In this review, the development of measurement techniques for thermal conductivity and thermal diffusivity, over the last several tears is presented. The review includes steady-state and transient techniques for solids, granular materials and powders, films and coating, fibrous materials, rocks and soils, liquids and melts, and gases.

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The effect of the location of pseudo-shock waves on the oscillations of pseudo-shock waves in a straight rectangular duct when the flows are choked at the duct exit has been experimentally investigated using high-speed schlieren photography and wall pressure flucuation measurements as five measuring points along a duct. The high-speed schlieren films of the pseudo-shock wave oscillations and the wall pressure fluctuations in the pseudo-shock waves were statistically analyzed using a micro computer. The characteristics of the pseudo-shock wave oscillations and the wall pressure fluctuations in the pseudo-shock waves are shown, and the mechanism of pseudo-shock wave oscillations is also discussed.

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The rapid expansion of moist air or steam in a supersonic nozzle gives rise to condensation, and the total pressure of the flow is reduced by this nonequilibrium phenomenon. In the present paper, a method is presented for calculating a loss in total pressure due to condensation generated by a rapid expansion of moist air in a supersonic circular nozzle. The loss in total pressure has been determined from the amount of increment in the entropy produced as the result of the irreversibility in the nonequilibrium condensation process. The calculated values of the total pressure loss are a little smaller than those of the experimental results, and they are about 2 to 5 percent in the present calculation. Based on the calculated results, the effects of degree of supersaturation of moist air and the shape of the nozzle on the total pressure loss have been clarified quantitatively.

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When a jet stream containing small particles impinges on a plane wall, the possibility exists that these particles will collide with the wall. By assuming that the flow is incompressible and irrotational, that particle motion is governed by Stokes' drag law, and that the interaction between particles can be neglected, the following characteristics can be theoretically determined by using the Stokes number and the inclined angle of the jet as parameters : The classification into various types of the collision between the particles and the wall, the critical conditions at which the particles first collide with the wall, the region in which the collision occurs, the distribution of the collision frequency along the wall, the ratio of the colliding particles to the total number of particles, the points at which the collision frequency peaks and so on.

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To obtain the behavior of cavitation bubbles in a radial-flow impeller pump, the equation of motion of a bubble and the Rayleigh equation expressing the change in the bubble diameter are solved simultaneously based on the flow field calculated numerically by a three-dimensional finite element method for an idealized potential flow. And the effects of suction pressure, the size of bubble, and discharge rate of water are discussed. When the bubble is in the range of pressure lower than the critical one, it grows abruptly, and the trajectories of the bubble shift toward the shroud surface and the direction of impeller rotation. In such ranges, the cavitation bubbles grow to a visible size. When the discharge rate of water becomes larger, the shift of bubble trajectories is intensified.

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Color flow-visualization photography and digital image processing techniques have been developed for the purpose of flow measurement in the flow field of a circular vessel with recirculation flow. The path-lines of aluminum powder were photographed on a color reversal film by illuminating it in red, white, and green in turn within an exposure time. The pixel values in red, green, and blue for 256 steps prepared by the drum-scanner as the digital image data of the film, the resultant stimulus and the trichromatic coordinates of each pixel were evaluated from them. The pixels for path-lines were distinguished from the background by the threshold-level of resultant stimulus, and their colors were determined by using the principal component obtained from combined and standardized residuals for the regression formulas of trichromatic coordinates. The velocity vectors can be derived from both the location and color of pixels, and the time interval of white color illumination.

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the present method is based on the fringe shifts of interferograms from different ray directions around a temperature field. The contours of the temperature field are obtained from the envelopes drawn at the boundary of each fringe shift. Temperatures are evaluated by solving the simultaneous equations of the first degree for the unknown refractive indices at the grid points in the contours of the temperature field. The method has been applied to the temperature fields of natural convention caused by heated plated, as well as to those of heated air jets with rectangular exit. The results have been compared with the temperatures measured by a thermocouple. It is found that the present method may be useful in evaluating temperatures and/or densities in some complex fields.

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This paper is mainly concerned with the dynamic structure of high-speed water jets, the damage process of metallic materials and a microscopic comparison of cavitation damage. The experimental conditions were an injection pressure of 30 to 90 MPa and a nozzle inner diameter of about 1 mm. Materials tested included aluminum, mild steel and stainless steel. The instantaneous behavior of the impact pressure was measured using a pressure transducer. Comparisons among stroboscopic observations for the structure of water jet, axial variation of the impact pressure and mass loss of the material caused by the jet impact showed that an axial location where the water jet begins to break up is close to the location of the maximum mass loss of the material. We have made a detailed comparative observation of the damage process for a water jet and for the cavitation (magnetostrictive vibratory method) using a scanning electron microscope and found some distinct differences in the damage process.

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the direct contact melting phenomena on a cylindrical heat transfer surface, set horizontally, is discussed analytically and experimentally. The basic equations for the thin liquid layer between the heat transfer surface and the phase change boundary are derived and normalized. Then numerical calculations are performed over wide parameter ranged to determine the liquid layer thickness distribution and the heat flux distribution on the heat transfer surface. The analytical and experimental results concerning the average heat flux at the heat transfer surface are found to agree well with each other. The exact solution for the heat flux distribution on the heat transfer surface is shown for the case of a small Stefan number, where the heat transfer through the liquid layer is approximated by the pure conduction.

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Numerical solutions of full Navier-Stokes and energy equations for two-dimensional laminar free convention between two concentric spheres are obtained for Pr=0.7∼120, Ra=1∼10³ and radius ratios of the outer to inner sphere r₂/r₁=5∼60. With decrease of r₂/r₁, the heat transfer coefficient for the inner sphere decreases first due to suppression of convective flow and then increases due to predominance of conduction heat transfer. The heat transfer coefficient at r₂/r₁>__=60 can be regarded as that for a single sphere immersed in an infinite medium for Pr=0.7 and Ra=1. The higher the Rayleigh number, the smaller is the radius ratio at which the Nusselt number can be regarded as that for a single sphere. An accurate correlation equation for the Nusselt number is proposed. A correlation equation for the relation among drag force induced by free convection flow, Rayleigh number and Prandtl number is also presented.

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The measured results of dropwise condensation curves for three organic substances, propylene glycol, ethylene glycol and glycerol vapors on a trilauryl trithiophosphite adsorbed copper surface were shown in the previous report. Two different modes of drop to film transition, the continuous and jumping modes were obtained. In this report, the variations in the condensation states measured simultaneously by high speed and video cameras are shown for both transition modes. Then, the contact angles of three substances during condensation were compared. The variations in the condensing states in all cases measured were generalized and tabulated. Furthermore, the mechanisms of the transition were discussed. It was certified that the contact angle and the viscosity of the condensate were the controlling factors in the case of continuous mode transition, and the curve shape of the jumping mode was similar to the continuous one, except for an unconnected part between the jumping and film points.

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Pressure-driven condensing flow through a porous medium which is initially subcooled below the saturation temperature at a given back pressure is investigated experimentally and analytically. The experimental results show that condensation occurs mostly in the form of a water slug accompanied by the stepwise change in temperature at its back interface even when the ratio of the inlet to outlet pressure is rather small. An analysis is carried out using the generalized Darcy law incorporated with the concept of relative permeability. It is then found that the initial subcooling significantly amplifies the slug growth rate and reduces the slug velocity due to the increase in the upstream pressure drop which is caused by the increased vapor flow rate. Comparison between the experimental and analytical results shows a fairly good agreement for porous media with small characteristic dimensions.

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Heat-transfer coefficients and maximum heat-transfer rates due to capillary limitation were investigated in horizontal heat pipes with stainless-steel screen-wicks, using water as a working fluid. The heat transfer coefficients in a condenser can be estimated by the equation of heat transfer across the liquid-saturated wick. The liquid-vapor interface in an evaporator seems to terminate between the first and second layers from the heated wall. For prediction of the maximum heat-transfer rate, it is important that the capillary radius, permeability and porosity are evaluated accurately. Thus, the capillary radius and permeability were measured experimentally. Also, an equation for porosity was proposed. Using the value obtained above, the recess of the liquid-vapor interface has to be taken into account. Consequently, the calculated maximum heat-transfer rates agree with the experimental ones within a ±20 percent error.

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The numerical analysis of unsteady heat conduction during quenching using the apparent heat capacity were investigated in this study. The temperature and the latent heat of phase transformation depend on the instantaneous cooling rate at the point A₁(727°C). The cooling curves accompanying the phase transformation were calculated using an iterative technique of implicit finite difference. These were calculated for two boundary condition cases : (1) the measured temperature of any radius (R 1∼R 3), and (2) the boiling curve. Agreement between the experimental and calculated results of case (1) was found. It was verified that the latent heat obtained by the previous study is useful for the numerical analysis of quenching. The calculated cooling curves for case (2) agreed well with the experimental results.

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This paper presents the characteristics of the breakup behavior and heat transfer of a single small droplet impinging upon a hot surface. Using the vibratory method, uniform-sized droplets of water were for med at constant intervals at room temperature and under atmospheric pressure. The breakup behavior relates well with the particular surface temperature, that is, the maximum evaporation point and the Leidenfrost point. The characteristics of heat transfer, i.e., the heat-transfer effectiveness and the heat-transfer coefficient, are also discussed.

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An equation of state for Refrigerant 114 (CCIF₂ CCIF₂) was formulated based on available PVT measurements, taking the thermodynamic consistency into consideration. The developed equation of state is expressed by the reduced Helmholtz function as a function of reduced temperature and reduced density. Derived isochoric specific heat capacity, isobaric specific heat capacity, speed of sound and vapor pressure were critically examined. The developed equation is effective for a range of temperatures 200 to 550 K and of pressures up to 20 MPa, which corresponds to the density range up to 1 750 kg/m³. With the aid of the proposed equation, the cycle analysis for the heat pump, refrigeration and Rankine cycle was carried out, and it became clear that Refrigerant 114 is a suitable working fluid especially for high-temperature heat pump systems.

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The flow and mixing in transient laminar jets of CO₂ emitted into an N₂ stream were experimentally studied. Time-and space-resolved measurements of velocity and concentration were made by a laser Doppler velocimeter and by the laser Rayleigh scattering method in transient jets, together with visual studies by Schlieren photography. The results obtained are as follows. (1) Axisymmetric large scale ring vortices are formed successively in the jet and travel downstream. (2) Out ward or inward radial flow is induced downstream or upstream of each ring vortex, respectively. The vortex has the velocity of solid body rotation in the central part, and free vortex in the outer part of the vortex. (3) The surrounding gas (N₂) is engulfed by the vortex to form the laminated layer which enhances micro-mixing in the molecular scale.

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It was believed that the increase of molecular viscosity due to high temperature raises the dissipation rate of turbulence in low-turbulent regions in a combustion field. Hence, the objective of the present study was to verify this both experimentally and theoretically. Experiments were carried out on jet diffusion flames of hydrogen, and then, a numerical simulation was conducted for the experimental results. In the simulation, the κ-ε two-equation model was used as a turbulence model and a new source term was added to the κ-equation to represent the dissipation rate of turbulence kinetic energy due to molecular viscosity. The calculated results agree well with the experimental ones. It was found that the new source term suppresses turbulence in low turbulent regions situated around the nozzle exit and the periphery of jets, and changes the condition in the whole combustion field greatly. The present work suggested that consideration of the viscous effect is important in the modeling of turbulent combustion fields.

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The catalytic reduction process of NOx by NH₃ has been applied mainly to the clean combustion flue gases of LPG or LNG, which do not contain the harmful component which reduced the catalyst activity. This paper describes the experimental results of a survey for the catalytic reduction removal of NOx from dirty gas containing higher concentrations of HCl, SOx and dust emitted from a municipal refuse incinerator. The effects of reaction temperature, space velocity and the amount of NH₃ injection on the NOx removal efficiency are studied experimentally, and the change of V₂O₅-TiO₂ catalyst performance with time is examined ; and the regeneration techniques for catalysts are also discussed on the basis of the results of the heat treatment.

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In order to reveal the effect of turbulence on combustion, the swirling flow of a propane-air homogeneous mixture was produced in a cylindrical combustion chamber. The mixture was ignited by an electric spark at the center of the vessel, and the flow and flame propagation were measured with a two-dimensional LDA system, high-speed laser schlieren photography and an ion probe. From these measurements, the burning velocity, S_T, and the burning zone thickness, σ_T, of turbulent flames were successfully determined under various conditions of turbulence intensity. Further, the turbulence characteristics of swirl and its decay process were investigated. The main results of this study are as follows : (1) S_T increases with increasing the turbulence intensity and σ_T increases with S_T, (2) the turbulence intensity increases in the burning zone of the turbulent flame, (3) the turbulence energy in the burned gas decays rapidly as compared with that in the unburned gas, and (4) after the completion of combustion, the fraction of higher-frequency components of turbulence decreases rapidly.

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A transparent model engine was developed which can generate an axially symmetrical flow field in the cylinder and which allows easy access to optical measurements of the in-cylinder air motion. Experimental data on flow characteristics such as mean velocity, turbulent velocity and turbulent scale in the entire space of the cylinder obtained with this engine are expected to be available for evaluating the reliability of the mathematical models popular at present. This paper describes the design concept and details of the structure of the engine, and offers some experimental data measured by both a flow visualization technique and laser Doppler velocimetry.

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A three-dimensional model for the combustion process in direct-injection diesel engines was established based on submodels for combustion and spray processes. The combustion submodel takes turbulent mixing into account to allow a description of the formation of a premixed combustible mixture, which undergoes an irreversible singlestep chemical reaction. The spray submodel uses the momentum theory, in which the spray is represented by a distributed sink and a source, to simulate gas entrainment and jet penetration, respectively. The ordinary two-equation model is employed as the turbulence model, and other factors are included in accordance with an existing multidimensional approach. Computations carried out for several different conditions in a high-swirl, deep-bowl diesel engine show a reasonable degree of reproduction of the entire combustion process. The combustion-induced flows and their effect on the flowfield are discussed in detail.

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The ignition delay of a diesel fuel was studied using a rapid compression machine that was developed in a previous study. By applying the hot-motored technique proposed by Yu and others, the delay from the start of injection to the onset of exothermic reaction and the delay required to pressure recovery were measured. The sum of the two delays was assumed to be the net ignition delay. Tests were performed for a range of air temperature dependence of the initial delay is low at high temperatures due to physical effects such as heating and vaporization. The pressure recovery delay is largely affected by the fuel-air mixing rate below 750 K. Based on the obtained data, an empirical formula of net ignition delay was proposed.

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The governor of a diesel engine often induces self-oscillations called "hunting", associated with the fuel injection system of the engine. It is very troublesome, however, to investigate hunting phenomena using real engines. In the present study, a fuel injection system simulator has been developed. By replacing the engine with an analog computer and a hydrostatic transmission system, the characteristics of the engine were easily varied. The frequency characteristics of this simulator agreed fairly well with those of real engine below 1 Hz. Using this simulator, the authors investigated the effects of some parameters on the hunting phenomenon below 1000 rpm, where it is difficult to apply the conventional linear stability theory because or irregular injections.

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