Showing papers in "Jsme International Journal Series B-fluids and Thermal Engineering in 1977"
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TL;DR: In this paper, the results of experiments on three isotropic and one anisotropic materials are discussed and compared with the criteria proposed up to the present, and a new criterion is proposed, which coincides with the Gough's empirical formula for the brittle materials under combined stress.
Abstract: Fatigue crack initiates in the slip band and exists also in it near fatigue limit; many slip bands are apt to appear in the direction of the maximum shearing stress; crack propagates by the normal tensile stress; the maximum shearing stress on a plane at fatigue limit is reduced by the effect of the normal stress on the same plane. From these results of the experiment, a new criterion is proposed, which coincides with the Gough's empirical formula for the brittle materials under combined stress. As the plane of the maximum shearing stress is varied by the various combination of torsion and bending, the isotropic material should be used in the combined stress experiment. In this paper, the results of experiments on three isotropic and one anisotropic materials are discussed and compared with the criteria proposed up to the present.
287 citations
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TL;DR: In this article, the authors analyzed the forced vibration prevention of the vibration system with positive or negative damping by the damped dynamic absorber and analyzed the optimum values in the above cases by the convenient empirical formulae.
Abstract: Main purpose of this paper is to analyse the forced vibration prevention of the vibration system with positive or negative damping by the damped dynamic absorber. The cases treated in this paper are: the case I (the alternative exciting force of a constant magnitude is acting on the mass of the main system), the case II (the alternative exciting force, of which the magnitude is proportional to the square of its frequency, is acting on the mass of the main system), and the case III (the alternative displacement is given to the foundation of main system), It is explained how the spring constant and the damping factor of the dynamic absorber are desirably optimized to make the vibration effect minimum. The optimum values in the above cases are given by the convenient empirical formulae.
130 citations
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TL;DR: In this paper, the authors derived the equation of motion of a spherical bubble in a viscous compressible liquid by taking account of the gas density inside the bubble, and the effects of the liquid compressibility on the variations of the bubble radius, bubble wall velocity and bubble wall pressure with time and the maximum impulse pressure accompanying the bubble collapse.
Abstract: With the help of the PLK coordinate perturbation technique the equation of motion of a spherical bubble in a viscous compressible liquid is derived by taking account of the gas density inside the bubble, and the effects of the liquid compressibility on the variations of the bubble radius, bubble wall velocity and bubble wall pressure with time and the maximum impulse pressure accompanying the bubble collapse are investigated. Further, by considering the liquid compressibility. the pressure distributions in the liquid during the collapse and rebound of bubble are numerically obtained, and natural frequency of bubble is analytically obtained. As a result, the relation between the maximum impulse pressure and the bubble natural frequency is numerically clarified.
76 citations
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TL;DR: In this article, three typical flow patterns were found for the inclination of the slit β for different typical flow characteristics around a circular cylinder with a slit and how-wire measurements of the wake flow and the distributions of the static pressure coefficients around the cylinder were made.
Abstract: Experimental investigations on the flow characteristics around a circular cylinder with a slit have been carried out. Flow visualization, how-wire measurements of the wake flow and the distributions of the static pressure coefficients around the cylinder have been made. The experiments were car-ried out in the Reynolds number region of 13800 to 52000 for two slit ratios of s/d=0.080 and 0.185. Three different typical flow patterns were found for the inclination of the slit β. For 0°≤β≤40°, the self-injection into the wake was observed. In this case, the base pressure rose and vortex formation region moved downstream. For 40°<β<60°, the effect of the slit was little. For 60°≤β≤90°, boundary layer suction was observed periodically with a period of the shed vortices. In this case, the base pressure coefficient dropped and the shedding frequency decreased.
71 citations
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TL;DR: In this article, five conical diffusers with different divergence angles were tested to clarify the influences of swirl on the pressure recovery coefficients, and the highest coefficient was observed in an 8-deg diffuser when the flow had a moderate swirl.
Abstract: Five conical diffusers with different divergence angles were tested to clarify the influences of swirl on the pressure recovery coefficients. Pressure recovery coefficients of all diffusers were improved by swirl, and the highest coefficient was observed in an 8-deg diffuser when the flow had a moderate swirl. The flow patterns in the diffusers were examined at various conditions to clarify the relationship between the swirl and the pressure recovery coefficient.
64 citations
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TL;DR: In this article, a finite element method was used to calculate the deformation of a ring gear in the direction of the line of action by using the deflection of the teeth and the equivalent ring whose stiffness is equal to that of the ring gear.
Abstract: The calculation for the deformation of a ring gear was carried out by using the finite element method. The results are as follows: (i) The deflection of the ring gear in the direction of the line of action can be calculated with the deflections of the teeth and the equivalent ring whose stiffness is equal to that of the ring gear. (ii) The expressions are obtained, for the amount of approach between two neighboring teeth, the load sharing factor and the interference of tooth tip with the ring gear. (iii) It is explained theoretically that the contact ratio increases constantly with an increasing gear tooth load. Further, the theoretically obtained result is confirmed by the experimental investigation.
32 citations
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TL;DR: In this paper, the authors considered the effect of rotational speed on the performance of the friction component, which is proportional to operating pressure and viscous friction component proportional to the viscosity of the fluid.
Abstract: In the mathematical model described in this paper, the following friction components are considered: (1) friction torque proportional to operating pressure, (2) viscous friction torque proportional to rotational speed and viscosity of fluid and (3) constant friction torque independent of operating conditions. The friction component which is proportional to operating pressure decreases with an increase of the rotational speed. This effect is also considered in this model. Therefore this mode can represent the whole torque performance from start to maximum speed.
32 citations
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TL;DR: In this article, an experimental investigation on the flow past a cone placed on a float plate and its wake was performed, where the vertex angle of the cone was varied 60°, 90°, 120° and 150°, and the surface pressure distributions on the cone and the flat plate, the velocity and the static pressure in the wake were measured.
Abstract: This paper presents an experimental investigation on the flow past a cone placed on a float plate and its wake. The vertex angle of the cone was varied 60°, 90°, 120° and 150°. The surface-pressure distributions on the cone and the flat plate, the velocity and the static pressure in the wake were measured, and the separation and the vortex formation were observed by visual means. The main results are as follows : (1) There occur necklace-like vortices around the cone of vertex angle 60°120°, and horse-shoe vortices generated behind the cone are shed downstream periodically. (2) The lift acting on the cone and the drag decrease with an increase in the vertex angle. (3) There exists a region of negative wake, which becomes maximum at a downstream distance of about twelve times the height of cone.
29 citations
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TL;DR: In this article, the transient responses to a step change in an inlet temperature are analyzed as an important example of dynamic characteristics of cross-flow heat exchangers with both fluids unmixed.
Abstract: The transient responses to a step change in an inlet temperature are analyzed as an important example of dynamic characteristics of cross-flow heat exchangers with both fluids unmixed. The numerical calculations are performed by two methods, namely, a method expanding a finite difference method used by Myers et al. to calculate accurately in the case where temperature changes discontinuously, and a central finite difference method to calculate more accurately with a small number of nodes in large values of a heat capacity of a solid wall. Consequently, the effects of an initial condition and the various parameters concerning heat transfer performance on the transient responses in the temperature efficiency are shown.
29 citations
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TL;DR: In this paper, the influence of the tightening velocity on the friction coefficient of fastener μ was investigated from the viewpoint of the central tendency and the dispersion, and some coating materials to reduce the standard deviation of μ, which are called "μ-stabilizers", were tested, and it was found that they are useful for decreasing the variation among subgroups.
Abstract: (1) The influence of the tightening velocity on the friction coefficient of fastener μ was investigated. (2) The influence on μ of the lubrication state, the surface treatment and the material combination of bolts and nuts was examined from the viewpoints of the central tendency and the dispersion. (3) The screw-thread friction coefficient μS and the bearing-surface friction coefficient μW were measured separately. Both the mean value and the standard deviation of μ were calculated statistically with the data of μS and μW, and a comparison between the calculated and the experimental results was made. (4) Some coating materials to reduce the standard deviation of μ, which are called "μ-stabilizers", were tested, and it was found that they are useful for decreasing the variation among subgroups.
28 citations
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TL;DR: In this article, an ionic exchange resin-tri·n·octyletrimellitate dispersion was developed, which produces the most typical shear stress and moreover has the greatest stability in all previously developed electroviscous fluids.
Abstract: Winslow effect is defined as an essentially instantaneous reversible change in apparent viscosity when a fluid is subjected to an externally applied electric field. Previously, we have obtained the conclusion that the mechanism governing Winslow effect can be explained most sufficiently by introducing an electric double layer. In our study, by adopting this hypothesis, we have developed new electroviscous fluids possessing ionic exchange resin as its disperse phase. And we considered parameters in electroviscosity from three points, that is, increase of shear stress, response to electric field, and stability. As the result, we have developed an ionic exchange resin-tri·n·octyletrimellitate dispersion, which produces the most typical shear stress and moreover has the greatest stability in all previously developed electroviscous fluids.
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TL;DR: In this article, the flow field in the main region has been divided into two regions at the point of maximum flow velocity, that is, inner layer near the wall and outer layer away from the wall.
Abstract: Mean velocity and turbulence together with pressure distributions of jets issuing from ring nozzles with various openings, and spreading out radially over a flat smooth plate were studied. By changing the diameter and width of nozzles and discharge velocity, the flow pattern was measured. Flow field in the main region has been divided into two regions at the point of maximum flow velocity, that is, inner layer near the wall and outer layer away from the wall. Velocity profile in the inner layer is similar to Glauert's curve obtained for a radial wall jet, and the one in the outer layer agrees well with Goertler's curve for a two-dimensional free jet. Maximum flow velocity decays and growth of the jet half width lie on a single curve by making use of an equivalent nozzle width which contains the diameter and width of the nozzle.
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TL;DR: In this paper, a criterion for ductile-fracture strain in torsion tests is proposed taking the pressure history into account, and it is found to agree with the experimental results of various pressure histories.
Abstract: Tensile and torsional machines were developed fro testing under high hydrostatic pressures of up to 4 kbars; experiments were carried out using these machines to investigate the mechanics of ductile fracture of 0.25 % carbon steel. The strain at which fracture-nuclei (voids or cracks) begin to grow is determined by a method in which the hydrostatic pressure is changed during deformation, and it is shown that the strain at which growth of nuclei begins increases with pressure. The rate of nuclei-growth is suggested to depend on pressure and strain. Based on these results, a criterion for ductile-fracture strain in torsion tests is proposed taking the pressure history into account, and it is found to agree with the experimental results of various pressure histories.
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TL;DR: In this paper, the sliding surface of the piston ring is approximated by a parabola and the viscosity of the oil film is constant, and the following end of the film pressure varies according to the Reynolds boundary condition.
Abstract: This paper reports on a theoretical calculating procedure of the oil film behaviour between the piston ring and the cylinder wall. The analysis assumes: (1) that the sliding surface of the ring may be approximated by a parabola; (2) that the oil film viscosity is constant; and (3) that the trailing end of oil film pressure varies according to the Reynolds boundary condition, namely the pressure profile ends at apposition where the pressure becomes a downstream pressure and also the pressure gradient becomes zero. The paper gives also an example of oil film behaviour between the circular-faced piston ring and the cylinder wall which has been calculated under the conditions corresponding to a small sized 4-stroke cycle kerosene engine.
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TL;DR: In this article, the relation between transmission errors and dynamic loads of spur gears was investigated using a power circulating type gear tester, and the dynamic loads on two pairs of gears were measured and their dependence on gear speed and tooth load was investigated.
Abstract: Some experimental results on the relation between transmission errors and dynamic loads of spur gears are presented. Using a power circulating type gear tester, the dynamic loads on two pairs of gears, i.e. an accurate one and a rough one, were measured and their dependence on gear speed and tooth load was investigated. The dynamic loads on the accurate gear pair showed recurrent time variations over a wide range of gear speeds. On the other hand, significant randomness of dynamic load was observed with an increasing speed in the rough gear set. An analogue computer simulation was also performed under the experimental condition. Good agreement was achieved between the experimental results and the simulation qualitatively; and it seems to show the propriety of the statistical theory on the estimation of dynamic loads which has already been developed in the previous paper.
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TL;DR: In this paper, the longitudinal vortices in a two-dimensional stagnation region of a cylindrical blunt body are expressed as a perturbation with respect to the mean motion in terms of the amplitude and the reciprocal of the square root of Reynolds number, in order to theoretically analyze their stability up to the second order of magnitude.
Abstract: The longitudinal vortices in a two-dimensional stagnation region of a cylindrical blunt body are expressed as a perturbation with respect to the mean motion in terms of the amplitude and the reciprocal of the square root of Reynolds number, in order to theoretically analyze their stability up to the second order of magnitude. As a result, a specific point can be determined where the integration of the kinetic energy involved in the vortices becomes minimum and the first and second orders of the magnitude of disturbances would never diverge at a considerable distance from the wall, and further, the damping factor of -α takes the minimum value. Moreover, the wave number for α=0 and the minimum kinetic energy reasonably agree with observations.
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TL;DR: In this paper, a technique to determine effectively an optimum shape of an axisymmetric body is suggested, which is a sequential search method consisting of the following two steps: in the first step, the superiority or inferiority of a given shape, which satisfies the design constraints, is judged by the deviation from the stress provided with a design object. In the second step, this given shape is modified by the proportional transformation method of the elements used in the finite element method.
Abstract: In this investigation, a technique to determine effectively an optimum shape of an axisymmetric body is suggested. The technique is a sequential search method consisting of the following two steps. In the first step, the superiority or inferiority of a given shape, which satisfies the design constraints, is judged by the deviation from the stress provided with a design object. In the second step, this given shape is modified by the proportional transformation method of the elements used in the finite element method. By the iteration of these steps the optimum shape will be obtained. As the application of this iterative method the optimum shapes of the thick-walled vessels under internal pressure will be obtained.
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TL;DR: In this article, it was shown that the limiting condition exists in a clear form for the onset of thermal oscillation, suggesting a possible means which enables to develope quantitative study on the thermal onset of oscillation.
Abstract: The oscillation of a gas-column, which occurs when a heater is held in a tube, being open at both ends and having a steady inner flow of gas, has been studied experimentally in order to clarify the fundamental natures of the limiting condition for the onset of oscillation. At the present stage, various experimental results obtained cannot yet be interpreted systematically on the basis of theoretical study, but it has been shown that the limiting condition exists in a clear form for the onset of oscillation, suggesting a possible means which enables to develope quantitative study on the thermal onset of oscillation. This type of oscillation occurs when a cooler as well as a heater is held in a tube with no inner flow, yielding a conclusion that there is a common feature in some fundamental respects with the case of having an inner flow.
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TL;DR: In this article, a three dimensional solution for the stresses around a hemispherical pit at a free surface of an elastic plate is presented, where the plate is subjected to all-around tension parallel to the free surface.
Abstract: This paper contains a three dimensional solution for the stresses around a hemispherical pit at a free surface of an elastic plate. At infinity the plate is subjected to all-around tension parallel to the free surface. In the analysis, the method of Boussinesq's two harmonic functions approach is used and these functions are expressed in simple forms of cylindrical and spherical harmonics. The boundary conditions both on the upper surface and at infinity are satisfied automatically, while the remaining boundary conditions on the lower surface and on the surface of the pit are satisfied with aid of the Hankel transform and relations between the cylindrical harmonics and the spherical ones. Numerical calculations are carried out for four different values of radius of the hemispherical pit.
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TL;DR: In this paper, the authors investigated the forced convection heat transfer for a fully developed laminar flow in horizontal circular tubes and concentric annuli in order to clarify quantitatively the effect of natural convection on their heat-transfer characteristics.
Abstract: Experimental investigations have been made of the forced-convection heat-transfer for a fully developed laminar flow in horizontal circular tubes and concentric annuli in order to clarify quantitatively the effect of natural convection on their heat-transfer characteristics. When the Grashof number Gr=βgLrTr/Ur2, defined using Tr=WGLr2/α, Lr=(d22-d21)(q1+q2)/(d1q1+d2q2), Ur= ν/Lr as the characteristic temperature, length, and velocity, respectively, is introduced, the heat-transfer characteristics of the secondary flows induced by natural convection can be expressed by the following equations; for inner tubes, Nui=0.44Gr0.20Pr0.28(d2/d1)0.35 for outer tubes, Nuo=0.38Gr0.20Pr0.28 These two equations are applicable to circular tubes and annuli, regardless of heating amounts of inner and outer tubes.
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TL;DR: In this paper, a finite difference equation for pulsating turbulent flow in a circular tube, in which the Reynolds stress is described in terms of eddy viscosity expressed with friction velocity, is approximated by finite difference equations.
Abstract: Fundamental equation for pulsating turbulent flow in a circular tube, in which the Reynolds stress is described in terms of eddy viscosity expressed with friction velocity, is approximated by a finite difference equation. Numerical solutions of the cross-sectional velocity distributions are obtained in two cases of time-dependent friction velocity and of time-independent one. It is shown numerically or experimentally that for very low frequencies the flow is in quasi-steady state. At low frequencies, only the results of the analysis with time-dependent friction velocity agree well with the experimental results. At high frequencies, the results of the analysis with time-dependent friction velocity agree with those those with time-independent one, and both of them coincide with the experimental results.
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TL;DR: In this article, the heat transfer problem of two dimensional steady state free convection from a horizontal cylinder with cross section of arbitrary shape is theoretically analized for both cases of uniform surface temperature and uniform surface heat flux.
Abstract: The heat transfer problem of two dimensional steady state free convection from a horizontal cylinder with cross section of arbitrary shape is theoretically analized for both cases of uniform surface temperature and uniform surface heat flux. As examples the heat transfers from a circular cylinder, a modified triangular prism and a modified quarangular prism are calculated, and to check the results, experiments have been carried out in water. The experimental values of the mean heat transfer coefficient are about 10∼30 percent higher than the analytical values.
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TL;DR: In this paper, cavitation erosion of several structure materials is studied by means of continuous observations by a scanning electron microscope, etc. Erosion damages are affected by the grain orientation on testing surfaces as well as the crystal structure of test materials.
Abstract: In the present paper, cavitation erosion of several structure materials is studied by means of continuous observations by a scanning electron microscope, etc. Erosion damages are affected by the grain orientation on testing surfaces as well as the crystal structure of test materials. On the whole, erosion resistance decreases according to an increase in the plastic deformation of grains.
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TL;DR: In this article, a two-degree-of-freedom vibrating system tuned to internal resonance with the higher natural frequency twice the lower natural frequency, having nonlinear characteristic of second and third order polynomials of the displacements, subjected to harmonic excitation, is taken up.
Abstract: A two-degree-of-freedom vibrating system tuned to internal resonance with the higher natural frequency twice the lower natural frequency, having nonlinear characteristic of second and third order polynomials of the displacements, subjected to harmonic excitation, is taken up. Steady forced vibrations are investigated in the vicinity of the higher resonance point of the system. Through the theoretical analysis it is found that the system has two types of resonances depending on the excitation frequency, namely one in which only harmonic occurs, and the other in which sub-harmonic with the frequency half the excitation frequency occurs strongly in addition to harmonic. Also found is the phenomenon that almost periodic motions occur in a certain range of the excitation frequencies. It is shown that the results of the theoretical analysis agree with those of an analog computer.
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TL;DR: In this article, the authors analyzed the dynamics of water waves and structural loads induced by a forced and periodical change of discharge from a sluice-gate, as the first approach for making clear dynamical characteristics of Tainter-gates which are being used with increased frequencies in order to control the water level of dam.
Abstract: Characteristics of water waves and structural loads induced by a forced and periodical change of discharge from a sluice-gate were theoretically analyzed, as the first approach for making clear dynamical characteristics of Tainter-gates which are being used with increased frequencies in order to control the water level of dam. It was concluded as follows: A basic parameter characterizing water waves and structural loads is the modified Froude number F0=√(d0/g)·ω(d0: the depth of the gate-opening, g: the gravitational acceleration, ω: the frequency of an oscillatory discharge). Characteristics of water waves are very analogous to the resonance characteristics of the forced oscillatory system consisting of a mass, a spring and a viscous damper. When F0 is equal to about 0.8, wave motions fall into a resonance state. Characteristics of fluid-induced structural loads suggest a possibility that Tainter-gates fall into a self-excited oscillatory state. These theoretically obtained results were proved by experiments.
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TL;DR: In this article, the stress-strain relations of metals in loading along straight stress paths (or straight strain paths) with a bend are investigated experimentally as well as theoretically in the deviatoric stress (or strain) space.
Abstract: The stress-strain relations of metals in loading along straight stress paths (or straight strain paths) with a bend are investigated experimentally as well as theoretically in the deviatoric stress (or strain) space. Equations of the equi-plastic strain surfaces of various metals after preloadings are given on the basis of the experimental results obtained by subjecting this-walled tubular specimens to combined axial load and torsion. Stress-strain relations for various loading paths are calculated using the equi-plastic strain functions. There is a good agreement between the calculation and the experiment.
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TL;DR: In this article, a turbulent region of axisymmetric jets of H2, He, Ar, CO2 and air with quiescent air is studied. And the results of experiments show that the turbulent exchange coefficients are proportional to a half power of those density ratios.
Abstract: Concentration and velocity measurements are carried out in a turbulent region of axisymmetric jets of H2, He, Ar, CO2 and air with quiescent air The spreading angles of concentrations and velocities are larger for the lighter issuing gases Though the decreases of concentrations with the axial distance are associated with the differences of the densities between issuing and surrounding gases, the decreases of velocities are proportional to the ratio of these densities The differences of these behaviors for each gas are displayed by the contour maps of concentration and velocity For lighter issuing gases, the velocities decay fast, but the concentrations remain at rather high values On the other hand, for heavier gases, both oh the decays have considerably small values And the results of experiments show that the turbulent exchange coefficients are proportional to a half power of those density ratios