A new method for calculating the growth rate of thin films fabricated by the sputtering method is prespnted. By use of the method, the effects on the growth rate of the bckground pressure. target-substrate distance, and sputtered material are examined in the case in which the circular target and substrate are in the cylindrical vacuum chamber.

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The growth rate of thin films formed on the flat plate immersed in a uniform stream of silane and hydrogen is calculated by means of the test-particle Monte Carlo method. The silane is diluted in hydrogen. The diffusion theory is shown to be applicable up to the Knudsen number less than 0.01. The growth rate is proportional to exp (-cx), where c is a constant and x is the distance along the substrate. The constant c decreases with increasing flow velocity and decreasing pressure, deposition probability, and deposition efficiency.

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A three-dimensional vortical structure of a lid-driven square cavity flow was studied by flow-visualization techniques. Several sectional patterns of the flow visualized by a thin laser sheet showed that the structure was characterized by cells periodically aligned in the spanwise direction of the cavity. The cell consisted of both a pair of two vortex rings whose sense of rotation was opposite each other and a pair of two U-shape secondary vortices at corners. The vortex rings were a part of a primary vortex, and similar to the Taylor vortices between two coaxially rotating cylinders. The cells fluctuated in the spanwise direction with a long period of time 56H/U₀, U₀ being the velocity of the lid. A time-mean interval of the cells was found as a function of Reynolds number which was defined in terms of velocity U₀ and the height H of the cavity in a range from 500 to 3000. The time-mean interval was independent of the aspect ratio A of the cavity, if A was greater than or equal to 3.

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The flow patterns and the associated impulsive pressures of the Karman-vortex cavity separation from a circular cylinder have been systematically studied for several Reynolds numbers, from Re=4×10⁵ to 7×10⁵, by high-speed photography and by wave analysis. The main experimental features are as follows. (1) In the first period of the cavity separation, the cavity separates in a bubbly cloudform, leaving the clear part, from the boundary of the clear and cloud cavity where the transitional waves appear at about θ=110°as measured from the stagnation point. Then, the bubble cloud makes up a Karman vortex. In the second period, the residual cavity breaks down into individual bubbles of which some collapse and others make up streamwise vortex-type cavitation. (2) The impulsive pressures in the second period are about 0.6∼0.8 MPa in amplitude and 40 μs duration, so they seem to be related to the bubble collapsing pressure of low cavitation erosion. The amount is several times higher than the dynamic pressure.

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Streamwise evolution of an artificial large-scale coherent vortex in a turbulent boundary layer was experimentally investigated by measuring velocity and shear stress distributions. The life of the vortex followed three stages; growth, self-preserving, and decay. In the growth stage, the induced velocity and the shear stress confined in the vortex increased rapidly as the scale of the vortex grew larger. The vortex kept its self-similar configuration during the self-preserving stage. The decay rate of the total induced shear stress confined in the vortex was about -1/3, the coherent component of which was still its dominant transporter. In the decay stage, the vortex had a passive structure being more inclined downstream and the decay rate was about -1. The vortex kept the coherency as far as 50δ downstream of its origin.

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Effects of an adjacent wall on turbulent jets have been investigated experimentally. The jet is discharged parallel to a flat plate from which a round nozzle with a diameter of 30 mm is 30, 45, 60, 90 mm distant. The velocity profiles, the decay and the location of the maximum velocity, and the spread of the half width are measured with a hot wire anemometer. These results of offset jets are compared with the results of wall and free jets, and the wall effects on some mean features of turbulent jets, such as the maximum velocity location, the half width and so on, are clarified.

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Three components of velocity fluctuation have been measured in a wall jet and offset jets which are discharged from a circular nozzle placed away from a flat plate. Measurments are made by the technique of rotating a probe with an inclined hot wire. Distributions of the turbulence intensity, the Reynolds stress, and the turbulence energy are shown in the cross section of the jets. Also, the balance of turbulence energy is estimated in the central symmetric plane of the developing region by using the measured data. The results of the offset jets are compared with those of the wall jet, and wall interaction effects on the turbulence structure are discussed. Main conclusions have been derived as follows ; (1) The turbulence energy in the offset jet grows and declines more rapidly than that in the wall jet. (2) The turbulence energy transfer toward the lateral direction due to the triple correlation in the offset jet is opposite to that in the wall jet near the wall. (3) In the offset jet, the new wall shear layer is brought up on the wall rather than the free shear layer of the upstream is attached to the wall. (4) The production and the dissipation of the turbulence energy keep in equilibrium on the whole even in the developing region of the offset jet, and so on.

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An experimental study of the transition from laminar to turbulent flow in a radial thin liquid film flow is reported for very dilute water solutions of polyacrylamide, ranging in concentration f rom 0.05 to 3 wppm. The liquid film flow along a horizontal flat plate is generated by the discharge of solution from a thin opening between the end of a circular nozzle and the plate. The process of transition is observed using a stroboscope. It is found that polymer additives shift the point of transition upstream and decrease the critical Reynolds number although the mechanism of transition is the same as that of the solvent.

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The promotion of the laminar-turbulent transition in a radial liquid film flow by polymer additives described in the previous paper is investigated by the linear stability theory. The constitutive equation used to present the response of the dilute polymer solution is that of the second order fluid model. The applicability of the model to the flow is examined by the Rouse model. The Orr-Sommerfeld Equation, modified by elasticterms, is solved numerically. Calculated results show that the elasticity of liquid given by the polymer additives increases the instability of the flow.

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The effects of four parameters such as the rotational frequency, the inner radius of disk, the thickness of disk and the cut-off clearance on fluid dynamic characteristics of a laminar flow fan were experimentally investigated over a wide range of fan flow rate and discussed in relation to the measured velocity at the outlet of the rotor. The agreement between the predicted values of the pressure head by the present method is satisfactory if the proposed correlation of K_m was used.

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A separated flow past a square cylinder located in parallel walls is simulated by a method combining the discrete vortex method with the image one. Calculations were made on mean and fluctuating features of surface pressure, lift, drag, and Strouhal number. Wall effects upon those flow characteristics are numerically clarified through detailed computations. It is found that the present results are in good agreement with existing experimental data, and this confirms the utility of the present method of analysis.

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This paper presents the results of an experimental investigation of a turbulent cylindrical wall jet impinging normally on a flat plate. This type of jet flow may have properties including boundary layer separation and reattachment on the wall. Before dealing with this jet flow, this report describes the fundamental properties of three types of jet flow : a circular free jet from a circular nozzle, a cylindrical wall jet from an annular nozzle, and the impinging jet of a circular free jet with the flat plate normally. The changes of the maximum jet velocity, the jet half-width, the turbulence at the velocity maxima, and the static pressure for each jet flow are examined, and the results are compared with those obtained for the jet flow by the other investigators.

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When thin films of liquid are produced by roll coaters, it is commonly observed that the liquid film is not uniform but shows either regular or irregular patterns resulting from hydrodynamic instabilities. The appearance of the liquid film has been consiedred to be governed by the flow geometry and dynamics in a nip region between two rolls. This ribbing pattern on the roll is called "ring pattern" in the present paper. Experimental studies are carried out on measuring the ring pattern pitch, the height of the wave and the average liquid film thickness by using two rolls. It is found that the pitch for Ca > 3 does not depend upon the Gapillary number but is constant. The height of the wave increased with the Gapillary number. Simple empirical correlations for the pitch and the wave height of the ring pattern are proposed.

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The author introduces a new oscillation phenomenon in which a three-dimensional rectangular jet oscillates periodically when it is issued from a rectangular nozzle with a height lower than that of the flow passage into an abruptly expanded flow passage. In this paper, a new fluidic oscillator or flowmeter without control port or feedback loop is proposed by utilizing the phenomenon mentioned above. Also, this paper clarifies the various conditions for the oscillation to occur, the relation between the oscillation frequency and various conditions such as dimensions of nozzle and flow passage or jet velocity for a trial model of the above-mentioned fluidic oscillator, and the mechanisms for oscillation and determination of oscillation frequency. The effect of nozzle shape on this oscillation phenomenon is also clarified by using both rectangular-and round-shaped nozzles.

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Developing flows of water and dilute aqueous solutions of polyethylene oxide in an inlet region of a curved pipe have been investigated by measuring velocity distributions in the Dean number range of 150 to 1200. The flows are visualized with small nylon particles having specific gravity of 1.02 and mean diameter of about 150μm. The particles are lighted by a stroboscope and photographed consecutively. Axial and secondary flow velocity distributions in the developing flow region are obtained from the picture of the particles. In addition, pictures of secondary flows in a cross section of curved pipes are taken in that region. It has been found as a result of the measurements that the flows of dilute solutions develop with the same process as water flow in laminar flow regions, but in the turbulent flow region the developing process of dilute solutions differs from that of water flow. Furthermore, the variation of boundary layer thickness and inlet length have been derived from velocity profiles.

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The laser Rayleigh scattering technique was applied for the remote and nonintrusive probing of the vapor concentration around two spheres of liquid fuel evaporating in a vertically upward free stream of air with uniform velocity and temperature profiles. The Rayleigh signal from a minute volume of vapor air mixture subjected to the monochromatic radiation of a focused argon laser was collected by the optical detection system. The results showed that the time-averaged vapor concentration profile directly upstream of the rear sphere resembled the one formed at the same position due to the evaporation of the front sphere alone for the inter sphere distance approximately four times longer than its diameter. It was also revealed that the vapor concentration profile downstream of the rear sphere was not affected by the existence of the front sphere. The vapor concentration increased with an increase in air temperature and the volatility of liquid fuel while it was independent of the air velocity.

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The flow behavior in a disk MHD generator was studied under high-MHD interaction conditions. Experiments were conducted using a blow-down facility, and argon seeded with cesium was used. The static pressure distribution, the flow velocity, fluctuations of the static pressure and the swirl were measured. The results show that when load resistances and seed fractions are high, a steep Pressure increase appears at the upstream region in the MHD channel owing to the enhanced Lorentz force. On the other hand, the location of the pressure increase shifts downstream with the decrease of the Lorentz force. At the same time, the increment of pressure becomes small. A large fluctuation of the static pressure was observed at the upstream region where the steep pressure increase appeared. Characteristics of the pressure fluctuation are found to be analogous to those of the pseudoshock observed in channels without MHD interactions. Furthermore, it is confirmed that the swirl becomes large with the increase of the Hall current.

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Oscillation modes of nearly circular shock waves in supersonic radial flow were investigated both theoretically and experimentally. The shock waves deformed from circular shape were obtained by the asymmetric back pressure produced by downstream obstacles. Oscillation modes of the shock waves were investigated by use of the statistical study of the phase function and the mean coherence in each static mode. The oscillation consisted of mode 0 and the same mode as the original static shape. The frequency of each static mode depended on the deformation from the real circle.

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The present report deals with an investigation of tensile stress waves in oil. Experimantally generated pressure pu1ses below absolute zero turn out to propagate through an oil column exactly as the ordinary wave theory predicts, which verifies the reality of tensile stress waves. Absolute negative pressures after the separation cavity collapses, which have been theoretically predicted under the assumption that gas is not released in an oil column during the separation, are also confirmed for the first time. However the measured pressure wave shapes do not agree with the theoretical predictions in this case. Considerations of these results lead to the hypothesis that oil loaded with a tensile stress wave ruptures, depending on the duration and amplitude of the absolute negative pressure and also on the defects in oil constitution.

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A numerical method calculating the two-dimensional MHD laminar and turbulent flow in a traveling sinusoidal magnetic field is shown. Some calculated examples which represent the relations between the induced mean velocity and Hartman number, magnetic Reynolds' number, traveling velocity of the magnetic field, wavelength of the field, etc., are shown. Some characteristic curves as a flat linear induction pump are calculated.

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Velocity measurement by LDV a the slip between the seeding and the fluid, and a reduction in the S/N ratio of Doppler signals when we apply LDV to the measurement of high speed gas flow. Firstly, we measured the velocity downstream of the supersonic nozzle, and the velocity in the wake of the cascade. In these cases the velocity reaches maximum speed in the actual turbomachinery. In a large actual-size air model turbine, the internal flow of shrouded rotating blades was measured. As a result, the flow field in the rotating blades which could not be measured by the conventional method has been detected. Moreover, it has been confirmed that the result agrees approximately with the measurements by Pitot tube at the exit of rotating blades.

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The current tendency to reduce the weight of vehicles having a low C_D value causes the decrease in stability against side winds. When a vehicle goes out of a tunnel or across a bridge, it is sometimes subjected to a strong-side-wind gust and the driving security is greatly decreased. In order to make safer vehicles, it is important to clarify the vehicle behavior and the steering response when it is subjected to the winds. In this paper, an experimental method has been developed to apply a yawing moment to a vehicle. A yawing moment equivalent to that due to the wind gusts is generated by a compact, high-pressure water-jet unit mounted inside the test vehicle. Test results showed that this method is valid for studying vehicle behavior and driver's response to side-wind gusts.

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A method is presented for the numerical analysis of the aerodynamic characteristics of the sail in an unstaggered cascade when all sails take the same shape. In this analysis, the authors apply a series of Chebyshev polynomials to express the pressure distribution and chordwise shape. It is found that the aerodynamic stability of a sail increases with increasing solidity from the viewpoints of the values of maximum tension eigenvalues, but it decreases when we judge from the critical excess-length ratio. The effects of solidity on the value of the lift coefticient and the position of the center of pressure are shown in diagrams as functions of the angle of attack and of excess-length of the membrane over the chord length.

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An automatic method for determination of flow directions in a one-digitalized path-line picture has been developed. Flow direction is locally determined by calculating the vorticity at an average position among four neighboring pathlines in four different ways. The four pathlines are taken on the Delaunay net, which is made on the positions of pathlines, in order to make the procedure of this method more universal than that so far in use. The final determination of flow directions is carried out based on the results in five different cells for improvement in accuracy. This method is applied to determine the flow directions in a separated flow around a circular cylinder using the velocity distributions obtained numerically by the MAC method. The average error is found to be only 0.8 % for 25 different velocity distributions. For the flow visualization picture in a square cavity, flow directions can be determined by the method without inducing error.

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The paper describes dynamic analysis of middle scale horizontal axis wind turbine. The result of computer simulation is compared with that of field test. Both results agree well. Local circulation method is used to analyze rotation force as a part of simulation theory. The rotor diameter of turbine is 8.2 mΦ and the rated output is 8 kW. As the results, the theory which is used in the paper is useful to calculate the wind power in any setting position of wind turbines.

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Nonlinear wave motion on the free surface in a two-dimensional container subjected to external periodical excitation is considered in this paper. In order to analyze the arbitrary container geometry, a solution scheme using Lagrange particles on the free surface is employed. Fluid motion is assumed to be governed by the Laplace equation in terms of the velocity potential with a nonlinear pressure equation on the surface. The boundary element method with an explicit time marching is used by the fluid region boundary discretization alone at each time. Various kinds of container with inclined side walls are analyzed for the horizontal sway motion and compared from a practical viewpoint.

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The successive overrelaxation method, also called the SOR method, is one of the iterative methods for so1ving a linear system of equations, and has been used in many programs. With the advent of vector processors, the SOR method is executed efficiently in parallel with the red-black or hyperplane ordering on vector processors. In this paper, a parallel scheme termed the 4-color SOR method is revised and compared with the natural and red-black SOR methods on a multiprocessor system. The 4-color SOR method has the highest parallel performance of the three. The parallel-vector calculation of the 4-color method with 4 processors is about 10 times faster than the scalar one with one processor.

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A new fish farming system based on the improvement of product values and energy saving and supported by a newly designed wave-energy pump has been developed. An experimental approach to the realisation of single-and double-acting wave-energy pumps and fish meat improvement by giving a suitable motion to the cultivated fish was taken. The correlation of motion speed and period with body muscle and fatness of the cultivated fish with low-temperature preservation characteristics was investigated, and the "jogging effect" was proven most effective at a speed of 2.5 BL/s. Furthermore, system investigations related to wave-energy pumps and fish training were performed in an integrated and optimum arrangement. The application of the double-acting pump with a suitable float piston weight gives a possible solution to compact design as well as optimum pump flow performance.

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The effect of ultrasonic vibrations on a saturated-pool nucleate-boiling heat transfer in the presence and absence of glass beads in distilled water as the working fluid is investigated under reduced pressure. Ultrasonic energy of 140 W with a frequency of 20 kHz expose the flat heated surface of 20 mm in diameter, which is immersed in the saturated working fluid. The heat-transfer coefficient with glass beads in distilled water is larger than that without glass beads, and up to a four fold increase in the heat-transfer coefficient is obtained in this experimental condition. The heat-transfer coefficient increases with the decrease of system pressure, but it decreases with the increase of heat flux. Observation by 35 mm photographs elicits some considerations on the mechanism.

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A theoretical study has been performed to optimize the fin dimensions of a horizontal low-finned copper tube used in shellside condensers. The study relies on a previously proposed theoretical model of film condensation in a bundle of horizontal low-finned tubes with negligible vapor shear. The fin spacing, fin height and fin thickness were systematically varied to obtain optimum fin dimensions using R-22, n-butane and steam as condensing fluids. The optimum values of fin spacing and fin height increased with the row number n counted from top row. The optimum fin spacing increased, whereas the optimum fin height decreased, in the order of R-113, n-butane and steam. At the optimum fin dimensions for n=30, improvements in the overall heat transfer coefficient over smooth tubes were 380% for R-22, 340% for n-butane and 60% for steam at the tube-side water velocity of 2 m/s.

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Heat transfer is experimentally investigated for refrigerant mixtures of R22 and R114 flowing in a horizontal evaporator tube. The heat transfer coefficients for the mixtures are always lower than the 'ideal' values estimated from the heat transfer coefficients for pure refrigerants. This reduction is significant in the region where nucleate boiling contributes to the heat transfer, and is attributed to the mass transfer resistance in addition to the change of fluid properties. In the convection dominant region, the reduction in the heat transfer coefficient is assigned solely to the 'unideal' effect of physical properties, and the heat transfer coefficients are approximately equal to those of an equivalent pure fluid with the same physical properties as the mixture. None of the correlations hitherto proposed for the heat transfer to binary mixtures successfully predict the present heat transfer coefficients.

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This paper deals with heat transfer in the melting process of phase-change materials around a horizontal single pipe and a heat exchanger with horizontal pipes. Through the rearrangement of experimental results by Bathelt and Sparrow a using single pipe, an experimental equation is found. Also, heat transfer experiments are conducted in a phase change material around a heat exchanger with horizontal pipes connected by a U-bend. The experimental results are investigated with the above results for a single pipe, and the U-bend effect on the heat transfer is clarified.

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Heat transfer from an isothermal cylinder placed in a porous medium and subjected to natural or forced flows in the axial direction has been studied experimentally. It is shown in a preliminary analysis that both natural and forced convective-heat transfer from the cylinder may be described as a perturbed case from a flat-plate problem. ξ=L/a√(Ra) and ζ=L/a√(Pe), each representing the curvature effect, serve as the parameters for natural and forced flow, respectively. The departure of the heat transfer rate relative to a flat-plate case is described as a function of ξ or ζ. Using a porous layer of glass beads and water, heat transfer rates from the cylinder are measured for three different sizes of bead diameters. The experimental results agree well with the theoretical predictions; the Nusselt numbers divided by √(Ra) or √(Pe), in general, increase as ξ or ζ increases.

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Fully developed steady laminar flow of viscous fluid in straight rectangular ducts rotating about a parallel axis is analyzed numerically. Thermal boundary condition of axially uniform wall heat flux is considered. Numerical results of flow and temperature field in ducts with aspect ratio from 0.2 to 5 are obtained for ReRa_Ω number upto 6.725×106 (for Re numbers upto 1346) and Prandtl number from 0.3 to 400. At low to moderate ReRa numbers, a double-vortex secondary flow is exist under the influence of buoyancy due to centrifugal force field. It is found that a pair of additional vortices appear and disappear for higher range of ReRa_Ω numbers. It is shown that tritical number of ReRa_Ω for onset of additional vortices is affected by Prandtl number and aspect ratio. The friction factor and Nusselt number are pressented. The solution is compared with other analyses.

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The local heat transfer coefficient of a ribbed surface was experimentally measured on the base surface between two ribs. Two-dimensional square bars were attached to the lower wall of a parallel channel, the upper wall being a smooth wall. Experiments were carried out using air flow at atmospheric pressure and room temperature. The Reynolds number ranged from 3×10³∼1×10⁵, the ratio of pitch to height of the rib from 2.5 to 60 and the ratio of the height of the rib to the hydraulic diameter of the parallel channel from 0.0324 to 0.174. The distance from the position of the maximum local Nusselt number to the rib, and the local Nusselt number upstream and downstream from the maximum position were experimentally studied.

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The entrainment rate of liquid droplets in a two-phase annular mist flow is investigated in the helically ribbed and wired tubes with the aim of suppressing the droplet entrainment to improve evaporative heat transfer in various steam generators of the one-through type. The results show that the entrainment rate in these tubes is lower than that in smooth ones. Large disturbance waves on the surface of the liquid film flow in the tubes are also smoothed, which may be a reason for the entrainment-suppression effect. The effect can be correlated with three nondimensional parameters. The pressure drop of two-phase flow through the tubes is influenced by some factors as well as by the hydraulic diameter of the tubes.

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This study was conducted to pursue the heat transfer enhancement in a forced convective field by utilizing the ionic wind induced by a corona discharge. Experiments were carried out in a straight channel where staggered wire-electrodes were set at right angles to the primary flow direction. A theoretical analysis was also performed on the electric and the flow fields taking account of the interaction between these fields. Comparing the experimental and analytical results, firstly, the combined flow field where cellular secondary motion occurred owing to the field's interaction was characterized with the wire-electrode arrangement. Secondly, the improvement of heat transfer enhancement under the condition of constant electric power was achieved by means of the staggered wire-electrode arrangement, and the optimum offset ratio was clarified in conjunction with the primary flow velocity and the electric power.

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The distribution of the mass transfer rate has been visualized by holographic interferometry. The real-time surface displacement of the naphthalene plate caused by the sublimation in the flow field was measured, from which the real-time distribution of the heat transfer coefficient was estimated. At first, the validity of this method and its accuracy were checked by using a laminar boundary-layer flow on the flat plate. Then this method was applied to backward-facing step flow in ducts with various shapes. It is clarified that this method appliable to the measurement of the mass transfer coefficient in various flow fields having a duct wall. The visualized distribution of the mass transfer rate for backward facing step flow correlated well with the frequency of high level turbulence spots.

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The contact melting problem of a phase-change matrial is studied theoretically. The phase-change material rotating with a constant speed is put a wall which is kept at a constant temperature higher than the melting point of the phase-change material. The problem is governed by four parameters, the Stefan number, the Prandtl number, the ratio of the centrifugal force to the externally applied force, and the ratio of the viscous dissipation to the externally applied heat. The fluid motion and the heat transfer in the narrow gap between the solid and the wall is examined by obtaining an approximate solution expanded in the form of the power series of the Stefan number with the precision up to the first order. It is found from order of magnitude analysis that the melting is caused by the heat transfer from the heated wall rather than the heat generation due to the viscous dissipation, that is, the latter is not important from a point of view of the heat transfer. However, since the attractive force due to the rotation easily exceeds the externally applied force in many practical cases, the effect of the convection on the melting speed is not always found to be negligible, and it causes the liquid-solid interface to be flatter.

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Transient behavior of an active thermal insulation system consisting of a semi-transparent porous medium with gas injection was considered. Numerical analyses were carried out on the semi-infinite layer of a porous medium, and hydrogen was chosen as the injected gas. During the early stages of heating, thermal penetration depth, surface temperature and surface heat flux do not depend on the gas injection velocity. As the heating time increases, the thermal penetration depth of the active thermal insulation system reaches a constant value for each gas injection velocity, and the surface heat flux vanishes keeping the back face at a low temperature. However, the thermal penetration depth of a conventional insulation without gas injection never reaches a constant value. Transient solid temperature distributions in the layer for two different surface boundary conditions are almost identical except in the vicinity of the surface.

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The transmittance and reflectance of radiative energy is analyzed by the Monte-Carlo method through randomly/regularly packed beds of uniform diameter spheres. This Monte-Carlo method through randomly/regulary packed beds of uniform diameter spheres. This Monte-Carlo simulation of radiative energy transmittance through the packed spheres surrounded by periodical boundaries shows that the transmittance and reflectance of radiative energy through the beds are strongly affected by the arrangement of the spheres. The transmittance obtained by using a continuous model is much higher than that of the present simulation for the packed spheres with higher densities.

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Field measurements of the heat transfer in an east-west oriented urban canyon are performed in the summer and the winter seasons, as preliminary research of the heat transfer in the urban surface boundary layer. The canyon is made of concrete buildings (16 m in height) covered with windows, standing face to face across an asphalt road (17 m in width). The heat transfer in the urban canyon is represented by the energy balance at the imaginary surface named "the top surface", which is the plane above the canyon at the same level as the roof surface. The net amount of the transferred heat into the urban canyon is more than four times greater than that into the roof, and reaches about 50% of the net radiation heat transfer on a summer day regardless of the meterological conditions. In the daytime, there is no significant difference in the convective heat transfer between the roof surface and the top surface.

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The performance characteristics of a small-size screw expander for energy conversion of hot springs are described in this report. Instead of lubrication oil, the test machine is fed with a high-temperature oily working medium liquid for the lubricant. This idea is proposed in order to omit the lubricationpump. By feeding of the oily working medium liquid lubricant, the working fluid must be of low quality (dryness fraction). For the calculation of wet expansion, we introduce the actual adiabatic expansion with thermophysical properties of the actual working medium. This expansion is the isentropic expansion in which the adiabatic exponent χ is variable. The calculated values of this method give fairly good agreement with the experimental results. In this paper, as the result of the calculation and experimentation, we report the performance characteristics of a small-size screw expander operated with a low-quality (χ=0.6∼1.0) actual working medium.

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Intelligent control of an electrohydraulic servo system can be realized comparatively easily by introducing microcomputer. To realize intelligent control systems, it is important to obtain a digital control valve with high transducer-actuator switching speed performance. In the case of a small valve opening, a poppet-type valve has some advantages compared to a spool-type one. The aims of this study are to propose a high-speed displacement control method for the valve poppet and to develop a high-speed digital valve whose switching time is within 100μs. By introducing feed-forward control and providing some improvements, a poppet-type on-off valvd with a high-speed switching response within 70 μs is developed. In application, a two-stage digital servo valve, whose second stage of the spool valve is driven by the high-speed poppet-type on-off valves, is devised.

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The Monte Carlo method was used to analyze characteristics of light scattering and absorption by living bodies. The intensity of transmitted light through a slab of emulsion which simulates living bodies was calculated. The emulsion contained two types of particles ; small particles with isotropic scattering and large particles with strong forward scattering. Time-resolved analysis clarified the profile of transmitted light intensity, and the optical density, which is calculated from light attenuation caused by absorbing particles, was found to be in proportion to the absorption coefficient of particles and the optical path length. From spatial analysis of transmitted light intensity, the mean optical pathlengths have been found to be four to ten times the geometrical pathlength.

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The tulular flames of lean methane/air mixtures in a rotating-flow field have been analyzed for their concentrations of stable species and temperature distributions, and their structures have been investigated. The results show that the tubular flame consists of an inner hot gas core of burned gas and an outer region of the unburned mixture, and that the flame structure is essentially the same as that of the one-dimensional, flat, premixed flame. As the extinction limit is approached, the flame diameter decreases and the concentrations of carbon monoxide and hydrogen behind the flame zone increase. Hence, the extinction of the tubular flame of lean methane/air mixtures is caused by incomplete combustion with stretch as it is with other stretched flames. As the density inside the flame is lower than that outside, the flame front is rendered smooth and cylindrical by the rotational motion of the flow.

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A picture processing technique is applied to the analysis of flame motion in a small direct injection diesel engine. The combustion sequences were taken from the underside of the combustion chamber by the high-speed photography. Adjacent two frames of the combustion sequence, one of which was a positive picture and the other was a negative picture, were overlapped. The picture obtained by the above process showed the moved area of luminous flame at a very short period, and enabled us to investigate the direction of the flame motion in the combustion chamber. In the middle stage of combustion, the flame spouted from the inside to the outside of the piston cavity induced the radial flame motion toward the cavity in the area outside the cavity. The effect of the configuration of a nozzle hole on the flame motions inside and outside the piston cavity was discussed. Engine performance was improved by increasing the radial flame motion.

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This paper describes a system of measuring the flame propagation of a spark ignition engine. A system using an electrooptical shutter known as the PLZT was developed and examined. Flame propagation photographs were taken by the still camera with the PLZT shutter. One characteristic of this shutter is rather lower transmissivity of light when opened. Another is slight transmissivity when closed. To solve these problems, a solution of sodium ethylate was added to the fuels to increase the brightness of the flame and a mechanical shutter was used together with the PLZT shutter. This system was examined and it was confirmed that the system satisfied the required specifications for the most part. Furthermore, an example of the flame propagation photographs and the cyclic variation of the flame area were shown when the swirl velocity was varied.

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This paper gives the experimental results obtained with a two-stroke cycle single-cylinder research engine using an electrically heated combustion chamber to simulate the combustion chamber of a low-heat-rejection(LHR) DI diesel engine with an M-combustion system. In this report, the experiment was performed to apply the ethanol to a LHR DI diesel engine with an M-combustion system by hot surface ignition using a glow plug. It was found that the ignition and combustion of the ethanol is greatly affected by tbe combustion chamber surface temperature and the ethanol mixture is self-ignited by increasing the combustion chamber surface temperature to a very high level.

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The combustion chamber surface and cylinder air temperatures during cranking have been investigated in a direct injection diesel engine with combustion chambers of various conductivity materials, and the influence of combustion chamber materials and surface deposits on the cold startability was tested. The insulated chamber made of bakelite indicated higher surface and air temperatures than did the copper chamber with larger conductivity. As the result, the starting time in the copper combustion chamber for cold operation was 5 times longer than that in the bakelite chamber, and it was found that there is a relationship between the cold startability and the thermal conductivity of combustion chamber materials, and that the cold startability is improved by the increase of the combustion chamber deposits.

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