The motion of a single bubble is simulated directly using the full conservation equations for mass, momentum and energy when the surrounding pressure increases stepwise. The numerical results for several cases reveal that considerable distributions of temperature and concentration of vapor are formed inside the bubble, and the heat and mass transfer inside bubble have much influence on the bubble motion. The heat transfer on the bubble wall which is mainly governed by the temperature gradient causes the thermal damping of the bubble motion. This damping behavior is influenced by the initial bubble radius. The mass transfer on the bubble wall, which is influenced by the diffusion phenomena between vapor and noncondensable gas, also has a great effect on the bubble motion.

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A numerical analysis of a plane shear layer between two parallel walls is made by using an improved discrete vortex method combined with the conformal mapping method. In the proposed method, each vortex is convected not in the physical z-plane, but in the transformed ζ-Plane by taking its own timescale into consideration. In the conventional method, the inversetransformation of the location of each convected vortex is generally indispensable for analyzing a flow field. In a case such that the inversetrasformation cannot be obtained analytically, a numerical iteration Should be relied upon, resulting in a decrease in accuracy. In this paper, therefore, a new method that does not require the inversetransformation is proposed in order to ease the application of the discrete vortex method with the conformal mapping to more complicated flows.

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The mechanism of the phase distribution formation in a bubble flow is one of the most important problems in the control of two-phase flow systems. The effect of mixing methods on the phase distribution was experimentally investigated by using upward nitrogen gas-water bubble flow under the condition of fixed flow rates. The experimental results show that the diameter of the gas injection hole influences the phase distribution through the bubble size. The location of the injection hole and the direction of injection do not influence the phase distribution of fully developed bubble flow. The transitive equivalent bubble size from the coring bubble flow to the sliding bubble flow corresponds to the bubble shape transition. The analytical results show that the phase distribution may be predictable if the phase profile is judged from the bubble size.

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An experimental study was made of shock wave propagation in polyurethane (PUR) foam. The experiment was conducted in a shock tube by measuring pressure along the PUR foam by means of holographic interferometry and streak camera recording. It was found that the stress-strain curve of PUR have an inflection point. When the pressure behind the incident shock wave was below the inflection point pressure P_C, the wave impedance ratio of the incident shock wave and transmitted pressure wave Z_i./Z_t increased sharply. This indicates that only a small amount of energy is transmitted into the foam if the pressure is below P_c. For pressure larger than P_c, Z_i, /Z_t decreases asymptotically to a small finite value.

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Pulsating laminar flows of a purely viscous non-Newtonian fluid in a curved pipe of circular cross section in the high Dean number region were investigated analytically by using boundary layer approximations. The governing equations were formulated for a Power-Law fluid. The momentum integral approach and Pohlhausen's approximate method were used to analyze the flow in some detail, and the governing equations were solved by the successive approximation. In the case of steady flow, the present theory was in good agreement with previous experimental data, and the friction factor becomes greater as the pseudoplasticity index n decreases. In the case of Palsatile flow, the phase lag of the mean sectional velocity from the wave of pressure gradient, Γ, and the amplitude of the friction factor, λ^^∼_ac, diminishes with increasing Dean number, and Γ diminishes with increasing n. The phase lag Γ and the amplitude of the friction factor λ^^∼_ac derived in this work are in qualitative agreement with available experimental data.

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In order to clarify the basic characteristics of heterogeneous two-phase flows, systematic experiments are carried out typically hetergeneous sand-water flows through a 7°divergent and a 7°convergent pipe. The recovery pressures in the divergent or the convergent pipe are acceptably higher or lower than the water-flow counterparts. The pressures increase or decrease considerably with the sand concentration C_υ. As C_υ increases, therefore, the apparent pressure loss in the divergent pipe decreases significantly and it often becomes negative unreasonably. But, if we consider the inertial energy of sand particles for the recovery pressures, the pressure losses are reasonably leveled up or down to the water-flow counterparts even at very high concentrations.

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In this paper, a simple FEM scheme is presented which simulates the natural convection of incompressible viscous flow. The Navier-Stokes equations in rotational form with the buoyancy effect is simplified by Boussinesq's approximation. The main algorithm of the GSMAC method is employed to obtain the time=dependent solutions. The equation of continuity is satisfied by the simultaneous relaxation of velocity and Bernoulli function. Natural convections in concentric horizontal annuli at various Rayleigh numbers are numerically investigated in order to validate the present method. The temperature distributions obtained here are in good agreement with the experimental results.

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Velocity and shear stress distribution of the fully developed turbulent pipe flow at any Reynolds number are calculated from another. Calculations are based on the defect law and the universal law of wall. Shear stress is based on the eddy viscosity model. Shear stress at the wall is calculated with the pressure drop which is based on the integrated turbulence energy production. Turbulence energy production is calculated from the velocity and shear stress distribution. Calculated results are compared with measured data reported by Nikuradse and Laufer.

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The velocity distributions and fluctuating velocities in the laminar-turbulent transition of spherical Couette flow with only the inner sphere rotating, have been experimentally studied at two meridian angles, θ=60°and 90°, for the case of clearance ratio 0.14. The distributions of azimuthal and meridian velocity components have been considered over a wide range of Reynolds number. Logarithmic laws were obtained on the azimuthal velocity profiles in the turbulent boundary layer near the outer sphere wall for θ=60°and 90°. The phases of fluctuating velocity advance radially from the outer sphere to the inner sphere at θ=90°, but they depend on the type of disturbances at θ=60°. The phase-averaged fluctuating velocity profile in the presence of spiral TG (Taylor-Gortler) vortices differs from that in the presence of traveling azimuthal waves. Amplitude of fluctuation becomes large in the gap a little toward the outer sphere wall in the presence of spiral TG vortices at θ=60°, but a little toward the inner sphere wall in the presence of traveling azimuthal wave at θ=90°.

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In this report, the relationship between iso-velocity sets of a turbulent boundary layer and instantaneous Reynolds stress is investigated by means of quadrant analysis. The fractal feature of iso-velocity sets belongs to the positive instantaneous Reynolds stress region, that is, the second or the fourth quadrant. Moreover, when this instantaneous Reynolds stress is two times larger than its time averaged value, iso-velocity sets show the faractal aspect. We use the method of the probability distribution function for fractal analysis. Scale similarity extends from the Kolmogorov scale to the large eddy scale. This is the first attempt to clarify the relationship between the fractal feature and the most important physical quantity in the turbulent boundary layer.

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The numerical simulation results of tracer gas diffusion from a continuous point source were obtained and compared with wind tunnel experiment results. The flow fields were predicted by the k-ε model, and the turbulent kinetic energy gained here was divided into directional turbulence intensities by using algebraic equations and an eddy viscosity concept. Using estimated turbulence intensities, tracer gas diffusion was simulated by a Lagrangian particle diffusion model. Predicted mean concentration profiles showed good agreement when turbulence intensities were obtained from algebraic equations. The Lagrangian time scale was estimated from the flow calculation results by means of the k-ε model. It was apparent that the optimum value of model constant C_1ψ for simulating the tracer gas diffusion was 2.0.

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Regarding the outlet condition of flow from thin-film evaporators, it was postulated that the liquid fillet adjusted the width at the exit so that the energy of flow was minimum at a section about 15 times the thickness of liquid fillet upstream from the exit. By comparing a series of experimental data with theoretical calculation, it was demonstrated that this postulate was good for liquid of viscosity less than 6mm²/s but not for liquid of viscosity higher than 17mm²/s. Based on the hypothesis, the exit width of liquid fillet is predicted, and the overall pattern of liquid fillet in an evaporator can be calculated using the predicted exit width as the initial condition. Predicted flow pattern in the entire evaporator was compared with experimental data at different operating conditions, and good agreement was demonstrated in all cases except near the inlet zone where the flow pattern was disturbed by the incoming condition of fluid.

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A new technique has been developed, based on the technique proposed by Goldstein (1978), in order to analyze unsteady aerodynamic responses of cascade airfoils subjected to incident wakes. One of the important features of this technique is the introduction of the additional perturbation potential for the purpose of preventing the solution being indeterminate due to the singular behavior of the unsteady perturbed velocities around the blunt leading edge. In this paper, the main focus is placed on the theoretical development of the technique, and some simple cases of numerical calculations with no stagger angle are made in order to show the validity of our method.

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Plasma jet is clean and reactive flow that has high thermal energy, velocity and various functional characteristics. It has been utilized in the plasma deposition process and in new materials synthesis. In the present paper a method of analysis based on the turbulent two-fluid model, in which the momentum and heat transfers between gas and particles are taken into account, is proposed for the plasma spraying problem. The SIMPLE method and line-by-line iterative procedure are used for the steady condition considering phase change of particles from the solid state to the molten one. Numerical examples are shown to clarify the effects of the particle diameter and particulate volume fraction and its radial distribution at the nozzle exit on the plasma spraying characteristics. Finally, the satisfied optimum condition of particles is obtained to produce the high-quality coatings.

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The recent development of a highly pressuriezed oil-hydraulic system poses serious problems of environmental pollution such as noise pollution, vibration hazards and so on. Hydraulic valves may frequently be a source of noise, especially cavitation noise. In this paper, we have carried out both noise tests and numerical simulations of oil flows on various configurations of the electroproportional relief-flow control valves, and set up some design criteria for the low noise valves by comparison of measured and computed results. In particular, we discuss and clarify the effects of the volume of a valve chamber, a two-stage restrictor, angles of a poppet and a valve seat, and the overlapping distance on a poppet.

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In the turbulent mixing regions which were formed by issuing gases of different densities into ambient air, the instantaneous values of concentration and velocity are derived by a set of probes consisting of an ordinary hot-wire and a probe for concentration measurement. The signals of the two probes are input into a microcomputer, and the calculations are carried out immediately. The instantaneous measuremests of concentration and velocity make possible statistical investigation into the turbulent mixing region. The present paper provides some illustrated instances on the power spectra. The integral length scales for concentration and velocity are estimated by the autocorrelation coefficients which are obtained by the instantaneous values. The comparison between the scales for concentration and velocity shows that the length scale for concentration is much larger than that for velocity. The accuracy of this method of measurement is discussed.

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In the present paper nonlinear evolution of disturbances at the meniscus between parallel circular plates is simulated by a boundary element method. To simulate accurately such a nonlinear phenomenon, the thickness of liquid remaining on the plates is obtained numerically against the low capillary number Ca<1.0, which is defined by the viscosity, velocity and surface tension. An integral equation for the boundary element analysis is newly proposed by taking into account the thickness of liquid remaining on the plates. The results in the simulation for the curvature, velocity and the tip position of disturbances growing at the fastest speed were compared with the experimental ones from various points of view, and it was shown that both agreed fairly well.

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This paper presents a finite difference scheme for solving the incompressible viscous fluid flow around an arbitrary vibrating body. This scheme is an extension of the SMAC method to a moving curvilinear coordinate grid. The scheme contains two stages. At stabe one, the new time-step velocity is calculated in the old time-step coordinate. At stage two, this calculated velocity is reobserved by the new time-step coordinate (rezoning). This scheme is applied to calculate a two-dimensinal flow around a vibrating flat plate, which is a fundamental model of the fin movement of some fishes or cetaceans and of the flutter of an airplane wing. The solution is compared with that from the discrete vortex method. In particular, the characteristics of thrust and its efficiency of the vibrating flat plate as a propelling mechanism show good agreement with those from the discrete vortex method.

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An experiment has been made on ribbing induced on a film coated over a roll surface in coating by means of a two-roll system, one roll rotating and the other fixed. Wavelength and depth of the ribbing are measured by a newly developed technique utilizing an image reflected on the ribbed film surface by a straight bar, and the following are clarified. Non dimensionalized wavelength is correlated with capillary number for Newtonian liquids, but it takes higher values for several viscoelastic liquids used. Viscoelasticity of the liquid has an effect of increasing the depth of ribbing, that is, the depth takes the value of 0.04mm to 0.1mm for Newtonian liquids, but 0.07mm to 0.2mm for viscoelastic liquids. The wavelength of spatial perturbations generated on the meniscus at the exit of the clearance between the two rolls coincides with the wavelength of the ribbing seen over the roll surface. This means that the perturbation of the liquid generated just after passing through the clearance is carried with rotation of the roll and results in the ribbing over the roll surface.

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Tensile stresses in liquids are not necessarily a familiar idea in fluid engineering, so much less accepted is the reality of tensile waves travelling through a liquid continuum. The present paper aims at giving evident proof for the premise. In a pipe with its end closed, branching from the main line where column separation is started, alternating tensile and compressive waves have been beautifully created and measured. It has turned out that the ordinary viscous wave equation can properly predict the time profiles of the masured pressures, which reveals that a tensile wave propagates in oil at the same speed as a compressive one. The observations by use of a transparent acrylic tube have also revealed the rupturing of an oil column under an excessive transient tensile stress; in the aftermath there has emerged a bubble which is usually mistaken for the cause of cavitation, but is actually brought about by diffusive separation of gas from the oil into the rupture.

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Under low speed operation the frictional characteristics of pistons with hydrostatic pads and conventional pistons were experimentally obtained and compared with the theoretical results already reported. The metallic contacting forces under mdium and high speed operation are theoretically given. Finally, the effect of conically arranged cylinder bores on reduction of the radial loads acting on pistons is discussed.

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A three-dimensional finite difference method was used to simulate the incompressible potential flow in the blade row of a screw-type centrifugal pump which was operated as the pump and the turbine, in turn. The Kutta condition was imposed at the trailing edge of the blade. The potential jump of the vortex sheet was introduced to produce equal pressure on the suction and pressure blade surfaces at the trailing edge. As a result, the flow pattern in the impeller channel became very complicated and three-dimensional due to the relative circulation which existed in the flow passage, and the reversed flow was observed on the pressure blade surface. The pressure distribution inside the impeller channel which was obtained by numerical computations agreed qualitatively with the measured results. Furthermore, the calculated pump and turbine characteristics of the pump operating at normal capacity were in good agreement with the experimental results.

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This paper describes an experimental and theoretical investigation of the delivery pressure ripples of a balanced vane pump which is commonly used for automobile power steering (PS) hydraulic systems. A linearized model which includes torsional vibration of the pump drive shaft is proposed. The backflow into the pumping chamber resulting from fluid compressibility is not taken into consideration in the mathematical model because the delivery pressure of PS hydraulic systems is relatively low. It is found that the delivery pressure ripple levels of the test pump become lower with decreasing speed and increasing delivery pressure. The theoretical calculation shows that it derives from the fact that the phase of the pressure ripple waveform caused by the leakage flow variation lags behind that caused by the theoretical flow variation by about 180 degrees. Torsional vibration of the drive shaft has influence on the pressure ripple levels.

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The paper describes about the rotation speed control of horizontal axis wind turbine by tip vane. Tip vane has the excellent ability to improve the performance of horizontal axis wind turbine. Also, we found that the rotation speed of wind turbine is controlled by the change of sweep angle of tip vane. The relationships among the sweep angle of tip vane, the change of wind speed and the rotor speed are investigated. As the results, the method to keep the constant rotor speed by means of electro-mechanical apparatus is developed, when wind speed changed.

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Effect of an overlap on the power mechanism of a Savonius rotor has been studied by measuring pressure distributions on the blade surfaces and by visualizing the flow field around the rotor with and without the overlap. It is found that the presence of the overlap induces a strong negative pressure on the convex side of the advancing blade of the rotating rotor, which produces a positive torque for the rotor rotation. This phenomenon is observd as a strengthened attached flow over the convex side in the visualized pictures, which indicates the reduced separating region by the flow through the overlap. These results together with the flow control effect inside the rotor show an improved mechanism of the rotor performance by the presence of the overlap.

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In this paper, compression waves produced by trains which enter a tunnel at high speed were numerically investigated. The equations of the one-dimensional, unsteady and compressible flow in which the area of a tube is dependent on the time and the distance were numerically solved by the method of characteristics. The calculations were performed for trains with various speeds, nose lengths and cross-sectional area ratios, and the effects of these parameters for the shape and the strength of compression waves were quantitatively crarified. The results show that the pressure gradient of compression waves is affected largely by all of these parameters.

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In the case of forced-convection condensation of a pure vapor, the equations of condensate film in which the viscosity depends on temperature are analytically solved for RH/Pr→∞ and RH/Pr→0, and it is derived that the viscosity should be evaluated at a reference temperature T=T_w+1/3(T_w-T_s), where T_w and T_s are the temperatures at the cooling surface and the vapor-liquid interface, respectively. The validity of this reference temperature is discussed by referring to various numerical solutions of the equations of condensate film with variable physical properties.

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Film boiling heat transfer of saturated methanol with decomposition reaction is investigated experimentally by using a cylindrical heater with catalytic surface. Platinum black powder which is stuck on the cylinder shows enough activity to catalyze the reaction. The heat transfer coefficient remarkably increases with the slight increase of the wall superheat and becomes about 50% higher than the Bromley's prediction of no reaction case. Such high heat transfer is considered to be due to the endothermic action and the evolution of hydrogen the thermal conductivity of which is about five times that of methanol vapor. However, once the wall superheat exceeds about 510K, the heat transfer coefficient decreases and approaches that of no reaction case. This may be due to the sintering of the catalyst used in the present study. The heat transfer coefficient which is predicted by taking account of the absorbed heat and the properties change of vapor phase due to the evolution of decomposed gases is in good agreement with the high coefficient measured by experiment.

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This paper reports the experimental results on the natural convection heat transfer to liquid helium in a rotating field in the range 1600-3700rpm. Test surfaces are vertical plates (10mm width, 5mm height) with rectangular channels in a radial direction and upward and downward horizontal plates (8mm diameter) at radial distances of 0.3m. The results show that the heat transfer for vertical plates is approximately the same as that for horizontal ones facing upward, independent of the channel gap sizes ranging from 0.4-5mm and directions of the Coriolis force. The heat transfer can be predicted from the conventional correlation: Nu=0.13Ra^1/3 in the Ra ranges of 10¹¹-10¹³, if the film temperature for evaluating properties is substituted for the pseudocritical temperature only when it is above the pseudocritical temperature. The heat transfer for the horizontal plate facing downward is 1/6-1/7 of that for the one facing upward and the Ra exponent of its correlation is 0.2 in the Ra ranges of 10¹²-10¹⁴, which is the same as that for laminar free convection.

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For a heated vertical tube which is connected with an upper liquid reservoir and closed at the bottom end, countercurrent annular flow is analyzed to disclose the cause of its critical heat flux. An equation governing the liquid film flow subject to the frictional resistance of both the tube wall and the core vapor flow is derived and thereby the thickness of the film can be determined. It is then found that there is a limiting condition for the existence of real roots of the equation which appears at the upper end of the tube with increasing heat flux. Physically, it is based on the character of the shear stress on the liquid/vapor interface that its magnitude increases with the liquid film thickness when the core vapor flow is turbulent. This limit is shown to agree well with the experimental critical heat flux condition obtained for water and R-113.

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Heat transfer in natural-convection film boiling with long vapor film is investigated experimentally. Experiments of film boiling on horizontal cylinders of large diameter and long vertical cylinders are conducted to investigate the effect of liquid subcooling on film-boiling heat transfer. The test liquid is R-113 at atmospheric pressure. For cylinders of both types, local heat transfer coefficients of saturated and subcooled film boiling are much higher than the predictions from two-phase boundary layer theory. In the case of vertical cylinders, local heat transfer coefficients do not depend on the distance from the stagnation point even if the liquid is subcooled. In the case of horizontal cylinders of large diameter, the local value of saturated film boiling dose not strongly depend on the distance from the stagnation point, but it comes to depend on the distance with increasing subcooling. In particular, the local value reaches a maximum at a distance from the stagnation point. As for averaged heat transfer coefficients of horizontal cylinders of large diameter, they increase with increasing subcooling but do not depend on the diameter even under subcooled conditions.

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The effects of the thermal conductivity of an inner body on the heat transfer phenomena in an inclined rectangular enclosure have been studied both numerically and experimentally. In the numerical analysis, the ratio of thermal conductivities of inner body and working fluid was varied parametrically. The numerical analysis was carried out for Pr=10, Ra_w=5×10⁴∼5×10⁶ and inclination angle γ=-30°∼60°. The experiments were carried out with water. A bakelite plate and brass plate were used for the inner body. The flow and temperature fields were shown in detail and the heat transfer coefficient was discussed from the results. It is clarified here that the inner body with large thermal conductivity enhances the heat transfer rate of the enclosure for the large inclination angle of the enclosure, but suppresses the heat transfer rate for the small inclination angle of the enclosure.

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Full measurements of thermal field were made for a turbulent flow of air in the entrance section of a two-dimensional curved channel. The wall heat flux develops more rapidly than the mean temperature distribution, decreasing and increasing on the inner and outer walls, respectively. Locations at which the mean temperature gradient and the radial component of turbulent heat flux become zero do not coincide in this case, and the eddy diffusivity of heat becomes negative in a region of about 20% of the channel width. In the vicinity of the wall, the temperature fluctuation intensity normalized by the friction temperature is not affected by the wall curvature, whereas the cross correlation coefficients between velocity and temperature fluctuations, the skewness and the flatness are appreciably affected by it. The triple correlations relating to the transverse diffusion decrease and increase remarkably in the inner and outer sides of the channel, respectively.

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A flexible thermal conductor composed of two finned members that fit together with a small clearance is studied. The analytical model predicting the thermal resistance of the finned members is developed, and the analytical results are compared with experimental data. Based on the model, a design procedure for minimizing thermal resistance is proposed. It is found that using the fins reduces the thermal resistance by more than an order of magnitude from the resistance that would arise if heat-dissipating components are cooled without using the fins.

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To predict the thermal contact resistance between a heat-dissipating component and a multifin-type thermal conductor, the existing theory for ideal surfaces is reconsidered, and the applicability to actual machined surfaces in contact with low contact pressure is discussed. The experimental data obtained using actual machined surfaces in a helium or nitrogen gas environment under very low contact pressure of below 0.1MPa are correlated by the theory within an accuracy of +12%∼-25%. The effect of helium gas concentration on the thermal contact resistance is also analyzed, taking into account the variation of accommodation coefficient.

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In this study, the effective thermal conductivity of porous metals, in which fluid of different thermal conductivity was contained, was measured. Since the porous metals have a mesh configuration, the values of the effective thermal conductivity estimated by the accepted equations reported up to now do not agree with the experimental values. Therefore, a simple one-dimensional analytical model and two three-dimensional numerical calculation models were examined and compared with the experimental values. Consequently, it was found that the values estimated by the three types of model agreed with the experimental values within a 30% error for the porous metals. These models could indeed be applied to estimate the effective thermal conductivity of materials such as porous metals.

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An experimental investigation was conducted into the enhancement of water vapor absorption in aqueous lithium bromide solution films falling on horizontal tubes. The variable parameters included the solution flow rate, the inlet temperature of the cooling media, the solution inlet temperature and the effective extended surfaces. The experimental results, which were correlated with the film Reynolds number, showed that the cooling by the tube wall was the governing factor in the absorption process for small solution flow rates, but the inlet subcooling of the solution dominated the absorption performance for large flow rates. Also, the R tube, which has a unique ridged fin shape, exhibited the best absorption performance among the tested tubes.

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This research aims at controlling the generation of Benard cells in a combined free and forced convection of a horizontal rectangular duct heated from below by properly heating the side walls. The experiment is carried out in a fully developed region under the condition of the Rayleigh number Ra≒3.4×10⁵ to reveal three typical flow patterns depending on the Reynolds number and the temperature profile on the side walls. We have found various conditions to produce the unsteady flows with a time-averaged uniform temperature, and these flows are shown to be chaotic by calculating a set of Liapunov exponents from the observed time series of temperature.

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An unsteady thermal analysis program has been developed to simulate transient heat transfer of molds in computer-aided engineering for injection molding of thermoplastic. The three-dimensional unsteady thermal conductive equation is solved by using the boundary element method (BEM). Heat flux on the cavity and the runner during the cooling stage, which is calculated from one-dimensional thermal analysis by using the finite difference method, is taken into consideration as boundary conditions. The change in boundary conditions due to mold opening is also taken into account in the analysis. A cycle average method is proposed for diminishing the computing time of the unsteady boundary element analysis. With the method, the mold temperatures of the past molding cycles are approximated by a set of average heat flux. Mold temperatures were calculated for the mold of a box-shaped part and were compared with experimental results. The calculated mold temperatures were in good agreement with the experimental ones during injection molding. The cycle average method was successfully applied to this analysis.

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This study examines the behavior of a two-phase mixture level in the case of bubbling of a stagnant liquid column in vertical pipes and also in the case of bubbling of the liquid column to which liquid is supplied as a falling film. In a range of low air flow rates where the flow state is a bubbly type, the mixture level swell and its fluctuation amplitude are small; however, these values increase sharply as the air flow rate increases and the flow state turns to a slug type. The mean height of the two-phase mixture level and the level amplitude are physically analysed and compared with the experimental results.

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The experimental study was carried out to clarify the low-quality dryout phenomena in helical coiled tubes placed horizontally. The results obtained are as follows. (1) The low-quality dryout is caused by the separation of liquid and vapor phases and it disappears at the transition from the separated flow to the slug flow regime. (2) The low-quality dryout generally takes place in the lower portion of a non-vertically placed helical coiled tube. (3) A criterion for disappearance of the low-quality dryout has been proposed based on the experiment.

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Collapses of detonation configurations due to interaction with the Prandtl-Meyer expansion and behavior of disturbances in regions losing the characteristic fish-scale pattern were experimentally observed, using a channel with two rectangular blockages and an equimolar gas mixture of oxygen and acetylene. As optical measurement methods, pulse laser schlieren photography was utilized for wavefront structures of detonations or existing various disturbances, and open-shutter photography was used for comprehensive propagation behavior based on emission trajectories of triple shock waves. It was found that at the initial pressure of 13KPa, reestablishment of detonation was obtained after passing through the second blockage arranged in the channel.

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Parameters dominating the characteristics of turbulent transport in swirling flows are derived, paying attention to the production terms appearing in transport equations of stress and scalar flux. Signs of (vw)^^^- and ∂(rW)/∂r are the factors which determine the characteristics of production of stress (uυ)^^^- and flux (υc)^^^-. In the case of ∂(rW)/∂r≤0 and (υw)^^^->0, swirl has an effect of promotion on turbulent transport, whereas in the case of ∂(rW)/∂r>0 and (υw)^^^-≤0. it has an effect of suppression. In the case of ∂(rW)/∂r>0 and (υw)^^^->0, swirl can take either of the effects.

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We observed the interaction between turbulence and combustion reaction near the lean flammability limit of a premixed flame supported by a hot burnt-gas stream, and elucidated the change in the fine flame structure with Damkohler number. A typical wrinkled laminar flame appeared when the equivalence fuel-to-air ratio of the mixture was 0.6, whereas for an equivalence ratio below the lean flammability limit (e. g., φ_m=0.4), the structure which looked like a distributed reaction zone was observed. This structure showed features similar to the distributed reaction zone, which was observed in a strongly turbulent shear layer, in many aspects of the statistics of fluctuating properties, such as temperature, ion current, and radical chemiluminescence.

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This paper examines experimentally the dehydrogenation process of soot particles. Acetylene and propane soots taken from a diffusion burner and soots from liquid fuels (benzene, n-butyl alcohol and benzine) sampled from a wick burner are examined. To collect soot particles with different sizes, the sampling station is shifted along the centerline of the burner. The size distribution of soot particles is measured using an electron microscope. Carbon/hydrogen ratios are determined by CHN analyzer. For all fuels tested, the measured C/H ratios plotted against mean diameter of soots fall on a straight line passing through the origin, proving the assertion that hydrogen molecules sit only on the surface of a soot particle, whereas the core consists of carbon molecules. We also see that although hydrogen molecules lie only on the surface, the thickness of the layer is several molecules thick. Loose correlations between the surface C/H ratio and the original fuel composition are also observed.

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A new seed injection system with a multihole type twin-fluid atomizer has been developed for the Fuji-1; blow down facility for closed cycle MHD power generation and applied in generation experiments using potassium seeded argon. Seed fraction in the working gas of the Fuji-1 has been determined from the measurements of total absorption of the potassium 5p-4s lines (404.4, 404.7nm)recorded with a multichannel spectrometer. The optical collision radius of the potassium lines in argon, which is necessary for calculation of the potassium number density from the total absorption, has been determined experimentally. It was found that the electrical power output had a maximum value at seed fraction of 1.8×10^-4 and decreased rapidly at seed fraction lower than 1.0×10^-4.

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Driving force of the engine output is transfered only via a contact point between the tire and road surface. Therefore, studies related to this seem to be very important. Allmost all the studies, however, are concentrated to subject which forcused to the maximum driving force or braking force, and the studies which forcused to the transfer efficiency η are scarce. Reported here is the simulation study of η for an one wheel vehicle model as object system. An unique display method for η was proposed. It makes the effectiveness of several factors for η visual at a glance. Moreover, the comparison of η between the automobile with and without a traction control device was carried out using this display method, and improvement of η by TRC device was recognized.

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Fuel consumption of the engine becomes tolerably economical when it runs under operating conditions of low speed and high torque rather than of high speed and low torque. Therefore, if an automobile engine is operated by consolidated control with continuously variable transmission (CVT), the minimum fuel consumption is achieved, satisfying the driver's demanded vehicle speed. The effect of this consolidated control on fuel economy depends on several factors such as specification of the object automobile, range of the transmission gear ratio (R_m) of equipped CVT, and the driving mode of the automobile itself. In this report, R_m range and driving mode were focused on and their influence on fuel economy was investigated by simulation studies.

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A part of methanol fuel can be converted to dimethyl ether (DME), which has very good compression ignition characteristics, in a catalytic reactor using exhaust heat. By introducing DME into the intake manifold, a diesel engine can be operated by pure methanol without any major engine modification. This report presents experiments on combustion and exhaust emission characteristics of methanol fueled diesel engine with pure DME supplied from a bomb. It was found that the methanol engine with DME could be operated with sufficient stability. The appropriate DME quantity at which thermal efficiency and emissions were optimum were identified.

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Numerical prediction of a steady intake airflow was performed with an unstructured grid. Changing surface rougheness and configuration of an intakeport, airflow rate and velocity vectors were calculated. Comparing the calculated results with the experimental ones by LDV measurements, the accuracy was evaluated. It was found that airflow rate can be predicted with the accuracy of 5 percent, and the predicted velocities, especially in the intakeport, agreed with the measured ones. The predicted airjets at the valve annular passage were slower than the experimental ones. The application of the standard k-ε turbulence model to the airjet at the valve passage was found to be an essential factor for the discrepancy.

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