For cascade with a high turning and a large camber, it is difficult to impose grid orthogonality as well as point-to-point periodicity simultaneously on a single structured grid. In this study, the effects of periodic and non-periodic grids on finite difference solutions are investigated for twodimensional transonic flows about rotor blades. The spatial derivatives of the Reynolds-averaged Navier-Stokes equations are discretized with central difference approximations and matrix dissipation models. The resulting system of equations is integrated in time with an explicit 2-stage Rational Runge-Kutta scheme. For turbulence closure, Baldwin-Lomax model, Baldwin-Barth model, and Spalart-Allmaras model are compared. The non-periodic grids have favorable resolutions for the shock system and the wase. The shock-induced production of the eddy-viscosity is remarkable in the Baldwin-Barth model. The Spalart-Allmaras model works well, even on the periodic grids, in comparison with the other models.

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The corner flow which runs between a rigid boundary and a free surface is examined analytically, in order to investigate the pressure distribution due to the flow induced by blade coating. The method of the solution is to extend Moffatt's solution by taking tension and curvature of the free surface into account. A new equation which describes the free surface meniscus is also obtained. The extended solution is applied to the flow in the vicinity of the blade edge and the results are compared with those of a numerical solution. They are in good agreement with each other around the blade edge, where both of them are valid. In this paper, it is shown that patterns of the pressure distribution on the free surface and the blade can be divided into four categories. Finally, the conditions to keep the blade edge pressure non-singular are given.

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It is pointed out that mass transport in an artery, such as LDL transport, influences the progression of stenosis severely. Mass transport in blood flow through an stenosed tube is analyzed numerically. Flow is assumed to be periodic, incompressible and axisymmetric. Non-Newtonian viscosity of blood and movement of arterial wall are considered. The effect of pulsation, non-Newtonian property of blood and wall movement on mass transport is investigated. Flow pattern, concentration pattern and distribution of concentration gradient on the wall are obtained. It is found that the effect of the vortex on mass transport on the wall changes drastically with Schmidt number. In low Schmidt number flow the strength of vortex and its center position is important. Therefore, time-mean mass transport on the wall has maximum value at certain frequency because of the resonance of the vortex. On the other hand, whether the vortex downstream of the stenosis flows away or not becomes important in high Schmidt number flow.

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It is reported that there is riblet-type membrane on the inner surface, just above the endothelial cells, of arterial wall. If arteriosclerosis occurs in the artery, this membrane is buried and the shape of inner surface of arterial wall becomes very rough. Scince this shape change may cause a bad effect on the arterial wall, turbulent structure on a riblet-type wall and that on a rough wall are investigated. Turbulent flow between a flat plate and a riblet-type wall or a rough wall with constant pressure gradient is computed by large eddy simulation. Movement of low speed streaks, low pressure regions and friction on the wall are obtained. It is found that the friction of rough wall increases with decreasing their projection length in flow direction, and that friction of a rough wall is larger than that of a riblet-type wall. The rough wall on which projections are arranged in a check pattern has less friction than the rough wall on which projections are arranged in straight order.

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Buoyancy-driven helium-air exchange flow through double openings was experimentally investigated. The double openings with rectangular cross-section (w/2×d) were settled side by side in w direction. The exchange flow rate and the flow pattern around the openings were simultaneously measured. To clarify the effect of geometry, the cross-section of the opening was systematically varied. Under the smaller d/w geometry, the separated flow pattern (s) was observed, in which the upward and downward flows flew separately in the double openings, respectively. Under the larger d/w geometry, the unseparated flow pattern (u) was observed, in which the upward and downward flows flew inside the openings. The counter-current flows were observed in the openings. The exchange flow rate was a function of the flow pattern. For the flow pattern (s), the exchange flow rate could be predicted using the flow network model with considering the entrainment. For the flow pattern (u), the flow in the opening was same as the exchange flow through a single opening with the same geometry.

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Linear stability analysis was performed for a hydrocarbon liquid fuel jet (butane) issued into stagnant gas (nitrogen) whose pressure and temperature exceed critical values of the fuel. There are two types of flow instability ; one is the Rayleigh type and the other is the Taylor type. The Rayleigh type instability is based on the radius of liquid fuel jet as a reference length, while the Taylor type instability is based on the boundary layer thickness. As results, the growth rate of instability waves depend on the square root of Weber number and the thermodynamic phenomenon such as phase equilibrium and evaporation. Within this high pressure-temperature environment, the liquid fuel jet experiences sub-to-supercritical transition and changes the method of mass transfer at the gas-liquid boundary and lose surface tension. So the fluid-dynamic instability can be strongly affected by the thermodynamic conditions and physical properties.

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We developed a numerical scheme to resolve the flow around a solid particle which is several times larger than the spacing of computational grid. The method was examined applying to the threedimensional flow past a sphere in a uniform stream and the agreement with experiment was reasonable up to Reynolds number 600. The momentum transfer due to pressure at the particle surface was exactly evaluated. The error in the energy budget was less than 6% in comparison with dissipation rate. Our method therefore has enough accuracy and efficiency to investigate the interaction between particle-induced eddies and background turbulence in particle-laden turbulent flows.

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The measurement of time varying holdup was conducted for vertical upward gas-liquid twophase flows in capillary channels with four kinds of different rectangular cross section. Each test section has the dimension of 1 mm×1 mm, 2 mm×1 mm, 5 mm×1 mm and 9.9 mm×1.1 mm. The equivalent diameters and the aspect ratios were respectively changed from 1 to 2 mm and 1 to 9. Almost all the correlations already proposed so far, which were based on the data of larger scale rectangular ducts, were clarified not to be applicable to the present data of the capillary channel. As a result we proposed a new correlation and an estimation method of holdup by using those measured data. In the correlation the effects of surface tension and viscosity are taken into consideration. The applicability and the modification of the correlation for the data of the larger scale duct were also investigated.

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The model expression for the subgrid-scale (SGS) Reynolds stress and the transport equation of the SGS energy are theoretically derived using a two-scale direct-interaction approximation (TSDIA). Applying the model to three-type flows, which are a homogeneous decaying turbulence, a mixing layer and a channel flow, the model constants are optimized and the results are compared with those of the Smagorinsky model in details. Consequently, it is found that this one-equation model has two deficiencies. One is that the model-constants are dependent on the variety of flows like the Smagorinsky model. Another one is that an exact asymptotic-behavior of the SGS energy in the vicinity of the wall is not satisfied by this one-equation model. Therefore, for the purpose of improving the near-wall profiles for the SGS quantities in this model, a new model for the SGS dissipation rate is suggested on the basis of the low-Reynolds-number K-ε model. Moreover, using the model including with a high-order term of the SGS Reynolds stress, a new one-equation model which is applicable to several flows with fixed model-constants is proposed.

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In this paper, an improved stochastic process model of a particle-pair for the predicting the statistical value of the scalar fluctuation fields in a turbulent flow is suggested. The past other stochastic process models use a Karman-Howarth (Eulerian) relation as a Lagrangian velocity correlation function between the two particles approximately. It looks like a good approximation, but it should be exact neither physically nor mathematically. The main points of improvement are as follows : (1) The Faller's velocity relations of the Lagrangian tracers is used as a Lagrangian velocity correlation (2) The function form of the Faller's velocity relations is expanded to the viscous-dissipation range for the simulation of the low-Reynolds number turbulence. Simulations of two types of scalar fluctuation fields (of a point source plume and of a line source plume in a gridgenerated turbulence) has been made and the simulation results are compared with the experimental data. In both cases, the improved model show a better prediction of the actual scalar fluctuation statistics.

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The evolution of two-dimensional unsteady viscous vortices perturbed by a compression/expansion wave has been simulated numerically. Direct numerical simulations of the time-dependent compressible Navier-Stokes equations are performed using a spectral collocation method. The numerical shock deformation shows a very good agreement with the observations in a shock tube. The results of the two-dimensional simulations show the creation of vortices that is attributed to the influence of baroclinic and dilatational effects and the elliptical vortex underwent slight precession (tilting) in the direction of vortex rotation. The mechanisms responsible for the onset of acoustic wave propagation by a vortex and its alternate compression-rarefaction nature are described.

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Sport science progresses step by step in the world. The paper describes, the first, the relationships between fluid drag for a model of woman swimmer and the flow around it. The flow around the model swimmer is very complicated, and includes, for example, wave, some kinds of vortices, hydraulic jumping and so on. The complicated flows are visualized by the surface tufts method and so on. Second, the possibility of the reduction of fluid drag for a woman athlete swimming suit is challenged. The boundary layer control is applied to reduce the fluid drag. The separation occurs around the breast of a woman swimmer. The separation can be suppressed by the boundary layer control. Many beads are distributed on the breast area of a woman swimming suit. As the result, it is found that the fluid drag for the model swimmer can be reduced in a range of 1.5%∼2% by the suit with the boundary layer control, which is carried out by many beads.

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Natural convection of suspension was studied experimentally using both refractive index matching and laser induced fluorescent (LIF) technique. A rectangular test section was filled with particle suspension and was heated from a horizontal bottom, and two facing vertical walls were kept at the constant temperature. The images of the fluorescent particles were captured by a CCD camera through a sharp cut filter which separates emitted fluorescence from scattered excitation light. The flow velocity fields were analyzed quantitatively using PTV. Interface between particle-free fluid and suspension as well as temperature field were visualized simultaneously. It was suggested that two-layer convection cells were driven by heating and sedimentation of particles which drives convection in the overlying layer due to the release of the heated clear fluid at the interface.

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The present paper deals with a fluid flow issuing from an annulus and turning back into an inner pipe. I present the experimental data using various types of concentric double pipes, in particularly, giving the loss of total head through a turning flow region from the annulus to the inner pipe. They are given in terms of a nondimensional clearance length L/d₁ (L is the distance between the annulus outlet and the outer pipe bottom and d₁ is the inner diameter of the inner pipe) for various values of area ratio and Reynolds number. It should noted that curves of coefficient of head loss against L/d₁ have the maximum value about L/d₁=0.625 for A_r=1.28 in the range from Re=4.4×10³ to 3.1×10⁴ and the maximum value about L/d₁=1.00 for A_r=3.38. Thus, L/d₁ against the maximum value of head loss changes with a area ratio increase. It became clear by the means of visualization that the increase of head loss against L/d₁ was caused by the vortex. Still due to the plate attached to the inner pipe inlet, the head loss for the clearance length ratio L/d₁=0.625 decreases.

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In the flow around a circular cylinder, the sudden decrease in the drag force occurs at around Reynolds number Re=3×10⁵, but the same phenomenon occurs at a lower Reynolds number in the case where there exist grooves or roughness on the circular cylinder surface. In this paper, in order to make clear the flow characteristics around a circular cylinder with grooves, the unsteady flow was analysed by applying the RNG (Renormalization Group) κ-ε turbulent model to a flow around a circular cylinder with grooves each of whose section shapes being as same as that of a dimple on a golf ball, with changing Reynolds number. This result made clear the characteristics of lift and drag, Strouhal number, flow pattern behind the circular cylinder, pressure distribution and separation points. Moreover, the time averages of these values almost agreed with the experimental values.

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The mechanisms of cavitation bubble near a rigid wall are analyzed numerically by using CIP and C-CUP method. Our scheme is useful for such complicated two-phase flow, which solves simultaneously both gas and liquid phases. Calculated micro-jet shows quick motion through the bubble towards the wall as expected by experimental observation. It should be noted that every transient phenomenon succeeding the first bubble collapse could well simulated, for example, the second expansion, second collapse, attachment to the wall, and second micro-jet. Our results suggest the important role of the second collapse as the cause of the erosion problem. The toroidal bubble and the vortex ring around it are also obtained after second collapse and found to stay for quite a long time.

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The evolution of vortical structure in an impulsively started round jet has been studied numerically by means of a three-dimensional vortex blob method. The viscous diffusion of vorticity is approximated by a core spreading model originally proposed by Leonard (1980). The jet is forced by axisymmetric, helical and multiple disturbances. The multiple disturbances are combinations of two helical disturbances of the same mode rotating in the opposite directions. The multiple disturbances are found to enhance both the generation of small-scale structures and the growth rate of the jet. The small-scale structures have highly organized spatial distributions. The core spreading method is effective in aquiring the core overlapping in regions of high extensional rate of strain.

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This paper deals with an experimental study on the flow visualization of cavitation for steady and unsteady flows in cylindrical chokes of oil hydraulics. Experiments for the steady and unsteady flows are carried out following the methods used in the previous paper. In the previous paper, the behavior of cavitating bubbles was clarified with an ultrahigh-speed camera changing the diameter of the cylindrical choke for a condition in which the choke length was kept constant. In this study, experiments are performed in many more combinations of the diameter, length and chamfered length of the cylindrical choke. Also, the incipient and choking cavitation numbers are obtained observing with the naked eye for steady flow. It becomes clear that the cavitation form which occurs in the long choke and the large inner diameter can be classified clearly into three ones ; seat, bubble and cloud cavitations, and the various behaviors are observed by changing in size and shape of the cylindrical choke.

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Cavitation bubbles induced by pulsed laser near a free surface have been investigated experimentally and numerically. The successive pressure waves from them and their vertical migrations and volume change were measured by using hydrophone and high-speed streak camera. The characteristics of the first and second rebound times due to the distance from the free surface enable us to guess the mechanisms of bubble collapse with microjet. Because our new scheme by CIP method is successfully applicable for such two-phase flow, the comparison between experimental and numerical results is also very useful to understand the fundamental factor of the complicated phenomena of cavitation bubbles.

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The self-excited tone of a circular jet impinging upon a coaxial pipe can be give rise to not simply a single, however as many as well-defined frequency components in the rage of Reynoldsnumber (based on initial momentum thickness and jet velocity) 171⪈Re⪈271. All of these components are traceble to the nonlinear interraction frequency of two primary components : the most stable frequency of the jet shear layer, β, and a low-frequency modulating component, β/2. The modulating component β/2 arises from vortex-vortex interaction at the impingiment edge. Its upsteram storongly modulates the sensitive regime of the shear layer at the nozzle lip. The most stable component can become sudden change (i.e. frequency down) when it is coincided with resonance of the air column in pipe.

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As a new type of engineering applications with using ER fluid, we propose rotating regulator that has also a role of braking device. Experimental study of static characteristics is conducted on. Experimental data of torque at a given angular velocity are arranged with taking into account the apparent viscosity for the purpose of convenient engineering designing. The static characteristics of current density and electric power as well as the apparent viscosity depend on the electric field strength and the gap of electrodes in the device. Time response of these characteristics to the applying electric field are also clarified.

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Boundary layer transition is an important subject for the thermal design of re-entry vehicle because aerodynamic heating rate increases very rapidly with the transition. As so many factors affect the boundary layer transition, this subject is still unsolved problem even today, therefore experimental studies are conducted on boundary layer transition of windward surface of HOPE-X. It was ascertained the transition correlation parameter used for Space Shuttle design is applicable as an approximate basis for HOPE-X, though parametric value differs depending on vehicle configuration.

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Aerodynamic heating prediction is one of the key technology in designing the reentry vehicles. To evaluate the aerodynamic heating environment, numerical simulation can be one of the option. From the view point of the computer resources limitation and required elappsed time, exclusive use of the state of the art Computational Fluid Dynamics simulation such as full Navier Stokes is not realistic. In the actual design process, aerothermodynamic designers are often required to produce prompt but reasonable estimation of the aerodynamic heating distribtuion. Authors have generated an aerodynamic heating prediction code which can rapidly and reasonably estimate the heating environment on the windward side of the reentry vehicles refelecting its three dimensional configuration. The capability of the code has been verified in the comparison between the calculation results and HOPE-X hypersonic aerothermal wind tunnel test results.

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To control the flow around a square prism, a small rod is set upstream of the prism. The flow pattern around the prism depends on the diameter of the rod, its location and the Reynolds number. For two cases of with and without vortex shedding from the rod, the maximum reduction of the drag coefficient is 50 and 70% compared with that without the rod, respectively. Using a new model of the flow field, the aerodynamic mechanism of drag reduction of the prism is clarified.

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The present study contains experimental works on a flat-plate boundary layer disturbed by periodic incoming wakes. Special interest is focused on effects of the wake passing upon the profile loss associated with the boundary layer under the influence of favorable pressure gradient. A spokedwheel type wake generator is employed to simulate the incoming wakes. Turbulence grids are also used to enhance free-stream turbulence so that a realistic flow environment in turbomachines is emulated to some extent in this study. Time-resolved behaviors of the wake-affected boundary layer are measured by a hot-wire probe, which yields time-resolved shape factor or time-averaged energy dissipation thickness of the boundary layer. These data are compared with the numerical results obtained with a boundary layer analysis code, indicating the effect of the wake passing upon the profile loss associated with the boundary layer, i.e., boundary layer loss.

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Present paper deals with control of turbulent transition in flat plate boundary layer developed on a fiber surface for the purpose of drag reduction. The previous measurement showed 9% drag reduction as compared with a smooth surface case in lower Reynolds number range because turbulent transition was delayed. Intensive investigation including the streamwise velocity and the spatial correlation measurements was performed in order to reveal transition process and mechanism of the transition delay with the fiber surface, using the trip wire or a turbulance grid'to generate initial disturbances. Hot-wire measurements showed that the fiber surface delays transition in both trip wire and turbulence grid cases. The delay in trip wire case is much later than in the turbulence grid case. The growth of the streamwise velocity fluctuation introduced by the trip wire is dumped by the fiber surface though it does not change in the turbulence grid case. The spatial correlation measurement suggested that there exists streak structures in the transitional boundary layer and that they are suppressed by the fiber surface.

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At the first part of this paper, the experiments and results to the blowing and suction on a fan are presented, and it is found that blowing toward the down stream direction are more effective and blowing location is suitable on the leading edge side of blades. On basis of these results, the reformed casingtreatments which the blowing air from the slots makes the large relative momentum for blade chord are build, and the experiments using the two conventional fans equiped with the reformed casingtreatment and conventional one are performed. So, the very large stall margin improvements (about 1.7 times) and about 0.5% efficiency penalty of 10% stall margin improvement at design flow rate are obtained for the reformed casingtreatment.

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The purpose of this study is to determine experimentally the effect of multiple guide-vanes and ring diffusers on the power augmentation for a Cross-Flow wind turbine. Wind tunnel experiments have been carried out for various parameters including the number of the blades of the Cross-Flow rotor, pitch angle, and the configuration of the ring diffusers and guide-vanes. The optimal configuration of the guide-vanes and the rotor is determined. Comparative studies have been undertaken with reference to relevant previous investigations to determine the C_p of the Cross-Flow wind turbine with the ring diffusers and the guide-vanes. On the basis of the wind tunnel tests, a field experimental Cross-Flow wind turbine has been developed and tested. The results of the field tests are compared to those of the wind tunnel tests and discussed in details.

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Key mechanisms relating to buffeting forces on tubes in fluidized beds have been identified by analyzing results from simultaneous measurement of force and pressure on a horizontal tube. Careful experiments have been carried out in a two-dimensional fluidized bed with an accurate sensor tube for single bubble passage, bubble chains and free-bubbling. It is shown that the buffeting force in fluidized beds consists of the net pressure force, i.e., form drag and lift, and additional forces induced by particles become so large for high-velocity free-bubbling beds that it is impossible to estimate the total force only from the net pressure force, while for low velocity beds the total force is mostly accounted for by the net pressure force. The wake particles play an important role for large bubbles, and therefore the details of this component have also been investigated for single bubbles as well as for bubbles undergoing splitting and coalescence.

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Following the previous works by Maekawa et al. (1991) and Kawada et al. (1991), some turbulence statistics including the triple velocity-temperature correlations were measured in a turbulent boundary layer with a constant temperature for a spanwise direction. Examination was given to the turbulent heat flux budget and also to the reliability of some existing turbulence models. It was revealed that there are remarkable discrepancy between the predicted triple velocity-temperature correlations by the gradient-type model (Launder (1978)) and the experimental result. However, the examination for the turbulent heat flux budget clarified that the budget lies in near local equilibrium except for the near-wall region. Thus, the reliability of the pressure-temperature gradient correlation model is found to be rather important for the prediction of the spanwise turbulent heat flux. The prediction performance of the pressure-temperature gradient correlation model was investigated using two kinds of the models (Launder (1975)), Maekawa et al. (1979). It was found that predicted values by these models show good agreement with the experimental result.

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Experimental study has been conducted on forced convection heat (mass) transfer in the rectangular duct with a sharp 180-degree turn. Detailed distributions of local heat (mass) transfer rates over the all duct walls have been measured using the naphthalene sublimation technique, directing special attention to the influence of turn clearance and Reynolds number on the mass transfer characteristics. It has been found that, in case of smaller turn clearance, the flow separated at the tip of the inner wall reattaches on the outer wall of the duct and the local mass transfer rate becomes the local maximum at the reattaching location. On the other hand, in larger turn clearance, the local maximum mass transfer rate caused by the flow reattachment is observed not on the outer wall but on the inner wall after the turn. The characteristics of the flow reattachment after the turn is also influenced by the Reynolds number in the ducts with a large turn clearance.

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Several investigators have found that heat transfer coefficient at the interface between two dissimilar solids depends upon the direction of heat flow across the interface. Although many factors that affect heat transfer across the interface are reasonably well understood, the directional dependence of heat transfer coefficient, called thermal rectification has not yet been completely explained. In this paper, we evaluate the thermal rectification from the result of linear response theory by considering scattering and transmission of phonons across the interface, which depends on the temperature of the interface. This model could explain the reported behavior of thermal rectification.

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The liquid ring compressor (LRC) is one of the compressors suitable for the heat pumps which use water as a working fluid. LRC has several features : 1) large suction speed, 2) low discharge temperature realized by the ring liquid, 3) simple structure. However, in order to enlarge the working temperature region of such heat pumps towards lower temperature level, it is necessary to improve the volumetric efficiency of LRC, especially at a low suction pressure region. Therefore a helical liquid ring compressor (HLRC) which has helical blades has been newly designed, as one of the attempts to obtain a higher volumetric efficiency. The HLRC is able to separate a suction space from a compression space along the axis and improve the volumetric efficiency. A test running has verified that the suction/compression mechanism of the HLRC functions as expected.

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The hydrodynamic and heat transfer characteristics of the impinging spray jet of an ellipsoidal liquid film were experimentally investigated in order to estimate the cooling performance of a rotating roll in a hot mill system. The following four conclusions were reached in the study. (1) In the case of a single spray jet, the local heat transfer coefficient at the center position depends on the forced convective heat transfer by the impinging jet. But the average heat transfer coefficient is proportional to the flow rate density of cooling water, and it does not depend on the distance between the nozzle and heated surface. (2) In the case of a double spray jet, liquid film interference occurs. The local heat transfer coefficient at the center position is greater, and the cooling performance increases with the increasing flow rate density of cooling water. (3) The cooling performance of a multi-spray jet is proportional to flow rate density of cooling water, it does not depend on the nozzle construction, distance or specifications. And there is no relation to the liquid film interference. (4) When the optimum specifications of the spray nozzle are used, the temperature at a 1.3mm depth from the surface is below 130°C according to the thermal analysis of the rotating roll.

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A composite surface formed by embedding high heat conductive elements in a base material is expected to enhance nucleate boiling. To fabricate several composite surfaces, small copper cylinders were embedded in a stainless steel disk of 30 mm diameter and 5 mm thick. The size and the number of them were varied from 4 mm to 1 mm and from one to seventy-seven, respectively. Saturated pool boiling experiments were performed by using distilled water at atmospheric pressure. It was confirmed that the surfaces of copper cylinders effectively functioned as nucleation sites and that boiling heat transfer coefficients on the composite surface were higher than on the plain wall of stainless steel. By a simple numerical analysis for heat conduction in the composite wall, the higher temperature and higher heat flux were substantiated on the copper cylinder surface.

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The present study investigates natural convection heat transfer from a heated cylinder cooled by a water slurry of Microencapsulated Phase Change Material (MCPCM). A normal paraffin hydrocarbon with carbon number of 18 and melting point of 27.9°C, is microencapsulated by Melamine resin into particles of which average diameter is 9.5 μm and specific weight is same as water. The slurry of the MCPCM and water is put into a rectangular enclosure with a heated horizontal cylinder. The heat transfer coefficients of the cylinder were evaluated. Changing the concentrations of PCM and temperature difference between cylinder surface and working fluid. Addition of MCPCM into water, the heat transfer is enhanced significantly comparison with pure water in cases with phase change and is reduced slightly in cases without phase change.

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The effect of inclination angle on the natural convection heat transfer from an inclined heated plate with rectangular grids is investigated. Experiments are performed in air for inclination angles in the range of -30 to +60 degrees measured from a vertical plane, for grid heights in the range of 5 to 10 mm, and for four values of the diagonal length of the grid. For each configuration, the surface heat flux ranges from 50 to 200 W/m². It is found that the rectangular grids enhance local heat transfer coefficients when these grids are applied to an inclined plate. The rectangular grids enhance the average heat transfer coefficients along the horizontal center line of the plate by up to 20 percent when compared to those coefficients for a smooth plate, even when the angles of inclination are ±30 degrees.

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Experiments have been conducted to obtain local heat transfer coefficient distributions and average heat transfer associated with impingement of single water jet and a row of circular, free surface-water jets on a constant heat flux surface. The nozzle configuration is reverse cone type, and nozzle exit diameter is 8 mm in the case of single water jet, and nozzle arrays are a row of 3 jets (nozzle dia.=4.6 mm) and a row of 5 jets (nozzle dia.=3.6 mm). Nozzle-to-target plate spacings ranging from 16 mm to 80 mm were investigated for two jet center to center spacings 25 mm and 37.5 mm in the jet velocity of 3 m/s to 8 m/s. For the single jet, the nozzle-to-target plate spacings of maxima in the Nusselt number were observed at r/D≒3 in the jet velocity V₀≥6 m/s for H/D from 4 to 10. Except for the condition of V₀=8 m/s of H/D=10, the average Nusselt number reveals the following ranking : a row of 5 jets, a row of 3 jets, single jet. Compared with the single jet, average heat transfer enhancement for a row of 3 or 5 jets was presented. Correlations for average heat transfer were presented.

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A drying process of paper on a heated roll and covered by a canvas was calculated based on a one-dimensional model which concerns nonsteady heat and mass transfer in the direction of paper thickness. The calculation could reproduce measurements of changes with time of temperature and moisture content profiles in the paper, and revealed the following details of the drying process. The drying of paper proceeds from the roll side. A marked distribution of temperature comes out in the direction of paper thickness in the region where the liquid water outside of the cell membranes has evaporated up and where is no feed of water by a capillary action. As the drying proceeds with time, this region, at front of which the evaporation rate takes a maximum, expands to the canvas side. Another maximum evaporation rate is always found at the surface contacting with the canvas.

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The kinetics of selective non-catalytic reduction of NO using pyrolyzed urea solution with reaction kinetic method are studied and effects of O₂ and H₂O concentration on NO reduction and N₂O formation are discussed. The products of urea pyrolysis are mainly NH₃ and HNCO, so the reaction scheme used in reaction kinetic method is based on mechanism of Thermal DeNO_x with NH₃ and oxidation of HNCO. Calculated results are compared with experimental data which were carried out by Koebel and Elsener, and show the reasonable agreement. We also investigate the role of each elementary reaction using sensitivity analysis and determine the reaction mechanism of NO reduction using urea.

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Direct synthesis of methanol from methane/water-vapor mixture has a high possibility to realize a highly sophisticated energy utilization system with exergy regeneration. However, this process can never occur by conventional thermochemical methods due to the large increase of Gibbs free energy. In this study, the direct synthesis of methanol from methane/water-vapor mixture has been successfully realized by low-temperature and nonequilibrium plasma chemical reactions using a newly developed ultra-short pulse plasma, and effects of reaction time, peak voltage, pulse width and initial gas composition on the methanol formation characteristics have been clarified. In the case of spatially uniform pulse-glow plasma, maximum yield of 0.2% and maximum selectivity of 3% have been achieved. The time dependent change of emission intensity for CH radicals also showed the advantage of using ultra-short pulsed voltage for high energy input into the reaction field. Further, the methanol synthesis has been significantly improved by use of a newly found "filamentary" discharge mode which is realized by adjusting gas pressure and pulse parameters of peak voltage, pulse width and pulse frequency, and much higher values of 0.52% and 10% for methanol yield and selectivity have been attained, respectively. It has been also found that the mixing of rare gas largely enhances the methanol yield and its mechanism is discussed.

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The dissipated effective kinetic energy in the refrigeration cycle can be recovered by using a two phase ejector. The performance of the two phase ejector depends on the mixing characteristics of the droplets with the large inertia and the relatively light gas. It is important for designing the two phase ejector to know characteristics of the two phase flows in it. In this study, two-dimensional differential equations in the mixing section and the diffuser of a two phase ejector are solved numerically. The calculated energy conversion efficiency which is used to evaluate the performance of the ejectors is in good agreement with experimental one using a refrigerant R134a. The effciency obtained by the present experimental study is about 35% which is lower than that for the single phase ejector. But, this efficiency would be increased by the development of the nozzle.

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The purpose of this study is to estimate the viability of frozen biological materials during cryopreservation with the thermophysical properties. Human red blood cells are selected as test biological material. Propylene glycol (0, 10 and 35%w/w) was selected as cryoprotectant. The test chamber was contacted with carbon heater on a copper block immersed in liquid nitrogen, and cooled from room temperature to -196°C at a cooling rate of 1 to 300°C/min. Temperature rise of 5°C was applied to the suspension at -190°C, the effective thermal diffusivity was determined with Laplace transform method. As a result, the effective thermal diffusivity decreased with decrease of intra-and extracellular ice formation fraction in their suspension, which affects their survival after thawing. Thus assessment of cryopreserved biological materials can be achieved with the thermophysical properties.

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The reliability of a two-thermocouple probe, which is composed of two fine-wire thermocouples of unequal diameters and provides a technique for estimating thermocouple time constants without any dynamic calibration, is appraised in a turbulent wake of a heated cylinder. A reference temperature was obtained simultaneously using a fine-wire resistive thermometer (cold-wire) with a fast response. A comparison between the cold-wire measurement and the compensated thermocouple ones shows that a previous scheme underestimate the thermocouple time constants, unless the noise in the thermocouple signals is negligible and/or the spatial resolution of the probe is sufficiently high. The scheme is improved so as to maximize the correlation coefficient between the two compensated thermocouple outputs, and it offers better compensation of the thermocouple response.

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The flame color method to measure mixture strength in laminar premixed flames was investigated as a new combustion diagnostic technique. Flame colors were quantitatively determined by chromaticity coordinates (x, y) defined by the CIE 1931 standard colorimetric system. Using 12 types of hydrocarbons, the (x, y) of an inner cone in premixed laminar flames held on a circular tube burner were measured with a colorimeter, and the relationship between the (x, y) and the equivalence ratio φ of the mixture was examined in a range of φ=0.9 to 1.4. The experimental results indicated that the equivalence ration could be measured with accuracy of 0.008-0.014 and error due to axial position in the inner cone was less than 0.02-0.05. Humidity of air had almost negligible effects on the accuracy of the measurement. Results also indicated that the effect of back-light could be corrected by introducing the concept of additive mixture of color stimuli.

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An experimental study was conducted in a constant volume combustion chamber for investigation of the flame propagation characteristics in the presence of non-homogeneous concentration distributions of the fuel-air mixture. Different levels of non-homogeneity of the fuel-air mixture distributions were produced by the reciprocating movements of a pair of perforated plates. By independent control of the mixture distribution and the turbulence intensity, the effects due purely to the mixture heterogeneity and those due to the turbulence under non-homogeneous mixture distributions on the flame propagation speed and the flame shape were investigated in detail. Results from direct photography of the flame propagation processes showed that flames in the non-homogeneously distributed mixtures are corrugated, and can propagate faster than those in the homogeneous mixtures at the same level of turbulence. An optimal mixture distribution for maximum flame propagation exists among the different non-homogeneously distributed mixtures.

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The author has previously reported that a work done by a power stroke of Gasoline Engine is written as a function of some factors (ignition timing, combustion duration, engine speed etc.) using a pressure diagram in cylinder which is an approximate solution of energy conservation equation. In this report, the author is going to express an rejected heat to cylinder wall and exhaust gas as a similar function of factors mentioned above as the work done by cycle. The analysis shows that ; (1) a rejected heat to cylinder wall is written as a 3rd order polynomial of ignition timing, and increases with advance of ignition timing. (2) a rejected heat to exhaust gas is also written as a 3rd order polynomial of ignition timing, and increases with retard of ignition-timing. (3) total rejected heat is approximatly expressed as 2nd order polynomial of ignition timing, and has a minimum value at MBT.

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A particle tracking velocimetry method utilizing an intensified CCD camera and a laser light sheet was applied to quantify the surrounding gas entrainment into an intermittent non-evaporating diesel spray. The ambient gas was seeded by light particles and the two dimensional velocity of the surrounding gas was measured at several positions and times during the spray injection. A double-spark-back light photography method employing two nano-spark light sources was used to measure the temporal and spatial distributions of the instantaneous two-dimensional droplet velocity and the size-velocity correlation of droplets were obtained. Results of the ambient gas and droplets velocity were used to describe the droplets and surrounding gas interaction. The maximum velocity of the ambient gas was about 1/10 of droplets velocity which was much lower than the spray tip velocity. Entrainment of droplets into the spray started at t=200μs from the injection start and at the middle of injection period most of droplets were following the ambient gas flow and entraining into the spray.

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Newly developed Stratified Fuel-Water Injection (SFWI) System was tested for the NO_x reduction on low-speed 2-cycle diesel engine. Compared with the ordinary water addition combustion system such as emulsified fuel oil combustion, this system enables to confirm the auto-ignition characteristics under the high water content condition, by means of the primary injected pure fuel. Test results show that the multi-layer stratified spray construction is effective to achieve the high NO_x reduction ration such an extent to 50% with minimum B.S.F.C. penalty of 1.5%. The combustion Characteristics of SFWI on low-speed diesel are also examined.

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Aiming at understanding the characteristics of unsteady heat transfer on the combustion chamber walls of diesel engine and obtaining the basic data to establish a prediction method, simultaneous multi-point measurement of unsteadey heat flux is conducted. To investigate the influence of combustion parameters on the heat transfer to the walls, a single cylinder test engine is operated under the various kinds of engine conditions, such as swirl velocity, fuel injection pressure, the diameter of fuel injection nozzle and fuel injection timing. As a result, the influences of those parameters on unsteady heat flux are clarified quantitatively and investigated in relation to the prediction of in-cylinder combustion phenomena.

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