To make clear the behavior of cavitation-violent-vibrations, we precisely investigated the lift-and the drag-fluctuations, the vibrational accelerations, and the corresponding cavitation aspects in the steady water flow around a Low drag Eppler-foil. The lift and the drag fluctuate considerably in the state of the periodic "cavity separation" of about 21 Hz in frequency, and these amplitudes reach ±24 percents of the time averaged values. A strong correlation is observed be tween the time-dependent cavity behavior and the corresponding fluctuations, i.e., the lifts, the drags and the vibrations.

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In order to distinguish the impulsive pressures of a microjet and a shock wave precisely, a local pressure sensor of linearly arrayed elements is manufactured. The sensor is composed of six sensor elements of 1mm×1mm in size and its sensitive area is 1mm×6mm. By the arrayed sensor and flash photographs of the cavitation bubble, the impulsive pressures of the microjet and shock wave are evaluated precisely. In the experiment, it is revealed that the microjet impinges on an area of 2mm-3mm in diameter, its impulsive pressure is in the range of about 2 MPa and its effective duration is at most 80 microseconds. It is also revealed that the effect of the shock wave is maximum at 2mm-3mm from the center of cavitation bubble, when the cavitation bubble collapses on the solid boundary.

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The propagation of pressure waves in dispersed two phase flow consisting of a suspension of discrete gas bubbles, which have size and number density distribution, in a continuous liqid is investigated numerically. The governing equations for the bubbly flow are formulated with emphasis on the radial motion of the bubbles and the relative motion between the phases. A numerical method, where individual bubbles are traced to calculate their transversal motions and volumetric changes, is developed. The numerical results reveal that the radial and transversal motions of the bubbles have significant influences on the relaxation phenomena behind the shock and rarefaction waves in bubbly flow. These relaxation processes are affected by the interaction between individual bubbles with different sizes. When the deviation of the size distribution of bubbles becomes larger, the amplitude of pressure oscillation behind the shock wave becomes smaller and the waveform is more deformed.

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The detailed wave structure of a reflected shock wave over a wedge with surface roughness is examined. The rough wedge has regular, two-dimensional geometric protuberances. The shape of protuberances was square in cross section and the spacing was the same as its height. The protuberances varied in size from 0.5 to 8 mm. The incident shock Mach number M was 1.4 and wedge angle varied from 20°to 45°. It is found that the geometric wave structure varies as time proceeds and a pseudostationary (self-similar) state is not attained in our experimental conditions. However the wave configurations are similar as long as the numbers of protuberances over which the incident wave traverses are the same. It is also found that there are four types of shock reflection corresponding to transition. They are MR→MR, MR→RR→MR, RR→MR, and RR→RR.

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A experimental study using the time-of-flight(TOF) mass-spectrometer technique is performed on the characteristics of particle beams skimmed from plasma ionized flow fields of the expansion chamber into which neutral argon molecules are injected through the orifice of the gas source, where electric discharge is actualized by the hot-cathode method. The characteristics are examined from the TOF spectrum signals obtained by changing the discharge voltage and current, and the orifice location. Two clearly distinguishable spectra are always observed in short and long time-of-flight ranges of all the TOF spectra. It seems from discussion that the former spectrum A is produced by the argon ion beam, and that the latter spectrum B is formed by the excited argon molecules of metastable states. A brief theory is also derived for the signal intensity decrement of spectrum A due to the Coulomb force, and the agreement with experiments is fairly good.

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The motion of a small particle in a viscous flow which is driven toward a plane wall by a steady uniform injection at a given distance from the wall is investigated. The particle is assumed to start with the same velocity as the injection velocity of the fluid and to be driven by the interaction force due to Stokes' drag law. The governing equations of the fluid and the particle are found to be simultaneously solvable in the form of similar solutions. That is, they can be reduced to the ordinary differential system. The following results are obtained: the collision between the particle and the wall depends only on the fluid velocity in the direction perpendicular to the wall; the critical Stokes number, above which a particle can collide with the wall, decreases as the Reynolds number increases; the collision can occur more easily in the case of a three-dimensional flow compared with the case of a two-dimensional flow; the critical Stokes number is asymptotically close to that in the case of an ideal fluid with increasing the Reynolds number when the value of the Reynolds number is several thousands, but the critical Stokes number in the case of viscous flow is rather different from that in the case of an ideal fluid, that is, the effect of viscosity is important; the collision in the case of this flow can occur more easily compared with the case of the stagnation-point flow; in the case where the particle collides with the wall, the collision must always occur on the wall at a finite distance from the origin, the frequency of collision increases as the Stokes number increases, and the frequency of collision increases as the Reynolds number increases.

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The annular separation bubble and radial flow between two parallel disks are investigated to understand the features of flow axisymmetric separation and reattachement flow in the inlet region by means of flow visualization and numerical calculation methods. The radius of the separation bubble depends only on the clearance ratio, h/r₀, independent of Reynolds number, Re, in the turblent flow regime where the reattachment point fluctuates randomly. In the transient regime, the reattachment point oscillates periodically. In the laminar flow regime, the reattachment point is stationary, and its radius is given by a function of Re, independent of h/r₀ for h/r₀ ≲ 1.2. Development of velocity distributions to the parabolic profile is investigated at h/r₀=1.0. When Re is smaller than about 25, axisymmetrical-two-dimensional flow exists with a separation bubble between two parallel disks. Furthermore, for Re ≳ 35, a vortex occurs downstream of the separation bubble, in which counterrotating recirculations exist, and circumferentially periodic disturbance appears.

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This paper is to simulate air pollution at atmospheric conditions forming an inversion layer over a plateau. A wind containing harmful substances blows from a plain to the plateau. A two-dimensional jet, accordingly, was ejected into a two-dimensional channel flow and diffusion of the jet was studied. This is a problem of the aeronautical interference for internal flows as compared with widely reported. external flows which apply to wind and a circular jet. The momentum theory was applied to the channel flow and the jet, treating it as an apparent solid wall. The entrainment effect was also taken into consideration. Theoretical equations were numerically solved. It is found that good agreements exist between the theoretical results and the experimental ones for the loci of the jet made visible by dyes.

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An experimental study of the instability of a flow in an axially rotating pipe is performed. It is found that periodic velocity fluctuations occur even in the developing region, when the pipe rotates. Under a certain value of swirl ratio N, the amplitude of the velocity fluctuations amounts to 30% of the axial velocity. This result is related to the occurrence of spiral waves predicted by other investigators by means of linear or nonlinear stability analysis. Velocity fluctuations are measured using the Laser Doppler Velocimeter, and measured azimuthal wavenumber is 1 or 2 and the angular velocity of spiral waves is less than that of the pipe. The rms value of the velocity fluctuation becomes the maximum at N=3, which means that periodic fluctuation is amplified most. As the swirl ratio becomes large (N > 3), the rms value decreases and the periodicity of the fluctuation is weakened.

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The flowfield of a ship's propulsion mechanism consisting of two-series of wings in a square channel is visualized by numerical simulations using the discrete vortex method and by the hydrogen bubble technique. The simulations are performed by assuming that the separations occur at the trailing edges of the wings. The streak-lines and the time-lines agree well with experimental results. The flowfield is unsteady and complex, but the properties of the flow are clarified by numerical and experimental visualization. The time histories of the thrust and the drag acting on the wings are also calculated. These calculated values agree well with the previously obtained experimental values. The effects of the interaction of the wings are explained in terms of the circulations around the wings.

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The effects of side walls of a channel in which a two-dimensional model of the Weis-Fogh mechanism is equipped are experimentally investigated. The effects of the elasticity of the spring which controls the opening angle of the wing are also studied. The thrust and drag increase after setting the side walls, but the efficiency of propulsion decreases when the opening angle is small ; otherwise it increases. By controlling the opening angle with the spring, the efficiency increases substantially, and it is cycle of the wing motion in the channel.

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Pressure fluctuation on the casing wall of an axial flow compressor rotor has been investigated experimentally to find a sign prior to rotating stall. Statistical characteristics of the pressure have been obtained by a phase-locked data logging technique with high frequency response pressure sensors. Periodicity of the fluctuation, which has been examined in the phase-locked patterns of cross-correlation between two points in the relative reference frame, disappears near the stall. In order to monitor collapse of the periodicity qualitatively during operation of a compressor, a detection parameter has been presented which can be obtained from signals of a single pressure sensor mounted on the casing wall.

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In order to investigate the low Reynolds number effects on the turbulent structures of a d-type rough wall boundary layer, the statistical properties in a transitionally rough and a fully rough regime have been examined experimentally. The measurements associated with the turbulent production rate, probability distributions, higher-order moments and energy spectra were made in the range of momentum thickness Reynolds numbers of R_θ=700 to 5140. The local equilibrium state can be recognized for a wide Reynolds number range down to R_θ=700. The probability distributions and the higher-order moments including Reynolds shear stress flux show that the ejection events due to positive high amplitude of υ fluctuating component play a dominant role on the turbulent transport process in the inner layer of the present rough wall flow for a transitionally rough regime of R_θ≤2000. The low Reynolds number effect on the outer layer, which enlarges the contorted surface of the viscous super layer, is found for the Reynolds number range R_θ≤800.

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The laminarization phenomenon of the turbulent boundary layer in an axially rotating pipe was investigated experimentally by introducing an undeveloped flow into it. In the inlet region, the turbulence in the boundary layer was seen to be largely suppressed by the pipe rotation. However, this laminarized boundary layer tended to be unstable as the flow proceeded downstream, and intermittent large-scale bursts of turbulence occurred periodically. Measurements of the Reynolds stress components using conditional sampling techniques revealed that the bursts exert a positive torque around the pipe wall.

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The domains of the spatial distribution of the turbulence velocity for the convergence of the series equation, obtained from a general hot-wire response equation and generally used in a high turbulence intensity flow, are shown by using a computer graphics technique for the case of an 1-probe. The turbulence velocity of an actual circular free jet was experimentally confirmed to exceed the domain of the convergence. Based on the normal distribution of the turbulence velocity, numerical experiments were carried out on the output from a hot-wire 1-probe and on the accuracy of the corrected mean velocity. The results show that the magnitude of the mean effective cooling velocity is always larger than the true mean velocity and dependent on spatial distribution and intensity of turbulence velocity as well as the yaw and pitch factors, and that there is an optimum number of terms of the series equation to obtain the most accurate mean velocity.

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A fully developed two-dimensional turbulent channel flow has been measured with the aid of the three-dimensional particle tracking velocimeter developed by Nishino et al.(1989). This technique can measure an instantaneous distribution of three-dimensional velocity vectors over a large extent of the flow field. By processing about 48000 TV frames, a total of 4.37 million velocity vectors were obtained. This sufficiently large sample size allowed calculating various turbulence statistics, which include mean velocities, Reynolds normal and shear stresses, triple velocity correlations, skewness/flatness factors of the velocity fluctuations and those of the Reynolds shear stresses. The present results show good agreement with those of the direct numerical simulation by Kim et al.(1987) although some differences are found in the near-wall skewness/flatness factors of the wall-normal velocity fluctuation as well as those of the Reynolds shear stresses. In contrast to these results, the well-known data measured by Eckelmann (1973) and Kreplin and Eckelmann (1979) with the hot-film probes show considerable discrepancies even in the fundamental turbulence statistics in the near-wall region.

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Results of the measurement of flow properties in the boundary layer on a cylinder rotating in an axial flow in the presence of a single protrusion are presented. A wedge-shaped region of turbulent flow extends downstream with streamwise vortices on either side. Mean and fluctuating velocities are measured at various rotation speeds of the cylinder. The mean velocity profiles become asymmetric with respect to the relative streamline of the main flow passing the protrusion point as the rotation speed becomes high; this asymmetry is presumably due to the Coriolis effect. Representations of the mean velocity distribution on the basis of relative streamline coordinates and polar plots confirm the existence of a pair of streamwise vortices. The profiles of the fluctuating velocities within the turbulent-wedge region suggest the existence of many small streamwise vortices. The effect of the Coriolis force on the streamwise vortices is examined by using the vorticity equation expressed in a rotating coordinate system.

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An implicit time-marching finite-difference scheme for solving the steady incompressible Navier-Stokes equations is proposed. This scheme is based on the SMAC method for the curvilinear coordinate grid, where the delta-form approximate-factorization and the flux vector splitting techniques are applied, and some upstream-difference schemes and a staggered grid are also employed to suppress spurious error and numerical instabilities, especially for high Reynolds number flows. Numerical results for 2-D duct flow over a backward-facing step are shown, and compared with experimental data and existing numerical results to inspect the validity of the present scheme. The convergence rate to a steady state solution is improved several times in comparison with the explicit scheme, showing the present scheme to be very efficient.

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Flow characteristics of compressible flow through eccentric and segmental orifices are investigated experimentally in subsonic and supercritical flow regimes bacause of the shortage of reliable experimental data in such high-speed flow. The results show that the ASME regulated figures for expansion factor can be applied up to the critical flow regime without remarkable error. Practical and convenient experimental formulae for expansion factors are proposed in this paper. Experiments to determine discharge coefficients and expansion factor for pipe taps are also carried out in order to provide a method of flow measurement with pipe taps. In addition, it is found that the pressure loss coefficient of a concentric orifice can be applied correspondingly to cases of both eccentric and segmental orifices.

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In order to make an accurate prediction of two-phase flow with a two-fluid model, it is necessary to establish a set of correct constitutive equations. The constitutive equations for the analyses of the solid-liquid two-phase flow in vertical pipes were examined in this study. Seven kinds of equations for interfacial momentum transfer were derived from the constitutive equations used in the gas-liquid two-phase flow analyses. It was confirmed that the most accurate prediction is achieved when Andersen's momentum transfer equation is adopted with correlations for the distribution parameter and suspension velocity of solid particles proposed by the authors. The constitutive equation for momentum transfer between a wall and each phase was deduced from the experimental correlation of frictional pressure drop. Calculated results agree well with experimental data with the assumption that there is no momentum transfer between the solid phase and the wall.

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The condensation coeffcient(c.c.) of vapours is investigated on the basis of the transition state theory which is treated in the framework of statistical mechanics of gases and liquids. The theoretical c.c. is reconfirmed to be the ratio of rotational partition functions for liquid molecules to those for vapour ones and is given by thermodynamic quantities available in literature. The applicable limitation of the theory is clarified by comparing molecular flux at the phase boundary with those based on molecular gas dynamics in the special case of mono-atomic molecules. It is shown that the theoretical values of c.c. for water, methaol, carbon tetrachloride, and glycerol vapours are in rather good agreement with experimental ones and are significantly smaller than unity.

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Previous theories of fundamental equations for magnetic fluids have not been able to describe the behaviour perfectly since they have not considered both viscoelastic effect and internal rotation simultaneously. In the present paper, to derive the complete set of equations, we unify the micropolar theory and the thermodynamical method. We introduce a micropolar method which describes the microscopic motion, and some strain tensors or strain measures are defined. The electromagnetic and the balance equations are obtained considering both the viscoelastic effect and the internal rotation. In this way, we assume that the velocity of fluid is sufficiently small compared with the velocity of light, and applied electric tield and polarization do not exist. Physical quantities concerned with the material coordinate and those concerned with the spatial coordinate are treated separately. The fundamental equations which we give are in micropolar continuum theoly.

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Most of the previous theories for fundamental equations of magnetic fluids have not been able to describe both viscoelastic effect and internal rotation simultaneously. They cannot give the behaviour of magnetic fluids completely. In the plesent paper, to derive the complete set of equations for magnetic fluids, we unify the micropolar theory and the thermodynamical method. First, thermodynamical equations for magnetic fluids, for example, Gibbs' equation and dissipative function, are obtained by using the strain tensors for micropolar theory, the balance equations and electromagnetic equations which were derived in the previous paper. And next, the constitutive equations including nonlinear terms are obtained by using the principle of material frame indifference and the principle of maximal dissipation rate. These constitutive equations can represent the behaviour sufficiently when we must consider viscoelastic effect, internal rotation and nonlinear effect.

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It is important to calculate accurately the pumping performance of the turbomolecular pump for the purpose of optimising the blade design. In this paper, the pumping performance of the finite-height blade with tip clearance is calculated accurately by the Monte Carlo method in the molecular flow range. To simplify this calculation, velocity components of molecules are given by random numbers. The influence of the two parameters, blade height ratio and tip clearance ratio, is investigated in several blades which are selected as optimum combinations of blade pitch ratio and blade angle. Consequently, the influence of these parameters on the maximum compression ratio is notable on the blade which has small blade pitch ratio and small blade angle. Finally, the results calculated by the present method agree well with the experimental results.

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The correlation of efficiency and tip clearance on a mixed-flow pump impeller was investigated by the measurement of characteristics with various tip clearances. The measured data were compared with the existing experimental and theoretical results. The influence on flow in an impeller with various tip clearance was obtained from the measurement of casing wall pressures as well as three dimensional flow at the impeller exit. The tendency of reduced efficiency on a design point showed good agreement with the calculated values based on the existing theory. The results of this study showed clearly that the flow pattern at the impeller exit varies largely from the casing to the half-height with increasing tip clearance and blade loading.

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The purposes of hyperbaric oxygen therapy (HBO), which is an allopathic treatment for gas embolism, dysbarism, etc., are to collapse the bubbles produced in blood and to improve ischemic hypoxia by increasing dissolved oxygen. A pertinent curative condition for additional pressure is required as HBO is carried out because the artificial addition of pressure to the human body is attended by certain danger such as barotrauma and oxyges toxicity. In the present paper, under the operative condition of HBO, the compound effect of additional pressure and gas diffusion on the shrinking process of bubbles in blood is made clear, and the dynamic mechanism of HBO is clarified. It is found that the shrinkage of larger bubbles in blood requires greater additional pressure, but that there is no need to decrease the time over which pressure is increased.

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The aim of this study is to make clear the mechanism of catalytic combustion on platinum wires. As a theoretical study, assuming heat and mass transfer analogy and taking into account the heat conduction along the wire, wire temperature is predicted. In the experimental study, platinum wires were set horizontally in a square tube. After the ignition of catalytic combustion, the temperatures of the wires were measured in a mixed gas composed of hydrogen, air and carbon dioxide. From these Studies, it was made clear that: (1)If the excess air ratio is less than 2.4, the wire temperature increases rapidly and linearly with the excess air ratio, and the gradient becomes small when the excess air ratio exceeds 2.4. (2)Theoretical analysis, assuming heat and mass transfer analogy and taking into account the heat conduction, predicts the above-mentioned features correctly. (3)In cases of large diameter or rich hydrogen, the influence of heat conduction cannot be neglected.

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The principle of the newly developed methods for measuring thermal expansion and specific heat using a rectangular rod sample is described. From the data of potential drop, current, and sample temperature under the condition of a uniform temperature in the longitudinal direction, electrical resistivity, total hemispherical emittance, and thermal expansion are simultaneously obtained. Specific heat is calculated from the cooling rate, which is determined immediately after current cut-off. Theoretical estimation of error in the measurement of specific heat is conducted, and thereby the optimum sample size is determined. Techniques of correction for the measured cooling rate with the error caused by thermal contact resistance between sample and thermocouple probe are presented. Experimental results on the rod sample of austenitic stainless steel SUS 304, of 1-mm thickness, 8-mm width, and 200-mm length, are shown in order to verify the applicability of this method in the temperature range of 300 to 900 K.

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In this report, we propose an optical fiber sensor which can be utilized to measure the void fraction. The sensor consists of two multimode optical fibers. They are glued together at the active part of the sensor. The tip of the probe is ground and polished in order to reflect back, depending upon the refractive indices of the surrounding liquid material and of the probe material, according to Snell's law. The method has been validated by comparison with an electrical probe and photographic methods. The experimental results show that the size of a bubble larger than 0.8 mm can be determined with an accuracy of 15% by using the optical fiber probe, 40μm in diameter. A profile of void fraction for Freon-11 nucleate boiling around the horizontal cylinder is measured.

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The unsteady heat transfer characteristics of a Stirling engine regenerator have been theoretically studied. The matrix of the regenerator was assumed to be a homogeneous continuum which absorbs and emits thermal radiation. The coupled energy equations for gas and matrix were solved taking account of conductive, convective and radiative heat transfer. The thermal response of the regenerator has been clarified for a wide range of incident radiation, frequency, gas velocity, and heat capacity ratio. It has been demonstrated that the incident radiation and gas-phase conduction exert considerable influence on the gas and matrix temperatures, and thus on the temperature efficiency of the regenerator.

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An experimental study has been conducted on the heat-transfer enhancement in a turbulent flow in which the motion of electrically charged solid particles was controlled by an electric field. The gas-solid suspensions consisting of 48.9μm glass beads and air flowed vertically downward in a circular pipe, and a steady electric field was applied radially. Measurements on pressure drop and heat transfer were made, changing the Reynolds number from 5200 to 12000, the loading ratio from 0 to 0.6, and the applied potential 0 to 6kV. It was found that both the pressure drop and the Nusselt number increase with increasing applied potential and loading ratio. The maximum Nusselt number obtained in the experiment was about 1.8 times as large as that without an electric field. The mechanism of the heat-transfer enhancement was discussed, and its dependence of the Reynolds number was explained in terms of the interaction between particles and the gas phase.

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In order to prevent an anesthetized patient's body temperature from decreasing in the operating room, a mat with warm water circulation is often used. However, burn injuries sometimes occur on a patient's body in spite of the correct use of the mat. The cause of this injury has not yet been clarified. In this study, heat transfer between the bio1ogical tissue and the mat was calculated numerically under the condition of heat transfer by blood flow. The effects of the thickness of biological tissue, water temperature, heat transfer coefficient of the water flow in the mat, metabolic heat production rate, and blood perfusion rate distribution on heat transfer in biological tissues were clarified. From the standpoint of these effects, the conditions of occurrence of burn injury were examined. Results indicated that the model in this study was capable of simulating the mechanism by which burn injuries in the operating room are caused.

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The paper reports measurements of the thermal diffusivity of four molten alkali chlorides (LiCl, NaCl, RbCl and CsCl) in the temperature range above 1000°C by the forced Rayleigh scattering method. The dye substance employed is K₂Cr₂O₇ in order to color the transparent molten salts. The accuracy is estimated to be ±4 to ±11% depending on the measured substances. In comparison with the present results converted to thermal conductivity, most of the previous experimental data obtained by steady-state methods show larger values (up to about five times) which may be due to the presence of convection and radiation. It is found that the thermal conductivity of these series of molten alkali metal chlorides decreases with increasing molecular weight, and the temperature coeffcients are weakly negative.

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Reflux condensation inside a closed two-phase vertical thermosyphon is examined experimentally and analytically, with attention focused on the local heat transfer characteristics. Based on the detailed visual observation of the flow pattern of the liquid flow in the condenser, we take into account the effects of the following two phenomena in the proposed theoretical model : One is the turbulence in the liquid film near the gas-liquid interface which is caused by the wavelike structure of the liquid surface and also by the vapor flow. This improves the heat transfer characteristics in the lower part of the condenser. And the other is the deposition of droplets from the vapor core to the liquid film which results in the increase of the film thickness and therefore, deteriorates the heat transfer near the top end of the condenser. The estimated values agree well with the experimental data.

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A simple heat transfer model is proposed for natural-convection film boiling on long inclined flat plates in saturated liquids. The vapor film along the plate is assumed to be divided into two-dimensional laminar vapor-film units lining up along the plate. To determine the pitch of the vapor-film unit, the Kelvin-Helmholtz instability is used. The predictions by the model agree well with experimental results regarding the effects of the following parameters on the heat transfer coefficient : fluid properties, surface superheat, surface height, and surface inclination. This model is then extended for film boiling around large horizontal cylinders in saturated liquids. The model fares well in this situation too. Finally, experimental results on the interfacial behavior of saturated nitrogen along a vertical plate are compared with results from the model.

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Experiments were performed to study the effects of surface geometry and porous drainage strip on the condensation heat transfer performance of downward-facing submerged and vapor space condensers to be used for the immersion cooling modules. A smooth surface and two finned surfaces with and without the porous drainage strip were tested for condensation of R-113 and methanol. For the submerged condensers, formation of vapor space under the condensing surface was observed in the low-heat.flux regime, whereas the surface was covered with rising bubbles in the high-heat-flux regime. For both the submerged and vapor space condensers, significant heat transfer enhancement over the smooth surface value was provided by the finned surfaces. For the vapor space condensers, further heat transfer enhancement was provided by use of the porous drainage strip.

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Vapor explosion caused by the failure of light water nuclear reactor fuels under a reactivity initiated accident condition is studied through in-pile experiments in the Nuclear Safety Research Reactor (NSRR). Previously pressurized fuel rods containing uranium dioxide pellets are subjected to a pulse irradiation in the NSRR and heated by nuclear fission very rapidly. Pressure pulses and water hammer forces generated at failure are measured during the irradiation. It is shown that the generation of destructive forces is strongly affected by fuel fragmentation, but is not very sensitive to the initial fuel rod pressure.

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Transient and steady radial temperature distribution in a wafer heated with halogen lamps was numerically calculated. Unsteady conduction in the wafer was combined with two-dimensional radiation heat transfer between the specular wafer and the lamps. As radiative properties of a quartz tube changed from transparent to opaque at a wavelength of 4.5μm, the band-energy approximation was used. When the lamps were divided into center and side lamp groups and their power ratio was controlled to remain in the 1.4 to 1.6 range, the steady temperature distribution in the wafer was minimized. The mimimum temperature distribution was 1.1°C when the wafer diameter was less than the width of the center lamp group. In order to minimize temperature distribution in the wafer at temperature rising or cooling periods, it was necessary to change lamp power ratio at each temperature level.

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EXCIPLEX-based fluorescence thermometry was developed for remote probing of fuel droplet temperature. The fuel mixtures tested were n-heptane, n-decane and n-hexadecane which contained 1% naphthalene and 2.5% tetramethyl-p-phenylene diamine (TMPD). Also examined was unleaded regular gasoline into which no naphtalene or TMPD was dissolved. The fuel mixture suspended at the tip of a quartz fiber was allowed to evaporate in a stream of air or gaseous nitrogen, and its temperature was monitored using a fine thermocouple. The droplet was irradiated with a nitrogen laser and fluorescence emission spectra were taken by means of a light collection system which consisted of a convex lens, a light stop, a double monochromator and a photomultiplier. The results showed that remote probing of the droplet temperature could be achieved by measuring the ratio of fluorescence emission intensities at two different wavelengths.

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To investigate the critical state of encapsulated drop formation in liquid-liquid-gas systems, the dynamic behavior of a rising gas bubble across the interface between two immiscible liquids was analyzed experimentally and theoretically. The experiment revealed that an encapsulated liquid drop formed due to gas bubbles remaining at the liquid-liquid interface or rebounding from the interface before the liquid film on a gas bubble ruptures. A theoretical analysis based on an effective model was developed by considering the interface tension, viscosity and density of two liquids, and the rupture of a thin liquid film on a gas bubble. The theoretical result based on the simple model agreed with the experimental data.

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The nondimensional parameters that govern transient sprays were derived on the basis of the fundamental equations, boundary and initial conditions which describe transient sprays. The number of parameters was minimized by adopting appropriate reference quantities. It is shown that non-dimensional dependent variables are function of the nondimensional independent variables and pamareters. The penetration distance, droplet dispersion and gas velocity for the sprays of different conditions are illustrated in terms of the nondimensional variables to verify the validity of the analysis.

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It is widely known that the composition of blowby and crankcase gases plays an important role in the formation of low-temperature sludge in engine oil. It is further known that NO_x reacts with olefin contents of unburned gasoline to form sludge precursors. It is acknowledged that engine operation during stop-and-go driving accelerates sludge formation. In this study, the authors developed an oil evaluation test which combines the stop-and-go driving elements into a single STOP/GO driving mode and investigated why stop-and-go driving accelerates sludge formation. It was found that in low-temperature engine operation in the stop element of the STOP/GO driving mode, NO_x and unburned gasoline are absorbed into the oil, and in high-temperature operation in the go element of the STOP/GO driving mode, NO_x and unburned gasoline are released from the oil. NO_x comes in contact with unburned gasoline in the combustion chamber during the compression stroke and in the vapor of the crankcase ; it reacts with olefins in the unburned gasoline to form sludge.

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The acceleration performance of a diesel engine usually becomes worse after a cold start, especially in intensely cold weather. Many researchers have touched on startability problems, however, the acceleration problems have not been analyzed in detail. This paper shows the output characteristics of a swirl chamber diesel engine in the cold state. The performance was evaluated by the output torque. As the soak temperature decreased to under -20O°C, the output torque deteriorated to 60-80% of that under the warmed-up condition. When the engine speed decreased, the torque decreased compared to that in the warmed-up condition. In this case, the combtlstibility hardly influenced the output performance. On the other hand, the mechanical loss accounted for 60-70% of total torque deterioration. The glow plug system also reduced the output torque, and this Suggests that electrical load cannot be ignored in cold engine operation.

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The relationship between Bosch smoke density and the dry soot concentration in a particulate emission is examined experimentally using various test fuels including water-emulsified fuel in the wide operation range of a small-sized, high speed-turbocharged DI diesel engine. A good correlation has been confirmed between them in the combustion tests of automotive diesel oil and marine diesel oil. However, parts of the data have deviated from the above correlation curve in the cases of water-emulsified fuel and heavy fuel. The reasons for the deviation have been clearly shown by electromicroscopic studies of trapped particulates in the filter and by analyzing a relationship between the sulfur content in the fuels and the sulfate content in the dry soot.

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To improve the volumetric efficiency of a crankcase-supercharged 4-stroke cycle engine in the high speed range, rotary disc valves were used at both the inlet and the outlet sides of the crankcase in an investigation of the effects of opening angle and timing of disc valves on the volumetric efficiency. As a result it was found that a volumetric efficiency of 120% was possible over a wide engine speed range of 3000-6000 rpm, which was not poss ble by using the reed valve system.

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A fundamental test apparatus of the hydraulic free piston internal combustion engine, whose pistons stop after every gas cycle, is constructed and tested. To eliminate the vibration of the system, an opposed-piston construction is used in this experiment. Other features of the test apparatus are fuel injection, compression ignition, uniflow scavenging, two-stroke cycle and single cylinder. For intermittent operation, a high-performance pilot-operated hydraulic check valve is necessary, and a newly designed and constructed valve is used in this test. The synchronization of the opposed pistons is achieved by positioning both pistons at mirror positions before the start of the gas cycle; no mechanical cynchronization system is employed. The test apparatus performs satisfactorily, and intermittent operation, stopping after every gas cycle, is realized.

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