Showing papers in "Jsme International Journal Series B-fluids and Thermal Engineering in 1979"
TL;DR: In this paper, the authors made experiments of impinging droplets on a heated vertical surface in a range of low droplet Weber numbers mostly from 10 to 200, and data of the heat transfer effectiveness of individual droplets measured by means of a transient technique are presented.
Abstract: Experiments were made of impinging droplets on a heated vertical surface in a range of low droplet Weber numbers mostly from 10 to 200. Data of the heat transfer effectiveness of individual droplets measured by means of a transient technique are presented. When the wall superheat is higher than a certain value, the droplet rebounds away from the surface with a very low heat transfer effectiveness. Behavior of the droplets on the surface was observed and heat transfer characteristics during the residence time of a droplet on the high temperature surface were examined based on the time-dependent variation of the wall temperature measured near the surface.
74 citations
TL;DR: In this article, the authors analyzed the pressure drop oscillation in a boiling channel system by using a lumped parameter model in which pressure drop characteristics was described by a third order equation of the flow rate.
Abstract: The pressure drop oscillation in a boiling channel system was analyzed by using a lumped parameter model in which the pressure drop characteristics was described by a third order equation of the flow rate. The momentum equation in the boiling channel system was thus reduced to a Van der Pol equation. The limit cycle and the period of the pressure drop oscillation obtained from the Van der Pol equation agreed qualitatively with experimental results.
49 citations
TL;DR: In this article, the authors measured the flow rate and size of entrained droplets in upward annular flow of air and liquid and derived the rate of droplets entrained from the liquid film to the gas core.
Abstract: The flowrate and size of entrained droplets were measured in upward annular flow of air and liquid. The rate of droplets entrained from the liquid film to the gas core was derived taking into account the rate of droplets transferred from the gas core onto the liquid film. The size distribution of the droplets in the gas core was approximated by a gamma distribution and empirical equations were proposed for the mean diameter of the droplets in terms of the conditions of gas flow and the surface tension.
42 citations
TL;DR: In this article, the best method to estimate the accuracy of the diameter of the parts and the working forces in tube spinning process is discussed, where the deformation energy of the tube consumed on the contact area between the roller and the mandrel is minimized.
Abstract: The best method to estimate the accuracy of the diameter of the parts and the working forces in tube spinning process is discussed. At first, the velocity of the metal and the strain rate in the deformation zone are estimated by introducing the parameters ξ and z0 obtained from the observation of the previous experiments. The optimum values of ξ which has an effect on the accuracy of the diameter or the parts are obtained by minimizing the deformation energy of the tube consumed on the contact area between the roller and the mandrel. Therefore, the proposed method is useful for selecting the working forces in tube spinning can be obtained with good agreement between the experimental and calculated results by this method by knowing the deformation resistance of specimen and the other working conditions.
41 citations
41 citations
TL;DR: In this paper, a contact rod clamped at one end is pressed in the radial direction on a rotating disk and the rod vibrates in the lateral direction as in the fundamental mode.
Abstract: The generating mechanism of frictional noise in dry friction is experimentally and theoretically studied, when a contact rod clamped at one end is pressed in the radial direction on a rotating disk. The results are obtained as follows: (1) Frictional noise is classified into two categories, rubbing noise and squeal noise. (2) When the coefficient of friction between the rod and the disk is small, the vibrating energy is small. Therefore, the frictional noise is rubbing noise, which is of a low level. (3) When the coefficient of friction grows great as the result of the tip of the rod being worn, the rod vibrates in the lateral direction as in the fundamental mode. Thus the vibrating energy increases and the frictional noise changes to the squeal noise, the sound pressure level of which is higher than the rubbing noise by 20-30 dB. These lateral vibrations seem to be self-excited vibrations caused by the friction.
37 citations
TL;DR: In this paper, temperature distribution and thermal correlation of piston rings and piston in high speed diesel engines under actual operating conditions, in spite of their importance, have not been clarified due to the difficulties involved in the measurement.
Abstract: Temperature distribution and thermal correlation of piston rings and piston in high speed diesel engines under actual operating conditions, in spite of their importance, have not been clarified due to the difficulties involved in the measurement. Authors overcame the difficulties and the temperatures were measured directly and precisely by means of thermocouples. As the result, concerning the heat flow pattern and the flow rate, interesting differences among the top, the second and the oil rings, and also between the plain and the taper faced ring were revealed. In addition, the amount of heat transferred to the piston, and the parcentage of each heat released from the piston to other parts were determined.
31 citations
TL;DR: In this article, the influence of relative particle-fluid velocity, Reynolds number and particle diameter on radial particle displacement (lateral migration) was investigated by measuring the motion of a suspended spherical particle in laminar flow through a circular tube.
Abstract: In laminar flow of suspensions through a circular tube, particles migrate into a concentric annular region with the radius about 0.6 of the tube radius. This phenomenon is well-known as the tubular pinch effect. To clarify the mechanism, the influences of relative particle-fluid velocity, Reynolds number and particle diameter on radial particle displacement (lateral migration) were investigated by measuring the motion of a suspended spherical particle in laminar flow through a circular tube. Consequently, it was found that the motions of particles could be classified by the particle Reynolds number. And, especially, the relation between the particle Reynolds number and the equilibrium radial position of particles and the existence of critical particle Reynolds number for shifting from unilateral migration to bilateral migration were clarified.
31 citations
TL;DR: This study deals with the manipulator control problem from the dynamical standpoint where the time factor plays an important role and a method of calculation of the global coordinative motion is proposed.
Abstract: This study deals with the manipulator control problem from the dynamical standpoint where the time factor plays an important role. It includes a coordinate transformation of the position and posture and the force and moment, a control of the coordinative motion, and a visual feedback control. In the first report, the coordinate transformation necessary to control the coordinative motion of the hand of a manipulator has been analyzed. As the result, it is shown that there are several singular points determined by the arm mechanism. At these singular points, the kind of the configuration of the arm for the same position and posture of the hand changes and the number of degrees of freedom of the hand decreases. Utilizing these results, a method of calculation of the global coordinative motion is proposed. This method eliminates the difficulties which may arise at the singular points and enables a change of the kind of the configuration.
28 citations
TL;DR: In this article, an experimental study was conducted on the oscillatory flow instabilities in an air-water two-phase flow system with upstream compressible volume, and the flow pattern during the oscillation and the effects of the compressible volumes and the average superficial velocity on the limit cycles were investigated.
Abstract: The purpose of this is to make clear the flow instability problem in two-phase flow systems. In this first report, an experimental study was conducted on the oscillatory flow instabilities in an airwater two-phase flow system with upstream compressible volume. The flow pattern during the oscillation and the effects of the compressible volume and the average superficial velocity on the limit cycles were investigated. The periods of the oscillations were well correlated by two characteristic parameters obtained from a simple non-linear analysis.
28 citations
TL;DR: The heat transfer mechanism in separated region of a cylinder immersed in a free stream with nonhomogeneous and unisotropic turbulence was made clear experimentally in relation to the wake formation process near the cylinder and the flow behavior in the layer close to the cylinder wall.
Abstract: The heat transfer mechanism in separated region of a cylinder immersed in a free stream with non-homogeneous and unisotropic turbulence was made clear experimentally in relation to the wake formation process near the cylinder and the flow behavior in the layer close to the cylinder wall. An experiment was conducted in the subcritical flow region. The appearance of a second peak of heat transfer coefficients in separated region is due to the existence of a three-dimensional unsteady flow close to the cylinder surface and the decrease of heat transfer coefficients in near stagnation region is caused by the formation of an apparent turbulent separation point.
TL;DR: In this paper, the authors explain the characteristics of a flow field affected by an interference between a nonuniform cross flow and unheated jets issued from a single circular orifice or a single row of equally spaced circular orifices on a flat floor.
Abstract: The present work is done to explain the characteristics of a flow field affected by an interference between a nonuniform cross flow and unheated jets issued from a single circular orifice or a single row of equally spaced circular orifices on a flat floor. Data from measurements of the total pressure and the flow direction and those from flow visualization experiments are presented for a low velocity ratio of 2. In the jet region downstream of a point, at which the minimum jet spread appears in the plane of symmetry of jets, there are large differences between characteristics of a single jet and a component jet of a multiple jet. The floor boundary layer downstream of jet orifices is affected greatly by a circulating flow, which is a vortexlike flow induced within the cross flow. The origin of the circulating flow also is discussed. The mutual interference between component jets of the multiple jet has a great influence on their spreads.
TL;DR: In this article, it was found that for reattachment jets having large offset ratios, an agreement if good between the experimental results and the results of the approximated calculations obtained by using the solutions of a two-dimensional jet can be found.
Abstract: It was found for reattachment jets having large offset ratios that an agreement if good between the experimental results and the results of the approximated calculations obtained by using the solutions of a two-dimensional jet. But flows having rather small offset ratios show different values from the results of calculation. Existence of similarity in the reattachment jet flows having large offset ratios can be well expressed by introducing an appropriate parameter which represents a bubble pressure. Experiments also show that the behaviours of a two-dimensional reattachment jet flow are independent of Reynolds number, but the behaviours of a reattachment jet flow are dependent on Reynolds number in the case of three-dimensional flows having small aspect ratios.
TL;DR: In this paper, the resolution of a Karman vortex street by controlling the generation state of a vortex was improved by arranging not less than two vortex generating element plates at a desired interval behind a karman vortex rod.
Abstract: PURPOSE:To improve instrumentation precision by increasing the resolution of a Karman vortex street by controlling the generation state of a vortex by arranging not less than two Karman vortex generating element plates at a desired interval behind a Karman vortex generating element rod CONSTITUTION:Inside flow-meter main body 2 equipped in duct 1, triangular vortex generating element rod 3 is provided and not less than two plate-shaped vortex generating element boards 5 of the same width as rod 3 are independently arranged at a fixed interval behind it This constitution generates an excellent Karman vortex under broad measurement conditions where the flow rate and flow velocity of a fluid are changeable As a result, the resolution is improved and the shape of vortex generating element rod 3 and the number and arrangement state of vortex generating element plates 5 are adequately set within the range of more than two in number so as to realize accurate instrumentation; and the structure is simple and various fluids can be measured Further, a closed pipe and open channel can be used for the duct
TL;DR: In this paper, an experimental study on geysering was carried out in an R-113 forced flow boiling system and the effects of flow rate, heat flux density, system pressure and heating condition on the threshold of geysers and on the period and amplitude of the differential pressure at the test section were studied.
Abstract: An experimental study on geysering was carried out in an R-113 forced flow boiling system. The effects of flow rate, heat flux density, system pressure and heating condition on the threshold of geysering and on the period and amplitude of the differential pressure at the test section were studied. The mechanism of geysering was analyzed by using a simple model. The analytically predicted period and amplitude of oscillation agreed qualitatively with the experimental results and thus supported the validity of the model.
TL;DR: In this article, the axisymmetric stress field in an infinite solid cylinder with an external crack under torsion is analyzed and the problem is reduced to the solution of an infinite system of simultaneous equations.
Abstract: We analyse the axisymmetric stress field in an infinite solid cylinder with an external crack under torsion. If the stress distribution on the crack plane is assumed as an appropriate series, the problem is reduced to the solution of an infinite system of simultaneous equations. Numerical results are illustrated for the distributions of displacements and stresses and the relation between stress intensity factor and crack depth.
TL;DR: In this paper, an experimental investigation has been carried out to study the effect of sound waves with a particular frequency on forced convective heat transfer from a heated circular cylinder over the Reynolds number range from 5000 to 20000.
Abstract: An experimental investigation has been carried out to study the effect of sound waves with a particular frequency on forced convective heat-transfer from a heated circular cylinder over the Reynolds number range from 5000 to 20000. The results indicate that the convective heat-transfer coefficient can be influenced by a given sound wave, and in this case it causes the Nusselt number to increase appreciably on the back half of the cylinder On the other hand, the approach of the vortex region formed in the wake to the cylinder surface plays an important role in the mechanism of an increase in the Nusselt number in separated region.
TL;DR: In this article, an analysis of the radiative transfer in a paint-type coating layer of absorbing and anisotropic scattering medium with two different boundaries of air-coating and coating-substrate Mie scattering equations are used to evaluate the scattering and the absorption coefficients of the spherical particles of the pigment.
Abstract: An analysis is carried out on the radiative transfer in a paint-type coating layer of absorbing and anisotropically scattering medium with two different boundaries of air-coating and coating-substrate Mie scattering equations are used to evaluate the scattering and the absorption coefficients of the spherical particles of the pigment A numerical approach to the solution of the transfer equation, using Gaussian quadrature formula and Gaussian elimination procedure, is presented The effects of the optical properties of the pigment (TiO2, Fe2O3 and carbon), the pigment volume concentration, the absorption by the vehicle and the reflection characteristics of the substrate (specular or diffuse) on the bidirectional and hemispherical reflectances are examined The wavelength dependence of the results is examined also in the range from 035 to 20 μm
TL;DR: In this paper, the free vibration of an orthotropic elliptical plate with a similar hole at the center was studied by means of the Ritz method using a spline function as an admissible function.
Abstract: This paper studies free vibration of an orthotropic elliptical plate with a similar hole at the center by means of the Ritz method using a spline function as an admissible function. For this purpose, the plate is transformed into an annular plate of unit outer radius, the transverse deflection of the plate is written in a series of the products of deflection function of a sectorial beam and trigonometric function of angular co-ordinate, and the frequency equation is derived by the Ritz method. The deflection of the sectorial beam is expressed approximately as a quintic spline polynomial, which satisfies the equation governing the flexural vibration of the beam at all the knots dividing it into small elements and also satisfies the boundary conditions at both ends. The present method is applied to orthotropic annular plates and elliptical plates with a similar hole at the center, the natural frequencies and the mode shapes being calculated numerically with high accuracies.
TL;DR: In the second report, a computer control system of the coordinative motion of the mechanical arm is described, which is a real time system which consists of a servo system to control themotion of the arm, tactile and visual information processing systems and some other subsystems.
Abstract: In the second report, a computer control system of the coordinative motion of the mechanical arm is described. This control system is a real time system which consists of a servo system to control the motion of the arm, tactile and visual information processing systems and some other subsystems. The servo system is a software servo system, of which the controlling unit is constructed of a computer software. In this controlling unit, a mathematical model of the arm and its driving unit is programmed. Making use of this mathematical model, the motion, force and moment of the hand and the stiffness of the servo at the hand can be controlled in various coordinate systems properly designated in the work space of the arm.
TL;DR: In this article, a technique to determine effectively an optimum shape of two-dimensional and axisymmetric bodies under body force is proposed, which is based on the iteration of a sequential search method consisting of the following steps.
Abstract: In this paper, a technique to determine effectively an optimum shape of two-dimensional and axisymmetric bodies under body force is proposed. This technique is based on the iteration of a sequential search method consisting of the following steps. In the first step, the superiority or inferiority of a given shape, which satisfies the constrained conditions of design, is judged by the deviation from the design object stress value. In the second step, this given shape is modified to an optimum shape by the proportional transformation method of the finite elements, which is considered an effect of body force. By using this technique the optimum shapes of the basic problems under gravity load or centrifugal force are obtained and the results are compared with the corresponding shapes given by elementary theory. Moreover and optimum shape of the rotating disk with a rim and a bored hole is obtained by applying the optimization technique. The validity of this shape is examined experimentally by comparing with the fracture strength of a bored, uniform thickness disk.
TL;DR: In this article, the authors analyzed the high Reynolds number flow of a two-dimensional liquid jet which ejects downwards from a channel of a constant width experiencing small gravitational force, and the effect of surface tension and that of interference between the jet and the neighbouring gas were not taken into account.
Abstract: The present work analyzed the high Reynolds number flow of a two-dimensional liquid jet which ejects downwards from a channel of a constant width experiencing small gravitational force. The flow is assumed to be laminar, and the effect of surface tension and that of interference between the jet and the neighbouring gas are not taken into account. The solution of the flow field is composed of the upstream solution which is valid in the neighbourhood of channel exit and the downstream solution valid in the region far from the channel exit. The flow is compared to the inlet flow of two-dimensional channel.
TL;DR: In this paper, the properties of air-lubricated slider bearings operating under submicron spacing conditions were investigated theoretically and experimentally, considering the modified Reynolds equation, considering slip flow effects, and calculated in the frequency domain by small perturbation method and finite difference method.
Abstract: Dynamic characteristics of air-lubricated slider bearings operating under submicron spacing conditions are investigated theoretically and experimentally. From the modified Reynolds equation, considering slip flow effects, the properties of air film stiffness and damping are calculated in the frequency domain by small perturbation method and finite difference method. Influences of the molecular mean free path on the dynamic characteristics of air-lubricated slider bearings are discussed and a design method for high performance slider bearings, operation under submicron spacing conditions, is presented. Experimental data on the frequency response of the submicron slider spacing are in good agreement with the analytical results.
TL;DR: In this paper, two kinds of fast-acting valves were developed to replace diaphragm-breaking as a means of generating shock waves in the conventional shock tubes, and one of them, called a type-H valve is used in a shock tube in this paper, and the strength of shock wave generated by the valve and the correlation between the shock formation distance and the opening time of the valve are experimentally clarified.
Abstract: In the previous paper, two kinds of fast-acting valves were developed to replace diaphragm-breaking as a means of generating shock waves in the conventional shock tubes. One of them, called a type-H valve is used in a shock tube in this paper, and the strength of shock wave generated by the valve and the correlation between the shock formation distance and the opening time of the valve are experimentally clarified. Furthermore, the experiments where a diaphragm is used are also performed, keeping all other operating conditions equal, and the results are compared with those by the valve. When the initial pressure ratio is comparatively small, valve produces as strong a plane shock wave as the conventional diaphragm shock tubes, although the shock Mach numbers are less than those produced by the breaking of diaphragm at a larger initial pressure ratio.
TL;DR: In this article, the statistical properties of errors of a rotor system and those of an earthquake (i.e., its period, magnitude and statistical character of wave) are known, and a period of the first collision with the guard of the rotor system is calculated in a statistical sense.
Abstract: High speed rotating machines, such as the centrifugal machine, may have deviations of mass, stiffness and damping coefficient in manufacturing process, and are also exposed to the danger of earthquake. In the design of a rotor system, these factors should be accounted for from a view point of reliability. This paper deals with this problem specifically, when the statistical properties of errors of a rotor system and those of an earthquake (i. e. its period, magnitude and statistical character of wave) are known, the statistical properties of the rotor vibration are obtained, and a period of the first collision with the guard of the rotor system is calculated in a statistical sense. It is concluded that the statistical property of the seismic wave has more influence on the reliability than that of the damping coefficient in the rotor system. If the statistical relation between the magnitude and interval of an earthquake is known, the period of the first collision with the guard can be obtained.
TL;DR: Experimental studies to improve the load carrying capacity of plastic gears are presented in this paper, where the load test of nylon gear, which have the same cutting as steel gears, is tried and the limit value of power-transmission and the distribution of temperatures which rise under no lubricant are examined.
Abstract: Experimental studies to improve the load carrying capacity of plastic gears are presented. In the first place, the load test of nylon gear, which have the same cutting as steel gears, is tried and the limit value of power-transmission and the distribution of temperatures which rise under no lubricant are examined. In the next place, after the consideration of the temperature distribution in gear toot, the load test of nylon gears which are cut with counter-crowning is tried. It is confirmed that these gears are able to be used for power-transmission under limited conditions.