The structure of the Karman vortex shed from two-dimensional bluff body placed in a fully developed turbulent pipe flow was investigated experimentally with air (mean velocity U_m=10m/s, Re_D=10⁵). The ratio of the bluff body width (w) to the pipe inner diameter (D) was 0.28. Velocity fluctuations were measured at 30w downstream of the bluff body by using a triple-wire probe. The flow behaviour was analyzed through the determination of the mean velocity distribution, velocity fluctuations during the vortex shedding period, the convection velocity of the vortex street and the vorticity distribution by employing the phase averaging method. The results showed that the convection velocity of the vortex street is lower than that in the free stream. The ratio of the streamwise distance of the vortices to the transverse distance is larger than that in the free stream. And also there are two groups of high vorticity areas, whose peak values are much larger than those of Karman vortex shed in the free stream.

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A finite-difference method for solving three-dimensional, time-dependent incompressible Navier-Stokes equations in spherical polar coordinates is presented. A new algorithm, which is second-order accurate in time and space, is considered, and decoupling between the velocity and the pressure is achieved by this algorithm. Further, the numerical method is used to simulate the spherical Couette flow between two concentric spheres with the inner one rotating. A comparison of the numerical results with the available experimental measurements was made. It is demonstrated that the numerical code is valid for solving three-dimensional, unsteady incompressible Navier-Stokes equations in spherical polar coordinates.

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A numerical simulation of particle flows in a centrifugal tumbling granulator was made by using DEM (Discrete Element method). Granulation process is driven by adding binding liluid. It is well known that a small amount of liquid has a significant effect on the motion of particles, so that it is important to model the effect of liquid bridge. We propose a model for the inter-particle force due to a liquid bridge which is based on the theory of liquid bridge. The present model is applied to the flow in the granulater. On the other hand, an experiment is made for the comparison. Particle velocities on the surface of moving particle bed is measured by using PTV technique. Tendency of particle velocities predicted by the present simulation agreed well with the experiments.

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The Lattice vortex method (LVM) by introducing virtual vortices has been proposed by the authors. This paper has focused on the treatment of viscous diffusion of vortices. From the result of calculation of a convection diffusion equation, giving a vorticity distribution of one vortex by the Gauss distribution offered good accuracy in the calculation of vortex diffusion and this method made the limitation of the Courant number relaxed. In the flow analysis by the LVM, the convection of vortices was calculated by secondorder area weighting scheme. It was found that the combination of this scheme and vorticity distribution determined by Gaussian distribution offered good result. Moreover, the result of cavity flow analysis turned out to be having sufficent accuracy by comparing with the result of the finite difference method. Therefore, LVM can be used for inner flow that the conventional vortex method is not so used.

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Rapid increase of available computational storage and speed has made possible the direct numerical simulation of the gas-particle jet, of which Reynolds number is about one thousand, based on the Navier-Stokes equation and the Lagrangian equation of particle motion. In this study three-dimensional Eulerian air velocities and Lagrangian particle trajectories are directly simulated to describe the effect of particle existences on the low Re number gas-particle free-jet flow using a two-way method. The results show that the small disturbances due to particle existences in the low Re number gas-particle free jet grow and develop the flow to the turbulence. This is fairly in good agreement with the results obtained by the experimental flow patterns of low Re number free jets and also the calculated flow characteristics of air and particles (mean velocity distributions and fluctuating intensity distributions) are fairly in good agreement with experimental data using laser Doppler anemometry. This means that the existences of particles enhance and develop unstable states in unstable laminar flows like low Re number free jets to turbulence. The turbulence growth mechanism and the effects that the appearance of many small scale eddies due to the particle existence has on the large scales and vice versa have been discussed.

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The authors have recently developed a new framework for multiphase LES. The framework is based on a new formulation of discrete-particle motion, referred to as GAL model. For extending the applicability of the new multiphase LES (GAL-LES model), a numerical simulation is performed on a plane bubble plume, as a typical gas-liquid phase turbulent flow. The present model has succeeded in reproducing the large-eddy motion of the fluid phase, which is found to be closely related to the discharge of the bubble at the inlet slot. The comparison between the computational and experimental results for the patterns of the bubble concentration demonstrates the validity of the GAL-LES model.

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A fully three-dimensional numerical procedure based on the two-fluid model in a general curvilinear coordinate system is proposed for the prediction of developing turbulent bubbly two-phase flow in a rotating complicated duct. A Coriolis-modified turbulence model is extended to the two-phase flows to account for the rotational effect on the lateral phase distribution. The governing equations are solved using a finite volume technique with a nonstaggered variable arrangement. Comparisons of the predictions with measured pressure and void fractions show good agreement.

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Motion of solid particles in a fully-developed channel flow of water was investigated by Lagrangian measurement techniques. Digital particle image velocimetry and a CCD camera mounted on a moving shuttle with mean streamwise velocity of particle were used to detect particle motion and fluid along the particle path simultaneously. Five classes of particles were dispersed in the flow upstream of the test section. It was observed that a force due to fluid pressure gradient and viscous stresses can be dominant in a particle dynamic equation when particle density ratio was close to unity. Lagrangian velocity spectrum of particle which has the density ratio less than unity was found to be higher than that of fluid along the particle path in the low-wave-number region, which is consistent with theory by Mei (1996). Lagrangian autocorrelation of velocity of both heavier particle and fluid decreased rapidly with increasing values of the particle time constant.

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Measurement of the mean flow quantities of turbulent boundary layer over two-dimensional spanwise groove with pitch ratio of 4, namely k-type rough wall has been made. The wall shear stress was determined from the direct measurement method with a floating element device. It is observed that the value of skin friction coefficient C_f is much larger than those of both the smooth wall and d-type rough wall flows, and is dependent of the relative roughness. Mean velocity and streamwise turbulent intensity profiles normalized with the outer variables are not similar, so the present k-type rough wall flow is not self-preserving. However, the logarithmic velocity profile having the same slope as that in the smooth wall flow is confirmed if the error in origin is considered. Roughness function correlates with u_rd_o/ν in a k-type rough wall, but the behavior of roughness function differs from that in the d-type rough wall. The tendency of wake strength vs. u_rδ/ν in a k-type rough wall is remarkably different from those in both a smooth wall and a d-type rough wall flows.

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A quasi-three-dimensional numerical simulation method for axisymmetric gas-solid flows was proposed. Fluid motion was calculated two-dimensionally by solving the local averaged equations in the cylindrical coordinates, in which the circumferential components were neglected assuming the axisymmetricity. Particles' motion was calculated by solving the Newton's equation of motion modeling the contact forces with DEM (discrete element method). This method was applied to spouted beds in a cylinder with a tapered bottom. The calculated radial distributions of the vertical component of the particles' velocities in the spout, fountain and the annulus were compared with the experimental results by He et al. The calculated velocity profiles agreed qualitatively well with the experimental results.

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In this study, a transient flow in a spool valve has been studied via numerical analysis. First, a numerical procedure is developed for non-uniform grid systems. A consistent formulation of the QUICK scheme is derived for non-uniform rectangular grid systems. A transient flow field was then investigated for the condition with several values of the spool stroke and a large pressure difference between upstream and downstream boundaries. The computational result was used to obtain a mathematical model for the spool valve flow transient in high Reynolds number condition of practical importance. Unsteady characteristics of the axial flow force acting on the spool valve was investigated based on the pressure and shearing stress distribution of the computational result. Prediction of the unsteady flow force based on the momentum theory was examined using the computational result.

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The cellular automata mathod was used to simulate fluid motion. In the FHP model of the deterministic lattice gas models, conservation of energy is ignored although mass and momentum is conserved. In nine-velocity model which is also one of the lattice gas models, energy can be conserved in addition to mass and momentum. Therefore the nine-velocity model can have a possibility to ensure the non-trivial thermodynamics. In the present study, the shock wave structure such as the transient of the pressure and temperature was numerically simulated by using the nine-velocity model. On the course of the present study, definitions of pressure and temperature were introduced for cellular automata simulation with the nine-velocity model.

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An experimental and numerical investigation of the characteristics of swirling flow produced by a double or multi right-angle bends has been carried out in order to examine the effect of upstream arrangements of pipes and bends in an electro-magnetic flow meter. Swirling flow profiles were compared in both cases of the multi right-angle bends in one flat plane and the multi righ-angle bend in two perpendicular planes which are typical arrangements in a sodium cooled fast breeder reactor power plant. The swirling flow profiles obtained through numerical analysis agreed with the experimental results for the single and double swirling flow in bends in one flat plane and in bends in two perpendicular planes, respectively. Unsteady or oscillatory flows were also discussed based on the experimental observations and numerical results.

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The laminar flows through a two-dimensional channel constructed of a fixed stenosis and a oscillating wall were calculated numerically in order to evaluate the effect of locally oscillating wall on the structure of separation bubble. In this study, the moving boundary problem was transformed into the fixed boundary problem using the coordinate transformation method. The calculated results are summarized as follows : (1) The local oscillation of wall has an effect to decrease the length of separation bubble. This effect becomes clear with the increase in the amplitude of wall oscillation. (2) Time averaged pressure drop of the flow through a channel is hardly affected by the local oscillation of wall. (3) The time course of the pressure difference across the oscillating region is strongly affected by the time course of the wall height even if the amplitude of wall oscillation is much smaller than the width of channel.

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Liquid jet ejected from a small capillary into air breaks up to the droplets. In ink jet technology, some of the droplets are inductively charged as they break off from the main stream of the jet, and their trajectories are then modified by high voltage deflector. The droplets coalesce at a certain length separated from the liquid jet in manner determined by the physical properties of the liquid jet and the droplets. Measurements of the velocity of ink jet droplets were made using a microscope of an experimental apparatus in which the nozzle is about 10μm in diameter. It was shown that the distance for the coalescence of droplets from the liquid jet increases with the increase of density of liquid. The equation of motion for the droplet is analyzed numerically by assuming the air velocity around a droplet, and the computational trajectories are obtained. The results of numerical simulation for the coalescence agree well with the experimental results. It is seen that the droplet stream stability is affected by the dynamic surface tension of the jet.

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The self-sustained oscillation is known to be excited by an axisymmetric jet impinging upon the sharp-leading edge of a ring. When a finite length of pipe, instead of a ring, is placed in a straight line with the jet axis, longitudinal resonant modes of the pipe are produced under a certain flow and geometerical conditions. In this paper, the influence of the inserted screen on the self-sustained oscillation and resonance of the pipe column oscillation are studied when a screen is placed between the nozzle exit and the ring or the pipe. Two patterns of the feedback loop are formed by the interaction between the vortical structure in the shear layer and the screen, or by the interaction between the former and the ring or the pipe. In the case of the pipe there are three frequency modes, namely oscillations in the two feedback loops and a resonant mode of the pipe. The resonance of the pipe is excited or suppressed according to the relationship among the three modes. When the screen is placed near the nozzle exit, the screen prevents the self-sustained oscillation and the resonance of the pipe dose not appear.

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Theories of aerodynamic noise generation from solid boundaries in airflow at low mach nmbers have been proposed by Curle and Powell-Howe. Acoording to the Curle's theory the noise sources are pressure fluctuations on the solid boundaries. On the other hand Powell-Howe showed that vortices in space are also the significant noise sources. The present authors verify that vortices in space can be effectively transformed to the pressure fluctuations on a solid boundary when the vortices approach in close vicinity of the solid boundaries. In the present experiment the parameters related to the noise generation such as the sound pressure level generated from separated airflow caused by a forward facing step or a fence on a flat plate, the pressure fluctuations on the solid boundaries and the flow velocity fluctuations were measured. By the examination of correspondence between the experimental results and the theories, it has proved that the agreement between the two is better in the Powell-Howe's theory than the Curle's theory. This result indicates that in the present experimental condition the dipoles of vortices distributed in space are stronger than the dipoles distributed over the surface of solid boundaries.

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This paper presents a new method for measuring the velocity of interfacial waves, flowing down a vertical wall in an entry region using two laser focus displacement meters. The purpose of the study was to clarify the effectiveness of the new method for obtaining detailed information on a wave velocity and to investigate the effect of the length of the entry region on the wave phenomena. The measured wave velocity agreed with that calculated using Nusselt's Law, thus indicating the flow to be laminar in the entry region even at a high flow rate. The measurments of wave velocity and maximum film thickness obtained by this method agreed well with those obtained in previous experimental and theoretical studies. As a result of this study, an empirical equation expressing the relationship between the maximum film thickness and the wave frequency in the entry region was formulated.

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The principles of this measuring method are based on the fact that air confined in a vessel to keep a strictly constant temperature is also kept at a constant pressure (reference pressure). The ventilating pressure, therefore, may be obtained from the pressure difference between the reference pressure and atmospheric pressure at opposite sides of the tunnel. In order to keep a constant air temperature in the vessel, the vessel is placed in a container which is controlled at about 40°C by means of on-off regulation of a heater. From this temperature regulation of the container and heat transfer characteristics of the vessel, the air can be structurally kept at a constant temperature within a high accuracy, 0.006°C. Accuracy of this measuring method practically, is evaluated from the correspondence between measurement of the pressure difference produced from the known height difference and the pressure difference obtained from the product of density of the atmosphere and its height difference.

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Structures of supersonic radial flow with the Lorentz force in a disk MHD channel have been investigated by experiments of the blow down facility. Total pressure profiles across the channel hight at the exit of the MHD channel, static pressure distributions and electric potential distribution along the radial direction on the wall were measured. It has been observed that the Lorentz force makes the flow uniform markedly while the working gas without the Lorentz force flows asymmetrically in the direction perpendicular to the flow direction in the downstream of the channel. It has been confirmed that the flow uniformity depends on experimental conditions, where increasing the load resistance and the seed fraction both make the flow more uniform. There is a strong correlation between the asymmetry of the Mach number distribution and the electric field near the exit of an MHD channel, namely the smaller the electric field is, the larger the degree of the asymmetry becomes.

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Supersonic combustion using catalytic wire at constant temperature in a cold supersonic flow field was investigated in a square duct with a backward-facing step. The free stream Mach number was of M_m=1.81. Hydrogen was injected transversely behind a backward-facing step into a cold air free stream. The heat release due to the catalytic combustion has no effect of the temperature of catalyst. It indicates that the reaction rate of the catalytic combustion observed in this study was determined by the consentration of H₂ and/or O₂ on the surface of the catalyst. The spatial distribution of heat release due to the catalytic combustion in supersonic turbulent mixing layer, that corresponds to the spatial distribution of consentration of H₂ and or/O₂ in local, was obtained. It was found that there exists the most suitable position for the supersonic combustion at the outer edge of mixing layer.

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This paper presents the experimental and theoretical results for thin-layer electrochemical deposition. The experiment is carried out on a horizontal substrate using a Hele Shaw cell. Morphological changes induced by ion drift are studied in the two-dimensional electrochemical deposition. It is shown that a locally electric migration has an important effect on the morphology of the deposits. For comparing with the experiment a DLA Monte Carlo simulation is carried to take into account a surface relaxation and the local electric field. It is found that the morphology obtained by the simulation is consistent with the experimental result.

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The thermal diffusivities of molten single carbonates (Li₂CO₃, Na₂CO₃ and K₂CO₃) and their binary and ternary mixtures have been measured in the temperature range up to 1445K by the forced Reyleigh scattering method using a CO₂ laser. The corrosion resistant material for the sample cell employed is sapphire glass plate, which was chosen through experimental evaluations. The accuracy is estimated to be ±11% to ±22%, depending on the measured salts. In comparison with the present results converted into thermal conductivity, the previous experimental data show values up to about three times larger, which may be due to the presence of convection and radiation. It is found that the thermal conductivity of molten single carbonates decreases with increasing molecular weight. It is also found that the temperature dependence of the thermal conductivity is weakly positive.

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Experimental and analytical studies of condensation heat transfer were performed for pure, binary and ternary mixtures of HFC32, HFC125 and HFC134a. These heat transfer coefficients were measured inside a horizontal smooth tube 5.8mm ID and 8m long. The refrigerant mixture in the test section was cooled by water flowing through an annulus around the tube. The refrigerant temperature was 40°C and the mass flux was varied between 150 and 400 kg/m²s for all the experiments. The heat transfer conefficients for nonazeotropic binary and ternary mixtures was about 20% lower than that for HFC134a at low mass flux conditions. A new predictive model for condensation heat transfer of multicomponent mixtures is proposed, in which the heat transfer deterioration due to the mass transfer effect is taken into account both in forced-convection condensation and in free-convection condensation. The predicted results are in good agreement with the experimental ones.

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A numerical study on a combined radiation and forced convection heat transfer of superheated steam, which is a radiation participating real gas, in thermally developing laminar flow through a parallel-plate channel has been conducted to investigate charactcristics of superheated steam drying. The integrodifferential energy equation was solved using an implicit finite-deference technique with a marching solution procedure and an exponential wide-band model for the treatment of the radiative transfer part. Comparison of results with and without gas radiation in various conditions shows that a fluid radiation decreases the temperature of main stream, but increases the total heat flux at a heat transfer surface. Furthermore, the results show that the fluid radiation decreases the inversion point temperature approximately to 150∼240°C with the increase of optical thickness. This numerical result agrees in the order of magnitude with the previous experimental studies, but is lower about 100K than that of former theoretical predictions without considering fluid radiation.

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Heat transfer measurements were carried out for an inclined impinging jet into a crossflow. Surface temperatures of a heat transfer target wall were measured using thermochromic liquid crystal sheets. Neural network method was applied to conversion of the colors of the liquid crystal sheet images into the temperatures. The inclined jet is characterized by the following two angles ; one is a pitch angle measured up from the jet-installed wall and the other a skew angle measured from the crossflow direction. The flow configuration of this experimental apparatus was designed in the new idea that longitudinal vortices could be generated by the inclined impinging jet into the crossflow to enhance heat transfer from the target surface. It was demonstrated that heat transfer enhancement was attained over wider spanwise region when the ratio of the jet velocity to the crossflow velocity is increased, and that peak Nusselt numbers appeared around z/d=5 constantly regardless of the velocity ratio.

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In this paper, we present an experimental study on the sink-mark generation of the press-formed glassware affected by the asymmetry of the thermal condition during the press-forming process, bottom surface of the press-formed glassware is in contact with the bottom mold during entire forming process, while the upper surface is cooled by the plunger mold only in the short pressing duration. The depth of sink-marks appear on the upper and bottom surfaces were measured for various forming conditions, and the obtained results were summarized as follows : (1) The depth of sink-mark on the upper (plunger-mold side) surface decreases with lowering the initial temperature of plunger mold and with elongation of pressing duration, while the sink-mark depth on the bottom surface is hardly influenced with them. (2) Lowering the initial temperature of bottom mold enhances the cooling of whole glass in the mold cavity, and thus results in reducing the depth of sink-mark on both surfaces of the glassware. However, when the initial temperature of bottom mold is set under 460°C, miniature wrinkles appear on the bottom surface of the glass, and the sink-mark depth on the upper surface increases with lowering the initial temperature of the bottom mold. (3) The sink-mark depth on the bottom surface decreases with elongating the take-out time, but sink-mark on the upper surface becomes deeper at the same time.

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In the compact closed two-phase thermosyphon which consisits of the multi-tube radiator and the refrigerant bath, it is observed that the heat radiation performance drops as the refrigerant bath becomes thin. We have found that this is due to vapor-liquid interaction and dryness in the upper side of boiling area. We have also improved that heat radiation performance with a new refrigerant flow controller.

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Two-dimensional numerical computations have been conducted to investigate combined forced and natural convection around a cylinder in a cross flow. Reynolds number, Re, ranged between 75 and 150. Rayleigh number, Ra, was changed from 0 to 7×10⁵. Combined convective heat transfer characteristics cannot be expressed by a simple summation of forced and natural convective heat transfer characteristics. An abrupt decrease of mean Nusselt number, Nu_m, is observed in transition from forced convection to natural convection. A hysteresis occurs in the transition region and Nu_m has two different values which depend on initial conditions. This is attributed to subcritical bifurcation of flow behind the cylinder. Nu_m is higher for unsteady flows than for stcady flow in such a transition region.

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Direct numerical simulation was performed for a turbulent channel flow where the time mean temperature has a spanwise gradient. As the first step of succesive investigations, turbulence statistics related to the spanwise heat transfer were examined. A computational code based on the finite difference scheme was developed for this purpose. The calculated statistics on the flow field were found to be in good agreement with the result of the existing direct numerical simulation by Kasagi et al. (1992). The eddy diffusivity ratio, ε_nz/ε_m and the Reynolds normal stress ratio, (ω²)^^^-/(υ²)^^^- show rapid increase toward the wall, as pointed out by Maekawa et al. (1991). However, the rapidincrease region of the ε_nz/ε_m was nearer to the wall than the Maekwa's result and found to roughly agree with that of the (ω²)^^^-/(υ²)^^^-. This result implies that, in the near-wall region, the spanwise turbulent heat flux per its production rate shows rough agreement with the wall-normal turbulent heat flux per its production rate. In addition, two point correlation coefficient, Q_wθ also agrees with Q_vθ in the range of y⁺<75. In these points, the heat transfer in the present case has some analogy with that in the heated-wall case. Moreover, the budget of the spanwise turbulent heat flux was examined. It was found that the budget shows near local equilibrium except for the near-wall region.

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The difference in turbulent diffusion between passive scalar (mass) and active scalar (heat) in a stable thermally-stratified flow was experimentally investigated in a liquid flow downstream of turbulence-generating grid. Passive mass was released from a point source located 60mm down-stream of the grid. Instantaneous velocity, concentration and temperature were simultaneously measured using a combined technique with a two-component laser Doppler velocimeter (LDV), a laser induced fluorescence (LIF) method and a resistance thermometer. The eddy diffusivities for passive mass and active heat were estimated. The results show that stable stratification causes the large difference in eddy diffusivities between passive mass and active heat. The difference suggests that an assumption of the same eddy diffusivity for passive mass and active heat, used in conventional turbulence models, gives a serious error in estimating heat and mass transfer in a plume in a stable thermally-stratified flow.

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Studies were carried out to develop a high-performance ceramic heat exchanger for ultra high temperatures using a fluidized bed. In the former study, Heat transfer coefficient had been improved by applying fluidized bed to the heat exchanger for high temperature with smooth ceramic tubes. In this study, finned ceramic tubes were applied instead of smooth tubes for more improvement of heat transfer and experiments were performed on condition that the maximum bed temperature was 1100°C. Fluidization remained stable and the bed temperature uniform in the bed similarly as the case of smooth tube. A heat transfer coefficient of finned tube was evaluated and it was improved about 3 times as large as that of smooth tube. The performance of the heat exchanger was also evaluated using temperature efficiency and exergy efficiency.

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This report deals with heat transfer in the melting process of crushed ice filling in a ice/water heat storage container. Volumetric heat transfer rate and melting end-time are measured when rectangular-type, small-stone-type and particle-type ice in the container are melted by circulation hot water. Melting end-time of small-stone-type ice is the shortest and that of particle-type ice is the latest. Volumetlic heat transfer rate of small stone-type ice and rectangular-type ice is larger than that of particle-type ice. The flow rate of circulation hot water throwing in container through a inlet pipe influences remarkably on heat transfer rate.

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The liquid air is produced by off-peak power and can be stored at atmospheric pressure in a large tank. When on-peak power is needed, the stored liquid air is pumped to high pressure and fed to a combustor of a gas turbine, then power generation is increased to more than double of the system with ordinary air. The energy storage efficiency of this system is greatly increased to more than that of a pumping-up power plant station, when cold heat of the liquid air is reused to produce new liquid air.

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In this paper, experimentally investigated was the effects of transition from laminar to turbulent oscillatory flow within a tube on the effective thermal conductivity of oscillation-controlled heat transport tubes. First, the streamline of oscillatory flow in a tube was experimentally visualized. The visual observation indicates that the transition criteria to the conditional turbulent flow coincide well with those of Kurzweg et al.. Next, heat transport experiments ware conducted to examine an effect of the transition on the effective thermal conductivity along the tube axis. Experimental results show that the transition does not result in a limitation of the effective thermal conductivity but produces an effective thermal conductivity higher than that predicted by the analysis assuming laminar oscillatory flow.

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Thermophoretic force acting on a particle suspended between two parallel walls a distance H apart has been ambiguous in the rarefied gas region where the Knudsen number Kn_H based on the distance H is in the slip and/or transition regime, i.e., 0.01<Kn_H<10. Present study simulates the thermophoretic force in such an ambiguous region by using DSMC method based on Boltzmann equation. It is shown that the force decreases with increasing in Kn_H. A comparison is made between the result of present method and theoretical analysis for continuum and free molecular regime, and good agreement is found in thermophoretic force profiles versus several temperature ratios.

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Behavior of gas and liquid was observed during the experiments, where a horizontally oriented closed glass pipe filled with air and well-wetting liquid was suddenly set in microgravity using a drop shaft facility. Just after it was set in microgravity, the liquid first crept up the inner surface of the pipe to form a liquid film and then broke into a number of groups to form liquid plugs with a nearly equal spacing. The mechanism of this interesting behavior was explained by the linear stability analysis of an annular liquid film, where the average pitch of these liquid plugs agreed well with the most-dangerous wavelength of disturbance obtained by the analysis. The theory was also checked by the microgravity experiment for an annular downward film flow as a initial condition in normal gravity.

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Vapor bubbles generated in conductive ink heated directly by electric current pulses can be used in an ink-jet printer to eject ink-droplets. To calculate the growth and collapse of the bubble and the flow of the ink induced by the bubble, a VOF (Volume of Fluid) method modified for computing the liquid-vapor interface with phase change was used. This modified method was proved to be valid by using a model of a spherical bubble. Because this method needs a fine grid resolution and therefore long computing time to obtain an accurate result in the three-dimensional system, a simplified method was devised to save the computing time. Using this simplified method, which was proved successful for non-spherical bubbles in the two dimensional axisymmetric system, calculations were performed to simulate the growth and collapse of the bubble and the flow of the ink in a single printhead. The calculation predicted the life of the bubble, and the velocity and volume of the ejected ink, which agreed well with measurements. For the optimum design of the print-head, the influences of the dimensions of the nozzle and ink-channel were discussed from the calculated results.

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The freezing process of 4.6 wt% and 10 wt% ethylene glycol solutions flowing in a cold pipe is investigated experimentally. The steady state ice profile and the heat transfer coefficient at the contraction region of flow area are examined. The onset of freeze-shut conditions for ethylene glycol solution is obtained analytically. It is shown that the ice of solution has smaller thermal conductivity than that of water and the mushy ice formed at the expansion region of flow area affects the freeze shut conditions. Consequently, it is found that flowing solution in a cold pipe is hard to freeze shut than flowing water.

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Spot monitoring of radical chemiluminescence is especially useful for flame diagnostics, if the measuring control volume size can be clearly defined. However, a typical light collection system consisting of a spherical lens and a pinhole suffers from its wide and long control volume, as well as its significant chromatic aberration between UV and visible ranges in simultaneous multi-color measurement. In some cases, researchers were obliged to insert a control-volume limiting device into the flame for observing the local emission intensities of radical chemiluminescence. To resolve these problems, we have developed a light collection probe of Cassegrain type, which consists of a set of concave and convex mirrors combined with an optical fiber cable, and is free from both chromatic and spherical aberrations, which was named Multi-color Integrated Cassegrain Receiving Optics (MICRO). The spatial resolution was analyzed by the ray-tracing method, and the effective control volume size was estimated as 1.6mm-long and 200μm diameter, which is as small as that of LDA or PDA.

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A numerical analysis of the time dependent behavior of a propagating premixed flame caused by concentration spots placed in a row in front of the flame was made. The special attension was focused on the effect of the sign of the curvature of the initial flame deformation induced by the spots on the subsequent flame behavior. When the spot accelerates the local burning velocity, the initial flame deformation is convex to the unburned gas, whereas the deceleration of the local burning velocity produces the deformation concave to the unburned mixture. When the separation distance between the spots is large enough, the concave deformation produces the number of wrinkling that is twice as large as that of the convex deformation. The subsequent development of the deformation is found to depend on this initial deformation. However, when the separation distance is small, the number of the produced wrinkling becomes the same for concave and convex deformations.

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The piston slap impact noise has been investigated using a piston secondary motion simulation, which has been developed with paying attention both to the simple modeling and the accurate estimation of the piston slap impact, by considering the hydrodynamic effects of the piston skirt oil film and the friction forces at various contact points. The calculation results were compared with the actual piston motion measured by the link mechanism, and with the cylinder wall vibrations on behalf of the piston slap impact. Consequently, the calculation accuracy was confirmed to be sufficient to make the precise estimation of the piston slap noise.

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Feasibility study of CaO/Ca(OH)₂ reverible exothermic reaction has been done as a source for heating three-way catalyst of a car, to decrease electric load demand. In this paper experimental results of reversible reaction and basic prototype heater with exothermic hydration reaction to heat catalyst are described. It has been clarified that exothermic reaction itself has plantiful amount of heat and a fast reaction rate. For practical use, it is necessary to increase heat conduction between reaction tubes and radiating fins, and to decrease heat capacity of a whole system.

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In this paper, new expressions are sought which will allow the rapid and accurate calculation of pressure variation, flow velocities, flow friction losses in crank-driven Stirling engine. The compression and expansion spaces of the Stirling engine are assumed to be isothermal and their volumes are assumed to vary sinusoidally. New expressions are deduced for the amplitude and phase of these variations. Using the expressions so deduced, these formula are derived for frictional losses inside the three heat exchangers (heater, regenerator and cooler), taking into account the variation in mass flow rate, fluid resistance, gas flow and shaft torque over the cycle, By comparing these expressions with the results of calculations using the quasi-steady flow model, it was found that confirmed coincide roughly with the low-temperature-difference Stirling engine.

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In order to clarify the characteristics of combustion fluctuation in diesel engines quantitatively, the fluctuations of pressure and flame temperature were measured, and the root mean square value, the autocorrelation coefficient and the power spectrum density of the measured fluctuations were analyzed by comparing the cases with and without pilot injection. The following concluding remarks are obtained. (1) The frequency power spectrum of the in-cylinder pressure history is reduced markedly by pilot injection in two frequency ranges from 0.2 to 2.0 kHz and from 2 to 5 kHz. (2) The fluctuation of combustion pressure is dependent on the maximum rate of pressure rise, which is dependent on the ignition delay. (3) The maximum rms of the flame temperature fluctuation during diffusion combustion has a clear correlation with that of the pressure fluctuation in the initial combustion. (4) The fluctuation of the flame temperature during diffusion combustion has the characteristics of isotropic turbulence.

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