This paper describes an experimental study on the characteristics of viscous coupling. In this study, the effect of Hump characteristics for the filling level, number of plates, number of slits and the frequency in viscous coupling is clarified. From these results, it was found that : (1) transfer torque of steady region in viscous coupling is proportional to the number of plates and is approximately the forth power of the filling level and inversely proportional to the clearance. (2) the torque is affected by the number of slits and it exists in the slits number of optimum.

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The purpose of the present is to report a contraction coefficient of a two-dimensional thick orifice for compressible flows. An experimental investigation was performed using a shock tunnel, and the orifice flow was visualized by a color schlieren method. The experimental results show that the compressible flows through an orifice can be classified into three patterns and the contraction coefficient of a thick orifice increases with increase in the length-height ratios.

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The effectiveness of parallel plate arrangement as a cryogenic pumping device is examined by use of the direct simulation Monte Carlo method. The arrangement consists of two parallel plates and an end plate. The molecular beam is incident on the 80K plate cooled by liquid nitrogen. Molecules reflected on this plate are then incident on the opposite 20K plate cooled by liquid helium, where most of molecules are condensed. The percentage of non-condensing flux depends on various factors. The effect of the condensation coefficient, the density of incoming stream, and the geometry of the arrangement is examined.

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Experimental results of the mean flow properties of a three-dimensional jet injected from a hole located on the downstream side of a circular cylinder into a uniform flow with a wake or into a quiescent fluid are presented. With regard to half widths, L_y and L_z of the jet injected into the quiescent fluid, L_z is slightly larger than L_y. The relative similar profiles of the jets with different Reynolds numbers injected into the uniform flow differ considerably between the vertical direction, y and the horizontal direction, z. The half width L"_z in this case is considerably larger than L"_y in the upstream region, but two length become nearly equal in the downstream region. The isopleth of the mean velocity is shown to exhibit nonsymmetry and three dimensionality of the flow field.

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The unsteady turbulent free jet of circuit breaker model nozzle is studied using the laser velocimeter. The velocimeter system was made in dual-scatter, forward-scatter mode. Also the natural particulates in the nozzle free jet are used as the laser velocimeter tracer particles. A Doppler signal is converted into a constant voltage by the LV data processor with a processing time of 30μs. The flow velocity is calculated from this constant voltage, and the velocity distribution is produced by a histogram. The circuit breaker nozzle produces a broader velocity distribution than a circular convergent nozzle, since the circuit breaker nozzle has a special shape.

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The flow around a pair of semi-infinite circular cylinders arranged side-by-side at various spacings on a flat plate has been investigated experimentally. The two cylinders were aligned with the axis normal to both the flat plate and the free stream. Pressure distributions on the cylinders and velocity distributions in the wake were measured. The flow patterns on the cylinders and on the plate were visualized using an oil-film-technique, and the flow visualization around the cylinders was done by the smoke-wire method. As the distance between the two cylinders increased in order, the flow changed from the biased flow pattern deviated from one cylinder to the straight advancing flow pattern, showing a violent variation at the boundary region between two patterns. For large spacing of cylinders on the flat plate, the change of the flow pattern occurred more quickly, resulting in the reduction of the distance between the two cylinders.

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Rarefied flows around a circular disk in a hypersonic stream are analyzed by the direct simulation Monte Carlo method. The domain of calculation is fully three-dimensional. The rarefaction effect upon such quantities as the flow field, the drag and heat transfer coefficients, and the recovery temperature is shown for Kn=0.1 - 20 at the wall to a stagnation temperature ratio of 0.5 and 1. The drag coefficient is in good agreement with the experimental data of argon by Legge. The cell network proposed here can easily be applied to lifting flows.

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The authors attempt to solve problems peculiar to a very small "long orifice", such as the strong mutual interference between the cavitation and the viscous boundary layer in such a long orifice and the various types and aspects of cavitation occurring in a special situation of this kind. The cavitation aspects and discharge characteristics are investigated experimentally in a two-dimensional high-pressure oil flow through a very small long orifice by means of high-speed photography, under various hydrodynamic conditions. The relation between the cavitation aspects and the discharged coefficient is shown.

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Many benchmark problems for the numerical analysis of the fluid flow have been proposed. In this paper, a lid-driven cavity flow which is one of the most famous benchmark problems is examined. Four numerical schemes are compared with each other in terms of the grid dependency and accuracy of the solutions. From the viewpoint of the interaction between neighboring computational cells, we choose a 'CONDIF : Controlled Numerical Diffusion with Internal Feedback' approach developed by Runchal and we check this scheme for this cavity flow problem. Consequently, it is found that the CONDIF' approach is very stable for the grid Peclet number condition and the time step is not sensitive to the Courant condition.

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A theoretical solution of a pulsatile flow in the entrance region of a porous pipe was derived by Oseen's approximation reported in the previovs paper when the radial wall velocity was constant along the pipe axis. According to Hornbeck's investigation, radial wall velocity alters due to the difference between the inner and outer pressure of a porous pipe. In the present paper, we dealt with a pulsatile flow whose radial wall velocity varies exponentially along the pipe axis. Dynamic characteristics such as velocity, and pressure coefficient are precisely discussed on the boundary conditions for pulsatile injection and suction from the pipe wall.

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The present experimental study was undertaken to answer demands for some basic data in the numerical simulation of pneumatic conveying. In this first report, the fluid forces applied on a circular cylinder in a linear turbulent shear flow were investigated by the pendant method and he measurement of pressure distribution on circular cylinders. The experiment was carried out using a vertical duct. The effects of the velocity gradients of the mean flow and the Reynolds number on the drag and lift were discussed. The following conclusions were obtained : (1) Lift was applied in the direction from the higher velocity side of the approaching flow to the lower velocity side on a circular cylinder in a linear turbulent shear flow. The coefficient of lift increased as the velocity gradient became sharper. (2) Both coefficients of drag and lift increased as the Reynolds numbers became higher and the turbulence of the duct flow became greater. As a result, the basic data of coefficients of drag and lift are proposed for the Reynolds numbers Re_.c=3 300∼13 000.

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An experimental study of transition to turbulence in the flow of a rotating disk with roughness in still air has been conducted. The results showed that the number of vortices is constant for a given roughness R_a at rotational speeds between 2 000 rpm-4 000 rpm, and it decreased from 32, without toughness, to 25 for a value of the roughness R_a of 15μm. The critical values of the Reynolds number γ²ω/ν, for instability, decreased from 0.95×10⁵, without roughness, to 0.5×10⁵ for a value of roughness R_a of 15μm. The corresponding values for transition decreased from 3.40×10⁵ to 2.55×10⁵, where R_a is the roughness of a center line average, γ the radius of the disk, ωthe angular velocity and νthe kinematic viscosity.

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The local similarity hypothesis was verified in quasi-isotropic turbulent flow fields with turbulence Reynolds numbers of over 3000. The quasi-equilibrium range was known to exist in a turbulence field with turbulence Reynolds numbers of Re_τ >60. The lowest wave number of the quasi-equilibrium range in the energy spectrum was dependent on T_L/T_O : the ratio between the time scale of decay of turbulence energy and the characteristic time scale o an energy-containing eddy. Turbulent eddies with characteristic time scales of less than T_L/4 were statistically stable. The energy dissipation rate was theoretically determined as ε=C₁(q²/2)^3/2/l_O, and the scales of turbulence were estimated from C₁ and Re_λ.

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A numerical technique for the analysis of two-dimensional unsteady turbulent flows in a turbine stage is presented. To calculate the unsteady interaction flow fields in a nozzle and bucket simultaneously, the nozzle outlet elements and the bucket inlet elements are overlapped in the axial direction and are used for unsteady data transfer between each flow region. To calculate the flows in arbitrarily shaped geometries, a control volume method combined with a body-fitted curvilinear coordinate system is used to obtain spatially discretized governing equations, while the second-order accurate Adams-Bashforth method is employed for time integration. In the present analysis, a two-equation model of turbulence is introduced to estimate the turbulence effect. In order to assure the effectiveness of the present method, computations are carried out for the flow in three turbine stages. It is shown that unsteady flow phenomena such as the nozzle wake and pressure field interactions are well predicted and the periodic aerodynamic forces acting on the buckets are obtained by the present method.

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Three components of velocity fluctuation have been measured in a square-sectioned 90° bend of 2.0 radius ratio with upstream and downstream straight ducts attached. Measurements are made by the technique of rotating a probe with an inclined hot wire under the Reynolds number of 40 000. The root-mean-square of longitudinal fluctuation √((w'²)^^^- ) and the products (w'u')^^^- and (v'w')^^^-, u' and v' being transverse fluctuations, are shown and are compared with each production rate which is calculated by using the measured mean and fluctuating velocities.

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A three-dimensional flow in the intake process of a reciprocal engine is calculated numerically under such complicated boundary conditions as moving valves and arbitary intake-port and combustion chamber configurations. A finite difference method using a third-order upwind scheme for convective terms is applied to solve incompressible Navier-Stokes equations. This model enables us to simulate the occurence of small vortices near the valve and valve seat or caused by curvature of the intake port, as well as the influence on flow in a cylinder of the vortices. The difference in flow pattern between single and double intake valves is compared as an application of this model. LDV measurements at 126 points inside an engine cylinder at an engine speed of 1 400 rpm are also performed in this study to evaluate the calculation results. It is clarified that the calculation flow field agrees fairly well with the measured results.

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This paper is concerned with a three-dimensional numerical analysis of trajectories of bubbles and solid particles entrained in Francis water turbines. The trajectories were determined by numerical integration of a equations of motion of a particle in the water, which was calculated by a finite element method under the assumption of a potential flow. The trajectories of the bubbles concentrate on the suction side near the crown and the pressure side near the band of the runner vane. The solid particles flow down along the band surface, and tend to collide with the pressure side of the vane at high speed.

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Flow analyses which were performed to design a new runner for upgrading existing Kaplan turbines are presented. The reliability of quasi-three dimensional flow analysis is confirmed by comparison with the measured flow pattern using a two focus laser velocimeter. Then the flow distribution at the runner inlet is investigated numerically at the best efficiency point and at the full load point. The strong effect of flow distortion due to the curvature of the meridional flow channel are discussed. The design concepts of a new runner adaptable to the existing turbines are presented and indicate that the new runner should generate the pertinent swirl flow to the existing draft tube and that the leakage through the runner tip clearance should be decreased. The performance of the new runner designed with the concept concerned is shown to be a great improvement on the existing one.

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Vortex shedding from spheres at Reynolds numbers from 3×10² to 6×10⁴ in a uniform flow was experimentally investigated. Standard hot-wire techniques were used to measure the vortex shedding frequency form spheres in a low-speed wind tunnel. Flow-visualization experiments were carried out in a water channel. Important findings resulting from the investigation were that (i) the variation of the Strouhal number St (=fD/U₀, U₀ : free-stream velocity, D : diameter of sphere, f : vortex shedding frequency) with the Reynolds number Re (=U₀D/ν, ν : kinematic viscosity) can be classified into four regions, (ii) the critical Reynolds number at which the horseshoe-shaped vortex loops are shed periodically is about 300, (iii) the vortex loops diffuse very rapidly and the wake structure of the sphere is not shown clearly when a Reynolds number of about 800 is reached, and (iv) at Reynolds numbers ranging from 8×10² to 1.5×10⁴, the higher and lower frequency modes of the Strouhal number which are caused by the periodic fluctuation in the vortex sheet separating from the surface of the sphere and in a wake with progressive wave motion are coexisted.

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The lift and drag acting on a circular cylinder with tangential blowing immersed in a uniform shear flow are presented for a shear parameter 0.15 and Reynolds number 6×10⁴, and the effect of the velocity gradient of the uniform shear flow on characteristic values is discussed for coefficients of momentum of the blowing jet ranging from 0∼0.4. Consequently, the shear parameters in the two cases where the location of the blowing slot is on the cylinder of the higher velocity side of the lift and drag, and yield different beginning points for the forced reattachment phenomenon. Comparison of various features such as the stagnation point clarified the contribution of each feature to the lift and drag on the cylinder.

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The development of turbulent boundary layers with blowing or suction in zero or finite pressure gradients is calculated using a second-moment closure that is applicable right up to a wall. The turbulence model was previously shown to give good predictions for several types of flow, including a rotating channel flow. In the present calculation, no special changes are made to deal with transpiration, except for a wall boundary condition fro the normal velocity. Published experimental data on the friction coefficient, the mean velocity profiles, and the turbulent normal stress profiles are used to assess the performance of the model calculation. It is shown that the numerical solutions are generally in agreement with the data. This paper thus shows the wide applicability of the turbulence model.

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Flow characteristics of screw-type slurry pumps are of great interest to both designers and plant operators. To data, however, such basic data necessary to the design of slurry pumps are not available. Then we try to observe the flow patterns in the internal flow by using of an oil-film visualization-technique, in order to give practical and useful design data. Here, it is worth noticing that a marked improvement in efficiency is possible by modifying the inlet part of the blade and the cross-sectional shape of a flow passage. It is not necessarily sufficient to design such a pump by means of a conventional design method for mixed flow pumps.

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The velocity distributions measured at the exit of two different types of unshrouded centrifugal impellers respectively under four different tip clearance conditions were reexamined with respect to the shroud wall surface. By increasing the tip clearance, the hub-to-shroud velocity distribution was hardly changed at the exit of the radial blade impeller, by contrast, the relative flow angle was reduced significantly and monotonously in the backward-leaning blade impeller. The change in input power due to the tip clearance was clearly related to the change of flow pattern at the exit of the impeller due to the secondary flow, which must be induced by the component, normal to the blade, of the shear force to support the fluid in the clearance space against the pressure gradient in the meriodional plane without blades.

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In previous simulations the modified, GSMAC method which is more applicable to in-out flow problems, was proposed. In the present paper, however this scheme is extended to the three-dimensional analysis. As an example, flow in a cubic lid-driven cavity which has many authorized experimental and numerical results, has been calculated at the Reynolds numbers 1 000 and 3 200. Consequently, the velocity profiles are in good agreement with the spectral method at Re=400 and 1 000 [4], and the TGL vortices, which give a three-dimensional effect, have been simulated.

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A numerical method for analyzing the steady incompressible viscous flow having complicated boundaries or an irregular shaped grid is proposed. In this method, the unsteady Navier-Stokes equations in terms of the primitive variables are solved using a convective-difference scheme, and an elliptic equation for pressure by Gaussian elimination. The distinctive feature of the method is to make use of the convective-difference scheme using the finite difference operators derived by the least square polynomial approximation for the irregular grid. The substantial derivative terms in the convective-difference scheme is integrated along a path line and the values at the upstream end are interpolated based on a total variation diminishing (TVD) scheme. Backward facing step flows and flows of 90 deg. bended duct were solved to verify the effectiveness of the method. The method can be applied to the relatively high Reynolds number flows.

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A design method for two-dimensional airfoils in cascades is presented. This is based on the panel method using piecewise constant vortices. Incompressible potential flow is assumed. Pressure distributions on the upper and lower surfaces are prescribed. The changes of the intensity of vorticity are calculated so as to make the difference of the pressure distributions detween prescribed and calculated equal zero, and the profile is modified in order that he changes of surface velocity induced by these vorticity variations satisfy the boundary condition. The design code gives satisfactory solution after several iterations. Three numerical results are shown. In each case the pressure distribution of Gostelow's cascade is given as specified. Initial guess profiles are (1) Gostelow's airfoil but partly flattened upper surface, (2) Gostelow's airfoil but flat lower surface, and (3) NACA 0012 airfoil. The obtained profiles agree well with Gostelow's airfoil.

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Implicit time-marching finite-difference methods for solving the two- and three-dimensional compressible Euler and Navier-Stokes equations are presented. The distinctive feature of these methods is to use the momentum equations of contravariant velocity components. By using such equations, accurate and easy treatments of the solid wall boundary condition are realized for the Euler equations, and simple treatments of he periodic boundary condition become possible for the impeller flows. The numerical method are based on the Beam-Warming delta-form approximate-factorization scheme, and take into consideration the diagonalization and upstreaming by the theory of characteristics. The computations of turbulent flows are implemented using the two-equation k-ε turbulence model with the law of the wall. Finally, some numerical results of transonic cascade flow are shown.

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In order to understand the influence of the cone angle of an impeller on pump characteristics at partial capacity, experiments were carried out for three impellers prepared with different cone angles. The results showed that the onset capacities of the suction and discharge inverse flow were larger at the impeller with a smaller cone angle, and that the impeller with a medium cone angle had stable H-Q characteristics, while the other two impellers had unstable ones. Measuring the velocity distribution upstream and downstream of the impeller and carrying out the flow visualization by the oil film method, the relation between the flow pattern change at partial capacity and the unstable H-Q characteristics was clarified. The influences of the cone angle on the flow pattern change were also discussed.

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The relationship between the flow pattern and the head curve was investigated by the measurement of flows at the impeller inlet of the single-stage pump and the three-stage pump. At low capacity, the multistage pump has a lower head coefficient than that of the single-stage pump. It is clarified that the decrease in the head coefficient at low capacity is caused by the increase of the prerotation of the inlet flow to the impeller, and the recirculation at he impeller inlet has a great influence on the prerotation increase.

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This paper describes a control method for a microhydropower system using a microcomputer. This method is different from that of large-scale hydropower plants. The theory and experimental results of this two year investigation are included in this report.

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The digital image processing technique is applied to quantify flow visualization pictures showing unsteady 2-D wakes past a circular cylinder at Re=100. A combined use of suitable image input devices and newly developed computer programs makes it possible to automatically obtain instantaneous velocity fields from the corresponding streak line photographs. The resulting local velocity vectors are rearranged as Cartesian mesh points with a view to facilitating the following numerical processing. The estimation of the unsteady pressure field is done through iterating finite-difference calculation of 2-D Navier-Stokes equation, in which the unsteady terms are estimated from 3 slightly delayed continuous photographs. It turns out that the order of the unsteady terms is often larger than that of the viscous terms, or even of the inertial terms, in vortical regions, and that the introduction of the unsteady terms brings remarkable improvement in the precision of the pressure calculation.

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The pressure-composition isotherms of the LaNi₅-H₂ system are measured in full consideration of the thermal history. Once the temperature exceeds 343K, the two plateaus in the desorption process appear in any case. We also find an increase in the plateau slope and a decrease in the hydrogen storage capacity and the plateau pressure. These phenomena become more remarkable with elevation of the maximum temperature in activation and operation processes.

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Inside a coaxial flow diffusion flame of the ordinary type (fuel ejection into an air atmosphere), another diffusion flame of the reverse type (air ejection into a fuel atmosphere) was formed. The sooting limits of this double diffusion flame were measured for propane with three different types of burners, and the effect of several factors, such as the amount of inner air, flame-to-flame distance, thermal condition between the two flames, and flow stretch, were investigated. On the basis of the results, the effectiveness of making use of the double flame in the suppression of soot emission from diffusion flames of the coaxial flow type was discussed. The main findings were : (1) The double flame condition suppressed soot emission more effectively. (2) The sooting limit was controlled by the outer flame temperature, and therefore, adjusting the factors so as to increase this temperature may lead to much stronger soot suppression.

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The high-intensity combustion of the Bunsen burner was examined for the purpose of the compaction of domestic water heaters. The experiments with a burner port model clarified the relations between the specifications of various burner ports, flame retention mechanisms, flame holder, arrangement of burner port slits, and combustion characteristics. Furthermore, it was found that the acceleration of the secondary air diffusion by installing diffusion plates between the burners downstream of the burner ports shortened the flame length. Consequently, the calorific capacity of the combustion chamber increased to 2×10⁴ kW/m³ which is equivalent to three to four times that of the conventional burners, and redued the combustion noise.

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An experimental study was conducted to investigate the effect of liquid-solid contacts on the low limit of film boiling in water under atmospheric pressure. The test specimens selected for the present experiments were a silver sphere (30 mm in diameter) and two kinds of silver cylinders (20 mm in diameter and 60 mm long). The heat transfer surface was coated with a thin, electrically insulating layer, and the impedance between the metal substrate and the boiling liquid was measured. This impedance was related to the average fraction of the heat transfer area which was wetted by the liquid. Direct liquid-solid contacts were observed on local portions of the heated surface in saturated film boiling, and the frequency of contact ranged between 1.0 and 3.1 Hz. In subcooled boiling, however, the contact frequency became extremely low with higher subcooling.

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Evaporation into a vacuum from a cylindrical crucible partially filled with liquid is studied by use of the direct-simulation Monte Carlo method. The evaporation rate is obtained in the near continuum to the free molecular regime for l/a =1, 3 and 5, where a is the inner radius of the crucible and l is the distance from the crucible exit to the liquid level. When l is small, the evaporation rate does not change so much with the Knudsen number Kn. The flow structure near the crucible is similar to that of the usual free jet expansion. In the far field, the density and radial velocity of gas and the probability of finding a molecule in the unit solid angle are calculated as a function of the polar angle. There flow properties in the far field are also obtained in the case of sonic efflux from a circular orifice.

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An experimental study concerned with the effect of surface roughness of a ceramic-coated surface on droplet vaporization was performed. Test surfaces used were almost identical in surface structure except for the surface roughness. Lifetime curves for several combinations of pure liquid and the hot surface with coating having different roughnesses were measured at surface temperatures up to 1 100 k by a high-speed video optical system. we also observed in detail the vaporization behavior using a 16 mm high-speed motion-picture camera, especially in the rapid vaporization region. The result showed that the higher the surface roughness was, the wider the temperature range yielding the short lifetimes became. In this temperature range, slightly reduced lifetimes caused by the surface roughness were obtained in some cases.

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Experiments and theoretical analysis were carried out to investigate the characteristics of natural filmwise condensation of a binary mixture of vapors on a vertical plate. Both PFP-H₂O and TFE-H₂O mixtures, which are azeotropic and nonazeotropic respectively, were used. These mixtures are considered to be the most promising working fluids for the Rankine cycle for moderate-temperature thermal-energy utilization. The dependencies of the heat transfer coefficient on the bulk concentration of water and the bulk-to-wall temperature difference were clarified. A similar solution (or pseudo-similar solution) can predict the experimentally measured heat transfer coefficient. The effects of the finned surfaces on the heat transfer performance were also investigated for two fin shapes.

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The aim of this study is to clarify the existence and performance of a three-dimensionally oscillating natural convection of a standing wavetype over a horizontal heated plate of a rectangular cross section in an air container. First, by use of flow visualization and fluid temperature measurements, it was shown that the oscillation motion occurred under a certain specified condition. The main parameter which controls the wave length of the standing wave is the distance between the two side walls of the container supporting the heated plate. Second, the time-mean heat transfer coefficient of the upper surface of the heated plate was found to be about 26% higher than that without oscillation in the case of Gγ≒10⁵.

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The body temperatures of anesthetized patients under going operations decrease gradually because control of the body temperature is suppressed and the temperature of the operating room is kept lower than the body temperature. In order to prevent a patient's body temperature from lowering during an operation, a mat with hot-water circulation is often used. However, it has been reported that burn injuries occasionally occur in such cases, even when no defect in temperature setting and control of the mat is found. The mechanism causing this burn injury has not been determined. This report analyzes the heat transfer of a body-mat system simulated by a simplified model to examine the possibility and mechanism of such burn injuries. The analysis discusses the effects of hot-water flow rates, hot-water temperature and metabolic heat generation on body temperature. It is found that burn injury can occur, particularly in the high metabolic state, when heat transfer by the blood flow is negligible and the rate of water flowing into the mat is reduced considerably.

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The subcooled nucleate boiling heat transfer was investigated in the confined space of a closed vessel surrounded by a cooling jacket. Characteristics of the heat transfer in the space exist in a radial heat removal from a long vertical heat source with a high subcooled condition. A wall temperature drop in a high heat flux range, which indicated a boiling hysteresis, was encountered due to a transition in the boiling regime from discrete to large coalesced bubbles. A single phase natural convection in this space could be predicted by the previous correlations. Nucleate boiling was affected by subcooling in a lower heat flux region, and in a higher heat flux region, the heat transfer rate decreased due to large coalesced bubbles, the heat transfer could not be correlated by a boiling curve. A correlation between Nusselt and Rayleigh numbers is presented for the nucleate boiling heat transfer in this study.

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A theoretical analysis has been made to elucidate the mechanism of the enhancement of heat transfer due to bubbles passing through a narrow vertical channel. This analysis is introduced based on a change in heated surface temperature with a time during which the bubble passes through it. The characteristics of enhancement are given for a constant heat flux and a constant temperature, having a similar tendency to those obtained in the experiment. The heat transfer coefficients obtained are about 2 times as large as those predicted by the analysis. The difference between the results arises from the effect of the flow which is not taken into account in the analysis. In addition, the thickness of the liquid film, which plays an essential role in the enhancement of heat transfer due to the passing bubbles, is 71.7 μm within the experimental range of q_w=1.3×10⁴-2.8×10⁵ w/m², T₀=0.1-1.0 sec, and l_b=10, 20, and 30 mm.

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An experiment on pool boiling on a circular copper surface in water was performed for a case in which the boiling space was restricted by an interference plate with many holes. The space between the heat transfer surface and the interference plate was hermetically sealed at the perimeter to simulate a large surface of heat transfer. Therefore, the vapor and liquid were exchanged through the holes in the interference plate. Many boiling curves were obtained, and appearances were observed for many patterns of holes on the interference plates. The following results were obtained. High heat fluxes were obtained in the narrow space at a small surface superheat of less than 1K. The interference plate of high heat transfer performance was found : it was comparable with other available heat transfer surfaces of high performance. In water, the best performance was given by the interference plate with two types of holes, i. e., 4 mm and 1 mm in diameter, if it was set 0.12 mm above the surface.

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An experimental investigation was made on the total performance estimation between the heat transfer and pressure drop characteristics using several kinds of spacer configurations in a rectangular channel. Performance differences between several kinds of spacer configurations were determined by considering the estimation method on heat transfer and pressure drop and introducing the configuration factor on heat transfer and pressure drop. As the result, there was not very much change of local heat transfer coefficient distribution, but pressure drop decreased very much in the case of front edge side and both front and rear edge side cutting against the spacer configuration. We obtained heat transfer and pressure drop characteristics with the spacer configuration factor against several kinds of spacer configurations and estimated the total performance. Cylindrical-type (CD), front edge side cutting-type (RU, EU, HPU), and both front and rear edge side cutting-type (RB, EB) spacers gave more excellent performance than standard-type spacer (SD).

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Alkali metal thermoelectric conversion (AMTEC) cycles and the cycles of high-temperature heat pumps using beta" alumina solid electrolytes are analyzed, and it is shown that the isothermal expansion or compression of the Na⁺ flow through the electrolyte coincides with the expansion or compression process, respectively, in the Ericsson cycle when the internal losses by the electrolyte and the thin electrode are small. It is also shown that the isothermal compression approximation in the heat pump cycle is more consistent with the AMTEC cycle than the adiabatic compression discussed in an earlier report. Typical results for voltage-current characteristics and thermal efficiencies of the AMTEC and the heat pump, including the high-temperature side Na conditions of not only the saturated liquid, but also the super-heated vapor, are presented. The super-heat operation shows a decrease in the power generation efficiency for the AMTEC and an increase in the coefficient of performance for the heat pump.

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The purpose of this study was to investigate the performance of the sodium heat pipe having a screen mesh wick with a hole for the relief of vapor bubbles yielded in a narrow space between the inner surface and the screen mesh layers at the evaporator section. The heat pipe was fabricated from Inconel 600 tubing of 1.5 mm wall thickness 25 mm in outer diameter and 1000 mm in length. A 50-mesh screen was used as the wick. In order to examine the effect of this wick, the performance tests of this heat pipe were carried out in the vapor temperature range of 500°C to 1000°C. As a result, it became clear that this type of wick is useful for removing the vapor bubbles from the narrow space and can prevent early generation of dry-out.

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Lighter organic particulates emitted from a high-speed four-cycle DI diesel engine at various loads for commercial diesel fuels and some blended fuels have been studied under steady operating conditions. Emissions of lubricating oil, fuel fractions, and combustion products in the lighter organic fraction have been evaluated by chemical analysis using a gas chromatograph and a mass spectrometer. Furthermore, flow reactor experiments under atmospheric pressure were conducted to simulated the effects of temperature on forming particulates in the engine cylinder. The fractions having higher boiling points than 300°C are hot fully decomposed even at flow-reactor temperatures of 880°C. Side-chained two-ring compounds which are the major aromatic component in commercial fuel rapidly decompose to yield a polymerized substance at much lower temperatures than other fuels. This explains the dependence of SOF emission on load and fuel property.

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The spectoscopic analysis of combustion flame yields information on the chemical reactions and intermediate products. The authors detected diesel flame spectra by means of a heat-resisting optical fiber inserted into a DI engine's combustion chamber. The combustion flame was recorded by a special spectroscopic apparatus, named "Streak camera". The result of the experiments confirmed the existence of band spectra emitted from some substances and CH radicals in the ultraviolet and visible ranges. The recorded data elucidated the progress of chemical reactions and the formation of intermediate products during the diesel combustion process.

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In the side-injection system where several injectors are arranged on the circumference of the combustion chamber, the interaction between spray jets and air swirl is more complicated than the conventional central-injection system. The authors have examined in the past the influences of air swirl on the combustion performances in this system by a test engine. In the present studies, the authors have rebuilt the engine to take high-speed photos from the lower part of the combustion chamber. Comparing the visualized data with the results of operation tests, it has become clear that the lowest exhaust smoke density and BSFC can be achieved when the fuel sprays curbed and dispersed by air swirl fully occupy the combustion chamber. Moreover, the effects of air swirl on the dispersion and combustion of fuel spray have been examined in detail with the observation of a single spray jet.

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