In order to establish the necessary condition for such cavitation experiments in an open type cavitation tunnel, the cavitation nuclei distributions were carefully measured in the test water sampled from a fixed point in the stilling reservoir for a typical flow quantity, by means of a Coulter counter. It is worth noting that in the cavitation tunnel, the nuclei distributions scarcely change with time in the entire working period past the initial unstable period. The waiting time to stabilize the distribution is also defined.

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In this paper, the behavior of a ferrofluid drop formed at the tip of a nozzle under the action of non-uniform magnetic fields is clarified by analyzing pictures taken by a high speed camera. Moreover, the period of drop formation and the drop diameter are experimentally examined. Then, various factors governing the period of drop formation are found by using dimensional analysis, and the empirical formula of a dimensionless period of drop formation is given.

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We investigated the behaviour of a steam slug which was rising in an isothermal vertical pipe at a reduced pressure. When the water temperature around the steam slug was higher than the saturated temperature, the slug grew upon rising in the pipe. The temperature difference between the steam slug and the surrounding water was increased, when water velocity in the pipe was increased or a static pressure to the system was decreased. The increase in velocity of the leading edge of a rising steam slug was caused by the slug growth. But the trailing edge velocity of a steam slug was equal to that of an air slug without growth in water. As the water temperature around the tip of the steam slug was locally higher than the mean flow temperature, it was regarded that the liquid vaporization, which caused the slug growth, occured at the front face of the slug.

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The characteristics of instabilities and the transition processes to turbulence are studied experimentally for the flow between a rotating disk and its casing. The spectral analyses of the velocity fluctuations show that, in the case of a larger clearance ratio (s/R=0.080), an inviscid instability of the boundary layer flow on the rotating disk starts at the local Raynolds number Re_L(=r²ω/ν) of about 8×10⁴, which is in good agreement with that obtained theoretically in our previous work. Visualization of the flow near the rotating disk reveals that two different types of instabilities occur at any clearance ratio tested (s/R=0.016∼0.160). It is believed that one of these is a viscous type and the other is an inviscid type. The characteristics of these instabilities are compared with those predicted by a linear stability analysis. The transition processes to tubulence are clarified for two different clearance ratios (s/R=0.080, 0.016) in view of the velocity power spectrum.

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The similarity of the internal flow in wall attachment devices has been examined experimentally for the Reynolds number range of 8×10³∼24×10³, based on the dimensions of the device model, the nozzle velocity and the kinematic viscosity of fluid. The nozzle width, which represents the characteristic scale of the device model, was altered in the range of 1.5 mm to 12 mm in the case of a water device model, and 1.5 mm to 6 mm in the case of an air model. Throughout the present study, the geometric shape of all the device models was made similar by altering both the splitter distance and the side wall angle. The results show that the internal flow in the water device models was similar for each model within the range of the experimental Reynolds number. The water models and the air models have different linear relationships between the reattachment distance and the maximum side wall pressure distance, respectively.

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This paper describes an experimental study of the flow past a cube with rounder side-corners placed on a ground plane. The experiment was carried out in an N.P.L. type wind-tunnel having working section dimensions of 400 mm×400 mm × 2000 mm at the Reynolds number 4.74×10⁴. The surface-pressure distributions on the cube were measured, and the drag and side force coefficient were determined from the surface-pressure distributions. Furthermore, vortices of two kinds generated around the cube have been observed. As a results, it is found that the drag coefficient decreases rapidly in the range of 0≤2R/D≤0.3, and the Strouhal number of arch-vortices shedding changes as the radius of corner increases.

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Laminar water flow with a free surface on a circular cylinder rotating about its axis aligned with a horizontal line has been calculated using the integral method. The result of the calculations showed that increasing the rotational speed of the cylinder reduced the wall shear stress and the displacement thickness to the negative value near the nozzle exit to pull the water in the downstream direction, which resulted in the rapid reduction of the water depth near the nozzle exit. The results of this calculation agreed well with the measurement of the water depth.

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Developments of vortices behind a circular cylinder with its impulsive start were investigated by flow visualization techniques. Special attention was paid to elucidating the relation between the structure of vortices and the Reynolds number Re, from the viewpoint of the convection of the vorticity generated on the surface of the cylinder. The structure of the vortices vary considerably with the Reynolds number immediately after the start of the cylinder for the duration, τ<1∼1.5, where τ is the nondimensional elapsed time. In a high Reynolds number, the separated shear layers roll up close to the separation points and form intense vortices near the rear surface of the cylinder. For Re>3000, the separated vortices induce not only secondary vortices but also tertiary vortices near the separation points. After a duration of τ>1.5, the variation of the structure of the votices with Re was found to be small. The ratio of the circulation to the area of vortex region indicates nearly a constant value.

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Numerical simulations of flows around two square cylinders arranged side by side in the middle of a flow channel between two parallel walls were investigated by finite-difference analyses of the two-dimensional Navier-Stokes equations given in stream function-vorticity formulations. For flows in a multiply-connected region such as this subject, the value of the stream function on each cylinder cannot be given a priori. A new method was proposed to determine this value by means of calculating the circulations flowing out through the control surfaces which were set around each cylinder. As the distance between two cylinders was changed, different flow patterns were successfully reproduced showing good agreement with experimental results.

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Effects attributable to shock wave movement upon cascade flutter were studied experimentally, using 13 miniature pressure transducers aligned at 3% chord length intervals on the blade surface of an transonic turbine cascade. The experimental range was for 4 outlet Mach numbers, 4 interblade phase angles and reduced frequencies from 0.028 to 0.330, based on half chord. It was made clear that the shock wave movement strongly affects the occurrence of cascade flutter. The effect was remarkably dependent on an interblade phase angle, not on a reduced frequency or an outlet Mach number. It acts as a blade vibration exciter or a damper. The pressure ratio of the time-variant pressure to the static pressure rise due to the shock wave on the blade surface was about 30%.

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On the basis of calculations of the pressure oscillation of a pipe system using transfer matrices, it has been experimentally established that the existing pipe model underestimates its dynamic damping. For practical use, the theoretical laminar model of D'Souza and Oldenberger has been thought to express the precise characteristics of the dynamic behaviour of the pipe. The authors have measured the dynamic characteristics of a centrifugal pump by using the hydraulic exciter. This report describes the successive experimental research to derermine the dynamic damping effect of the pipe. The measured damping term increased when the Reynolds number increased in the turbulent flow region, although they are almost the same as the theoretical model at the laminar flow region. The pipe transfer matrix model for the turbulent flow is proposed using the correlation of t he measured results and the equilalent kinematic viscosity.

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It is industrially important to clarify the unsteady characteristics of an underexpanded sonic jet In this paper, to investigate the instantaneous structure and behavior of an underexpanded sonic jet. issuing from straight circular pipes toward the atmosphere, the visualization of instantaneous flow and measurements of fluctuating pressure with time were carried out over a wide range of mean flow Mach numbers, 0.4∼2. The flow visualization was conducted by booth the spark schlieren and spark shadowgraph methods, and the instantaneous structure of flow was clarified. The fluctuating wave forms of the total and static pressures were measured by a particular microminiature probe with a built-in silicon diaphragm pressure transducer. In particular, the pressures fluctuation with time along the central axis and radial axis of jet flow were investigated. As a result, it was found that the self-excited flow vibration was generated and the characteristics of jet divergence were influenced by the vibration.

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A series of measurements was made simultaneously by using arrays of hot-wire anemometers with X-probes. The data show the rows consisted of doughnut-type large-scale vortices and their frequent pairing which results in larger vortices. The interaction of these vortices beyond the jet centerline breaks the doughnut^type large-scale vortices and forms three-dimensional medium and small-sized vortices. The flow is randomized through this process. Some large scale vortices continue to pair and form the configuration of counter-rotating vortices approximately alternating on opposite sides of the jet centerline in the region far from the nozzle.

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The flow in small venturi of a double venturi system in a carburetor with a main nozzle protruded at the throat is calculated in two dimensions by the finite element method. The governing equations are based on the stream function and the vorticity. Analysis is performed for seven kinds of main nozzle protrusion lengths in three types of diffuser angles. The separation region behind the main nozzle extends with an increase of the nozzle length. The results are evaluated in terms of the effective flow area at the exit of the venturi. The area change with protrusion length shows three stages, which is similar to the change of the air flow ratio for the small venturi observed in the former experiment using a three-dimensional model. The effective flow area is concluded to be responsible for the air flow ratio.

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Developing turbulent flows in the entry region of a curved rectangular duct are studied experimentally for both inlet conditions of uniform flow and fully developed flow. It is found that the developing flow region can be divided into the following three regions in spite of the difference between two inlet flow profiles : (1) The first region, the duct turning angle φ=15∼45°, in which the secondary flow exists only near the end wall, so that the main flow has little effect of the secondary flow on its velocity profile ; (2) The second region, φ=45∼105°, in which the cross-section of the duct is filled with strong secondary flow which affects the main flow extensively ; (3) The third region, φ=105∼195°, in which both the main and secondary flow are relaxed gradually to be a fully developed equilibrium state.

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An experiment is conducted to reveal the near field characteristics of the axisymmetric jet discharged from a sufficiently long circular pipe in which a fully-developed turbulent flow has been achieved at the exit plane. Two different configurations of the pipe exit are tested in order to examine their effect on the jet development. Up to an axial distance of about 4d (d is the inner diameter of the pipe), it is found that the mean velocity and turbulence intensity in the core region show relatively more gradual variation, and the volume flux is larger, compared to those found in the jet with a potential core. At further downstream stations, various flow properties exhibit qualitatively the same behaviour as the jet with a potential core. Turbulence quantities in the jet with a right-angle flange at the pipe exit are slightly but consistently larger than in the jet with a thin lip. Marked differences in turbulence quantities and the entrainment rate are observed between the present data and Boguslawski-Popiel's data in spite of both being obtained from similar experimental conditions.

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Three components of mean velocity have been measured in a square-sectioned 90 degree bend of 2.0 radius ratio with upstream and downstream straight ducts attached using rotable hot wires. Measurements were made for a Reynolds number of 40, 000 and in various cross-section planes. The contours of the longitudinal velocity and the velocity vector diagrams of the secondary flow were obtained at successive streamwise stations. The main conclusions derived from the experimental results are as follows : (1) The flow is biased towards the inner-radius wall of the bend over the range from the entry of the bend to the streamwise coordinate θ≒80°, θ being an angle measured from the entry of the bend in the streamwise direction ; (2) On the contrary, the flow is biased towards the outer-radius wall at θ<gsim>80° and the bias is the most remarkable just behind the exit of the bend ; (3) The intensity of the secondary flow induced in the cross-section is maximum near the exit of the bend.

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When a bubble is accelerated in a flow field or its diameter changes violently due to cavitation, the history effects induced by unsteady motions of the bubble and the surrounding liquid appear in the bubble behavior. To estimate the history effects on bubble movements, the equation of motion of a bubble and Rayleigh's equation expressing the change in the bubble diameter are solved simultaneously for the flow around a body with an ogive nose. And the effects of field pressure and bubble size are discussed. The history effects made the trajectories of bubbles flowing near the body shift more toward its wall, and the effects are intensified when cavitation occurs. The bubbles flowing far away from the body are, however, hardly affected by them.

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Numerical viscosity is evaluated for a difference scheme of high Reynolds number flow and a new skew upwind scheme, having the following characteristics, is proposed : (1) The value at the center of the calculational mesh is assumed to flow out at the outflow boundary of the mesh, and the volume weighted value of the upwind points is used for the inlet boundary. (2) The net transported quantity varies due to the flow direction, which is obtained by the remainder of the outflow from the inflow quantity. (3) Numerical oscillation is suppressed and the computational resolution is superior to that of the upwind scheme for a steep temperature field with pure convection. (4) The direction of the mainflow agrees with the experimental value which was obtained by Tanaka et al..

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An experimental study has been made to elucidate the fundamental aspects on the structure of two-phase jets in a cross flow. A steady circular jet of air laden with water droplets generated by thee ultrasonic atomization was discharged normal to a uniform stream of air. The spatial distributions of the size and number of droplets were determined with the use of the laser Mie scattering technique. The forward scattering LDV system was provided for measuring the velocity profiles of droplets and air. Oil mist was seeded in the jet for its visualization and air velocity measurement was made by LDV. An attempt was also made to predict the jet configuration on the basis of the calculated trajectory of a single droplet, as well as the empirical correlation for a turbulent air jet. The effect of cross flow on the structure and configuration of the jet was discussed.

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An experimental study has been performed on the turbulence properties of two-dimensional impinging jets on a wedge, in which the angle between the wedge-surface to the jets axis is 45°. The non-dimensional profiles of the turbulence intensities √(u²)^^^→/U_m and √(v²)^^^→/U_m, and the Reynolds-stress (uv)^^^→/U²_m in the fully-develloped flow region are non-similar and they are different to and larger than those of the two-dimensional wall-jets. It was found from the results on the isopleths of the turbulence intensities and the Reynolds-stress that the production of the turbulence is large in the impinging region at the vertex of the wedge. In the same region, the (uv)^^^→ has negative value over a fairly wide range near the wall. The velocity component in the normal direction to the wall is negative near the vertex of the wedge, and becomes positive in the region of x/b_j<gsim>4.

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Turbulence structures in the field of a free pulse jet discharged from a circular nozzle are measured and are compared with those with the coaxial surrounding flow and those when the jet is impinged against the opposed wall. The measurements showed that the existence of the surrounding flow and the wall depresses the peak velocity downstream from the nozzle and widens the radial distribution of the peak velocity. It was, however, known that the surrounding flow reduces the fluctuation of the arrival time of the peak to the measuring point, the axial and radial turbulence intensities, and the turbulent shear stress. In the case of the impinging jet, the existence of the wall hinders the decays of the turbulence powers of the axial and radial velocities in the higher wave number regions.

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A new method that can measure velocity and concentration profile simultaneously has been developed using computer aided flow visualization. In a water flow model, polystyrene particles only contained in a jet are used as tracers. They are illuminated by a slit beam light. This tomogram is caught by a TV camera and sent to an image processor. Velocity vectors are calculated from the path-length of the particles. The concentration profile of the jet is calculated from a brightness profile made by the addition of many instantaneous tomograms. At a high concentration region, brightness is high because there are many particles ; and at low concentration regions it is low because there are few particles.

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In our 1st report we reported on the simultaneous measurement of velocity vector and concentration. But there were some problems in the measurement of concentration. So we have conducted a basic experiment. Water containing polystyrene particles is agitated in a square vessel and illuminated by a slit beam light. A TV camera takes many instantaneous pictures and sends them to an image processor. A computor translates these pictures into binary images and adds these images to a gray image. Finally we can get brightness proportional to particle concentration. From this experiment, we have shown that (1) a proper threshold value and a low concentration is needed ; and (2) the variance of brightness decreases by the number of additions and dilatations.

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In piping systems, including centrifugal pumps, a pressure pulsation is generated. In this report, a centrifugal pump is assumed to have two characteristics : one is the generation of pulsation and the other is the propagation of waves. The combination of these two characteristics is linear, and the latter is described by a transfer matrix. The values of these characteristics are obtained by experiments and the above assumption is confirmed. The mechanism for pressure pulsation generation and the roll of the pump in pressure pulsation are grasped more exactly. The pulsation source of a centrifugal pump is the pulsating pump head. These experiments make it clear that the strength of the pulsation source is independent of piping systems, and its amplitude and phase are both almost constant at constant revolutions of the impeller.

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A centrifugal pump is assumed to have two characteristics for pressure pulsation : one is the generation of pulsation and the other is the propagation of waves. In this report, pressure distributions in a pump-piping system with the same pump as the first report are obtained by experiments, and are compared with calculated values based on the result of the first report. The pressure pulsation may be explained clearly based on the propagation and generation phenomena of pressure waves in a simple pipe system of resonable length, instead of a pump. Effects of pump configuration on the pressure pulsation become clear by experiments using two dimentional centrifugal pumps which have a different divergent angle of the volute, clearance gap between an impeller and a tongue, and blade number.

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If air bubbles or solid particles are entrained in a pump, they will cause degradation of the pump performance as well as erosion damage to its materials. This paper concerns the theoretical estimation of the three-dimensional movements of the particles entrained in a mixed-flow pump. The particle motions were numerically decided by a finite element method for water flow under the assumption of potential flow, and then by integration for equations of particle motion. The trajectories of air bubbles generally coincide with the streamlines of water ; however, they deviate considerably from the shround to the hub at the pressure side of the impeller blade. The solid particles move straight forward irrespective of the curvature of the water streamline, and collide with the hub surface.

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The experiments on the newly-developed water jet pumps, which have jet nozzles out-side of water transportating pipes, show the practical usefulness for the water transportation of solid materials. The tested water jet pumps are (1) a 90° bend connected directly with a water jet nozzle, (2) a 30° elbow with a water jet nozzle and (3) a straight pipe with a conical jet nozzle. From the experiments on the 90° bend connected directly with the water jet nozzle at various positions, it is shown that the 90° bend connected directly with the water jet nozzle along the centerline has the same characteristics as the previously used water jet pumps, which have jet nozzles inside of water transportating pipes.

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A tested aerator are consisted of a vertical cylindrical vessel with a coaxial inner casing, and an axial flow impeller is arranged in an inner casing. As a circulatory flow is built up between the inner tube and the outer annulus, there isn't any dead zone in the flow area in this new-type stirred aerator. Moreover, a high efficiency of the impeller may be expected compared with the conventional stirred vane. First, the effect of the existence of inner casing on the performance of aeration, and secondly, the effects of the air supply position, air flow rate, impeller speed and the diameter of air bubbles on the oxygen transfer rate coefficient are studied. Moreover, the dissolution efficiency of the oxygen and the power consumption are investigated.

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The purpose of this report is to investigate the fluid flow and heat transfer in an opposed plane jet in a uniform stream. In the previous paper, experimental results indicated that there were unsteady motions of low frequency and large scale, which are known as flapping of the jet. In the present paper, the unsteady motions for Reynolds number of jet Re_o=1500 and the ratio of jet to uniform stream velocity α=3.75 are studied numerically by the finite difference method. Previous experimental results are simulated in outline by numerical calculations. Time histories and instantaneous or time-averaged contours for velocity, pressure coefficient, temperature etc. are obtained, and the mechanism of fluid flow and heat transfer is clarified.

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This paper investigates how heat transfer and fluid flow are affected by channel width as it is varied from small to large scale in a wavy sinusoidal channel. The mean Nusselt numbers in periodic fully developed regimes depend on the maximum Nusselt number at the reattachment point of the flow separated from the top of the peak, and achieve maximum at P/H=2.0∼1.6 (P : pitch, H : width) ; the friction factor, on the other hand, is maximum at the same ratio P/H=2.0∼1.6. The performance ratio η_II, at equal pumping power, attains a maximum at P/H=2.29∼2.0. Thus, it can be concluded that the channel is optimum at P/H=2.0 for augmenting heat transfer.

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The critical heat flux in narrow tubes with 1-3 mm inside diameter was investigated for the exit equilibrium qualities from subcooled to quality regions using water at ambient pressure. In the subcooled region, critical heat flux increased with the decrease of the tube inside diameter, and in the quality region, vice versa. Further, the critical heat flux for the 2 and 3 mm inside diameter tubes was confirmed to increase with the increase of qualities in the near zero quality region. This means the existence of a minimum in the critical heat flux in the region. These characteristics were explained qualitatively with the difference of the mechanisms of the critical heat flux between subcooled and quality regions.

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Various types of moments of velocity and temperature fluctuations of the first to the fourth order have been measured and analyzed. An orthogonal series expansion for the three-dimensional joint probability density is developed using the cumulants and Hermite's polynomials. This density function is found to provide satisfactory predictions for the statistical characteristics, including triple products, of turbulent heat and momentum transfer.

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On the basis of the results of the 1st Report, the conditional sampling and averaging technique is employed to investigate the statistical characteristics of coherent turbulent transfer processes of heat and momentum. Conditional probability density functions are developed for various moments of velocity and temperature up to the third order. It is shown that the present density functions can predict the detailed role of coherent motions in the dynamics of wall turbulent shear flows and in the relevant process of scalar transport by turbulence. In particular, the importance of coherent motions in the turbulent diffusion process of turbulence energy and temperature variance, i.e., triple products, is demonstrated for the first time by the present theory.

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The purpose of this study is to study a heat transfer augmentation method for a two dimensional wavy duct with a bend angle of 60° by means of the instertion of flow guide-plates. Experimental studies were carried out by inserting two guide-plates with different features, the main heat transfer augmentation factors of which are the flow acceleration and the flow separation and reattachment. It is clarified that the augmentation of heat transfer performance by the flow separation is superior to the flow acceleration, and the effect by the former was found to spread in a very wide region. On the contrary, the flow acceleration method was found to have a limited heat transfer enhancing area. The average Nusselt number in the case of the insertion of guide-plates for flow separation was found to increase about 1.52 times compared with a wavy bare duct, and about 1.41 times that of a straight duct for the given pumping power.

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Two-dimensional impinging jets in line have been used for many industrial applications for cooling and heating, but the effectiveness of the heat transfer augmentation has not been well established. The purpose of this study is to clarify the augmented heat transfer performance of impinging air jets in line by means of providing roughnesses on a heat transfer surface. The optimum position of the roughnesses are studied experimentally for the jet Reynolds number of 1×10⁴ when the jet-to-plate spacing is equal to the jet slot width. It is clarified that, even though of no roughness the two jets increases the total heat transfer performance by about 1.4 times that of one jet without roughness regardless of the jet spacing, under the optimum condition the average surface heat transfer coefficient in a semi-enclosed environment increases by about 2.30 times that of one jet without roughness.

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Basic experiments and statistical analysis were performed concerning the effects of cooling surface properties on the degree of supercooling. In experiments, pure water layers were cooled from the top by five kinds of copper cooling surfaces (electrolytic polished, buffed, gold-plated, nickel-plated and porous copper disks) under various cooling rates, and the degrees of supercooling at the appearance of dendritic ice were measured. The results were compared under a statistical concept to discuss the effects of cooling surface properties on the mean degree of supercooling. As a result, the porous surface showed the lowest degree of supercooling. Next in the analysis, a method to estimate the probability of ice appearing on a cooling surface was proposed. The probabilities for the above surfaces were calculated as the functions of the surface temperature.

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Experimental study of the condensation of pure and mixed refrigerants of R22 and R114 inside a spirally grooved horizontal tube is carried out for a tube-in-tube counter flow type condenser in the ranges of 3∼21 bar of pressure and 26∼70 kg/h of mass flow rate. Axial distributions of refrigerant, tube wall and cooling water temperatures, wall heat flux and vapour quality are graphically shown and circumferential distribution of tube wall temperature is also shown. The characteristic of the local Nusselt number depends on the molar fraction, while the average Nusselt number can be correlated well by an equation, which is modified from a previously established equation for pure refrigerants inside a smooth tube.

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Film condensation of downward flowing R-113 vapor at near atmospheric pressure on in-line and staggered bundles of smooth tubes was experimentally investigated. The inlet vapor velocity range (based on the minimum flow area) was varied from 2.1 to 20 m/s, while the condensation temperature difference range was varied from 3 to 30 K. Based on the momentum and heat transfer analogy for the condensing film flow, empirical equations for the heat transfer coefficient were derived for both the in-line and staggered tube bundles. These equations compared well with most of the available experimental data for both refrigerants and steam.

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The object of the study is to clarify the transition modes of film-to-dropwise condensation on the lyophobic surface. From the measured results of the propylene glycol vapor for three surface edge conditions, changing the wettability, i.e., for wetting, partially non-wetting and non-wetting edge conditions, the transition modes were greatly affected by these conditions. Comparing the curves for decreasing surface subcooling with those for increasing subcooling, the reversible curves and the hysteresis curves, depending on the edge conditions, were obtained in the case where the overall cooling-side conductances were large enough to obtain the continuous curves for the increasing subcooling process. When the overall cooling-side conductances were small and the condensation curves had jumping regions, the hysteresis curves were essentially obtained for any edge conditions. The transition modes, for decreasing subcooling cases, were closely related to the variations of the condensation aspects, and were controlled by the edge conditions and the instability in an overall heat transfer system.

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The unsteady one-dimensional heat conduction equation is transformed into Kummer's equation unifiedly in the linear, cylindrical and spherical coordinate systems. This ordinary differential equation (similarity equation) is solved in terms of the confluent hypergeometric functions. The conditions under which such solutions (similarity ones) exist are that boundaries must lie at the origin and infinity, or otherwise move with their positions proportional to the square root of time. For the already known similarity solutions in the case of fixed boundaries which are expressed in terms of other functions such as an error function, its repeated integrals and the exponential integral function, the corresponding confluent hypergeometric expressions are given. The conduction similarity solutions can be applied to solve such a moving boundary probmem that the moving boundary moves as the square root of time. However, if there is phase change, only one solution exists in each coordinate system.

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In toner fusing techniques for electrophotographic machinery, the basic analysis of fusing phenomenon has been required. In the first place, it is necessary to understand the unsteady temperature field in the toner during fusing. Actually, the temperature variation is nonlinear with property changes according to melting. However, even the linear analysis of the temperature field has not been carried out because of the difficulty of the phenomenon. As the first approach to the analysis, the one-dimensional unsteady temperature distribution assumed to be the linear temperature field is analysed using finite element method. Heat flux which is supplied to the toner layer, thermal properties of the toner and paper, toner layer thickness, paper thickness and toner coverage are measured. The results of these measurements are used in the boundary condition and properties of FEM calculation. In this way, the temperature distribution during fusing is obtained.

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An apparatus for measuring local humidity with optical fibers is reconstructed and applied to the measurement of water-vapor concentration in a boundary layer, in which combined heat and mass transfer in free convection between vertical parallel plates occurs and the temperature distribution is not uniform. The two optical powers of 1.37um (absorbed) and 1.24um (un-absorbed) is measured simultaneously with a beam splitter and these ratio immediately computed. Then, it is able to compensate for lowering these optical powers by the beam shift due to the temperature distribution. The water-vapor boundary layer is generated between vertical parallel plates, one of which is wetted and heated. Measured distributions of water-vapor concentration at the upper end of the plates agree well with numerical ones.

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The instantaneous spatial temperature profile is measured by the Laser Rayleigh Scattering method using a detector which has 512 photodiode elements in one line. It was applied to two typical turbulent diffusion flames with different degrees of turbulence. The results obtained are as follows. (1) A comparatively large scale of temperature fluctuation dominates the temperature fluctuation intensity in turbulent diffusion flames. (2) The average and instantaneous maximum temperature tends to decrease when the Re number increases, and consequently the turbulence seems to increase.

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For the development of de-NO_x combustion technique of pulverized coals, a fundamental combustion test was carried out using a combustion electrically outer heated test furnace (the inside diameter : 115, the length : 1500) with co-axial burner. This report is concerned with behavior of coal nitrogen in combustion. The main results are as follows. The high swirl of the secondary air is effective for low-NO_x emission because emitted NO_x is deoxidized by NH₃ which is produced in the reduction zone near the burner. NO_x reduction process is very much influenced by the temperature of the reduction zone. The formation of NH₃ from coal nitrogen results from volatile matter in coal, and the formation of HCN results from chemical combinations of fuel-N.

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In order to confirm the performance and characteristics of plasma jet ignition quantitatively, combustion tests were carried out by varying the governing parameters of plasma jet ignition. Three plasma cavity sizes of 37, 75, 170 mm³, two orifice diameters of 1 and 2.5 mm, and three discharge energies of 0.3, 1.5, and 6.7 J were tested in two different types of combustion vessels with lean hydrogen-air mixtures at equivalence ratios of 0.3 and 0.4. From a series of tests, the combustion enhancement by the plasma jet ignition is revealed only in the initial stage of combustion. Then a comparing parameter of the performance of plasma jet ignition in its initial stage of combustion is proposed by comparing the pressure diagram of plasma jet ignition and that of conventional single-point center ignition. The performance and the characteristics of plasma jet ignition are revealed quantitatively by the comparing parameter.

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It was shown experimentally that the thermal performance of a heat pump system with a collector (evaporator) which had high convective heat transfer coefficient was not bad even when the solar incident radiation became small. However, with this collector the solar radiation increased the coefficient of performance (COP) little. On the other hand, with a collector which had a low convective heat transfer coefficient, the COP was very high when the solar radiation was available and was very low when it was not available. Thus, each collector had an advantage and disadvantage depending on the weather conditions. It was considered to use these two different types of collectors arranged in a row in the heat pump system. As a result, the weak point of each collector was covered by the other collector resulting in a good performance.

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It is important to utilize water-dominated geothermal resources and waste heat sources from factories from the viewpoint of energy saving. The cycle performance of single and double total flow turbine systems (1TS, 2TS) and a single flash turbine system (1FS) is analyzed under the condition of wet steam at the inlet of the systems in a way similar to that described in the 1st report. First, the available energy of the systems is expressed on a T-s diagram, and an optimum intermediate temperature which maximizes the system efficiency of 2TS, 1FS, is clarified. Second, the efficiency of the two-phase flow turbine required for 1TS to achieve the system efficiency higher than 1FS is shown and an increase of the system efficiency of 2TS over 1FS is estimated .Moreover, the effects of factors such as inlet pressures and temperatures on the cycle performance of 2TS are shown.

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Three techniques were employed, in this paper, to clarify the origin of impact noise in a two-stroke spark-ignition engine. First, the frequency analysis for a particular time segment involved in one engine cycle of vibration and noise was examined. It became possible to find the frequency characteristics of any instantaneous response which occured in an operating engine. Next, an attempt was made to identify the origin of the impact by isolating vibrations and/or eliminating parts in the drive system of the idling engine. Finally, the time history of each one-third octave band frequency component of the engine response was schematically shown to visualize the generation of vibration and noise. As a result, it became clear that the primary reduction gears in the crank case were the predominant source of the vibration and noise responses in the idling test engine.

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