In the previous paper, a flow pattern converter composed of five stages of porous plates was devloped. Three kinds of sintered porous plates of spherical particles were selected for the converter under fixed gas and liquid flow rates. In this paper, a diagram is proposed to predict a minimum length of the bubbly-flow region for arbitrary gas and liquid flow rates and three kinds of porous plates. A distribution of the area-averaged void fraction and fluctuation of the void fraction in the downstream of the converter were measured to improve the performance of this converter and to predict the location at which a large bubble is regenerated. This prediction includes an attempt to clarify the mechanism of transition from bubbly flow to slug flow. It was confirmed that fluctuation of the void fraction played an important role in the transition from bubbly flow to slug flow.

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Accurate estimation of volumetric fractions in liquid-solid two-phase flow is required to design fluid machinery such as lifting facilities of manganese nodules and hydraulic transport systems for solids. The volumetric fraction of the solid phase is measured in vertical pipes of 20.9, 30.6 and 50.8 mm inside diameters. The solid particles used in the experiments are four kinds of spherical particles of 1.14, 2.57, 4.17(aluminum ceramics) and 2.96 mm (aluminum) mean diameters. A method of estimation of volumetric fractions has already been proposed by the authors ; it incorporates the suspension volumetric flux into the drift-flux model. In this paper, the correlations in the method are modified to be applied to the extended range of flow conditions. The results estimated by this method agree well with the present experimental results, and also with those obtained by other researchers.

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Measurements were made in order to investigate the effect of tangential blowing on the near wake of a circular cylinder. It was found that the state of the flow field in the near wake was divided into two, one of which occured when the blowing jet intensity was weak, and the other when it was strong. In the case of the weak blowing intensity, the formation region and the strength of the karman vortex became longer and weaker, respectively, when compared to the nonblowing state. On the other hand, when the blowing jet intensity was strong, they became shorter and stronger, respectively. The thickness of the separated shear layer, as well as the width of the fluctuation of both the separation point from the cylinder and the position of the separated shear layer, also varied according to the blowing intensity.

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A discrete vortex method is developed to estimate the wall effect on a separated flow past an inclined plate located in parallel walls. Present numerical results for pressure distribution, base pressure and Strouhal number are in good agreement with existing experimental data at angles of attack from 30°to 90°. The wall effects on unsteady characteristics of pressure distribution and normal force are numerically shown at a wide range of angles of attack and blockage ratios.

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Friction coefficients have been measured for turbulent flows through curved circular pipes with rough surfaces. An experiment has been carried out under the conditions of equivalent relative roughness k_e/d=3.59×10^-3∼3.25×10^-2, Reynolds number Re < 7×10⁴ and curvature radius ratios R_c=15, 30 and 45. An approximate expression, which expresses the experimental results well, has been derived using the boundary layer approximation.

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The evaluation of heat transfer characteristics of a helical coil heat exchanger of the decay heat removal system, where the primary coolant flows at a low velocity through horizontal banks of the tubes in the direction of gravity, is a growing concern in the engineering safety of fast breeder reactors. The purpose of the present study is to clarify the applicability of an inviscid flow model for the prediction of the heat transfer characteristics in combined convection in the helical coil heat exchanger. A sodium experiment of combined convection is carried out using two test cylinders with a diameter of 75 mm. The local Nusselt number obtained by the experiment is found to be in good agreement with the analytical value predicted under the assumption of an inviscid flow field.

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Turbofan engines may use a device known as a lobe mixer in the exhaust duct, in which the core flow and the fan flow are rapidly mixed with strong secondary flows. This mixing process provides a means of achieving significant performance gains and reducing jet noise. Although this fact has been known for some time, the details of the mixing process within the mixing duct and exhaust nozzle have not been well understood. We measured the three-dimensional turbulent flow in a scale model of an exhaust duct with a lobe mixer by using a hot-wire anemometer, and clarified, experimentally, the basic characteristics of the mixing process.

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The occurrence mechanism of an inlet reverse flow was studied in axial flow turbomachinery. A helical inducer, in which there is no accompaniment of stall or significant radial flow, was selected as the experimental piece. The flow between the blades was measured by a laser Doppler-type velocimeter and investigated using the end-wall boundary-layer theory. Results showed that the inlet reverse flow occurs adjacent to the pressure surface between the blades in the vicinity of the casing wall. Inlet reverse flow, caused by the momentum defect in the axial direction at the boundary layer on the casing wall and a significant pressure gradient in the axial direction adjacent to the inlet blade pressure surface in the partial discharge range, was found even though there was no presence of signiticant radial flow or stall.

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A new upwind differencing scheme is proposed and can be confirmed to be valid by simulations of the Karman vortex street and experiments in a water tunnel. The 3rd order upwind scheme (KAWAMURA scheme) is usually applied for high Reynolds-number flows, because of the stability of solutions and the correspondence to real flows, while the centered conservative difference scheme is still valid for low Reynolds-number flows. The new scheme evaluates local nonlinearity of the flow field, and assigns one of these two schemes. Strouhal numbers of simulated Karman vortex street are improved by this scheme when compared to the conventional KAWAMURA scheme, and flow patterns are much more similar to the experimental results of water.

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The techniques reported in the preceding paper have been modified to remove defects in the methods. The trichromatic coordinates specifying white pixel were regarded as the values which were the average values at each resultant stimulus, S passed through a low-pass digital filter. The principal component obtained from residuals between their values and the coordinates of pixels was used to detect the co1ors of path line pixels, red, white or green. For pixel changing in colors found by the threshold of the derivative of the principal component, the colors were determined by cluster analysis. The correct combination of initial and terminal points in overlapping pathlines was obtained by using deviations in the length of the straight line joining initial and terminal points, averages of S for the pixels on the lines, and average angles between two lines. The procedure mentioned made it possible to derive velocity vectors automatically, and the results obtained were consistent with the photograph.

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This paper is concerned with an experimental verification of the correlation between the local structure of a high-speed water jet in air and the damage process in a metallic material resulting from the impingement of the water jet. The experiment was made under the conditions of 30 MPa to 90 MPa in injection pressure and a nozzle inner diameter of 1 mm. The metallic material tested was aluminum. Three kinds of liquid (tap water, polymer solution and ion-exchanged water) were used as working fluids. Stroboscopic observations of the structure of the liquid jet and erosion tests were carried out for various liquid temperatures. The following facts were clarified : The mass loss increases remarkably with the addition of the polymer. The effect of the polymer additive on the structure of the water jet is to reduce the number of small-scale droplets, while leaving large-scale motions unchanged. Increasing the liquid temperature causes an increase in the mass loss.

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The equation of motion for the dissolution of an oxygen bubble in blood is derived by combination of an equation of motion for the bubble in Casson fluids taking into consideration the effect of hematocrit and an approximate solution of diffusion equation. According to computational analyses, the effects of hematocrit H_ct, the ratio &fnof; of the initial dissolved O₂ concentration to the cencentration at saturation, and the initial bubble size on the process of dissolution of an O₂ bubble in human blood are made clear. It is found that the dissolution of an O₂ bubble in blood is strongly influenced by hematocrit. The completely dissolved time T of the bubble is the least at H_ct=40∼50 which is the value of hematocrit for a healthy body.

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The lubrication modes of line contacts between vane and camring in oil hydraulic vane pumps with and without intravanes have been investigated. First, the variations of the radial acting force of a vane were calculated on the basis of the results measured for the dynamic internal pressure in the four chambers surrounding a vane in addition to the results in the previous paper⁽⁴⁾. Next, distinctions of the lubrication modes were made with Hooke's chart which represents an improve-ment over Johnson's. Finally, the influence of the boundary conditions in the lubrication region on the fluid film lubrication was examined by calculating the film pressure distributions. The results show that the high-frequency pressure ripple acts as the force causing separation of vanes from the camring, that the lubrication mode of the vane tip is the rigid-variable-viscosity region, and that discharge pressure higher than 7 MPa exerts a great influence on the oil film pressure in the large arc section because of the Piezo-viscous effect.

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As microcomputers have become widespread and the response speed of on/off solenoid valves has been improved, digitally controlled hydraulic systems are used in many applications. This paper deals with speed control of a hydraulic motor using an on/off solenoid valve which is driven according to PWM control. Intermittent flow through the on/off solenoid valve causes large pressure fluctuations accompanied by speed fluctuations. In order to reduce these, the on/off solenoid valve and a hydraulic motor are connected by a high-pressure flexible hose. A compromise is made between the magnitude of pressure fluctuations and system response speed. The present work shows the usefulness of the speed control method in applications where simplicity of the hardware is desired and high response speed is not needed.

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The thermal interaction between a molten metal drop and water is applied to produce rapidly solidified particles such as amorphous powder. When the atmosphere above the water surface is steam and the water temperature is low, particles of smaller size are obtained. When a pressure pulse from an exploding wire is applied to the boiling film on the molten metal drop, the particle size also becomes small. If the water temperature is high enough and the pressure pulse is applied, particles become more spherical. In the case of Pd-Si alloy with 20at % Si, it is confirmed that an amorphous phase is formed.

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A new simple method has been developed to measure the fouling factor inside a removed condenser tube. The principle of this method is to detect the temperature increase of the outer tube surface due to fouling inside the tube, where the condensation heat flux on the outer tube surface is substituted by thermal radiant heating. Equations for evaluating the fouling factor are presented.Tests have been performed by using several alminum brass tubes and titanium tubes which were removed from a few actual power condensers. Accuracy of the present method is estimated to be at most 1×10^-5m²·K/W of the fouling factor.

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A problem regarding the steady solidification of a liquid on a moving horizontal wall which is cooled to below the melting temperature of the liquid is treated in this paper. The liquid is assumed to flow out through a fixed wall, which is parallel to the moving wall, at a temperature above the melting temperature. The walls are assumed to extend infinitely in the horizontal direction. The problem is governed by four parameters: the Reynolds number, the Prandtl number, the temperature difference ratio, the ratio of the temperature difference between the melting point and the moving wall to that between the fixed wall and the melting point, and the ratio of the thermal conductivity for the liquid phase to that for the solid one. The governing equations can be reduced to ordinary differential equations. They are solved by using a numerical method and an asymptotic one. The thickness of the solid layer solidified on the moving wall is found to be independent of the velocity of the moving wall. That is, it is determined by the temperature difference and the distance between the fixed wall and the moving one, the velocity of the liquid flowing from the fixed wall, and the material properties of the liquid phase and solid one. In the case of a large Reynolds number and large Prandtl number, it is found to depend strongly on the value at the interface of the second derivative of the velocity in the direction perpendicular to the interface between the liquid and solid.

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An experimental study has been conducted to investigate the fluid flow and heat transfer of natural convection past a backward-facing step. The step and the vertical plates upstream and downstream of the step are heated uniformly with a constant heat flux, and water is used as a test fluid. The flow and temperature fields over the step are visualized. The result shows that the high-temperature fluid ascending from the upstream plate separates from the step after flowing over a certain distance from the step edge, while the low-temperature fluid above the step rushes onto the step surface after the separation. The local heat transfer coefficients of the step are also measured, and the results reveal that the above separation and inrush of a high- and low-temperature fluid yield the minimum and maximum heat transfer coefficients of the step. It is also found that the locations of the minimum and maximum heat transfer coefficients are determined solely with the local Grashof numbers of the step.

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Heat transfer experiments have been conducted on strongly heated gas flow in an annular duct. Special attention is paid to the laminar-turbulent transitional region. The results show that laminarization was not observed within the range of the experiments although this phenomenon took place in a heated circular pipe when other conditions were the same. Above a certain heat flux, heat transfer coefficient in the downstream tends to follow a new correlation: Nu_s=0.071Re_b^0.6Pr_b^0.4 which is independent of the heat flux. Numerical analyses are made using 3 types of turbulence models: k-kL-(uv)^^^-, k-ε-(uv)^^^- and k-ε models. The calculations were compared with the measurements and better agreement was obtained for the k-kL-(uv)^^^- model.

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Combined radiative and convective heat transfer is analyzed numerically in the combustion chamber of aeroengines by using the Monte Carlo method to obtain the profiles of heatflux onto the surfaces of high-pressure turbine-cooled nozzle vanes and cooled rotor blade group. The following results are obtained from the parametric studies : (1)radiative heat flux onto the nozzle vanes is over l0% of the convective flux for the nozzle-inlet temperature of 1700 K, (2)the radiative heat flux onto the rotor blade group is about half of that onto the leading edge of the nozzle vanes and (3)the radiative heat flux onto the nozzle vanes is affected by the absorption coefficient of the flame zone rather than by the nozzle-inlet temperature.

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The effects of frosts deposition on heat transfer and pressure drop were investigated using a finned tube heat exchanger composed of four rows. The concentration of water vapor decreases along the direction of air flow due to mass transport in the upstream section, so that the frost layer is thickest on the lst row and becomes thinner along the direction of air flow. The efficiency of heat transport strongly dependes on the number of rows in the heat exchanger since it relates to the growth of the frost layer. The increase in pressure drop through the heat exchanger due to frosting is related to the Reynolds number and the modified diameter after consideration of the frost thickness. It is found that the total pressure loss is calculated as the sum total of the pressure loss for each row.

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The performance on the extended surface heat exchanger composed of several rows with frosting was predicted based on a uniformly frosting model. The predictions for frost thickness, apparent heat fransfer coefficient and pressure drop through the heat exchager were in agreement with the experimental results using a finned tube-type heat exchanger. By this prediction, it was found that the performance of the counter flow type was higher in comparison with that in parallel flow type because of a uniform distribution in the thickness of the frost layer over the heat exchanger surface.

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Heat transfer due to thermal radiation at cryogenic temperatures was experimentally studied. The purpose of the study was to collect practical data and to establish the prediction method for heat transfer. Heat flux between various radiation surfaces was measured by the evaporation loss method. There were two sets of temperatures between radiation surfaces : one was between room temperature and liquid nitrogen temperature, the other was between liquid nitrogen temperature and liquid helium temperature. Effective emissivities obtained by measurements were well explained by using the total hemispherical emissivity of the cold surface at a "warm" temperature in place of that of the cold surface at a "cold" temperature in the "diffuse-gray" approximation.

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Measurements have been made for the effective thermal diffusivity of dispersed materials which consist of different thermophysical properties. The measurement results are obtained by the periodical heating method, and are compared with the predicted value calculated from effective thermal conductivity, effective specific heat and effective density. The equation to predict the effective thermal diffusivity may be applicable in the range in which the volume fraction of dispersed particles is less than 0.25. It may be recognized also that the effect of particle shape is exerted with increasing thermal diffusivity ratio of particle to matrix.

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An experimental study was performed on the permeability of screen wicks using water. A1so, an equation for the wick porosity influencing the permeability was proposed based on a model of the screen geometry. In the present experiment, screen mesh size, number of screen layers, packing condition of the screen and flow rate were changed. For the friction factor, a correlation C_f=A/Re was obtained ; here the coefficient A was related to the packing number ω defined by the ratio of n-layer thickness to n-times the single layer thickness of the screen. Consequently, it was found that the permeability of the screen wicks could be predicted considerably well from the expression presented in this study and became steeply large with the increase in the packing number ω, which showed the degree of hold-down pressure for screen wicks.

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The effective pore radius in screen-wick heat pipes, which is very important for the prediction of maximum heat-transfer rates due to capillary limitation, was investigated. An equation for the effective pore radius of the screen wicks was derived based on the model of the screen geometry. The capillary height for stainless steel and phosphor bronze screens was measured using water, ethyl alcohol and R 113 as test liquids. The influence of surface treatment (acid cleaning and oxidation) on the capillary height was also examined. From the comparison of the experimental data for water and ethyl alcohol with those for R 113, it was indicated that the contact angle was 24.2°for water and 16.9°for ethyl alcohol. Consequently, it was found that the effective pore radius of the screen wicks could be predicted considerably well by the expression presented in this study, and that the contact angle should be taken into consideration to accurately evaluate the maximum capillary pressure.

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A method using an ion probe to detect a flame by its plasma potential signal has been developed. The spatial resolution of the probe is demonstrated to be well improved over that of the conventional one. The plasma potential signal obtained by this method from a premixed propagating turbulent flame front shows one to six peaks for the investigated flames, each of them being regarded as a flamelet in the reaction zone of the flame. Based on this consideration, the propagating speed, the thickness of the reaction zone and the number of flamelets in the zone, the separation distance between two adjacent flamelets, etc. of the flame, were then obtained. Results of this experiment suggest the existence of "reactant islands" in the reaction zone, and show that the averaged number of flamelets in the zone increases with an increase in the turbulence intensity and/or a decrease in the Damkohler number.

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A new characteristic temperature, the "adiabatic limit flame temperature", has been proposed in this paper; it is an inherent temperature of a combustible mixture based on the thermochemical properties of the constituents. The concept of this temperature is very important, especially when considering a combustion system with energy recirculation between products and reactants. Since this is the highest temperature attainable in a combustion system without any auxiliary energy input, the available energy and the efficiency of the system should be estimated based on this temperature, instead of on the adiabatic flame temperature. An illustrative example of a system of reaction between diatomic molecules is shown, and the characteristics of the temperature are discussed. The low calorific limit of flammability is also discussed in this paper.

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To obtain design data of a subsonic ram.combustor for a hypersonic plane, hydrogen combustion tests were were made by an approximately one-tenth scale model. It was composed of a constant area combustion duct, a flame holder and a center body which simulate the turbofan engine to be used as a booster for the take-off mode. The conditions of supplied air velocity, air temperature and mixture strength were equivalent to those of the combustor inlet at flight speeds ranging from take.off to Mach 3. Gas velocity and temperature distributions along the axis and the values of total pressure loss were obtained by measurements of total and static pressures. Combustion efficiency was derived from gas analysis of the sampled gas at the exit. It was found that the fuel distribution in the combustor makes significant effects on the combustion efficiency near stoichiometric mixture condition.

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The application of a holographic interferometry technique for measuring the steady and unsteady state temperature distributions in two liquids, water and n-propanol, were demonstrated. The deflection and temperature errors caused by refraction, which is the most important source of errors within a steep temperature field such as the thermal boundary layer were discussed and estimated. Estimated errors in the measured temperature of the liquid phase under spreading flame conditions for a 0.5 cm path length of n-propanol with 250°C/cm temperature gradient is within 2% below 36°C. The technique required:(1) transparency of the liquid, and (2) availability of the relation for the thermooptic coefficient of the liquid with temperature. If these requirements are satisfied, the temperature distribution of the liqid phase can be measured with a high spatial resolution of 20μm.

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Applications of polarization S-branch CARS to thermometry and the nonresonant susceptibility(χ_NR) measurement are reported. The pressure and temperature dependence of background-free S-branch CARS spectra of N₂ is investigated in the temperature range of 300-700K and at pressures of 0.1-2.0MPa. The individual S-branch lines are clearly resolved in the whole range, and the temperature can be determined by the intensity ratio of S-branch lines. Collisional narrowing for S-branch CARS is theoretically discussed and it is proved that the S-branch CARS thermometry is the collisional narrowing free meadurement. The measurement of χ_NR of N₂ has been demonstrated using S-branch suppressed spectra. The measured value of χ_NR is 8.7±^0.2_0.1×1O-^-18 [(cm³/erg)/amagat].

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The size distribution of small praticles can be obtained by optical analysis of the Fraunhofer diffraction light scattered by particles. In this study, direct photographs of the diffracted light from particles or spray drops were taken using a pulsed laser and analyzed. Error due to the characteristic properties of this pulsed laser diffraction method were investigated for many groups of particles. The mean particle size was measured within an error of less than ±10%, even if the diffmacted light from particles passed through a high ambient temperature and pressure envirnment. The Fraunhofer diffraction pattern of a diesel spray in a vaporizing process was analyzed by this method to obtain the Sauter mean diameter of the spray.

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The Sauter mean diameter and size distribution of a diesel spray in a vaporizing process were studied using the pulsed laser diffraction technique presented in the lst report. The Sauter mean diameter and size distribution were introduced to study the overall vaporizing phenomena of the spray. The liquids used were diesel fuel and n-Heptane. The Sauter mean diameter increased once, then decreased with an increase of the ambient temperature, under the ambient gas density, which was kept constant at a high pressure level. This change of the Sauter mean diameter was different for the evaporation rate of a fuel. The increase of the Sauter mean diameter of the n- Heptane spray occured at a lower ambient temperature condition than for the diesel fuel spray.

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Diesel soot formation processes were simulated, using several models previously proposed for soot formation and oxidation. The models were assessed and improved by comparing the results with the experiments. Consequently, the model which represented qualitatively the total mass history, the formation position and the spacial distribution of soot was established. The outline and characteristics of the model are as follows. (1) The soot formation model consists of both the Tesner and Farmer models. The soot oxidation model consists of both the Nagle and Magnussen models. The model giving a smaller rate was selected for both models (formation and oxidation). (2) Some of the coefficients in the Tesner model were corrected depending on the in-cylindr volume change. (3) The Farmer model was used only to cover the deficiency of the Tesner model which must be improved due to tempareture dependence.

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In the experiments presented here, diesel fuel oil was injected into a high pressure chamber in which compressed air or CO₂ gas at room temperature was charged. A single spray was impinged on a flat wall at a normal angle. The growth of the spray was photographed, not only with transmitted light but also with scattered light through a narrow slit. The temporal and spatial distribution of the droplets density in the impinging spray applying the concentric circle model was calculated using data collected by the laser light extinction method. From these results, detailed information concerning the droplets density in the impinging diesel spray was obtained. The effects of ambient density, distance from the wall to the nozzle, and injection pressure on the impinging spray were revealed. Finally, experimental equations for the radius and the height of the impinging spray were obtained.

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Prediection of instantaneous heat flux to a cylinder head surface in a direct injection Diesel engine has been made, solving the energy-conservation equation for the one-dimentional unsteady thermal boundary layer in the cylinder. The authors have proposed a simple algebraic expression for equivalent thermal conductivity, taking into account the heat transfer of turbulent eddy and its enhancement due to combustion. The results show good agreement with the measurements of instantaneous heat transfer rates for a typical position on the cylinder head surface in a non-swirl engine, over the fairly wide range of operating conditions.

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In a two-stroke-cycle gasoline engine, the scavenging flow plays a very important role in the combustion performance. The scavenging flow discharges the burned gas from the cylinder and draws the mixture of fresh air and gasoline into it. But the flow pattern in the loop-flow scavenging system of this type of engine is very complicated and measurement of the gas velocity and the gas concentration is difficult. Thus there is little information about the flow characteristics in the cylinder. The authors have developed a simulation method for the uniflow scavenging two-stroke-cycle diesel engine. In this report, we outline the development of this method, applying it to the loop-flow scavenging two-stroke cycle gasoline engine. The characteristics of the gas flow and the gas concentration in this engine are made clear by the simulation method.

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This paper describes measurement and analysis of intake flow characteristics in a two-cycle engine which have an important effect on engine performance. For a two-cycle engine, there is close correlation between gas flow velocity and pressure. Therefore, it is necessary to elucidate these relations. The gas flows in the intake pipe were measured with a fiber laser Doppler velocimeter (FLDV) which has excellent optical properties. Furthermore, we measured the intake pipe pressure, the exhaust pipe pressure and the scavenging port pressure as well as the intake flow velocity using a developed simultaneous measurement system to clarify their mutual relations. From these measurements, the relations between gas flow velocity and pressure became obvious. In addition, the flow characteristics in the intake pipe were investigated by measuring the velocity at several measurement positions for various operating conditions.

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A rational and efficient method of selecting optimum principal particulars of two-stroke, low-speed marine diesel engines in the early stage of planning during development has been developed. Its effectiveness has been investigated in this study. When planning diesel engines, selection of the optimum principal particulars is desirable, which meet the user's needs and market trends and can maintain a good balance in the performance and production cost aspects, ensuring reliability. The authors have developed a simulation method to estimate the precise production cost, which is one of the most important factors for selection, in the stage before making the drawings, and have established the method of selecting optimum principal particulars incorporating prediction of performance and evaluation of economy. This paper describes the outline of this method and reports examples of the calculations by this method.

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