The title problem is treated on the assumption that the numbers of impeller and diffuser vanes are so large that the flows are perfectly guided by the vanes. It is shown that the interaction with the vaned diffuser may cause destabilizing fluid forces for whirling motion even at the design flow rate. Discussions are made to elucidate the cause of the destabilizing fluid forces. The losses in the impeller and the diffuser are assumed to be given by the quasi-steady application of steady incidence and hydraulic losses. Based on this assumption, the effects of rotating stalls due to the impeller and the diffuser on the impeller whirling forces are discussed. The impeller forces are divided into components due to impeller inlet/outlet pressure distributions and momentum transfers and to the rate of momentum change of the fluid in the impeller. It is shown that the pressure forces around the impeller outlet dominate in a range of small positive to negative whirl velocity ratios.

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The fluid forces on a centrifugal impeller rotating and whirling in a volute casing were studied experimentally. Experiments were carried out for various flow rates and whirling velocies in several volute casings to clarify the volute/impeller interaction effects. The results showed that the fluid forces excite the whirling motion at a design flow rate with a low whirling velocity, and the volute/impeller interaction enlarges the unsteady force. It has been determined that the tongue configuration is very important to reduce the unsteady forces on a whirling motion.

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A viscous diffusion model for the vortex method is developed for calculating two-dimensional viscous flow. The vortices whose core-shapes are fixed are carried by the convection velocity and newly defined diffusion velocity to satisfy the Navier-Stokes equation. To examise the validity of this model, calculations of the flow around a circular cylinder at Re=40, 1 200 are carried out. Vortices separate from the surface and become wake vortices. The results are compared with those of the finite-difference method and good agreement is obtained. The unsteady boundary layer of a semi-infinite plate is also calculated and the transition from an unsteady state to a steady state turns out to be expressible by the present method.

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Unsteady flows near the surface of a circular cylinder which is started impulsively at the Reynolds number Re=1 200 and 9 000 were investigated by flow visualization techniques. Measurements were performed on the details of the velocity profile in the boundary layer near the separation points to clarify the mechanisms of the occurrence of unsteady separation. When Re=1 200, no singular phenomenon in the boundary layer could be observed even after the time of the appearance of a singular point of the boundary layer equation, which has been suggested from some recent theoretical studies. When Re=9 000, some singular phenomena in the boundary layer are observed a little after the time of the appearance of the singular point suggested by the theoretical studies. Both at Re=1 200 and 9 000, the criterion on the unsteady separation proposed by Taneda indicates nearly the same separation points as that of Wang's criterion.

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The flow near the front stagnation point on a circular cylinder oscillating transversely in a uniform flow was investigated by flow visualization techniques. A piece of short fine wire (5 mm in length) was set on the cylinder like a whisker for the generating wire of hydrogen bubble techniques. This whisker-like generating wire was found to be useful to visualize the flow near the stagnation point. In contrast, a long fine wire (40 mm in length) set along the streamline toward the stagnation point strongly disturbed the flow and induced a pair of necklace vortices around the cylinder. The velocity and wall shear stress near the stagnation point were measured with the phase angle of the oscillating cylinder. Under a constant amplitude of the oscillating velocity of the cylinder, the maximum value of the wall shear stress at the center of the displacement of the stagnation point was found to increase with the oscillating frequency of the cylinder. The increase of the shear stress is closely related to the excess displacement of the stagnation point.

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The flow past a circular cylinder oscillating transversely in a uniform flow was investigated by flow visualization techniques. The frequency of the oscillating cylinder was set in the synchronized range in which the vortex sheds periodically with the same frequency of the oscillating cylinder. The experimental conditions were Re=1 100, and A/D=0.2, where Re is the Reynolds number based on the diameter D, and A the amplitude of the oscillation of the cylinder. The characteristic values (the displacement thickness, the shape factor, and the velocity at the outer edge of the boundary layer) were measured using hydrogen bubble techniques. From the values, the local skin friction on the cylinder was estimated with the oscillating phase angle during a cycle. The characteristics of the unsteady boundary layer near the separation points, where the dye filaments separate from the cylinder, are discussed in comparison with those of a steady one.

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A new Reynolds stress model applicable right up to a wall is developed. The invariants of the stress anisotropy tensor are introduced to incorporate the effect of high anisotropy of turbulent stresses in the vicinity of the wall. The model constants in typical models adopted for the pressure-strain correlation are thus replaced by functions of the invariants as well as the turbulent Reynolds number. The algebraic stress approximation is then utilized to obtain relative stress levels. The form of the model functions is explored using the stress levels and finally determined by computer optimization. The coefficient of the generation term in the dissipation rate equation is also made to depend on the invariants and the Reynolds number to extend the applicability of the model. The numerical solutions for the development of a flat plate boundary layer are shown to be in good agreement with experiments including the distributions of turbulent quantities.

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The Reynolds stress model proposed in the 1st Report is applied to the development of the boundary layers in pressure gradients. First, predictions are made for two sink flow boundary layers : a laminarescent and a laminarized flow. The numerical solutions are extensively compared with experimental data including the distributions of the streamwise turbulence intensity. It is shown that the predictions are generally in good agreement with the data, reproducing a distinctive feature between the two flows. Next, two adverse gradient cases are tested. For the case of a non-equilibrium boundary layer in a strong pressure gradient, extensive comparisons of the numerical solutions with the data are made including the distribution of all the Reynolds stress components. It is shown that the overall agreement is satisfactory. However, a sound conclusion is not drawn concerning the difference in the logarithmic law intercept, which suggests a need for further consideration.

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Analyses were made on a homogeneous turbulence field with large turbulence intensity generated by a mechanical turbulence generator in a small wind tunnel. The large turbulent Reynolds numbers, Re_L > 3000 and Re_λ > 200, were obtained in the present experiment. These values were proven to exceed the criteria allowing the wide internal subrange to exist in the energy spectra. The turbulent Reynolds numbers decreased monotonously in the streamwise direction and attained a quasi-steady state for about X/M ≥ 50. These results suggest that it is possible to simulate the fluid dynamical phenomena of the actual large-scale turbulent flow fields in the test section of a small wind tunnel. The universal constant of Kolmogorov, α, was determined from the spectral distributions. The resultant value, α ≒ 0.64, agreed closely to those obtained in the recent results of field experiments and theoretical analyses.

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The pulsatile flow of Bingham plastic fluids in a high Reynolds number region is studied experimentally. The fluid properties are measured with a modified capillary viscometer, whose capillary tube tip is immersed in the test fluid. An analysis based on the quasi-steady approximation is performed and the results are compared with the experimental ones. It is found in the range of the present study that : (1) the quasi-steady approximation is effective when the value of η (=√(ω*/Re^3/4), ω* : square of Womersley number, Re : Reynolds number) is less than 0.3, (2) the measured time-averaged flow rate decreases compared with the one without the pulsation if the value of η is greater than 0.6 and this phenomenon can not be explained by the quasi-steady approximation.

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In order to predict the aerodynamic forces acting on the H-II Rocket under development in Japan in a strong wind, experimental studies were carried out. A one-hundredth test model of the actual object is composed of a main circular cylinder and two subcylinders closely arranged in line. The pressure distributions around the cylinders and the Strouhal number behind the cylinder were measured for various attack angles α in the range of the subcritical Reynolds numbers. At α=22° and 33°, the drag and lift coefficients of the main cylinder and the individual subcylinders have either a maxima or minima. These phenomena are closely related to the reattachment of the separated shear layer on the downstream cylinder.

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An experimental and computational study is reported for macroscopic flow phenomena over a vertical disk or disks, held coaxially with a cylinder at a short distance downstream of an abrupt enlargement in a circular tube. The effects of geometric conditions such as axial direction distances between the disks, inlet lengths so far from the enlargements to the first disk, disk numbers, and ratios of a circular tube diameter to a disk diameter, on macroscopic flow phenomena are discussed. Flow pattern changes by Reynolds number, Knudsen number, and momentum accommodation coefficient are revealed using finite difference solutions with viscous and slip boundary conditions for rarefied gas.

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To obtain the best performance and the optimum geometries for a wide range of conical diffusers, experiments have been performed using air flow on many conical diffusers having a uniform inlet flow except for the thin inlet boundary layer and tailpipe discharge. When the cone angle, 2α, is between 4° and 30°, the performance may be expressed with a fair degree of accuracy by the functions of cone angles and area ratios with and without appreciable stall, respectively. Pressure recovery coefficients and effectiveness are shown on one chart, together with the optimum geometry lines of diffusers when the tailpipe length is longer than its pressure recovery length. The pressure recovery length of the tailpipe is examined experimentally. If the tailpipe length is longer than three times the diameter of the tailpipe, the decrease in performance is less than two percent, even in the case of such a large cone angle as thirty degrees.

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The secondary flow pattern was clarified experimentally by the visualization method, for a fully-developed pulsating flow through a circular curved pipe with a curvature ratio of 7.6. The experiments were carried out under the conditions of the Womersley numbers α=5.5∼18, the mean Dean numbers D^^-=90 and 200, and the flow rate ratios η=0.5 and /or 1. The pictures were taken at selected four phase positions, i. e., Θ=0°, 90°, 180°and 270°. The instantaneous velocity profiles, the center of vortices and the kinetic energy of the secondary flow were determined with the aid of the photographs and compared with the results obtained by the numerical analysis. On the experimental and analytical results, a discussion is given for the transition of the secondary flow patterns in a period and the effects of the Womersley number on the flow behavior.

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The rotational flow of a water-based magnetic fluid with a three-phase, four-poles rotating magnetic field was experimentally investigated. The shapes of the free surface were measured by a contact probe, and the velocity profiles by the surface floating method. The deformation was increased with an increase in the strength of the applied current irrespective of the frequency. On the other hand, the induced flow velocity was almost propotional to that of the phase of the magnetic field, and was in the same or the opposite direction to it, depending on the strength of the applied current. The centrifugal force of the induced flow has little effect on the shape of the free surface.

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In this paper, analyses of the experimental results in the 1st report are presented. The shape of the free surface are analyzed by a perturbation method neglecting the circulation velocity and the surface tension. Results were in good agreement with experimental ones and showed that the deformation was induced mainly by the radial gradient of the magnetic field and Maxwell's surface stress. The profiles of the rotational velocity were calculated using Glazov's equation and they agreed qualitatively with experimental results. The induced velocity was so small that the centifugal force of the flow had little effect on the shape of the free surface.

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A numerical method is developed for solving three-dimensional incompressible viscous flow in a rotating system using the boundary-fitted curvilinear coordinate transformation technique. The modified SMAC scheme is applied to solve Navier-Stokes equations and the Rational Runge-Kutta method is used for time integration. Laminar flow in typical chemical agitators is analyzed and the effects of the shape of impellers and baffles on flow patterns are investigated.

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A homogeneous anisotropic turbulence field was realized without distortion of the mean flow by installing a honeycomb into a nearly isotropic strong turbulence. The resultant turbulence showed strong cigar-shaped axisymmetry, in which the longitudinal component of the turbulent fluctuation had a far larger intensity than the other two components. It gradually recovered isotropy in the course of its streamwise decay. Its decay rate was smaller than that of the strong quasi-isotropic turbulence. The intensity of the longitudinal component decreased slowly downstream. On the other hand, the intensities of the lateral components increased in the first stage of their decay and thereafter began to decrease. The features of the decay process of the axisymmetric turbulence were closely related to the degree of isotropy, the energy level of each component and the wave-number range in the spectrum.

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This experimental study aims at investigating the influences of buoyancy on the characteristics of turbulent free jets. Concentration and velocity measurements are carried out in vertically up or down jets of He, CO₂ and air into still air. As a result, it is clear that the distance from the nozzle outlet to the starting point of the buoyant jet region depends upon the Froude number, and that, in the case of a large difference in density between the jet and the surroundings, the axial and radial distributions of concentration and velocity are different because of the interaction of the momentum and mass diffusion.

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The instability of Taylor vortex flows in a gap with a small aspect ratio of concentric rotating cylinders has been investigated. In both the asymmetric and symmetric and conditions, the critical Reynolds number of transition from Taylor vortex flow to wavy Taylor vortex flow was revealed. In the asymmetric case, the bifurcation between odd number cells and between odd number and even number cells was examined in relation to the aspect ratio and Reynolds number. In addition, the bifurcation diagram was drawn in the neighborhood of one aspect ratio, and the relations, as priority, between primary flow and secondary flow on a bifurcation set were discussed.

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This study investigates the structure and dynamic behavior of a linear system which describes the perturbation of a laminar pipe flow. In the preceding papers a numerical method for calculating the eigenvalues with sufficient accuracy was proposed, and the characteristic distribution pattern of eigenvalues for Poiseuille pipe flow and the classification of the modes of the perturbations were presented. This paper discusses the effects of the Reynolds number on the distribution pattern of eigenvalues. In the first place, for the Poiseuille pipe flow, it is shown how the distribution of eigenvalues in a complex phase velocity plane takes a tree like shape as the Reynolds number increases. Then the distributions of eigenvalues are calculated for the laminar developing pipe flow and the Poiseuille pipe flow with rigid rotation, which are known to be unstable for high Reynolds number. It is found that these distribution patterns take the same shape as that of Poiseuille pipe flow, and that the unstable eigenvalues belong to the specified modes of perturbations, as predicted in the former report.

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In case of employing a wedge nozzle for CO₂ Gasdynamic Laser (GDL), it is necessary to consider generating an oblique shock wave at the nozzle exit. The translational temperature of the gas increases behind the oblique shock wave. Therefore, the population inversion becomes extinct and the small signal gain is decreased. The laser medium is reheated by passing through the oblique shock wave. In this paper, two dimensional numelical analysis which considers the influence of the oblique shock wave was carried out. In the shock wave configuration, good agreement between the schlieren photograph and the result of calculation is obtained. Experimental value of small signal gain coefficient agrees well with the calculated one.

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When a viscous liquid is confined between two parallel plates and the plates are rapidly separated from each other, the free surface of the liquid is disturbed. As a result, tree-like patterns of the liquid remain on the plates. This phenomenon is called meniscus instability. The authors have reported the relation between the minimum wavelength of the disturbance and capillary number. It is very useful to study this phenomenon, if the minimum wavelength can be obtained from the patterns on the plates. In the present paper, the tree-like patterns on the plates are analyzed with respect to fractal geometry in the field of modern mathematics and the relation between the patterns and the minimum wavelength of disturbance is investigated. The maximum force and energy required to separate the plates are also studied against the modified capillary number.

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A theoretical model for predicting the circumferential film thickness distribution in a horizontal annular two-phase flow is presented. It is based upon a two-layer film model which consists of a wave layer and a base film. It differs from Laurinat's and Lin's models in that liquid is transferred in the circumferential direction by the disturbance wave spreading which counteracts the drainage due to gravity and that the effects of induced secondary flow in the gas flow and the surface tension force have minor effects on the formation of the liquid film near the top of the tube cross section. The film thickness distribution predicted by the present model agrees with the experimental data much better than that by Laurinat's model.

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In order to improve the unstable characteristics of a high specific speed diagonal-flow fan, the effect of design angle of attack on the performance characteristics has been investigated experimentally. In the design of blade elements, two kinds of design angle of attack were specified ; the one corresponding to an optimum incidence angle and the other beeing lower angle of attack near to a negative stall angle. According to the performance test, the rotor with a low design angle of attack indicated a postponement of stall in a low flow range and fan efficiency was improved there. The design method with variable angle of attack extends the degree of freedom and it is effective when off-design conditions have to be taken into consideration in the design of a diagonal-flow fan.

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As a continuation of the research to improve the performance of a high-head axial-flow pump, composed of tandem impellers (an inducer and a main impeller), the purpose of the present study was to make clear the effect of the inducer on the pump performance. The internal flow measurements showed that the inducer reduces the pump efficiency as compared with the no-inducer case because of the lower inducer efficiency and the pre-rotation at the main impeller inlet due to the inducer. On the other hand, cavitation tests suggested the inducer has the effect of delaying the cavitation inception on the main impeller and thus results in the improvement of suction performance. Also, the improvement of the suction performance by the inducer effects was presented quantitatively.

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The instantaneous flow distributions around a propellor-type 0.8 m diameter, two-bladed rotor in a wind tunnel were measured using a 2-color 4-beam LDV system. The axial and tangential velocity components were measured at 110 points on the horizontal plane which includes the rotor axis. The axial and radial components were measured on a vertical plane. All axial, tanegential and radial components were composed form these data. Especially, we measured instantaneous velocity distributions on a rotor plane where due to the bashing rotor, the velocity could not be measured by using a conventional anemometer such as a hotwire anemometer or a pitot tube. On the plane, the measured data showed the axial velocity component increased gradually after a blade passed, and decreased suddenly with the next passing blade. The calculated results from a simplified vortex model showed that the sudden decrement with the passing blade was almost induced by the bound vortex on that blade.

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We report on a manometer with an ultrasonic distance measurement circuit which we have developed and found for practical measurements of low pressure differences in many fields. It uses a separate transmitting and receiving ultrasonic transducer pair with associated circuitary operating at 215 kHz. We explained it's structure, measurement principle and performance by comparing measurement results regarding the pressure difference (<70 mmH₂O) with the results of a Gottingen manometer and high response pressure transducer. As a result, it was found that the present manometer provides measurement resolution as great as 0.01 mmH₂O and that the maximum error was less than 0.2 mmH₂O up to 70 mmH₂O pressure difference.

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An investigation was performed to reduce secondary flow and losses in a linear turbine rotor cascade by attaching boundary layer fences to the blade suction surfaces. Kiel and X-wire hot-wire probes, used to measure total pressure and flow velocity, were traversed downstream of the cascade with varying endwall distance of fences. Surface oil flow visualization were carried out. Losses, thickness of secondary flow region, secondary vorticities, outlet flow angle changes, and secondary kinetic energy were obtained with two distinct optimum endwall distances. Losses were minimized at the distance equal to the inlet boundary layer thickness, other secondary flow properties showing minima at a shorter distance. Limits of endwall distance within which fences trap passage and trailing vortices were shown. Fences were found to reduce pitch-averaged underturning between the position of maximum underturning and midspan, but hardly to change the maximum underturning itself.

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Boundary layer fences have been attached to channel-confining endwalls of a linear turbine rotor cascade to reduce secondary flow and losses. Local and averaged secondary flow propeties obtained from hot-wire and Kiel probe measurements downstream of the cascade are shown for the different pitchwise locations of fences. The fences are most effective if located half the pitch away from the blades. The optimum fences reduce the secondary vorticities by half, the enbwall distances of these vortices by 30%, and the maximum underturning by 60%, compared with an unfenced blading case. They decrease the secondary loss by 22%, the net loss produced within the cascade by 10%, and the gross loss including secondary kinetic energy dissipation far downstream by 25%, in spite of an additional loss production due to friction and flow separation at the fences.

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Numerical experiments are performed to investigate the effects of buoyancy on the hydrodynamic and thermal characteristics of downward-flow laminar convection in the entrance region of inclined parallel plates. Numerical solutions are given for three thermal conditions of parallel plates with uniform wall temperature or insulation. These results are discussed in conjunction with those of an upward-flow case. For use in practical applications, correlation equations are developed for the friction factor and the local Nusselt number. The critical values of Ra/Re for the occurrence of flow reversal are also presented by the use of correlation equations for the friction factor.

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The mechanisms of the retardation and the enhancement of heat transfer in the combined convection region of the aiding and the opposing flows were investigated both experimentally and analytically in the present paper. The surface temperature distributions were visualized by the liquid crystal sheet. The results show that the low-temperature streaks or spots of large sizes appear in the whole regions of forced, natural and combined convections, and they exert a significant role or the heat transfer. Such low-temperature streaks or spots are generated as the result of the penetration of the low-temperature fluid lumps into the near wall regions. The surface renewal model was proposed to simulate the heat transport by the above fluid motion. It was found that the model predicted the heat transfer of the combined convection quite satisfactorily.

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The turbulent heat transfer of combined forced and natural convection along a vertical flat plate is investigated experimentally both on the aiding and the opposing flows of air. Local heat transfer coefficients are measured in the vertical direction. The results show that the local Nusselt numbers for the aiding flow become smaller than those for the forced and the natural convection, while the Nusselt numbers for the opposing flow are increased significantly. These results are compared with the previous results for water. It was found that the non-dimensional parameter Z (=Gr*_x/Nu_xRe_x)^2.7Pr^0.6) can predict the behavior of heat transfer both for air and water. Furthermore, the natural, the forced, and their combined convection regions can be classified in terms of the above parameter.

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Experimental results of forced convective boiling of nonazeotropic refrigerant mixtures of R22 and R114 inside a horizontal tube with internal spiral grooves are presented. Pure refrigerants R22 and R114 and three kinds of their mixtures containing about 25, 50 and 75 mol% R114 are tested in the ranges of mass velocity of 77 to 347 kg/(m²s) and of pressure of 0.6 to 7 bar. The axial distributions of refrigerant temperature and heat transfer coefficient for mixed refrigerants depend on the concentration, while those for pure refrigerants of R22 and R114 show similar behavior. An empirical correlation concerning the heat transfer coefficient of pure and mixed refrigerants is proposed as a function of the boiling number, Lockhart-Martinelli parameter and liquid heat transfer coefficient for a smooth tube.

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The separation point of a cylinder in a uniform oncoming flow moves upstream and downstream due to the Karman vortices far downstream in the wake. In contrast to studies and reports made so far on the time-averaged heat transfer performance around the cylinder, this paper aims at an experimental clarification of instantaneous and local heat transfer performances and an explanation of the relation of time / local performance and time-averaged performance, particularly in the vicinity of the separation point. Experiments were done using a heat flux sensor and an anemometer of triple fine wires for the measurement of unsteady surface heat flux and the flow field, respectively. Based on the measured results it is concluded that the separation point is found to move in the way of sinusoidal motion, which is somewhat modified by the fluctuation of the normal probability distribution. The measured time-averaged heat transfer performance near the separation point is shown to be well explained by the estimated instantaneous heat transfer coefficient distribution and the probability function obtained.

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This paper deals with the experimental studies on body forced convection film condensation of pure single, component vapor on a vertical smooth surface. A vertical plate and a smooth tube are used in test section. R-11, R 113, R114 and ethanol is used as the working fluid. The flow patterns of condensate film are classified into laminar flow, sine wavy flow and harmonic wavy flow. Nondimensional expressions of the local heat transfer coefficient are obtained for laminar flow, sine wavy flow and hamonic wavy flow, respectively.

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The effect of an external magnetic field on the natural convention of a melt, which is electrically conductive, has been studied in relation to the process of crystal growth. It is known that the convective flow of a melt seriously affects the quality of the crystal, and that the application of a magnetic field could be one of the most promising procedures. Both the Bridgman and the Czochralski growth processes have been modeled under the assumption that the external magnetic field is imposed vertically. The result of a numerical analysis has revealed that there is a minimum intensity of the magnetic field that is necessary to suppress the convective motion of the liquid, and that above this threshold intensity the flow velocity decreases as inversely proportional to the magnetic field squared.

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In order to theoretically approach forced-convection filmwise condensation in a vertical tube numerically, the governing equations for both water vapour flow and condensate film flow were solved with a finite difference sheme simultaneously. The wave on the vapour-film interface was taken into account with a model previously used in the two-component two-phase annular flow. The present numerical results are compared with the experimental data given by Blangetti. The computed heat transfer results agree fairly well with Blangetti's data for the condensation of water vapour over a wide range of film Reynolds number, 50 < Re_f < 2 000, and for three different vapour flow Reynolds number. The present type of numerical analysis is found to be useful for the prediction of forced-convection condensation heat transfer.

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A transient method with pulse heating has been developed to determine the specific heat and thermal conductivity of Bakelite (phenol-formal dehyde resin) in the temperature range of 4.44-9.15K. The temperature excursion in an infinite cylinder with an insulated outer surface and with a cylindrical heat source embedded in it was calculated initially. In the calculation, the heat source released heat as a rectangular-shaped pulse in the time direction. The ratio of the temperature rise at any two time instances was found to be a function only of the Fourier numbers associated to those instances. Therefore, by measuring that ratio, thermal diffusivity was determined while the specific heat could be calculated by the ultimate temperature rise. It was recognized in the temperature range tested that the specific heat and thermal conductivity increased with temperature while the thermal diffusivity decreased with it. The temperature dependence of the specific heat measured is similar to that for Formite Bakelite varnish in the literature.

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This paper presents a variational principle which connects solid and fluid temperature fields in the analysis of thermally coupled problems. The principle satisfies the equilibrium condition of heat flux on the boundary. The combination of the principle and a hybrid type of virtual work principle for flow problems is applicable to the analysis of the thermally coupled problems between solids and fluids. This paper describes a finite element method (FEM) based on the combined principle. The FEM eliminates an iterative calculation to satisfy the equilibrium condition on the boundary. The FEM is applied to a thermally coupled problem between a finite vertical plate with heat source and surrounding fluid.

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The temperature distribution of a molten carbonate fuel cell was investigated experimentally and analytically under electric power generation. A numerical method for the solution of the fuel cell temperature disribution was proposed and examined ; the method is posed to solve the steady-state temperature whose changes were coupled with the electrochemical reaction and gas flow. Calculation results have been compared with experimental results, and reasonable agreement has been obtained. As a consequence, the effect of heat conduction was observed to be considerably related to the temperature distribution of a fuel cell.

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An experimental study was carried out on the combustion of ultralean-fuel/air mixture by preheating the mixture by means of a heat recirculating burner. The combustion chamber of the burner was made of transparent glass to allow the observation of flame appearences. A laminar, continuous flame was stabilized in the combustion chamber. The conclusions obtained are as follows : (1) Almost completely burned gas is produced with a negligibly small amount of nitrogen oxide. (2) If the combustion of the mixture is incomplete in the combustion chamber and the residual of the mixture burns secondarily in the inner cylinder, the temperatures of the preheated mixture and the flame drop leading to inferiority of the burner performance. (3) The flame blows off prior to the approach to the proper limit of flammability for the preheated mixture, so that the flame stabilization in the combustion chamber is important since the mixture at the blow-off limit is still flammable.

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The combustion characteristics of a single CWM and COM droplet on a hot surface were investigated in a test furnace in which the ambient and surface temperature were equivalent ; this is to say, were at a uniform temperature. The droplet was simply set on the hot surface without using any suspending equipment like a silica thread. The following results were obtained. The ignition delay time of the COM droplet was shorter than that of the CWM droplet. The total burning time of the COM droplet was only slightly shorter than that of CWM. When the initial diameter of a droplet decreased, the total burning time was proportionally decreased by the square of the initial diameter. The effect of size distribution of the pulverized coal appeared on a surface combustion process of fixed carbon. The effect of coal properties on the surface combustion process was also studied using ten kinds of coals.

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An inter-droplet interference effect on the burning of fuel droplets in a uniform stream was theoretically studied. Fuel droplets were assumed to be monodispersed, uniformly distributed and to flow with the same velocity as that of the ambient flow. Following the Schvab-Zeldovich formulation, the combustion of a cloud of fuel droplets was reduced to a problem in which spatial variations of the diameters and burning rates of the droplets must be determined by an integrodifferential equation. Solutions were numerically obtained for some combinations of parameters associated with the distribution and the size of the fuel droplets.

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As experimental investigation using an LDA system revealed important parameters to determine the shape and strength of an IRZ (Internal Recirculation Zone), which is created by isothermal expanding swirling flows initially in solid body rotation with a uniform axial velocity. It was found that the expansion geometries had only an minor influence on the characteristics of the IRZ when the flow was confined in a small furnace space, while they became important in determining a flow pattern when confined in a larger furnace. The recirculating mass flow rate (Mr/Mo)max, was found to be a function of both swirl number S and vortex diameter expansion ratio D₁/Do, which led an experimental formula ; (Mr/Mo)max =0.1 [S(D₁/Do)²]^0.85. For small furnaces, D₁/Do can be replaced by furnace diameter, Df/A.

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A large number of old FRP boats, that were constructed in the early days of the practical application of FRP, lasted for a prospective life span of more than 20 years and will have probably been retired from service in a few years. Therefore, the disposal of waste FRP materials by combustion with a fluidized bed furnace is investigated together with an investigation on the secondary influences of emission gas in the atmospheric environment. The results indicate that a uniformity of the temperature in the furnace is maintained without any occurrence of adhesion of melted glass contents to the furnace wall and that the plastic components of FRP are almost completely fired in the fluidized bed furnace with restricted concentrations of black smoke and offensive odor confined in the emission gas. A decrease in the furnace temperature to 700°C causes choking of the dust separator in the exhaust line of the furnace due to fibrous glass entrained in the emission gas.

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Two phase closed thermosyphons are highly efficient heat transfer elements applied in terrestrial heat transport and heat recovery systems. In the present work, a corrugated copper tube was used as the container of the thermosyphons and distilled water was used as the working fluid. The influences of the liquid fill charge and inclination angle on the heat transfer performance were studied. It was found that optimum liquid fill ratio to evaporator volume is 40% and the maximum performance is obtained at an inclination angle of 30°. A useful formula to calculate the heat transfer coefficient in the evaporator has been derived.

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In order to pursue a high-performance mist-cooled heat exchanger, development of heat-transfer tubes with various surface structures, such as grooved, wire-wound, and screen mesh wrapped tubes, has been performed on the basis of the previous results of smooth surface tubes. The effect of surface structures on heat-transfer enhancement was clarified experimentally and theoretically with relation to the extension of a wetted area.

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This study aims at making an original proposal to install twisted tapes in plate-fin heat exchanger channels for making uniform the outlet temperature of heated gas or for decreasing thermal stresses. First, in order to clarify flow and temperature performances by the insertion of twisted tapes up to 650°C, experiments are made using two kinds of channels with aspect ratios 1 and 2. Second, numerical calculations are made to obtain the optimum pitch ratio distributions of the tape to have a uniform heated gas temperature profile. Experiments on the temperature fields are made using a heat exchanger and the validity of the theoretical prediction is confirmed. Third, by use of the other heat exchanger of brazen construction, the change of thermal stresses by the insertion of tapes is measured. It is shown by the experiments that the maximum stress appears near the piping connecting part of the cover plate, and that this is decreased nearly 1/3 by the insertion of twisted optimum tapes.

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