日本機械学会論文集 B編
Online ISSN : 1884-8346
Print ISSN : 0387-5016
53 巻, 487 号
選択された号の論文の67件中1~50を表示しています
  • 大場 利三郎, 高山 和喜, 伊藤 幸雄, 宮倉 秀人, 野崎 智, 石毛 忠志, 園田 修次, 坂本 健二
    1987 年 53 巻 487 号 p. 671-677
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    To make clear the mechanism of cavitation erosion, the spatial distribution of cavitation shock pressures were quantitatively measured by a pressure sensitive sheet in the l/l0 scale model of a jet-flow gate-valve, for various valve-openings and cavitation numbers. The dynamic pressure response of the sheet was corrected by the shock wave generated from detonation explosives. It is made clear that the erosive shock pressures are distributed in a limited part of the whole cavitation region, and the safety region without the fatal cavitation erosion is defined.
  • 松尾 一泰, 屋我 実, 望月 博昭, 小田 浩
    1987 年 53 巻 487 号 p. 678-682
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    The response of a normal shock wave in a transonic diffuser to small-amplitude pressure disturbances introduced downstream of the shock wave is analyzed with the method of small perturbations. The subsequent shock wave motion is classified into a stable oscillation about the initial steady flow shock position and an unstable case where the shock wave moves upstream of the throat, depending on the initial shock position and the pressure recovery in the subsonic region downstream of the shock wave. The stability criterion of the shock wave is presented as a function of the Mach number where the shock is initially located and the diffuser efficiency of the subsonic region downstream of the shock, and it is shown that the criterion agrees well with the previous experimental results.
  • 金井 恵理也, 棚橋 隆彦
    1987 年 53 巻 487 号 p. 683-691
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    We present a new fast finite element method which is called the generalized-simplified marker and cell method (GSMAC) as an extention of the SMAC finite difference method of Amsden and Harlow. There are several new features of the GSMAC method, which is distinguished from other iterative finite element methods. We use two important concepts, orthogonal decomposition and cycle-to-cycle self-adjustment, which allow a stable and accurate calculation of unsteady flow fields at high Reynolds numbers without any artificial modification. As a result, the GSMAC method has proved to be faster than the other finite element methods and to require only the same amount of CPU time and storage as the standard finite difference method. The results of calculation in a square cavity agree very well with those of Ghia et al.. Especially for Re=5000 and 10000, the same degree of accuracy can be obtained with 1/26.4 of mesh points.
  • 金井 恵理也, 棚橋 隆彦
    1987 年 53 巻 487 号 p. 692-698
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    The unsteady flowfields in a square cavity at high Reynolds numbers are investigated numerically by solving the unsteady Navier-Stokes equation through the GSMAC finite element method which includes two important concepts: orthogonal decomposition and cycle-to-cycle self adjustment. Unsteady flow simulations in terms of streamlines, isobars, equi-vorticity lines and equienergy lines are obtained at Reynolds numbers of 5000 and 104. The conclusions are as follows; (1) The influence of the spiral motion of the main vortex to the shapes and sizes of secondary vortex are explained. (2) It is observed from the results that the flows in a square cavity at a Reynolds number of 104 show turbulent-like behavior. (3) The GSMAC finite element method requires only the same amount of CPU time and storage as a standard finite difference method and shows the great capability of solving unsteady flow problems.
  • 野崎 理, 花村 庸治, 田中 英穂
    1987 年 53 巻 487 号 p. 699-705
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    The effects of periodic gusts on the performance of an airfoil are investigated. Periodic gusts were generated by the movement of a row of cylinders crossing in front of an airfoil. Total pressure loss, unsteady pressure distribution on the airfoil surface and velocity fluctuation were measured. The airfoil investigated here has a separation bubble on its suction surface, which increases total pressure loss even if the angle of attack is small. But as either frequency or solidity of cylinders increases, the separation bubble tends to disappear, followed by recovery of total pressure.
  • 井口 学, 近江 宗一, 竹内 博明
    1987 年 53 巻 487 号 p. 706-713
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    Hot wire measurements of the fluctuating velocity components u', v' and w' have been carried out in a pulsatile turbulent pipe flow of a pulsation frequency which is lower about one order of magnitude than the mean burst frequency. The root mean square values of fluctuating components u'rms, v'rms, w'rms, and the Reynolds shear stress <u'v'>^- were determined. Their instantaneous profiles differ appreciably from those of steady flow. Furthermore, the ordered motions were classified into four distinct categories, i. e. sweep, outward interaction, ejection and wallward interaction, and the contributions of these classes of motions to the Reynolds shear stress <u'v'>^- and turbulence energies u'2^- and v'2^- were obtained. Also given is the relative frequency of occurrence of these motions. The inspection of the data disclosed the following fact. The turbulence is caused by the same ordered motions as those in a steady turbulent pipe flow and it propagates monotonically from the vicinity of the wall toward the pipe center while decaying. The rate of decaying is not affected by pulsation. But the propagation time is not negligible compared to the present pulsation period. Therefore, the propagation time is the main cause of the difference in the turbulence intensity and Reynolds shear stress profiles between pulsatile and steady pipe flows.
  • 坂本 弘志, 羽二生 博之, 小畑 芳弘
    1987 年 53 巻 487 号 p. 714-721
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    Characteristics of vortex formed behind a circular cylinder placed in a laminar boundary layer have been investigated experimentally by flow visualization and analysis on fluctuating velocity signals. Three nondimensional paramerers of Re = U0d/v(U0 : freestream velocity, d : cylinder diameter, v : kinematic viscosity), h/δ(h : cylinder height, δ : boundary layer thickness) and h/d govern the flow field. In the present study, h/δ is kept constant to unity, and h/d and Re were varied. The following new results were obtained: (i) Within the range of Re=70∼613, separated shear layers from both sides and the free-edge of the cylinder were linked to form an arch-type vortex for h/d up to 4. (ii) At h/d=3 where an arch-type vortex is formed, the Strouhal number St(=fd/U0) against Re can be classified into three regions based on different time rates of intermittent vortex shedding. (iii) Simiraly, at h/d=6 where Karman-type vortex is formed, St against Re can be classified into two regions.
  • / 佐古 光雄, 千葉 徳男, Tokuo CHIBA
    1987 年 53 巻 487 号 p. 722-730
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    Flow characteristics have been investigated numerically for a well-developed steady laminar flow in various wavy sinusoidal channels. The finite element method, using an up-wind technique, is applied to obtain the analytical solution of the vorticity transfer equation. Numerical results are presented for the stream lines, vorticity distribution, velocity profiles and friction factor versus Reynolds number. Dependence of the friction factor on the Reynolds number varied remarkably with flow pattern. The ratio of the friction factors in wavy channels and in parallel flat plates was correlated as a function of the geometry as well as the Reynolds number.
  • 佐田富 道雄, 佐藤 泰生
    1987 年 53 巻 487 号 p. 731-737
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    Experiments have been performed on the two-phase flow of air-water mixtures through a multiple channel consisting of two interconnected subchannels. The purpose was to obtain data on the void fraction and to observe the flow pattern when the cross-sectional area of the subchannels is different. The mean void fraction of each subchannel was well correlated with the Smith equation. Photographs showed that a void drift is more prominent in a slug or churn flow, while it is less pronounced in a bubbly flow and an annular flow. The flow pattern in each subchannel has been mapped on a diagram of the superficial velocities of both phases, and its flow pattern boundaries were found to be close to those proposed by Taitel et al.
  • 佐田富 道雄, 佐藤 泰生, 深野 徹
    1987 年 53 巻 487 号 p. 738-743
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    In the subchannel analysis of nuclear reactor rod bundles it is necessary to predict the flow distributions among different regions of the bundle. In this paper, the fully developed two-phase flow distributions in two interconnected subchannels of different cross-sectional area were calculated. The mathematical model consists of four equations: the two continuity equations for gas and liquid phases, the equation of equal pressure drop of both subchannels and the empirical correlation of the flow distribution of the gas phase. The experimental data presented in the previous reports of this series have been used for this empirical correlation. Comparisons are made between the calculations and the experimental data reported by other investigators as well as by the present authors. Good agreements are obtained.
  • 仮屋崎 侃
    1987 年 53 巻 487 号 p. 744-749
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    Lift force acting on an air bubble, a liquid droplet or a solid spherical particle in a uniform shear flow was investigated both experimentally and theoretically to obtain fundamental knowledges of a lateral void distribution in a gas-liquid two-phase bubbly flow. Two side walls of a vertical test channel were constructed by driven belts running counterwise for each other. In this way a flow field with a linear velocity profile was produced in a measuring section in the central part of the channel. From the time trace of a bubble, a droplet or a solid sphere introduced in this flow field, the lift force was obtained experimentally. It was found that the direction of the lift force acting on a deformable particle such as a bubble and a liquid droplet is opposite to that on a solid sphere. Based on a theoretical consideration a correlation was proposed to estimate the lift force acting on a bubble or a droplet.
  • 杉山 司郎, 山本 正明, 林 太郎
    1987 年 53 巻 487 号 p. 750-756
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    An experimental investigation is carried out. The fully developed steady laminar flow in the entrance region of a curved rectangular channel is studied under the velocity profile of Poiseuille flow at the inlet and the Dean number is 220. The channel has an aspect ratio of 2 and a curvature ratio of 8. The axial velocity and the radial component of the secondary velocity are measured by using a laser doppler velocimeter (LDV), at 15 sections from the inlet (θ=0°) to the outlet (θ=270°) of the channel. The developing secondary flow is clearly presented and is in good agreement with the results obtained from a flow visualization carried out by the authors.
  • 長谷川 英治, 瀬川 正樹
    1987 年 53 巻 487 号 p. 757-764
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    A viscous source flow between a curved circular plate and a flat one is studied theoretically and experimentally. Assuming the ratio of the gap between two plates to the radius of the curved plate to be small, an approximate solution is found with the accuracy of the second order of that ratio. The stream function, the pressure and the flow rate are found as a function of the profile of the curved plate. In a case of the curved disk with a cross-sectional profile consisting of the several straight lines, the theoretical pre5sure distribution is found to fairly agree with the experimental one obtained by using air. The conditions under which the pressure gradient in the radial direction becoTnes positive are found in the space of the Reynolds number and the depth of the hollow on the curved disk. When the force acting on the curved disk is represented as a function of the depth of the hollow, it is found to take a maximum value.
  • 中村 育雄, 酒井 康彦, 角田 博之, 荒尾 寅彦
    1987 年 53 巻 487 号 p. 765-773
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    The effect of the disturbance of a circular cylinder on the diffusion process of dye solution by a non-buoyant plume from a point source in grid-generated water turbulence has been examined experimentally. The cylinder is fixed so that its axis intersects the plume axis perpendicularly at the far downstream location from a source where the plume has developed to have a comparable width with the cylinder diameter. In this paper, the experimental results concerning the mean concentration field are presented. It is found that the vertical profiles of the mean concentration behind the cylinder show flatter shapes, and the profile's half width grows downstream more rapidly than those without the cylinder. These characteristics are apparently caused by the disturbance effect of the cylinder. The vertical and horizontal profiles of the mean concentration appear to be nearly similar at various downstream locations beyond about 20 diameters from the cylinder.
  • 中村 育雄, 酒井 康彦, 角田 博之, 荒尾 寅彦
    1987 年 53 巻 487 号 p. 774-781
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    Experimental examination has been made of the disturbance effect of a circular cylinder on the diffusion process of a dye solution by a non-buoyant plume from a point source in grid-generated water turbulence. This paper is mainly associated with the characteristics of the fluctuating concentration field upstream of, around, and behind the cylinder. The results for the velocity and mean concentration fields have been already reported in ref. [1]. The interesting result upstream of the cylinder is that the concentration fiuctuation r. m. s. values on the plume axis (i. e. the stagnation line) show a rapid decrease near the stagnation point. This is because the turbulence distortion by the cylinder promotes the mixing of matter. The data behind the cylinder show that the vertical profiles of r. m. s. values have double-peaks and their center-line r. m. s. values obey the hyperbolic decay law in the downstream direction. Further, as in the mean concentration field, the vertical and horizontal profiles of r. m. s. values appear to be nearly similar behind about 20 diameters from the cylinder.
  • 中林 功一, 土田 陽一, 鬼頭 修己, 一宮 誠
    1987 年 53 巻 487 号 p. 782-788
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    Fundamental frequencies and characteristics of four types of disturbance in the flow between a rotating inner and a stationary outer sphere are clarified by flow visualization and spectral studies of both scattering intensity power spectra and velocity power spectra. The dependencies of the fundamental frequencies on meridional angle θ and Reynolds number Re are considered. Consequently, it is found that fS, fW, fH and fB are fundamental frequencies characterizing spiral Taylor-Gortler (T. G.) vortices, travelling azimuthal waves of toroidal T. G. vortices, shear waves within the Ekman boundary layer and an up-down fluctuation of toroidal T. G. vortices, respectively, and are independent of θ and Re. Further, the fundamental frequencies are discussed in comparison with those of a flow between two concentric cylinders with the inner one rotating.
  • 大坂 英雄, 望月 信介
    1987 年 53 巻 487 号 p. 789-796
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    Conditional sampling techniques have been used to investigate the coherent structure of the turbulent boundary layer over a d-type rough surface at a momentum thickness Reynolds number of Rθ≒5000 at which the skin friction coefficient took a constant value. In this study, the effect of imperfect spatial resolution on hot-wire measurement was removed and the operational parameters included in the detection scheme of the VITA technique were adjusted to the most probable values. The ensemble averaged patterns obtained from the VITA technique showed that there existed events associated with the bursting phenomena even in the present d-type wall flow, and that these structures were observed in the region of y+≤480(y/δ≤0.26). Although the mean bursting frequency depended on the distance from the wall across the inner layer for the present rough wall flow, its value scaled with the wall variables at y+ = 15 was almost the same as that found in smooth wall flow. In addition, the events contributing to the Reynolds shear stress were measured using the four quadrant method. Compared with the results obtained from the boundary layer over both a k-type rough surface and a smooth surface, the present results were found to differ significantly. The ratio of the fractional contributions of the ejection events to the stress to that of the sweep decreases with increasing Reynolds number.
  • 鈴木 雍宏, 木谷 勝, 高橋 剛
    1987 年 53 巻 487 号 p. 797-803
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    The phase-averaged structure of the coherent and random components of turbulence is obtained in the wake of a thin fiat plate rotating in a uniform stream with low and high free-stream turbulence. Measurements are made for a spin parameter of 0.28 and a Reynolds number of 1.25×104 in a crossflow section 9.4 plate heights downstream of the axis of rotation. The fluctuating-velocity vector, Reynolds normal and shear stresses and turbulence intermittency are presented in a spacetime domain. Eurbulent-energy production by the vortex-stretching at saddles is found only in the case of the high free-stream turbulence. This is probably because few random turbulent eddies are present near saddles of this wake when the free-stream turbulence is low.
  • 赤池 志郎, 根本 光正
    1987 年 53 巻 487 号 p. 804-809
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    In the preceding paper, the flow pattern in the flow developing region of an axisymmetric laminar water jet has been made clear. The experiments, however, were carried out by using a single nozzle, so that the potential core radius at the nozzle exit was determined only by the jet Reynolds number. In this paper, four nozzles with which the length of straight pipe section differed from each other were used, in order to clarify the effect of the initial jet profile at the nozzle exit on the flow in the flow developing region. The numerical examples obtained from the preceding method were also given. The effects of the supply nozzles on the velocity profile, the centerline velocity, the half-radius and the potential core radius were discussed.
  • 土方 邦夫, 三松 順治
    1987 年 53 巻 487 号 p. 810-815
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    The turbulent structure near the stagnation point of an axisymmetric impinging jet is investigated quantitively from the data of cross-correlation between pressure fluctuation on the impinged plate and velocity fluctuation at various points in a jet. The movement and collapse of a large eddy are traced from maps of maximum values of cross-correlations which show that a large eddy impinges on the plate and soon collapses. The eddy impingement on the plate produces a pressure fluctuation, and it induces a new velocity fluctuation near the wall. By comparing this result with the pressure pattern on the impinged plate visualized by holograpic interferometry, it is clarified that the spot and arc shaped patterns in the pressure visulization correspond to the impingement of large eddies and the induced velocity fluctuation respectively.
  • 宮内 敏雄, 斎藤 拓也, 谷 雅弘
    1987 年 53 巻 487 号 p. 816-823
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    The aim of this study is a clarification of the relation between the coherent structure of a turbulent shear flow and turbulent mixing, especially the relation between the amalgamation of vortices and turbulent mixing. To achieve this purpose, Large Eddy Simulation of a turbulent shear flow with passive scalar mixing was conducted. As an initial value, a two-dimensional small perturbation was overlapped on the mean velocity profile. From the calculated results, without pairing of vortices, it was made clear that the gradient of the mean concentration profile changes in three stages, and that the turbulent mixing is enhanced by the vortical motion. From the calculated results with pairing of vortices, it was shown that the gradient of the mean concentration profile also changes in three stages, and an inversion of the concentration gradient is observed. From these calculated results, it was also made clear that the turbulent mixing is enhanced by pairing of the vortices.
  • 大坂 英雄, 藤井 英樹, 杉原 正浩, 望月 信介
    1987 年 53 巻 487 号 p. 824-831
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    Quadrant analysis has been used to investigate the events associated with the production of the Reynolds shear stress in a fully developed plane turbulent wall jet. By partitioning the stress into four quadrants, it was shown that the second and the fourth quadrants were the dominant events contributing to the stress in the inner layer, whereas the first and the third quadrants dominate in the outer layer. The flow at the location where the mean velocity has a maximum value, is affected by both the inner and the outer layer structure. At the location where the Reynolds shear stress is zero, the ratio of the fractional contributions to the total Reynolds shear stress from quadrant i and the ratio of the mean periods of quadrant i are almost equal among the quadrants.
  • 深野 徹, 林 秀千人, 葛田 鉄也, 中西 宏典, 原 義則
    1987 年 53 巻 487 号 p. 832-838
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    The characteristics of a velocity fluctuation in the wake of an axisymmetric body were measured from a rotating frame of reference. The results were compared with those in a two-dimensional flow. The following was made clear. In the rotating flow field, the mixing and diffusion of the wake are promoted by both the oncoming flow which is sheared in the spanwise direction and the intense radial outward flow in the dead flow region of the wake. Therefore the dead flow region becomes narrower and the wake width increases more quickly than in the two-dimensional flow. Vortex shedding is less regular and the circulation of the vortex is weakened. The amplitude of velocity fluctuation is smaller and its maximum position, representing vortex shedding, is closer to the body than that in the two-dimensional case. The velocity fluctuation shows a cellular structure in the spanwise direction, the scale of which is about one characteristic length of the body. This mechanism is related to the radial flow in the wake.
  • 須藤 浩三, 高見 敏弘, 檜原 秀樹
    1987 年 53 巻 487 号 p. 839-842
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    A jet issuing from a curved nozzle has been investigated experimentally under Re=4×104. The curved nozzle has a 90° circular bend with a diameter 40 mm and a curvature radius 80 mm. Mean velocity is measured by using an inclined hot wire. The following conclusions are derived from experimental results: (1) The jet axis shifts gradually from the curved nozzle axis ; (2) The maximum axial velocity of a curved nozzle jet decays more rapidly than that of a straight nozzle jet ; (3) The velocity profile, which is skewed by a secondary flow near the curved nozzle, turns out to be similar to that of the axis-symmetric jet in the down stream.
  • 築地 徹浩, 高橋 浩爾
    1987 年 53 巻 487 号 p. 843-849
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    The complete equations which describe a viscous axisyrnmetric flow are formulated using a streamline coordinate system (φ, ψ), where ψ is the stream function. The independent variable φ is constant along the orthogonal trajectories of streamlines in a plane including a symmetric axis. The axisymmetric laminar jet leaving a Poiseuille tube into an inviscid outer fluid phase is solved numerically using parabolic differential equations which are simplified by a boundary-layer type analysis. The prediction of the velocity distributions and shape of the free surface profile, under the influence of both gravity and surface tension, is undertaken. The results obtained by the present method are found to agree very closely with experimental results. The behaviour of a laminar jet issuing from a convergent nozzle is also investigated by the same method.
  • 高見 敏弘, 須藤 浩三, 富田 幸雄
    1987 年 53 巻 487 号 p. 850-857
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    Turbulent friction coefficients are measured for fully-developed flows in curved pipes with a circular and square cross section using non-Newtonian liquids (aqueous solutions of CMC and PAA). Effects of power-index, Reynolds number and curvature radius ratio are made clear. The turbulent friction coefficient for non-Newtonian liquids is lower than that for Newtonian liquids, and becomes larger as the curvature is stronger. Also, the turbulent friction coefficients fall on a single line in terms of Re(d/Rc)2 for circular pipes and Re(d/Rc)2 for square ones. The transition Reynolds number increases as the curvature is stronger.
  • 富田 幸雄, 進邦 紀夫
    1987 年 53 巻 487 号 p. 858-864
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    One equation of oscillation is obtained from both the pressure balance in the reservoir-capillary system and the momentum balance of the jet between the exit of the capillary and some downstream cross section where the velocity of the jet is uniform. Through the examination of this equation, the following results are obtained. (1) The critical shear rate, at which the unstable flow begins to occur, may be defined by the coefficient of the first derivative of this equation. (2) It becomes clear that, the same as in experimental results up to this time, the principal cause of the unstable flow is the flow in the vicinity of the capillary entrance.
  • 金田 武司, 志澤 一之, 棚橋 隆彦
    1987 年 53 巻 487 号 p. 865-874
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    Generally, A conducting magnetic fluids has considerably complex behaviour that depends upon electromagnetic field. Therefore even the fundamental counducting magnetic fluid flow has not been examined enough. In the present paper, a Couette like flow is discussed, which is so important and fundamental for engineering problems. At first, some nondimensional parameters, caused by magnetization are newly defined, and some relations between various nondimensional parameters defined in usual magnetohydrodynamics and parameters newly defined here are given. And the influence of these newly defined parameters on electromagnetic field and on flow field is cleared. Furthermore, a pressure distribution caused by electromagnetic forces is analytically obtained which can not appear in the nonconducting magnetic fluid.
  • 井上 雅弘, 山本 芳久, 富岡英俊
    1987 年 53 巻 487 号 p. 875-879
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    A technique for three-dimensional flow measurement has been developed by use of a single pressure sensor buried in a cone-type head. The probe actuator involves a stepping motor to rotate it about its axis as instructed by a microcomputer. A great number of output data are obtained with random sampling pulses at each rotating angle, and the average and the variance of these outputs are calculated by the on-line computer. The three-dimensional velocity components and pressure can be obtained by solving the calibration equations. The turbulent intensity is also estimated from the variance. The accuracy of the measurement has been investigated in a potential core and fully developed turbulent region of a circular jet.
  • 辻 俊博, 長野 靖尚, 江村 哲二
    1987 年 53 巻 487 号 p. 880-884
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    A method of turbulence mesurements at low velocities with V-shaped hot-wires is described along with associated probe arrangements. The present method is based on the simultaneous solution of exact nonlinear equations for the effective cooling velocities, thus providing instantaneous values of velocity components. The validity of the technique was tested for the measurement of turbulent velocity components which were artificially produced by shaking the hot-wire probe with an accurately known motion in a steady flow. Instantaneous velocities obtained with the proposed method were in almost perfect agreement with the corresponding imposed values.
  • 靄崎 展, 宗像 篤
    1987 年 53 巻 487 号 p. 885-893
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    The unique peripheral distribution of the amplitudes of pressure fluctuations on a diffuser wall was observed under the rotating stall of a diffuser. The distribution changed according to the number of cells for the same scroll. The reason why the distribution occurs is not evident. A study is carried out to clarify the principal cause for the unique distribution. The instantaneous pressure distributions on the diffuser wall are measured and they are analized by the authors' original technique. The measured pressure fluctuation is separated into two components and the factors for the above unique distribution are made clear. The mechanism of the occurrence of the unique distribution is clarified by the experiment and the numerical analysis. Some interesting facts observed in the experiment are also presented.
  • 森 康夫, 水上 雅人, 武士俣 健
    1987 年 53 巻 487 号 p. 894-902
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    This research focuses on fundamental and general studies of sound generation by rigid spheres or droplets falling vertically down to a water surface and by water flow in tubes. This first report aims to make clear phenomena and reasons of sound generation caused by a rigid nylon sphere, water droplet or droplets falling in series to a water surface. In case of a rigid sphere, it is shown that only the impulse sound consisting of one wave is generated for the wet sphere. But for the dry sphere about 30 ms after the impulse sound, sounds are generated by the cavity behind the cylinder caused by surface tension and the bubble. It is also shown that a droplet generates an impulse sound, but that when a following droplet impulses the water surface at the lowest instant of the indented part caused by the impulse of the preceding droplet, a bubble is formed in the water and generates sound.
  • 森 康夫, 水上 雅人, 武士俣 健
    1987 年 53 巻 487 号 p. 903-910
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    The aim of this paper is to report experimental results of sound generated by water flow such as in a waterbasin, curved tube or vertical tube. First, it is made clear that the main sound generated at the outlet of the washbasin provided with the vertical outflow pipe at the bottom is caused by an acoustically resonating cavity formed in the outflow pipe by surface tension and that the tisy sound in a bend tube connected with the outflow pipe of washbasin is caused when the bubble flow strikes the tube inside wall and results in sound generation. In case of the vertical elastic tube, sound is generated by the elastically bending motion of the tube caused by the unsteady change of the momentum of water film along the inside of the tube. Lastly, based on the results obtained above, a method to control sound generated in the vertical tube is proposed.
  • 望月 修, 木谷 勝, 田住 正弘
    1987 年 53 巻 487 号 p. 911-916
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    Sound generated by a two dimensional jet impinging on a circular cylinder was studied by systematically changing its diameter. Frequency of the sound decreases in a step-like manner with an increasing distance xe between the nozzle and the leading edge of the cylinder. The frequency normalized by Uo/xe, Uo being the exit velocity of the jet, is a unique function of the non-dimensional distance xe/H, H being height of the nozzle. This is similar to the case of the jet-wedge interaction. The diameter of the cylinder determines both the longitudinal position of the frequency jumps and the position where the intensity of the sound attains a maximum. The highest intensity of the sound appears when its frequency is the exactly the same as the frequency of the vortex shed from the circular cylinder which would be placed in the uniform stream whose velocity is equal to the undisturbed jet velocity at the leading edge of the cylinder.
  • 大蔦 勝久, 岩村 義巳
    1987 年 53 巻 487 号 p. 917-921
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    An experimental investigation is carried out on the noise reduction of thin blade propeller fan. The center line of the cord of the circular blade inclines toward the inlet direction, and, at the same time, the rotative direction. The effect on the specific noise level is determined for the inclination angle toward the inlet direction (IATID). The most suitable angle for the noise reduction was found for IATID. The specific noise level in free air decreases as IATID increases. When the fan operates between the free air point and the so-called unsteady point of the characteristic, the specific noise level is the lowest at an IATID of 22.5°.
  • 西脇 英夫, 藤井 昭一, 武田 克己
    1987 年 53 巻 487 号 p. 922-927
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    For the purpose of observing the acoustic and aerodynamic phenomena of counter rotating propellers under take off and landing conditions, a 400 mm diameter scale model was tested. The test was made in an anechoic chamber with 68 m/s incoming flow, keeping the front blades at 9000 rpm. The rotational ratio, the axial space between two rotors, front and aft blade angles were chosen as parameters. From noise data analysis, reinforced high harmonics were recognized, which haven't been observed in single rotating propellers. While large spacing yielded good results on noise level reduction, unfavorable effects were recognized on the aerodynamic performance, due to increasing axial velocity acceleration in two rotor blades. When there were nonsynchronous rotational speeds between two rotors, spinning sound waves occurred with a beat frequency of three times the rps difference.
  • 鵜飼 義雄, 丸田 芳幸, 鈴木 昭次
    1987 年 53 巻 487 号 p. 928-932
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    For decreasing the noise of turbo-machineries, making clear the generation mechanism of fluid-dynamic noise is important and an air flow having quiet noise is very useful for the study of aerodynamic noise. A "Quiet Flow Wind Tunnel", whose measuring section is in the annechoic chamber, has been developed and established. The maximum velocity of air flow from the nozzle with a section size of 400 mm×400 mm is 42 m/s and its turbulence is less than 0.5 %. The noise levels around the measuring section are less than 48 dB(A) at a velocity of 35 m/s. By using this facility, further studies have been made, "vortex sound from crossing two cylinders", "flow-noise from finned-tube bank", "noise from ventilating-gallery", "noise of inner flow in straight ducts" etc.. It has been recognised, through these experiments, that this facility can measure both phenomena of fluid-dynamics and acoustics at the same time although these are still impossible by usual wind tunnels.
  • 妹尾 泰利, 山口 道照, 玄 容翊, 速水 洋
    1987 年 53 巻 487 号 p. 933-939
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    The turning angle of nozzle blades is smaller and the pressure loss is larger as the tip-clearance of turbine nozzle is increased. The mean flow angle at the nozzle exit was measured in four independent ways and the results agreed well with each other. Furthermore a simple flow model was proposed based on the measured pressure distribution on the nozzle blades, and the predicted exit mean flow angle and the pressure loss or the flow coefficient agreed well with the experimental data.
  • 井上 雅弘, 九郎丸 元雄, 福原 稔, 江口 剛
    1987 年 53 巻 487 号 p. 940-944
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    The detailed flow measurements were done in an isolated axial compressor rotor with various tip clearances, and the development of the casing boundary layer through the rotor was investigated for various inlet boundary layer thicknesses. The flow behavior for the thick inlet boundary layer was distinguished from the case of the thin inlet boundary layer at an off-design condition, in spite of almost the same incidence angle near the blade-tip. As the inlet boundary layer is thicker, a leakage vortex becomes slightly stronger but isn't so strong as that at the off-design condition. The input work changes little in comparison with that for the thin inlet boundary layer at the design condition, while the output work increases by the uniforming action of blades. Therefore, the thicker the inlet boundary layer is, the higher the blade-tip efficiency calculated from the integral parameters of the casing boundary layer.
  • 瀬戸口 俊明, / 金子 賢二, 井上 雅弘, Masahiro INOUE
    1987 年 53 巻 487 号 p. 945-949
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    Factors determining stall conditions of a Wells turbine were discussed from the viewpoint of design. Experimental investigations were performed to study the effect of the inlet flow turbulence and the setting position of the blade axis on the performance of the Wells turbine. It is concluded that due to the peculiar nature of the Wells turbine the performance is less sensitive to the inlet flow turbulence and more sensitive to the setting axis of the airfoil on the rotor.
  • 金子 賢二, 瀬戸口 俊明, Srinivasan RAGHUNATHAN, 井上 雅弘
    1987 年 53 巻 487 号 p. 950-956
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    In order to clarify the running and starting characteristics of a biplane Wells turbine, an experimental investigation has been performed under steady operating conditions. The performance test was conducted for some kinds of rotors with various gap-chord and stagger-chord ratios. The results have been compared with those of a monoplane. It is found that, in general, a biplane rotor has a wider operating range with a smaller drop in efficiency and has better starting characteristics than a monoplane rotor. The rotor with a non-staggered arrangement shows the best performance both in efficiency and stall margin.
  • 黒川 淳一, 永原 英明
    1987 年 53 巻 487 号 p. 957-965
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    In order to establish a design method of the optimum configuration for the spiral casings of water turbines, three different shapes of spiral casings, that is, the decelerated flow type, the free vortex type and the accelerated flow type, are tested and the flow characteristics and losses are compared and discussed. The results show that the optimum configuration is attainable by lowering tangential velocity in a spiral casing to suppress a secondary flow and making the vane angle fit for the flow angle in the range π/2<θ<3π/2. It is also shown that the flow in the spiral casing of a free vortex type is axisymmetric but the total pressure loss of the whole fixed channel is not always the minimum. At the middle of the guide vane channel the velocity and the static pressure become almost axisymmetric for three spiral configurations but the total pressure decreases largely in the rangeπ/2<θ<3π/2 and is different for each spiral configuration. The above tendency is confirmed to be still effective when the upstream boundary layer becomes thick.
  • 中瀬 敬之, 福富 純一郎, 新村 剛
    1987 年 53 巻 487 号 p. 966-970
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    In recent years the study on a Cross-Flow Turbine has been done by many reseachers. The purpose of this experiment is to recover energy by incorporating this Cross-Flow Turbine into a pipe line (for example, waste water, sewage plant effluent), that is, "reutilization of energy". This turbine has the features that the axes of both entrance and exit pipes and the center of turbine are on the same straight line, and it has considerably simple structure without moving parts. The effusion side casing form is determined by the length of cutwater and the effusion side open angle. Consequently we obtained a maximum efficiency of 78.4%. Improvement is expected by use of the experimental data for the flow condition of a turbine exit.
  • 品田 正昭, 小嶋 英一
    1987 年 53 巻 487 号 p. 971-979
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    A generation mechanism has been developed describing the surge pressures produced in the return line during the decompression cycle of a hydraulic machine press and a mathematical model produced capable of predicting the pressures with good accuracy suitable for practical usage. Experiments were carried out on a small-sized model dynamically similar to a real machine in the 2000-ton (20-MN) class. Concerning fluid transient phenomena, the following three topics of industrial interest were mainly examined. (1) the pressure surge produced during the decompression process, (2) the cavitation duration following a column separation and (3) the pressure surge at the collapse of the first cavity. Particular attention has been paid to observating the mechanism of appearance of gas bubbles near the downstream valve, and of their growth and sequence collapse. The calculated values from the proposed "bubble model", in which the effects of gas (air) released from the liquid at the early stage of decompression and of surface tension due to a minute gas bubble were taken into consideration, agreed with the measured results with errors within some 10% under ordinary operating condition.
  • 高野 清, 棚沢 一郎, 西尾 茂文
    1987 年 53 巻 487 号 p. 980-983
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    This study is a part of a research program whose objective is to determine an optimum way of enhancing forced convection heat transfer using turbulence promoters. Effectiveness of turbulence promoters with clearance between the heat transfer surface is tested. Flow friction and heat transfer coefficients are measured at Reynolds numbers ranged from 1.5×104 to 9×104. Inclination of the rib plate used as a promoter is also varied in addition to the variation of clearance. The result of performance evaluation suggests that a turbulence promoter with clearance and inclination shows a slight improvement of performance in the case where the clearance is small. A possible reason that such a type of turbulence promoter does not show much improvement in its performance characateristics may be the considerable reduction of the local heat transfer rate around the region where the separated flow reattaches.
  • 島田 了八, 内藤 昭二, 熊谷 哲, 武山 斌郎
    1987 年 53 巻 487 号 p. 984-990
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    The local and average coefficients of heat transfer and moment coefficients from a rotating disc with turbulence promoters were measured. The experiments covered the range of rotating Reynolds numbers from 103 to 6×104 and were performed using the naphthalene sublimation technique. Two types of promoters, plain rib type and plain rib with slit type, were tested. The conditions of promoters, the height of promoters, the height of slits and the numbers of promoters, were varied. A performance comparison was made of the heat transfer ability from the surface with these turbulence promoters under the condition of constant pumping power. The following results were obtained. The heat transfer coefficients from a disc with a promoter without a slit are enhanced the most. at W/R =0.1. The heat transfer coefficients are enhanced by a suitable slit between the promoter and the surface of the disc. The best performance promoter is the best heat transfer promoter, when the energy loss is considered.
  • 青山 善行, 土方 邦夫, 二神 浩三, 野本 泰浩
    1987 年 53 巻 487 号 p. 991-996
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    A new heat transfer promoter is devised. It is composed of a row of thin plates twisted by 90° alternately in different directions. The heat transfer coefficient and pressure loss are measured in an air flow through a circular tube around which the promoter is set. Six types of promoters are examined. The heat transfer coefficients are found to increase. This result is explained by two enhancement mechanisms, namely some swirl motions and raised turbulence intensity. As the flow proceeds along the twisted plates, many axial vortices are produced and a flow-separation occurs at the lateral edge of the plates. The heat transfer performance is evaluated in terms of the area goodness factor and increase of the Nusselt number under the same pumping power.
  • 木本 日出夫, 吉信 宏夫, 米山 久一
    1987 年 53 巻 487 号 p. 997-1004
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    In this experiment a kind of mixed-convection heat transfer of a horizontal circular cylinder in a vertical rectangular conduit is examined, by using a straight acoustic streaming by an audio-speaker as an aiding flow, and the results are compared with the ones for a fan. As a result, it is revealed that the augmentation mechanism of heat transfer of a cylinder by acoustic streaming is the same as that by a fan. i. e. it is due to the increase of the aiding flow speed of the forced convection. It is also revealed that the frequency dependence of the augmentation is the same as that of the flow speed of the acoustic streaming, and that the intermittent flow characteristics of the acoustic streaming are somewhat important for the augmentation.
  • 吉田 敏寛, 田中 貞行
    1987 年 53 巻 487 号 p. 1005-1008
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    For heat transfer through the extended surfaces of fundamental configurations one dimensional analytical solutions have been obtained in relation to the specified boundary conditions. After the examination of the effect of the configuration and heat Transfer parameters on the ratio of the system effectivenss η12, where η1 and η2 are the system effectiveness for one dimensional heat flow and that obtained numerically for two dimensional heat flow, repectively, comparatively large differences between η1 and η2 are seen in the case of one dimensional analysis with the traditional boundary condition. On the other hand, only small deviations are found in the case of another slightly complicated boundary condition in the region of practical design parameters.
  • 馬淵 幾夫, 山田 和信, 熊田 雅弥, 檜和田 宗彦
    1987 年 53 巻 487 号 p. 1009-1015
    発行日: 1987/03/25
    公開日: 2008/03/28
    ジャーナル フリー
    In order to improve the performance of heat transfer inside a tube, an investigation of three-dimensional rib-roughened surfaces was undertaken to determine the effects of rib shape and pitch along the tube circumference (the number of ribs) on flow friction and heat transfer characteristics. All ribs were in the shape of a regular triangle whose vertical angle was 60'. Four types of rib height were tested. Also, five types of ring height were tested for comparison. They were arranged in line with a constant pitch along the flow direction by varying the pitch along the tube circumference. Finally, as a result of performance comparisons of heat transfer enhancement under the condition of constant pumping power, (1) High-performance was given in the case of a small number of ribs in which three dimensionality was shown in the local heat transfer coefficient distribution. (2) But by increasing the number of ribs, the distribution changed into two djmensional and these performances were lower than or equal to that of the ring. (3) Under the condition of a constant number of ribs, the rib height for excellent performance can be found.
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