This paper deals with an experimental study on the collapsing process of bubbles produced by a focused ruby laser beam in water. The behavior of the collapsing bubbles, and propagation of shock waves induced in the process were observed using double a exposure holographic interferometer and an Ima-Con Camera. The impact pressure was measured by changing the distance between the focusing point of the laser beam and a pressure gauge. Results indicated that the impact pressure induced at the instant of bubble rebound was more intense than that induced at bubble initiation due to the laser focusing, and showed how the impact pressure was attenuated with the distance.

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In order to make clear the dominant factor on which cavitation initiates, I statistically analyzed the acoustic pressure pulses generated from cavitation in a typical orifice flow and simultaneously observed the cavitation aspect in the near-desinent cavitation range, for various dissolved CO₂-gas contents C in naturally air saturated water. The CO₂-gas was dissolved into the water under almost the same cavitation-nuclei-distribution. Since both the aspect and the corresponding stochastic behavior of the acoustic pulses change considerably with C, it is concluded that the dissolved gas could be a dominant factor on the cavitation through a typical process by which the nuclei rapidly grow within the dead water region.

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The flow around the criss-crossed two circular cylinders set normal to the uniform stream was examined from the measurements of the surface pressure distributions and the behavior of the vortex behind the cylinders. The estimation of the drag on the crossed two cylinders shows that the drag coefficient of each cylinder is lower than that of the single cylinder except in the vicinity of the crossed region. On the surface region close to the contact point the secondary flows were observed from the oil-film visualization. The vortex shedding from the four cylinder parts away from the contact point is almost equal to that of a single cylinder, but these vortices are not correlated with one another.

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The laminar, fully-developed pulsatory flow of an incompressible viscous fluid through curved pipes with rectangular cross-section has been investigated analytically and experimentally. The flow fields are made clear by numerical analysis for mean Dean numbers D^^-=10∼150, Womersley numbers α=2∼20, and flow rate ratios η=0.5 and 1. The experiment is made of power losses and the results are compared with the numerical ones. The effects of the aspect ratio of a pipe on the flow are fully discussed. Consequently, it is found that the flow in the square-sectioned pipe is greatly under the influence of the curvature of the pipe.

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A viscous flow squeezed between a moving flat disk and a stationary one, whose radii are finite, is studied theoretically. Then, assuming that the ratio of the gap between two disks to their radii is small, an approximate solution is found in the form of the power series of the ratio with the precision of the fourth order of its ratio, because the governing equations represented in the dimensionless form consist of the various terms up to the fourth power of the ratio. The general formulas of the velocity, the pressure, the forces acting on the disks and so on are found from the approximate solution obtained here and compared with the results obtained by other workers.

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Two-dimensional flow around an automobile is calculated by solving the incompressible Navier-Stokes equations numerically. The basic equations are transformed into a general coodinate system and discretized by a third-order upwind scheme without any turbulent modes. Computational results show small vorticies being generated one after another at the leading edges of the hood and roof, which start to increase in size over the rear window and become extremely large behind the vehicle. The pressure distribution on the surface of the body indicates several minus-peaks corresponding to the vorticies at each time step. However, when the surface pressure is averaged over a long period, agreement with the experimental data measured in a two-dimensional wind tunnel is good.

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A discrete vortex method combined with a singularity method is applied to the flow around two rectangular cylinders arranged side by side. The effects of the applied boundary conditions, the size of the time step, and the gap size between two bodies on hydraulic forces (drag coefficient, lift coefficient, Strouhal number etc.) are investigated. Results show the existence of appropriate boundary condition and the steep augmentation of the interaction effect between bodies with a narrower gap, in which the location of a stagnation point changes abruptly below some value of a gap size and the time variation of a lift coefficient does not become periodic due to the steep development of the interaction effect. They are in good agreement with experiments. Consequently, it is shown that a discrete vortex method is very practical and useful in interaction problems of flow.

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Conditional averages of streamwise, lateral, spanwise velocity and of their products have been examined by using a VITA technique to study the well-organized vortical structures associated with the bursting phenomenon, in the turbulent boundary layer over a d-type rough surface at a momentum thickness Reynolds number of R_θ≒800. The ensemble averaged patterns suggest that pairs of counter-rotating streamwise vortices associated with the ejection events probably exist in the wall region of a present rough wall flow but occur randomly in space and time, and that broad large scale three-dimentional vortical motions associated with the sweep events move around the low speed streak as the sweep passes over the wall region. These vortical structures are associated with high Reynolds shear stress and also high streamwise vorticity and hence make a significant contribution to turbulent-energy production.

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Developing region of the 3-D turbulent free jet issuing from a 60mm×60mm square nozzle was investigated experimentally both by conventional and conditional sampling techniques. As opposed to the turbulent corner boundary layer, contours of the mean velocity and those of the fluctuating velocity components obtained by conventional averaging do not show any significant difference in distorsion between them. Nearly the same contours were observed in the conditionally averaged quantities, although some characteristic differences exist in the inner and in the outer intermittent region of the mixing layer. It is found that turbulent zone-averaged eddy viscosity takes practically a constant value over the mixing layer and that turbulence production occurs essentially when the flow is turbulent. From the results of conditionally averaged secondary flow field, a possible entrainment mechanism is proposed.

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By using the third order upwind finite-difference method for the convective term in a Navier-Stokes equation, numerical stability can be improved because of the numerical viscosity which is proportional to the fourth derivative of velocity. So high Reynolds number turbulent flow can be simulated directly without any explicit turbulent models. In this study, homogeneous and isotropic turbulent flow is simulated by this method, and the calculated results are compared with experimental data. As a result, it is shown that this method is equivalent to the method in which basic equations are spatially averaged by a filtering operation, and this equivalent filter width is a function of the mesh size and the coefficient of the numerical viscosity term. Energy spectra and turbulent kinetic energy of the calculated results are in good agreement with the experimental data when filtering operation is taken into account.

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Explicit and implicit time-marching finite-difference schemes are proposed for analysing three -dimensional steady and unsteady inviscid transonic flows. These schemes are different from the existing methods since the Euler equations of contravariant velocities in general curvilinear coordinates are used. However, some computational techniques used in the existing methods, such as linearization, diagonalization and upstreaming are also applied to these schemes. The finally obtained equations for the numerical computation have almost the same complexity as the corresponding existing methods. The remarkable feature of these methods is the ability to treat solid wall boundary conditions easily and exactly including, implicit schemes. A calculated result of shocked transonic flow through a converging-diverging square nozzle is shown.

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Structures of interacting free jets from two sonic nozzles are studied by flow visualization for various angles between centerlines of nozzles and various ratios of the source pressure P_s. to the pressure in the expansion chamber P_b. Experiments are carried out with I₂-seeded Ar which easily radiates fluorescence by irradiation of a laser beam. Characteristic shock systems and density distributions of the interacting two free jets are qualitatively elucidated from the analysis of many photographs of visualized entire flow fields.

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In pneumatic transport of P.V.C. powder of which the mean diameter and material density are 134μm and 1 330 kg/m³, the solid velocity is measured by the activable tracers method in a vertical line of 100.0 mml.D. and 24 m length, where the air velocity is changed from 16.5 m/s to 28.9 m/s and the solid loading ratio is between 48.8 and 82.5. It is possible for the method to measure solid velocity at the highest solid loading ratio that have not ever been measured.

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The heat transfer characteristics of a V-shaped hot-wire, which was originally developed for reliable measurements of near-wall turbulence, are investigated for measurements of small gas velocities. The effective cooling velocity of a V-shaped hot-wire can be represented by the relation U²_e= U²_n+k²U²_t1+h²U²_t2 for the fluid velocity range 0.05 to 1.0m/s, where U_n, U_t1 and U_t2 are the orthogonal velocity components in the hot-wire oriented coordinate system. For a given type of wire, the sensitivity coefficients, k and h, are dependent primarily upon the fluid velocity and almost independent of the wire orientation. The effect of the wire configuration on heat transfer characteristics is shown and discussed.

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Peristaltic flow generated in a two-dimensional channel is investigated numerically and experimentally, in the range of large wave amplitude and large Reynolds numbers where peristaltic pumping has a possibility of engineering application. The Navier-Stokes equations are solved numerically by using the finite-difference method employing the modified upwind scheme proposed by Dennis and Chang, which provides both computational stability and good solution accuracy even at a high Reynolds number. Visualized photographs of the streamline and the particle trajectories are shown, and the velocity profiles in the flow are obtained by using image processing. In addition, the Lagrangian trajectories of the fluid particles are investigated in detail to elucidate the reflux phenomenon. Comparison between the results of numerical and experimental analysis shows a good agreement and gives verification to the theoretical analysis. In the light of the results, a distinctive feature of peristaltic flow at a large wave amplitude and large Reynolds number is discussed.

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In order to clarify the flow characteristics of a circular turbulent air jet impinging normally onto a fiat surface, the distributions of jet velocity and its turbulence intensity in the impingement region of the jet were measured in detail by hot-wire anemometry by changing the jet nozzle diameter, initial jet velocity and impinging height etc.. Consequently, those measurements were found to be similar to the velocity distribution in the free or wall jet region respectively, and also showed a reasonable agreement with the results calculated numerically assuming a new velocity distribution on the inflow boundary line of the impingement region.

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Experimental studies have been conducted to investigate the effects of the swirl on the turbulent transport of momentum in a concentric annulus with a rotating inner cylinder. Direct measurements of turbulent transport of momentum were made by correlating fluctuations of two velocity components which were detected by a two-color laser Doppler velocimeter. It was observed that the Reynolds stresses increse due to the swirl. The magnitude of the production terms of the transport equations of the turbulent fluxes of momentum were estimated. The dominating terms are pointed out to illustrate the processes of interactions between momentum fluxes and the swirl.

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The characteristics of the viscous type instability of the boundary layer flow on a rotating disk in a still fluid are investigated in detail by means of a linear stability analysis. The critical Reynolds number for the viscous type instability is found to be 55.5. The phase speed, wave number and wave front orientation are also calculated. The results are compared with those for inviscid type instability. The viscous type instability is visualized experimentally for the first time.

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Measurements are performed on aerodynamic drag coefficients, C_D, of a two-dimensional bluff-based body over the range of blockage ratios of the body breadth to the wind tunnel width, d/W=0.1∼0.4, C_D increases with an increase of d/W, exponentially at d/W>3.5, being subject to the blockage constraint. A modified drag coefficient C'_D introduced by the clearance freestream velocity between the body and the tunnel side wall, U'_∞, remains a constant value, independently of blockage ratios of d/W<3.5. C'_D implys the base drag coefficient without the blockage effects, C_D0, and the latter may be predicted by an empirical formula C_D0K²·C_D and K=U_∞/U'_∞=1-d/W-2(δ^*_b+δ^*_w)/W, where δ^*_b and δ^*_w are the boundary layer displacement thicknesses produced on the body and the tunnel wall. The drag characteristic is also discussed with the results of the pressure and velocity distributions around the body and the wake, the prevailing frequency of shed vortices, and the flow visualization.

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The cross-sectional average velocity, U_m, of a pulsatile flow fluctuates with the Womersley number of 45.2. The ratio of the amplitude of U_m to its time mean value, U^^-_m, is 0.366 and the Dean-number, based on U^^-_m, is 1.58×10⁴. The results obtained are as follows : (1) The axial velocity componet, U_φ, fluctuates synchronously with U_m. The amplitude of U_φ is smaller than that estimated from a quasi-steady state assumption based on U_m at the outer wall region and is larger at the inner wall region. At the inner wall region the amplitude of secondary flow velocity component, U_r, becomes about two times larger than the estimated one using U_m : (2) In the large part of the skewed boundary layer on the end wall, non-dimensionalized secondary flow velocity decreases exponentially with distance from the end wall, although the distribution in steady flow has wall jet type similarity.

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Bubble flow characteristics were investigated experimentally in nitrogen gas-water in a spuare channel using a laser Doppler anemometer and a double-sensor conductance probe under the same flow rate conditions. The size of the bubbles was controlled by changing the mixing conditions and by adding a surface active agent to water. Thus, four sets of experiments were conducted. Experimental results show that the reduction in bubble size flattens the gas-phase distribution and increases the number density of bubbles. The reduction in bubble size leads to a decrease in turbulence and an increase in water and bubble velocities, but an extreme reduction does not bring about a further increase in both velocities, although it leads to a further decrease in turbulence. Turbulence suppression was observed in layer-type bubble flows. This type of flow has a peculiar profile of water velocity.

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Experiments have been carried out to investigate direct contact condensation of saturated vapor bubbles introduced into a quiescent subcooled water environment. The experiments were performed for a range of pressures from atmospheric to 1 MPa, for subcooling from 10 to 70°C, and for initial bubble diameters of about 10 mm. Flow visualization by high speed motion pictures was based on a frame by frame analysis. The photographs showed that the successive shapes of the bubbles during their collapse histories proceeded from a sphere to a hemisphere, to an ellipsoid, to a sphere, and finally to collapse. Two-dimensional photographs showed that the cavities of the bubbles during their collapse histories proceeded from the bottom to the top. The time to collapse increased with increasing pressure and with decreasing temperature difference. The rising velocities of the bubbles were essentially constant, with an overall range of 20∼25 cm/s.

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Progressive change of flow pattern of two phase flow was studied experimentally in the transition region from bubble flow to slug flow or annular flow. In the experiment, three transparent straight circular tubes which had different diameters were employed for the test section. The water flew upward in the test section and the air was issued from a circular nozzle located at the bottom of the test section. The experiment was performed at atmospheric pressure and temperature. The transition from bubble flow to slug flow is classified into three parts for the region of flow state in the result. The first part is a lump of air contacting the nozzle, the second part is a developing region from bubble flow to bubble cap and the third part is a region between the bubble cap and Taylor bubble. The entrance region from the air nozzle to the Taylor bubble is independent of Reynolds number of the water flow, but depends considerably on the ratio of air flow rate to the flow rates of air and water.

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To predict axisymmetrical fluid-pipe coupled vibrations, there have been proposed a variety of theories ranging from the sophisicated shell model to the simplest but convenient one-dimensional approximation neglecting Poisson's ratio. In contrast, experimental works to verify the theories are sparse as yet. The present paper intends to experimentally single out an appropriate model for longitudinal vibrations of a pipe containing viscous fluid, and also to estimate the internal friction of pipe metals, which is supposed to take part in energy dissipation. Frequency response tests have been carried out in oil hydraulic pipes with one end fixed and another free. The shell model neglecting rotary and transverse inertia proves to be most available, while the one-dimensional model is incorrect to describe the pipe behavior. It also turns out that the solid viscosities of the metals must be less than one-tenth of their conventionally obtained values.

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This paper is concerned with a sliding vane type rotary compressor for an automotive air conditioner, The return of liquid refrigerant to the compressor increases the compressor load and affects the compressor performence. Fundamental characteristics of the liquid compression during the steady operation of the compressor were examined experimentally. Pressures in the cylinder and the torque of the shaft were measured by changing the speed of the compressor and the amount of liquid refrigerant stored in a reservoir which was set up parallel to the suction line. Peaks in the pressure and the torque due to liquid compression were not observed when the amount of liquid refrigerant was small. However, the slow rise of the pressure in the cylinder suggested the detachment of the vane from the cylinder wall. The increase of the sound level of the compressor with the liquid back implied the collision of the vane with the cylinder wall.

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Although a supersonic centrifugal compressor develops a very high pressure ratio, it can hardly change the flow rate at a given shaft speed, therefore, it is seldom used for industrial applications. In this paper two types of impellers were tested, clarifying the problems ralative to stall and choke which decide the flow range. Regarding choke, it is shown that the throat blockage is increased with the inlet relative Mach number due to the deceleration to the throat in the case of supersonic inflow. Regarding inducer stall, it is clarified that the camber of the inducer is an important parameter in addition to the inlet relative Mach number and the incidence angle.

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The tip-clearance effects of centrifugal impellers are usually related to the clearance/bladewidth ratio at the impeller exit, and the relationship has been experimentally examined. In some cases the clearance was changed by the axial movement of the shroud casing relative to the impeller, and as a result the radial clearance in the inducer was hardly changed. If the tip clearance is changed uniformly along the shroud, the effects of tip clearance must be larger than predicted based on those experiments. In the case of a centrifugal compressor with 6 : 1 pressure ratio, the decrement of impeller efficiency due to tip clearance is theoretically examined for five types of clearance-distribution along the shroud, and significant influences of the radial clerance in the inducer are demonstrated.

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The previous report presented an elementary description of a cross-flow turbine for a tidal or a wave power plant. In order for the turbine to rotate in the same direction in reciprocating flows, this turbine performance is influenced by the symmetrical nozzle shapes around its axis. Then we investigate the relation between the turbine performance and the changes in the flow passage area. It is desirable that the changes in the flow passage area be smooth and the diffuser angle be small. Therefore, the separation in the diffuser become smaller and the turbine performance is improved.

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The velocity distribution around a rotating cone in a casing, and the pressure distribution on the casing wall are measured for a variety of combinations of the clearance ratio and the throughflowrate. The cone vertex angle, 2_θ, used in the experiment, is 60°. The results of the velocity measurement for a large clearance ratio show the presence of a potential core in the flow field. The ratio of the angular speed of the potential core to that of the rotating cone, K, is almost the same as for the case of a rotating disk, if C_q·sinθ is kept constant (C_q is the dimensionless throughflow rate). The pressure distribution and the axial thrust coefficient are almost the same as those for a rotating disk and they are independent of the Reynolds number R_e, when C_q·sinθ·R_e^-0.8 is kept constant.

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Concerning the flattening of temperature distribution of a steel slab, the characteristics of local heat transfer due to impingement of a confined turbulent two-dimensional air jet on a heated surface have been conducted experimentally for a jet Reynolds number up to 20 000, for 6 heated surface-slot nozzle spacings and for 3 heated side surface-porous plate spacings. It was found that the spanwise heat transfer exhibits two or three local maxima. Nusselt number at the stagnation point was constant for the dimensionless spacing 1<h/2d<3 and also increased with decrease in h/2d(<1).

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Natural convective heat transfer from a vertical wavy surface with discontinuous heating has been studied experimentally by considering the effect of heat conduction in unheated elements. The wavy surface is constructed with concave and convex semicircular cylinders and has discontinuous heat sources on concave or convex surfaces. The behavior of the flow and the temperature distributions in the boundary layer of surfaces have been discussed to clarify the effect of heat conduction in the unheated elements on local Nusselt number for the case of convex- or concave-heating. Empirical formulas have been derived to predict the average Nusselt number along the wavy surface.

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This paper presents the results of a theoretical analysis of the laminar film-wise condensation heat transfer to a cooled small downward surface. A quasi-steady solution is obtained and compared with previous experimental results having different physical properties. The theory shows that the circumferential area of the surface is very important in the small condensing surface because the ratio of the circumferential area with a thin film to an overall heat transfer surface increases remarkably than that of the large surface. It is shown that the analytical solution can well predict the heat transfer to a small surface.

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Heat transfer in nucleate boiling from a tube in a horizontal bundle deviates from that on a single tube in a pool. This difference refers to the tube bundle effect for brevity, which implies enhancement or deterioration in heat transfer. This paper presents a predictive method for enhanced heat transfer by adopting a model similar to that proposed by Mikic and Rohsenow for pool boiling, in which heat is transferred by two convective components, one due to generating bubbles and another due to flowing bubbles, and the latter contribution accounts for the enhancement of heat transfer in a tube bundle. The prediction for various bundles of different numbers of tubes in a vertical row and for different distributions of heat flux reproduces well the experimental data in the whole range of heat flux supplied to the tube concerned under various pressures.

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This experiment is one of basic boiling heat transfer research concerning a solar-powered absorption-type chiller. A heat transfer tube, which was surrounded by a porous, polyurethane, heat-insulating layer of different porosity-size and different radial thichness, was tested under atmospheric and reduced pressure conditions and the saturated boiling heat transfer characteristics were determined. Obtained experimental data for the porous tubes indicates that the minimum incipient boiling heat flux is reduced to the order of one of twentieth and the boiling heat transfer coefficients are improved to the order of several times (2 to 5 times) that of a conventional submerged heater boiling case under the same experimental conditions.

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This paper deals with the theoretical analysis of laminar forced convection condensation of binary mixtures on a flat plate. Similarity solutions for seven kinds of binary mixtures of ethanol-water, R 22-R 114, R 114-R 11, air-water, air-ethanol, air-R 22, air-114 along with several pseudo-mixtures of low Shmidt number and low ρ-μ ratio are numerically obtained. Two expressions among the boundary values at the vapour-liquid interface concerning heat and mass flaxes through the vapour boundary layer are newly proposed, which contain the characteristics of condensation of superheated and saturated pure vapours and those of single phase forced convection. The heat and mass fluxes calculated from the simultaneous algebraic equations which are composed of the present new expressions, previous expression for liquid film heat transfer, phase equilibrium conditions and miscible condition, agree with those from the similarity solutions within 1-3% error.

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It is well known that the behavior of condensate drops have important significance in the heat transfer of dropwise condensation. However, it is difficult to clarify the behavior of the condensing drops on the condensing surface, because of their constantly changing weight and shape. Therefore, in the air, the behavior of a water drop with a constant weight on an unwet tube was investigated using a video-tape-recorder. The critical still mass, the falling velocity of a water drop and the condition in dropping from the tube, for some tube diameters, were clarified.

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The ice shape formed inside a pipe containing a water flow was examined experimentally. It was shown that two transition modes of ice shape were observed; one is a smooth transition mode and the other, a step mode. The onset conditions of the step transition mode, which were correlated in terms of pipe Reynolds number and cooling temperature ratio, were derived by analytical considerations and confirmed by experimental results. It was also found that a laminarization of flow is related to the formation of an ice-band for smaller Reynolds numbers, while a turbulence of flow may affect the ice shape for larger ones. It was found that the ice shape pattern can be classified into four large groups in relation to the pipe Reynolds number as well as the cooling temperature ratio.

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The accuracy of measurement of mixing-cup temperature is discussed for a cylindrical mixing chamber in which specially designed baffle plates are inserted. The temperatures measured by the chambers at the inlet and outlet of an electrically heated vertical tube are compared with those predicted by heat balance. The flow pattern in the mixing chamber is observed by the hydrogen bubble method. Pressure loss is also measured. For the accurate measurement, two baffle plates are sufficient in the laminar flow region when the distance between them is relatively large, while no baffle plate is necessary in the turbulent flow region. In the laminar-turbulent transition region (R_e=2 000∼3 000), temperature fluctuations at the heated tube wall as well as at the outlet of the mixing chamber are outstanding in comparison with those in laminar and turbulent regions. It is clarified, by simple analysis using a lumped-heat-capacity model, that the temperature fluctuations at the transition region are due to a combined effect of both laminar-turbulent flow intermittency and heat capacity of the heated tube.

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The problem of free convective heat transfer from a non-isothermal two dimensional or axisymmetric body of arbitrary geometrical configuration in a fluid saturated porous medium is analysed on the basis of boundary layer approximations. Upon introducing a similarity variable (which also accounts for a possible wall temperature effect on the boundary layer length scale), the governing equations for a non-isothermal body of arbitrary shape are reduced to an ordinary differential equation, which has been previously solved by Cheng and Minkowycz for a vertical flat plate with its wall temperature varying in an exponential manner. Thus, it is found that any two dimensional or axisymmetric body possesses its corresponding class of the surface wall temperature distributions which permit similarity solutions. A more straightforward and yet sufficiently accurate approximate method based on the Karman-Pohlhausen relation is also suggested for a general solution procedure for a Darcian fluid flow over a non-isothermal body of arbitrary shape. For illustrative purposes computations are performed on a vertical flat plate, horizontal ellipses and ellipsoids with different minor to major axis ratios.

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An improved transient calorimetric method for measuring total hemispherical emissivities ε_h of thin metal wires is reported. In order to reduce heat losses through a pair of thermocouple leads suspending a specimen, guard wires are carefully designed and used. Copper and iron wires of about 0.5 mm diameter are used as samples. Measurements of ε_h have been made in the temperature range 300∼800 K. The lead-wire heat losses and the temperature distributions of the specimens are exactly analyzed. It is confirmed that the heat losses have been kept considerably small by using the guard wires. The ε_h values are determined by taking account of the heat losses. Comparisons of the results are made with the data of previous investigators and those carried out for disk- and wire-type specimens. The examination of the experimental results reveals that the present technique is suitable even for thin metal wires.

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The heat transfer and friction performance of single row plate fin and tube heat exchangers which are mainly used in air conditioners was obtained at low Reynolds numbers ranging from 70 to 700. The fin spacing, tube spacing and other geometric parameters were varied systematically in the experiments. The experimental results suggested that the flow was in the regime of boundary layer development. By using the newly determined characteristic length and velocity, the experimental data were correleted and dimensionless equations of the heat transfer coefficient and friction factor were obtained.

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In the former paper the authors presented experimental data showing the effects of fin spacing, tube spacing and other geometric parameters on the heat transfer and friction performance of single row plate fin and tube heat exchangers. This paper describes the results of a continuation of that earlier study. Heat transfer and pressure drop measurements have been made for 24 plate fin and tube heat exchangers in which the primary physical variable is the flow depth, which varied from 2 to 5 tube rows. The experimental results revealed that the performance of multi row heat exchangers was affected by vortices generated from the outerwall of the tube, and the vortices are activated and strengthened with increasing Reynolds number. Dimensionless equations for the performance of multi row plate fin and tube heat exchangers were obtained.

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A combined type of latent-and sensible-heat thermal energy storage (TES) is proposed, and it-s performance is investigated experimentally and theoretically. The theoretical treatment is made taking in account recirculating flow in the capsule. In comparison with the theoretical answers and the experimental results given by preceding report, the optimum design of TES is determined in relation with the operating conditions and Phase Change Material (PCM).

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This paper describes experiments and the analysis of the heat transport capability of axial grooved heat pipes. The heat pipes were made of aluminum axial grooved extruded pipes and the working fluid was R11. The effects of fluid inventory and inclination angle on the capillary pumping limit were investigated. A theoretical model has been developed to predict the temperature rise in the evaporator and the heat transport capability. In this model, the puddling effect, liquid recession into the groove bottom and the heat conduction in the evaporator were taken into consideration and the prediction agreed well with the experimental data. It was found that the temperature at the evaporator end began to increase just after all the grooves dried out at the evaporator end. The flooding limit and the evaporator and condenser film coefficients in the case of the gravity-supported operation were also investigated and compared with the performance of closed two-phase thermosyphons.

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This paper aims to propose and study a new open-cycle ocean thermal energy conversion featuring binary heat sources and multi-purpose uses. The circular pipe solar heater of warm sea water is cleand by sponge balls and the flow system adequate to this new cycle using high, medium and low pressure turbine stages is shown. Heat transfer performances of the solar heater are experimentally studied by use of halogen lamps simulating uniform flux. Based on the experimental results of the solar heater, the conditions for optimum thermal efficiency and specific output for various solar heater outlet temperatures are calculated. The results show that under the given sea water flow rate, the day-mean output is over four times more than the conventional one and the steam flow rate of the low pressure steam to produce fresh water is about five times than that of the conventional open cycle OTEC.

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This paper presents the steady characteristics of a water-cooled lithium-bromide/water absorption chiller used for the solar cooling system installed in the Co-operative Research Center of the Yatsushiro National College of Technology. From the analysis of experimental results, the empirical equations of the heat transfer rates from the hot water, cooling water, and the chilled water are obtained by multiple regression analysis for the purposes of convenience for computer simulation of a solar cooling system. Further, it is shown that their heat transfer rates can be calculated by making use of the concentration-enthalpy diagram of a lithium bromide water solution, if the volumetric flow rates and the inlet temperatures of the hot water, cooling water, and the chilled water are given.

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This paper describes an experimental study on the relationship between fluctuating velocity in a muffler and flow induced noise for an expansion cavity type muffler and a perforated straight-through pipe type muffler. The visualization of internal flow and the measurement of fluctuating velocity in a muffler were performed using the smoke-wire method and hot-wire velocimeter. From these experiments. the flow pattern and the distribution of fluctuating velocity were able to be clearly shown for each type of muffler. The correlation between fluctuating velocity on each point in a muffler and flow induced noise radiated from the open end was also studied by calculating the coherence function between them. It was seen that the flow induced noise was closely correlated with fluctuating velocity of internal flow especially in the ranges of tail pipe and/or cavity resonance frequencies.

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The application of spectrum analysis in the visible wavelength region of a large flame was studied theoretically and experimentally. Theoretical study of a flame model, which has a temperature distribution with some variations of optical thickness, indicated that the apparent mean emissivity of continuum emission, calculated on a hypothesis of gray approximation, was applicable to large industrial flames to evaluate flame conditions. An experimental study using a large (12 MW) oil flame also supported the appropriateness of the theoretical study and the apparent mean emissivity was evaluated to correlation well with NO_x emissions corresponding to the various kinds of flame conditions.

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Various methods were examined for determination of the burning velocities of liquid fuel sprays. Difficulties existed in finding the reference flame surface which governed the burning velocity of sprays since spray flames were usually thick and rather unsteady. The surface where the OH radical emission had a peak intensity was more suitable as a reference flame surface than the surfaces determined by schlieren or direct photography. The burning velocities of premixed sprays of kerosene were determined using a carefully-designed premixed spray burner. The coburning characteristic of premixed sprays of kerosene were also determined for the case of propane-kerosene spray-air mixture combustion.

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The change in heat release rate at the flame zone was assumed to be presented by polynomials of the velocity and the pressure fluctuations. Then the equilibrium condition between the thermodriving and the damping energy of the oscillation was applied to determine the stability of the system. For the case of a single flame, solutions of the combustion oscillation were obtained and the condition for the suppression of the combustion oscillation was identified.

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