where the distribution of heat generation satisfies the harmonic equation. In order to divide the domain, the contour lines of heat generation, which approximate the actual heat generation, are used. A new computer program is developed and applied to several problems.
  • 渡辺 章弘, 小竹 進
    1993 年 59 巻 568 号 p. 3913-3918
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    The molecular process of heat conduction is studied with the molecular dynamics method for Lennard-Jones potential solid atoms. The probability density of the heat flux and its two-point time and space correlations are investigated for an understanding of the transfer mechanism of heat energy on the molecular level. The heat flux in the direction of the temperature gradient has a larger probability for carrying the molecular energy toward the low-temperature side than that toward the high-temperature side. The spatial length of the heat flux correlation is about 4 or 5 times the lattice length. Lattice defects in the solid reduce the correlation of heat flux, whereas lattice particles having deeper potential wells yield a stronger correlation of heat fluxes.
  • 菱田 公一, 岸沢 浩, 富永 努, 前田 昌信
    1993 年 59 巻 568 号 p. 3919-3924
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    A novel technique for enhancing and controlling local heat transfer coefficients from the hot wall to the cooling gas flow using soft magnetic solid particles has been proposed in order to eliminate the disadvantages of inefficient gas-solid two-phase flow. The characteristics of the flow and local heat transfer were examined in a vertical rectangular channel flow involving ferrite particles of 145 μm in diameter. The Reynolds number of the channel flow was set at approximately 104 and the particle mass loading ratio was varied up to 1.6. The result indicated 60 percent enhancement of heat transfer downstream from the location of the magnet at a mass loading ratio of about 1.6. Further enhancement in heat transfer is provided by increasing the particle mass loading ratio and the magnetic field intensity. The mechanism of heat transfer enhancement can be clarified by considering the increase in the local heat capacity near the heated plate.
  • 刑部 真弘, 彭 自明, 二又 浩文
    1993 年 59 巻 568 号 p. 3925-3931
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    Top flooding experiments in annuli with various aspect ratios were conducted to study the flooding characteristics and similarities with those in thin rectangular channels. Top flooding in high-aspect annuli were characterized using the average circumference W as a characteristic length in Wallis nondimensional velocity. The flow in the high-aspect annuli consisted of approximately four "unit cells" around the circumference, each of which was similar to that in the thin rectangular channels. Therefore the characteristic length was the circumference corresponding to the wider span in the thin rectangular channels. When the annulus was actually divided to four "cells" by inserting vertical walls, the descending-water flow rate was increased due to the nonuniform flow distribution among the "cells".
  • 岡本 芳三, 稲垣 照美, 関谷 将三
    1993 年 59 巻 568 号 p. 3932-3937
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    The visualizing technique using the infrared radiometer, which is useful in estimating a two-dimensional temperature distribution on a surface, has been attractive. Infrared radiometry is one of the most fundamental methods of various remote sensing techniques. In the measurement using the infrared radiometer, radiation energy is analyzed to determine surface radiation temperature. However, the radiosity of the surface, which is a summation of emissive and reflective energy should be considered in measuring surface radiation energy. In particular, the influence of reflective energy on radiation energy transfer becomes important when measurement is performed at the normal temperature. In this study, we clarified various fundamental characteristics of infrared radiometry by use of 3 kinds of the infrared radiometer to visualize temperature distribution on a surface.
  • 冨田 栄二, 浜本 嘉輔, 堤 広行
    1993 年 59 巻 568 号 p. 3938-3944
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    It is very important to investigate the entrainment process of ambient air into a transient gas jet in order to discuss the combustion of the fuel jet in gas diesel engines. In this study, a gas jet was injected into still air during a very short period of 11.5 milliseconds. Cross sectional images of the jet were visualized at various times from the initiation of the injection. The mass of air entrainment into the jet was also obtained from the path line method proposed by the authors, and the spatial and temporal change of the ambient air entrainment into the jet was approximately clarified. The air from upstream side of the unsteady part of the jet is entrained more than that from the steady part. The ensemble averaged air mass entrained from across section perpendicular to the jet axis is axisymmetric; however, the entrainment mass of every jet is not always axisymmetric.
  • 梅宮 弘道, 郡司 進
    1993 年 59 巻 568 号 p. 3945-3950
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    River water can be changed to useful energy and waterresouces, in spite of the danger of groundwater pollution, by utilizing the aquifer thermal energy storage method. A new purification method for the water supply system, utilizing an aquifer was proposed, i.e.. artificial groundwater recharge through a biofilter, for example, ferriccolloid and photosynthesizing microorganism layer, and named the aquifer biofilter method. The main objective of this paper is to investigate filter effects on the aquifer biofilter in the field. Experimental investigation led to the following results: (1) the purifying effect of organic materials by the aquifer biofilter was confirmed on the basis of a reduced COD value; (2) a numerical simulation model of the purifying effect of the aquifer biofilter was validated by field experiments.
  • 石川 正昭, 平田 哲夫, 玉木 恕乎, 小原 公和
    1993 年 59 巻 568 号 p. 3951-3958
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    Phase change phenomena in horizontal cylindrical capsules located in fluid flow were considered both analytically and experimentally. In a single-capsule model, the wall temperature was determined by considering the balance between the wall heat flux and the outer flow heat transfer. By stacking these models, the phase change phenomena of capsules in alignment with flow are analyzed. The analytical results show good agreement with experimental results. According to the results, the main heat exchange at a certain time occurs in some capsules around a certain capsule, and the range of capsules goes down to the flow direction. This model will be useful in optimal designing and controlling of the energy storage system.
  • 矢部 彰, 高橋 克行, 青野 秀文, 牧 博司
    1993 年 59 巻 568 号 p. 3959-3966
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    To realize higher performance heat pump systems utilizing nonazeotropic mixtures, the EHD (Electrohydrodynamic) evaporator and condenser have been experimentally studied. Conventionally manufactured surfaces have not been effective for the evaporation and the condensation of nonazeotropic mixtures because of the accumulation of less evaporative or less condensable components of the mixture near the heat transfer surface. By setting the perforated coaxial cylindrical electrode inside of the 3.75-m-long evaporator tube, the evaporation and boiling heat transfer of the nonazeotropic mixture of HCFC 123 and HFC 134a on the inner surface of the tube have been enhanced by the factor of about 3 times over a wide range of qualities with the application of 7 kV at the electrode distance of 2.5 mm. Furthermore, using the electrically conducting transparent glass, it was clarified that the flow pattern has been changed and that some EHD phenomena such as the EHD surface instability have been observed. As for the condenser, the necessary tube length for condensation outside of the vertical tube has been shortened by two kinds of EHD effects, the increase of the condensation surface and the realization of the thinner film of the condensate.
  • 増岡 隆士, 谷川 洋文, 鶴田 隆治, 伊崎 弘
    1993 年 59 巻 568 号 p. 3967-3973
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    This study is concerned with the improvement in performance of insulating porous layers which contain a thermal screen consisting of a row of heat pipes. Numerical analysis shows that the thermal screen, which is set parallel with heated and cooled surfaces, introduces strong uniformity in temperature distributions such that conduction temperature profiles are approached. Thus, it is found that the thermal screen can reduce the average Nusselt number Num for the insulating porous layers and improve the performance of the insulation.
  • 北野 三千雄, 小林 秀昭, 小平 英俊, 柴田 潤
    1993 年 59 巻 568 号 p. 3974-3980
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    In an inverse conception of spray combustion, we attempted to increase the air-fuel contact area and promote evaporation and mixing by blowing air bubbles into liquid methanol. The ignition of the mixture formed in this way showed that a premixed flame could be stabilized over the surface of a foam layer, although the flame was in turbulent conditions and rather heterogeneous owing to small droplets flying away from the surface. The mixture was rich on the whole because of the high volatility of methanol. However, by setting a flame holder in the combustion tube and adjusting the distance between the holder and the foam layer surface, it became possible to control the mixture equivalence ratio and carry out lean side combustion.
  • 大岩 紀生, 石野 洋二郎, 山囗 譽起
    1993 年 59 巻 568 号 p. 3981-3987
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    Effects of nonsymmetrical wake structure on turbulent diffusion flames, stabilized behind a semicircular cylinder are experimentally investigated. Interactions between two vortex sheets in cold flows are also examined. By varying the ratio of the lower airstream velocity U2 to the higher U1 from U2/U1-1.0 to 0.083, detailed optical observations and measurements of velocity and temperature are made on nine flames. Cold flows behind a semicircular cylinder are classified into three patterns depending on the velocity ratio : wake-type flow ( U2/U1 ≥ O.5), transition flow with strong interaction between two vortex sheets (0.5≤<U2/U1≤0.15), and free shear flow type (U2/U1≤0.15). Flames also exhibit a sudden transition from the bluff-body- stabilized wake flame to the plane diffusion flame, indicating good agreement with transition in the cold flow. A comparison of the vortex characteristics in the cold flow with those in the reacting flow shows that the flame-flow interaction originates mainly from a combined effect of the suppression of the K-H instability due to the positive temperature dependence of the kinematic viscosity, the expansion and acceleration due to the exothermic reaction and the strong pressure fluctuations associated with turbulent combustion.
  • 酒井 幸夫, 小西 克享, 石原 敦
    1993 年 59 巻 568 号 p. 3988-3993
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    Tip opening and burning intensity of Bunsen flames diluted with nitrogen have been experimentally investigated. Methane/air and propane/air flames were used in the experiment. The tip opening limit was mapped as a function of the equivalence ratio φ and added nitrogen ratio X, and the tip temperature was measured. Results show that the burning at the tip was intensified in rich flame for methane and lean flame for propane. The maximum allowable dilution by nitrogen also occurs in rich flame (φ=1.05) for methane and lean flame (φ=0.94) for propane. The tip temperature steeply decreases with increasing X on the lean side for methane and the rich side for propane, while it gradually decreases on the rich side for methane and the lean side for propane. These results at the tip were due to the preferential diffusion and nonunity Lewis number through negative stretch induced by flame curvature. The present flame responses to preferential diffusion and Lewis number are ompletely reversed for those of positively stretched stagnation flames.
  • 村瀬 英一, 小野 信輔, 花田 邦彦, 松本 正和, Oppenheim K. Antoni
    1993 年 59 巻 568 号 p. 3994-4000
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    The ignition mechanism of lean mixture by a pulsed jet is investigated. In order to examine the combustion phenomena in the cavity of the pulsed jet igniter, a transparent cavity was made and schlieren photographs were taken. The electric characteristics in a jet issuing from the orifice of the pulsed jet igniter were measured using an electrostatic probe. The schlieren photographs revealed the combustion process in the cavity, and the signals from the electrostatic probe showed that the ejection duration of the chemically active products of incomplete combustion in the cavity was very short. This duration is governed by the period of spark discharge, and the re-establishment of combustion in the jet is confirmed.
  • 飯田 訓正, 木戸口 和浩, 久保 進
    1993 年 59 巻 568 号 p. 4001-4007
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    The possibility of combustion diagnostics through the measurement of radical luminescence is discussed in this paper. Radical species in premixed flames of gasoline, methanol and methane are explored using spectroscopic measurements. It was found that major species having strong radical luminescence are OH, CH and C2 for gasoline and methane, and OH and CH for methanol. The effects of the equivalence ratio and premixed gas temperature on spectral intensities are discussed. We found that the correlation between the equivalence ratio and spectrum intensity ratio of two radical species is linear. There is a possibility of predicting the equivalence ratio from the measurement of the radical emission intensity of a flame.
  • 葉 啓南, 小酒 英範, 神本 武征
    1993 年 59 巻 568 号 p. 4008-4013
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    A new technique is proposed to measure the two-dimensional local Sauter mean diameter (S.M.D.) distribution of droplets in an unsteady diesel spray. The technique is based on the principle of fluorescence and Mie scattering of droplets in the spray. NNN'N'-tetramethyl-p-phenylene diamine (TMPD, 1% by weight) is dissolved in fuel as a fluorescence dopant. When the laser light sheet illuminates particles in a cross section of the spray, they emit the fluorescence and the Mie scattering light. The fluorescence and scattering signals are imaged simultaneously by an optical system composed of a doubling prism, optical filters, and a high-speed gated image intensifier coupled with a CCD camera. The local particle size distribution is obtained by calculating the ratio of the two light intensities at each point on the image.
  • 飯田 訓正, 久保 進, 吉田 行輝, 木戸口 和浩
    1993 年 59 巻 568 号 p. 4014-4021
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    To analyze the combustion mechanism of the so-called ATAC (active thermo-atmosphere combustion) in a two-stroke S.I. engine, the measuring system to get an image of radical luminescence in the combustion chamber was developed. The ATAC engine tested was equipped with a quartz window at the cylinder head. The instantaneous luminescence image from radical species was observed using an image intensifier with a band pass filter for both conventional combustion and ATAC operation conditions. Before starting heat release, emissions from OH radicals were observed, and after that, emissions from CH were observed. It was found that the ignition was initiated over the ennre area of the combustion chamber and that "bulk"-like and/or "non propagate" combustion occurred during ATAC engine operation.
  • 趙 福全, 竹富 正彦, 西田 恵哉, 廣安 博之
    1993 年 59 巻 568 号 p. 4022-4029
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    An experimental study was made of the two-dimensional measurements of the mixture concentration distributions in the combustion chamber of a propane-fueled SI (spark ingnition) engine with laser-sheet-induced Rayleigh scattering. A commercial engine was modified to introduce YAG laser sheet light into the combustion chamber. The scattered light from the measuring plane was allowed to transmit the optical glass window installed on the extended piston and captured with a charge-coupled-device camera fitted with a gated double-microchannel-plate image intensifier by lens coupling, and the resulting images were digitized in a computer. The effects of several engine-operating parameters, including the fuel injection conditions and the intake air flow, were investigated.
  • 飯田 訓正, 細沼 伸司, 吉村 謙一, 高瀬 繁寿, 藤原 康博
    1993 年 59 巻 568 号 p. 4030-4037
    発行日: 1993/12/25
    公開日: 2008/03/28
    ジャーナル フリー
    When methanol is used as fuel, a hazardous unburned methanol, aldehyde, is exhausted. To solve this, a low heat rejection engine with an ATAC (active thermo-atmosphere combustion) system was adopted. By using a ceramic combustion chamber, the surface temperature of the combustion chamber is kept at high temperatures of 200 to 250 K. The characteristics of the combustion process and emissions from the ceramic methanol-fueled ATAC engine are examined. widening of the ATAC operation region with the use of methanol, and reduction of Formaldehyde emission due to the adoption of the ceramic combustion chamber are achieved experimentally. When the temperature of the combustion chamber wall becomes high, the thermal efficiency is reduced because the ignition timing is too early in ATAC operation. Supplying a lean fuel mixture to the engine yields a good result in both exhaust emissions and fuel consumption.
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