Showing papers in "Jsme International Journal Series B-fluids and Thermal Engineering in 1985"
TL;DR: In this article, a computer simulation is used to analyze the radial vibration of ball bearings in order to overcome the experimental and theoretical difficulties: the experimental difficulties are due to complicated interaction of the dominant factors, while the theoretical difficulties were due to the nonlinear spring behaviour and time-dependent excitation of ball bearing.
Abstract: Computer simulation is used to analyze the radial vibration of ball bearings in order to overcome the experimental and theoretical difficulties : the experimental difficulties are due to the complicated interaction of the dominant factors while the theoretical difficulties are due to the nonlinear spring behaviour and time-dependent excitation of ball bearings. The inner ring motion, which involves the Perret-Meldau problem, is considered in the radial plane for an ideal bearing the massive inner ring of which rotates at a constant speed under a constant radial load. The results show that superharmonic, subharmonic, beat and chaos-like vibrations appear, in addition to harmonic vibration which synchronizes with ball passage.
108 citations
56 citations
TL;DR: In this paper, the authors studied the turbulence structure in the intermediate wake of a circular cylinder by a conditional sampling technique and found that lateral velocity fluctuations at each position of measurement correspond to a proper reference signal to make the conditional sampling if they were combined with longitudinal velocity fluctuations along the wake axis.
Abstract: Turbulence structure in the intermediate wake of a circular cylinder was studied by a conditional-sampling technique. The measurements were made at a section 8 diameters downstream of the centre of the cylinder. Lateral velocity fluctuations at each position of measurement were found to a proper reference signal to make the conditional sampling if they were combined with longitudinal velocity fluctuations along the wake axis. Velocity fluctuations were decomposed into those produced by large-scale coherent structures and those associated with small-scale structures. Maps of streamlines, vorticity, velocity vectors and correlation of velocity fluctuations were presented in the large-scale structures. Intensity, correlation and intermittency of the small-scale fluctuations were also presented and discussed in relation to the flow field in and around the large-scale structures. A mechanism of entrainment by the large-scale structures and diffusion of their vorticity was suggested on the basis of the above results.
49 citations
TL;DR: In this article, the cooling effect of coolant is measured and the fraction of mechanical energy conducted as heat into the workpiece is estimated by Jaeger's moving heat theory extended to include cooling effect.
Abstract: This paper aims to clarify workpiece temperature and the mechanism of grinding burn in creep feed grinding. The workpiece is modelled thermally by a three dimensional finite element method. The cooling effect of coolant is measured and the fraction of mechanical energy conducted as heat into the workpiece is estimated by Jaeger's moving heat theory extended to include the cooling effect. The analytical results are shown to agree well with the experimentally obtained temperature distribution. From the experimental evidence that the onset of grinding burn is closely related to the boiling of the coolant used, the mechanism of the grinding burn can be considered as follows; when the grinding zone temperature reaches a point at which bubbles begin to form, the bubbles grow up rapidly in the wheel-workpiece interface and block heat transfer to the coolant. This is verified by the above-mentioned thermal mode.
43 citations
TL;DR: In this article, an experimental investigation was performed on turbulent boundary layers with injection and suction through a slit, and the velocity profile, turbulent energy, auto-correlation function, energy spectrum, and energy balance were measured in detail.
Abstract: An experimental investigation is performed on turbulent boundary layers with injection and suction through a slit. The velocity profile, turbulent energy, auto-correlation function, energy spectrum, and energy balance are measured in detail, and the influence of injection and suction through a slit on the turbulent boundary layers is presented. The process of recovery to an equilibrium state from non-equilibrium state is investigated. Main results are summarized as follows. The effects of injection and suction on velocity profiles and turbulence characteristics are small in the vicinity of the wall. On the other hand, the effects of injection clearly appear in the outer layer region of the turbulent boundary layer. Convection, production, and dissipation of turbulence energy increase with injection and decrease with suction.
40 citations
TL;DR: In this article, a condensation shock wave was observed optically by a method in the case of moist air expanding in a supersonic nozzle, and the effect of the relative humidity of the moist air on the shape of the condensation wave was discussed.
Abstract: An expansion of moist air or steam in a supersonic nozzle gives rise to nonequilibrium condensation phenomenon, and a condensation shock wave appears in the supersonic section of the nozzle. In the present paper, a condensation shock wave was observed optically by a method in the case of moist air expanding in a supersonic nozzle, and the effect of the relative humidity of moist air on the shape of a condensation shock wave was discussed. Furthermore, a flow of moist air expanding in a supersonic nozzle was analyzed by the method of characteristics. Based on these experimental and calculated results, the mechanism of formation of a condensation shock wave was clarified.
38 citations
TL;DR: In this article, the optimum thin-film thermocouple in terms of materials, shape and dimensions has been determined as follows, and the effects of thermophysical properties and dimensions of materials constituting the thermocouples have been studied.
Abstract: The optimum thin film thermocouple in terms of materials, shape and dimensions has been determined as follows. Equations of different element method capable of determining the temperature distribution in such a thermocouple are introduced in order to obtain the temperature distribution by which the combustion gas temperature and heat transfer coefficient affect the thermocouple under steady state and unsteady state conditions. Further, effects of thermophysical properties and dimensions of materials constituting the thermocouples have been studied. On the other hand, thermocouples made of different materials and in different shapes have been trially produced and embedded respectively into the piston of a 4-stroke gasoline engine. Actual measurements of such thermocouples proved the validty of calculated results, and it has been demonstrated that the above mentioned thermocouples have an adequate durability under high speed/high load conditions.
35 citations
TL;DR: In this article, the authors used an unique half cut model of an oil hydraulic poppet valve and measured the pressure distribution in the metering restriction between the valve seat and the surface.
Abstract: By using an unique half cut model of an oil hydraulic poppet valve, the cavitation phenomena were directly observed and the pressure distribution was measured in the metering restriction between the valve seat and the poppet surface. As a result of this research, the occurrence process of cavitation in a poppet valve and the effects of it on the flow performance were made clear. Also, the differences in a performance of cavitation between the diverging flow and converging flow were understood.
33 citations
TL;DR: In this paper, the radial vibration velocity of the outer ring was determined by a moving coil type converter and using the output so obtained, vibration waveforms were produced, real time frequency analysis of the vibrations was done by Fast Fourier Transform analyzer and the effect of the measuring position of the inner ring on the vibration, etc. was examined.
Abstract: An investigation was undertaken with a view to establishing a procedure for diagnosing the extent of rolling bearing defects from their vibration and sound. In the investigation the vibration of a ball bearing with multiple dents on the race surface of either the inner or outer ring was studied. The inner ring of the bearing was caused to rotate at a constant speed under a given thrust load applied to the outer ring. The radial vibration velocity of the outer ring was determined by a moving coil type converter and using the output so obtained, vibration waveforms were produced. Real time frequency analysis of the vibrations was done by Fast Fourier Transform analyzer and the effect of the measuring position of the outer ring on the vibration, etc. was examined. As a result, the fundamental characteristics of ball bearings having multiple defects were clarified, and an effective method by which to locate the defects and to determine their number and size was established.
33 citations
TL;DR: In this paper, the characteristics of the flow around rectangular cylinders were carried out in the range of subcritical Reynolds numbers, and the width-to-height ratio (C/d) of the sections was varied from 0.1 to 4.0.
Abstract: Experimental investigations on the characteristics of the flow around rectangular cylinders were carried out in the range of subcritical Reynolds numbers. The width-to-height ratio (C/d) of the sections was varied from 0.1 to 4.0. The fluctuating pressure coefficient has a maximum in the same tendency as that of the drag coeffecient when C/d=0.67 and 2.8 become clear. The flow around the cylinder with an arc-like leading-edge corners has been found to agree closely with one around the cylinder with a larger value of the ratio of C/d.
33 citations
TL;DR: In this article, integral equation methods for boundary value problems of elastic bodies with cracks are investigated, and the integral equations are solved analytically for the case of penny-shaped crack.
Abstract: In this paper, integral equation methods for boundary value problems of elastic bodies with cracks are investigated. We use Somigliana's identities to represent displacements in elastic bodies, and deduce integral equations from the boundary conditions on the crack surfaces. In these integral equations, unknown functions are displacement differences between the upper and the lower crack surfaces. Divergent integrals are contained and they are evaluated in the sense of Hadamard's finite parts. The integral equations are solved analytically for the case of penny-shaped crack. Methods for numerical solutions of the equations are also studied.
TL;DR: In this article, the characteristics of centrifugal pumps handling air-water mixtures are analyzed on the basis of a gas-liquid separated flow model, which is generally accepted in the analysis of the data on a two-phase flow in piping systems.
Abstract: Characteristics of centrifugal pumps handling air-water mixtures are analyzed on the basis of a gas-liquid separated flow model, which is generally accepted in the analysis of the data on a two-phase flow in piping systems. And a method for predicting the pump characteristics is presented with use of parameters of friction-loss and shock-loss multipliers. Size of air bubbles flowing through pump impellers was measured. The bubbles in the inlet region of the impellers have an extremely uniform size with fairly small diameters. But in course of flow, the bubble diameter grows gradually due to coalescence of the bubbles.
TL;DR: In this article, a water drop impinging on a heated surface in the surface temperature range from the maximum boiling rate point to the nonwetting region was investigated. And the boiling curves were obtained by analyzing the transient temperature variation inside the heated surface taking account of the time variation of the area covered by the drop.
Abstract: This paper deals with transient heat transfer for a water drop impinging on a heated surface in the surface temperature range from the maximum boiling rate point to the non-wetting region. The boiling curves were obtained by analyzing the transient temperature variation inside the heated surface taking account of the time variation of the area covered by the drop. Comparing the boiling curves obtained in this way with that for pool boiling, the heat flux in both cases increases with an increasing subcooling, while the heat flux in the present case is several times higher than that for pool boiling. It was proved that the maximum heat flux point of the boiling curve was located on an extension of the nucleate pool boiling curve and that the boiling heat transfer for a drop on the heated surface was classified into four types according to the degree of subcooling and the heated surface temperature.
TL;DR: In this paper, a pair of conical involute gears transmit a rotational motion between two shafts whose axes intersect, and the deviation of a shaft angle, a small offset, and errors of mounting distances of the gears do not affect accuracy and uniformity of the transmitted motion.
Abstract: When a pair of conical involute gears transmit a rotational motion between two shafts whose axes intersect, the deviation of a shaft angle, a small offset between two shafts, and errors of mounting distances of the gears do not affect accuracy and uniformity of the transmitted motion. For easy understanding of this ability of the conical gears, this paper first describes results of running tests on a tooth bearing and an angular velocity ration, which verify this ability of the conical gears experimentally. Second it studies a theory of a gear tooth action which proves this ability theoretically. Furthermore, a contact ration and a relative curvature at a point of contact between tooth surfaces are described, and the tooth bearing is analyzed. Finally hertzian contact ellipse and the maximum contact stress are obtained.
TL;DR: In this paper, an analysis of a transient turbulent flow after instantaneous closure of a downstream valve is made by applying a previous method in which wall shear stress is evaluated from the cross-sectional distribution of instantaneous axial velocities.
Abstract: Numerical calculations of a transient turbulent flow after instantaneous closure of a downstream valve is a single pipe line having an upstream reservoir are made by applying a previous method in which wall shear stress is evaluated from the cross-sectional distribution of instantaneous axial velocities. The variations of pressure, wall shear stress, and the cross-sectional distribution of axial velocities are shown schematically. Numerical analyses of a turbulent-laminar, a laminar, and a quasi-steady flow, and furthermore an analysis using an expression for wall shear stress reported previously are done. Thus calculated results of pressure are compared with experimental data. The critical condition in which analysis of laminar flow is applicable to the region of a transient turbulent flow is also presented.
TL;DR: In this article, the thermal load conditions of the combustion chamber wall, by the use of precise thin film thermocouples which the authors have developed recently, surface temperature variation and instantaneous heat flux of the piston and the cylinder of a 4-stroke gasoline engine, for each stroke, are obtained.
Abstract: In an attempt to find out the thermal load conditions of the combustion chamber wall, by the use of precise thin film thermocouples which the authors have developed recently, surface temperature variation and instantaneous heat flux of the piston and the cylinder of a 4-stroke gasoline engine, for each stroke, are obtained. As a result, thermal load conditions of parts of the piston and the cylinder are made clear, and along with this, the ratio of heat loss is determined. Thermal load aspects under abnormal combustion conditions i.e. knocking are also crarified.
TL;DR: In this article, the effects of guide vanes with circular-arc profile have been investigated experimentally by model testing under steady operating condition, and it is found that the running characteristics as well as the starting characteristics are considerably improved by the guide vanES.
Abstract: In order to improve the performance of a Wells turbine the effects of guide vanes with circular-arc profile have been investigated experimentally by model testing under steady operating condition. The experimental results have been compared with those of the case without guide vanes. It is found that the running characteristics as well as the starting characteristics are considerably improved by the guide vanes. The improvement is mainly due to diffuser effect of the outlet guide vanes.
TL;DR: A theoretical and experimental study for the dynamic behavior of two liquid layers with a free surface in a container subject to vertical vibration is presented in this article, which is concerned with two fluids sloshing phenomena.
Abstract: A theoretical and experimental study is presented for the dynamic behavior of two liquid layers with a free surface in a container subject to vertical vibration. This study is concerned with two fluids sloshing phenomena. The stabilities of the plane free surface and interface of two superposed fluids with different densities are analyzed theoretically. In the analysis, the two liquids are ideal fluids, the interfacial surface tension is considered, and wall contact effects are neglected. An experiment was made on vertical vibration of a rectangular container holding kerosene and water. The agreement between theory and experiment was satisfactory on the occurrence of 1/2-subharmonic wave motions. The response amplitudes of the free surface and interface wave motions were measured. Many drops formed by the interfacial disintegration were observed in the lower fluid.
TL;DR: In this article, the authors analyzed the dynamic characteristics of a counter-shaft on which there are two pairs of gears in mesh and showed that the natural frequencies and mode shapes change when the shafts are rotated inversely and the flexural mode shape is not confined in a plane.
Abstract: Gear train system sometimes consists of more than 2 shafts. But dynamic characteristics of such system have not been analyzed in detail. Especially, on a counter shaft on which there are 2 pairs of gears in mesh, their power transmitting direction does not coincide each other. As a result, vibrations of power transmitting direction and tooth sliding direction couple together even if gyro effect is ignored. We discuss the dynamic characteristics of a counter shaft from this point of view. The results obtained from this investigation are : (1) Affected by the angle between 2 power transmitting directions on a counter shaft, the natural frequencies and mode shapes change. (2) Usually, when the shafts are rotated inversely, its natural frequencies and mode shapes change. (3) The flexural mode shape is not confined in a plane.
TL;DR: In this paper, the melting phenomena of a solid, pressed on a surface with the temperature higher than the melting point, were analyzed and calculated numerically The analytical results concerning non-dimensional heat flux agreed well with experimental results for water and octadecane shown in the former report.
Abstract: The melting phenomena of a solid, pressed on a surface with the temperature higher than the melting point, were analyzed and calculated numerically The analytical results concerning non-dimensional heat flux agreed well with experimental results for water and octadecane shown in the former report Then, an approximate formula relating non-dimensional heat flux with Stefan number and non-dimensional contact pressure was proposed The liquid layer thickness distribution between the heat transfer surface and the melting solid, besides the distributions of pressure, velocity and temperature within the liquid layer, was also calculated and discussed
TL;DR: In this article, the relation between contact ratio and vibration was investigated on a pair of power transmission helical gears with a comparatively narrow facewidth for the purpose of decreasing vibration and noise.
Abstract: On a pair of power transmission helical gears with a comparatively narrow facewidth, the relation between contact ratio and vibration is investigated experimentally for the purpose of decreasing vibration and noise. It has been confirmed that the power transmission helical gears are classified into three categories related to the transverse contact ratio and the overlap ratio as follows. The pair whose overlap ratio is over 1.0 has good vibration characteristics. When the total contact ratio is less than 2.0, the vibration characteristics are similar to those of spur gears. Under the condition that the total contact ratio is over 2.0 and the overlap ratio is less than 1.0, the pair shows a good performance by a modification of tooth profile and trace of the driven gear.
TL;DR: In this paper, the peak value of vibrational amplitude response curve caused by friction, where main component of the vibration is synchronized with meshing frequency, is almost independent of lubricating oil viscosity and transmitting power.
Abstract: A lot of investigations have been made on the friction between gear teeth, but most of them discuss its coefficient and few do its vibrational characteristics. As an element in a vibrational system, the friction has two aspects, that is exciting source and damping. In this paper, its vibrational characteristics are discussed. The results obtained in this study are: (1) The peak value of vibrational amplitude response curve caused by the friction, where main component of the vibration is synchronized with meshing frequency, is almost independent of lubricating oil viscosity and transmitting power. (2) Its effect as damping element to forced vibration depends on the kind of exciting source.
TL;DR: In this article, microstructures and segregations of silicon carbide fiber reinforced copper-added aluminum and aluminum-added magnesium alloy composites, fabricated by squeeze casting, were discussed and the effect of the microstructure on the tensile strength of composites.
Abstract: The present paper deals with microstructures and segregations of silicon carbide fiber reinforced copper-added aluminum and aluminum -added magnesium alloy composites, fabricated by squeeze casting, and refers to the effect of the microstructure on the tensile strength of composites. The results obtained are as follows: The results obtained are as follows: 1) Microscopic examination showed a solute element rich layer with semicircle surrounding was locally formed on fibers in the composites, whichever matrix alloy was used. The layer was identified as a eutectic constitution by EPMA decreased in thickness and area fraction, and for the case of 1% copper-aluminum matrix, no copper-rich layer was detected. 2) The appearance of the layer decreases the tensile strength of composites because of its brittleness.
TL;DR: The authors calculate numerique de l'ecoulement pour une buse ayant des surfaces courbes asymetriques arbitraires par la methode de Schwartz-Christoffel.
Abstract: Calcul numerique de l'ecoulement pour une buse ayant des surfaces courbes asymetriques arbitraires par la methode de Schwartz-Christoffel. Comparaison avec des resultats experimentaux. Etude des effets de la forme de la buse sur l'ecoulement de sortie
TL;DR: In this paper, the parametric instability in chuck work process is investigated and an analytical criterion of stability is given, and experimental confirmation is carried out. But the applicable isolation of this vibration has not been done.
Abstract: In this paper, the parametric instability in chuck work process is investigated. And an analytical criterion of stability is given, and experimental confirmation is carried out. The vibration of this type is considered to have a significant influence on machinability. However, the applicable isolation of this vibration has not been done. The results obtained are as follows: (1) The parametric vibration is generated by the directional orientation in the stiffness of chucked workpiece. (2) The theoretical analysis for predicting the conditions of parametric instability could be verified by good agreement with the result of cutting test. (3) In the chuck work process, the parametric vibration is amplified with mingling regenerative chatter by the condition of low and fluctuating stiffness.
TL;DR: In this paper, the parametric nonlinear forced vibrations of a beam with a mass subjected to alternating electromagnetic force are investigated analytically and experimentally, and the analysis, the governing partial differential equations are solved by harmonic balance method and the second order superharmonic and the one second order subharmonic vibrations are carried out by the Newton Rapson method, and are compared with the experimental results.
Abstract: In this report, the parametric nonlinear forced vibrations of a beam with a mass subjected to alternating electromagnetic force are investigated analytically and experimentally. The beam is fixed at one end, and an alternating electromagnetic force acts on the mass attached to the other end of the beam. In the analysis, the governing partial differential equations are solved by harmonic balance method, and the second order superharmonic and the one-second order subharmonic vibrations are carried out by the Newton Rapson method, and are compared with the experimental results.
TL;DR: In this paper, the phase change process of a melting solid pressed on a hot heat transfer surface was investigated experimentally, as a basic research of the heat storage process in a latent heat TES (thermal energy storage) capsule.
Abstract: The phase change process of a melting solid pressed on a hot heat transfer surface was investigated experimentally, as a basic research of the heat storage process in a latent heat TES (thermal energy storage) capsule. Along with measurements for various conditions, the physical parameters deciding the phenomena were analyzed, normalizing the basic equations and boundary conditions. It was shown as the result that the nondimensional heat flux expressed as a function of the Stefan number and the nondimensional contact pressure. Based on the experimental results, the relation among the bove nondimensional quantities was shown by a simple formula.
TL;DR: In this article, a quantitative measurement of contact pressure by means of ultrasonic waves has been proposed to measure the contact pressure distribution between two elastic beams, and the experimental results agree approximately with the theoretical ones and the proposed ultrasonic method is practically useful.
Abstract: A quantitative measurement of contact pressure by means of ultrasonic waves has been proposed to measure the contact pressure distribution between two elastic beams. At first, in a new proposed calibration method, the relation between mean contact pressure and sound pressure of reflected waves is obtained by using calibration blocks made of the same material and height as the beams. After such preparation, both sides of the laminated beams are compressed under locally uniform pressure, and the sound pressure of reflected waves is measured. From these relations, the contact pressure in beams is directly obtained. It is clarified that the experimental results agree approximately with the theoretical ones and the proposed ultrasonic method is practically useful.