Following the experimental study reported in the previous paper, this report describes a theoretical analysis based on the potential flow. By use of the vortex lattice method, calculations were performed to obtain unsteady aerodynamic forces acting on oscillating blades with tip clearances. Calculated damping forces in the case of large tip clearances show good agreement with experimental data. When the clearance is small, however, there can be found a discrepancy between experimental and analytical results. This discrepancy was thought to be ascribable to the viscous effect of the flow near the blade tips. To explain the experimental data it was necessary to apply a model such that each blade should retain finite circulation at the extremity of its tip. From the calculated results for various reduced frequencies it was confirmed that aerodynamic characteristics found in the experimental study should be accepted in the wide range of reduced frequencies.

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The generation and propagation of turbulent slugs in a circular pipe were studied under transient flow conditions. The Reynolds number of the final steady state was chosen above the critical Reynolds number of the experimental apparatus. A turbulent slug initiated bout 10 diameters downstream of the entrance, which was preceded by unstable waves with frequency very similar to that of the Tollmien-Schilchting wave. After the passage of the first slug many slugs appeared in the region of x/D ≒ 14 40, where x is the axial distance and D is the pipe diameter. The axial propagation velocities of the leading and trailing edges of the first slug were determined and compared with those of slugs in steady pipe flows. Velocity distributions inside and outside the slug were discussed.

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Turbulent plane Couette flow has been experimentally investigated to consider the structure of turbulent flow on the lubrication in an unloaded journal bearing. Mean velocity and turbulence has been measured in essentially fully developed flows from the laminar to the fully developed turbulent region. Mean velocity profiles are compared with theoretical profiles and the results of direct numerical simulation in the transition region. The skin friction coefficient, law of the wall, velocity-defect law, turbulence intensity, Reynolds shear-stress and energy-density spectra in the turbulent region are also discussed in comparison with the oter previously obtained results.

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The mechanical and/or the thermal fatigue fracture of pipelines due to the pulsating characteristics of slug flow will be prevented, if slug flow is changed to bubbly flow. Ten kinds of flow pattern converters are developed and tested in a vertical tube of 30.3 mm I.D. The converter composed of five stages of porous plates is useful. The sintered porous plates of spherical particles made of acrylonitrile-butadiene-styrene resin and bronze are selected from 76 kinds of porous plates.

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The application of tracer technique to the measurement of the liquid flow rate of two-phase flow is tested. The principle of this method is as follows : A solution of a certain dye is introduced into the liquid continuously and next, at a far downstream distance, some additional fresh liquid is injected into the main flow. If the flow rate of this additional liquid is known, the rate of the main flow can be determined from the dye concentration in the liquid phase detected at the two positions, the upstream and downstream sections of the additional liquid injection. The results measured by this method agreed with true flow rates within ±6% regardless of flow pattern.

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The effects of the velocity gradients on hot wire anemometry with an X hot wire probe were theoretically analyzed. Analysis showed a strong possibility that the values obtained from the traditional way of measurements with an X hot wire probe involve serious experimental errors caused by the velocity gradients. A new method of measuring which eliminates those errors was proposed based on the results of the analysis. The new method includes the use of two X hot wire probes, one of which is the reflected image of the other, and the taking of arithmetic means of the values obtained from those probes. The validity of the analysis was confirmed by measuring a turbulent flow in a square duct with rough walls on two opposite sides. The results of measurements showed that the new method is very effective for the measurement of quantities, such as the secondary flow velocities and the turbulent shear stresses, quantities which are very sensitive to the effects of velocity gradients.

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Unsteady liquid film flow on a rotating disk, which is related to a spin coating technique to form a thin uniform film on a plate, is calculated numerically. Vewly developed calculation method, where the surface tension on the liquid surface can be taken into account, is applied. The numerical results reveal the followings : The hemi-spherical liquid on the disk, which starts to rotate impulsively from rest, spreads by a gravitational force at the first stage. The development of the distribution of radial and azimuthal velocities is affected complicatedly by the Coriolis force, viscous force and centrifugal force. The liquid spreads mainly by centrifugal force and forms a uniforml thin film on the disk at the last stage. The surface tension has a little influence on the spreading process only at the first stage.

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This research focuses on making clear, theoretically and experimentally, the squeeze phenomenon of liquid film between two parallel coaxial circular discs when one disc vibrates sinusoidally in the direction axial to the other stationary one. Fist, the full Navier-Stokes equations were numerically solved taking into complete consideration the nonlinear inertia terms after clearing up the nondimensional parameters predomdnant in the squeeze phenomenon in this study. Second, exact experiments corresponding to the theoretical analysis were performed to prove the predicted performances of the squeeze phenomenon discussed. Finally, general and practically useful results obtained from the theoretical calculations associated with such factors as pressure fluctuation in a cycle, velocity profile and time-averaged loading capacity of the disc due to the nonlinear inertia terms were reduced and discussed.

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The flow in a logarithmic impeller with trailing edge separation is analysed by using a conformal mapping method. The problem is linearised by assuming that the thickness of the separated region is small. The flow can be determined by specifying the location of the separation point, and by the application of the condition that there should be no singularity at the closure point. The latter condition results in the location of the closure point shortly downstream of the trailing edge. It is shown that the head is significantly reduced by the separation. Discussions are made about the angular momentum conservation relations for a few models and it is found that the conservation relation is better satisfied for those cases with a thinner separated region, without much dependence on the model used.

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The rotating stall of centrifugal compressors which often causes low frequency shaft vibration in high pressure compressors is experimentally examined. Pressure fluctuations of low specific speed centrifugal compressors with a vaneless diffuser are measured by pressure transducers. Rotating stall is caused by a vaneless diffuser. The critical inlet flow angle for rotating stall depends not only on diffuser width ratio b/r₂ but also contraction ratio b/b₂. An empirical prediction formula of critical flow angle for stall based on the Senoo method is derived.

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Surge phenomena in fluid lines often produce vibrations and noises, or even result in system breakdown. In order to absorb the surge waves, accumulators are conventionally employed in oil hydraulic circuits. In the present paper an attempt to utilize branch pipes for decreasing pressure surge is experimentally tested. The idea depends on the fact that a pipe which branches from the main line and has a dead end dissipates transient waves without affecting the steady-state flow. It has turned out that although branch pipes cannot completely eliminate surges, they are from the practical point of view useful enough to diminish surge pressures, having their own advantages over the conventional accumulator in several aspects.

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The performance of reaction hydraulic turbines such as Francis, Kaplan and reversible pump-turbines is analytically studied in this paper. The one-dimensional loss analysis method coupled with flow analyses for a runner, stay vanes and guide vanes is presented in order to improve the accuracy of the prediction method. The Francis turbine with a specific speed of 240 (m, rpm, KW) was tested and compared with prediction results for efficiency and discharge characteristics. From the comparisons between predicted and measured performances, it is shown that the present method is available for the performance prediction of Francis turbines and can predict the performance with a good accuracy even at off-design points.

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The self-rectified air turbine for wave power convertors, the so-called wells turbine, has been fundamentally studied by many research groups, who found that there exists a big difference between then of stall angle on rotor blades even if they employ almost identical rotors in their own facilities. This research reveals that the difference is caused by the tip clearance which induces the tip vortices so as to prevent the flow separation on the rotor blade. The bigger the tip clearance is, the bigger the stall angle becomes, which results in the operational region in the sea being extended. . Furthermore, the performance is improved even in the stall region, making the self-starting of the turbine easy, although the maximum efficiency is decreased owing to the leakage loss. The influences of another factors on the performance, that is, the boundary layer of the casing and the intensity of turbulence at the inlet, are much smaller than that given by the tip clearance. It is now possible to compare the experimental results between research groups as far as they use the same clearances.

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A fully three-dimensional inverse solution to the axial-flow rotor of a constant hub to tip ratio by means of the finite-pitch actuator duct method for inviscid and incompressible flow is presented. The blade is expressed by a vortex sheet and a source sheet superposed on the mean surface, and the blade shape is determined to satisfy the specified thickness and loading distributions for free-vortex type flow. Two-dimensional numerical calculations are performed by modifying the present method in order to show the difference between the blade shape obtained by the two-dimensional inverse method and that obtained by the three-dimensional inverse method. Three-dimensional numerical calculations show the influences of the stacking position and the blade spanwise pressure distributions. The direct solutions for the designed two-dimensional and three-dimensional rotors are calculated in order to examine the numerical accuracy of the present inverse calculation.

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In this paper, we investigated the effects of the resistance of an oil feeding pipe on the discharge characteristics of an oil pump for a horizontal type compressor. This pump uses fluidic diodes in place of conventional valves. The discharge characteristics of this pump depend on the resistance balance between the discharge line and the suction line. The resistance of the oil pipe is as remarkable as that of fluidic diodes. This resistance is composed of not only friction and velocity head, but also the inertia of the oil in it. The effect of the resistance becomes larger as the diameter of this pipe decreases. So we analyzed the resistance of each section of this pump and calculated the change of the flow rate under various pipe diameters. As a result of this study, we have found that the optimum diameter of the pipe gives us the greatest discharge of the oil feeder pump.

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The effect of the noncondensable gas contained in a vapor film upon vapor explosion is investigated. Vapor explosion on a small scale is initiated by dropping a drop of molten tin into water. Quite different phenomena are observed when a space above the pool of water is filled with steam instead of an air-steam mixture, indicating that the noncondensable gas mixed in the vapor film affects vapor explosion greatly and make the process stochastic.

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A practical calculation for the capacity of the varying pressure accumulators is developed in detail in the present paper. To facilitate the calculation of the amount of self-evaporation and the fraction of steam space, two functions of pressure are introduced and are evaluated with the use of the JSME steam table. Their approximate expressions which assure quick and exact calculations are also given. One of the great merits of our method over the existing ones is that the effect of the initial steam space on the accumulator characteristics can be easily and accurately evaluated without any use of additional correction operation.

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This paper describes the experimental results of the characteristics of the freezing heat transfer of layered air-water flow in a circular tube, in which cooled air and water co-flow. The experiments were carried out under a variety of conditions of water velocity, water temperature, tube-wall temperature, and air temperature. Special attention was focused on photographic visual observations of the developing ice layer along the tube wall. Two different regions characterizing the ice formation were observed, one of which was the freeze-off region, and the other was the steady-state region. It was found that the criterion between the regions was obtained by the equation θ_c = 0.192Re^0.35_w. The onset of freeze-off was also found to be predicted by the equation F_o = 0.743Re^0.14_wRe^-0.03_aθ^-1.01_c.

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An analytical study of simultaneous heat and mass transfer in laminar free convection of ternary vapor mixtures on a vertical flat plate is presented. The concentration equations for ternary vapor mixtures. which are coupled to each other, are orthogonally transformed to two uncoupled equations similar to those of binary vapor mixtures. Similarity solutions of the equations under the conditions of zero wall velocity are numerically obtained for practical ranges of dimensionless parameters, namely Prandtl number, Linearized Schmidt number and buoyancy term. Correlation equations for heat and mass transfer are proposed and an example for applying these equations to a condensation problem, of ternary vapor mixtures for the case of negligible heat resistance in the liquid film is expeained. Correlation equations for multicomponent vapor mixtures are also inferentially proposed.

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A numerical study was carried out for the transient responses of the temperature and velocity distributions of heat generating fluid in a horizontal cylinder. The frozen layer was formed on the inner surface of the cylinder which was cooled uniformly below the freezing temperature of the fluid. The rate of heat generation was assumed to be stepwise and uniform throughout the liquid and solid phases. The solution of the governing partial differential equations were obtained by a finite difference method. As a result, the maximum temperature, the maximum temperature, the maximum value of the stream function and mean Nusselt number on the frozen surface were correlated in term of Rayleigh number, Stephan number, Fourier number and the dimensionless temperature of the cylinder wall.

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This paper dealt with the effects of heat condition within the wall on the heat transfer of a patchily heated tube : considering both the circumferential and longitudinal heat conduction within the tube wall, the heat transfer coefficients and the wall temperature profiles of the tube were numerically obtained. The numerical results show that the substantial heat transfer coefficients of the heated region decreases with longitudinal wall conduction. but circumferential wall conduction has little effect on the substantial heat transfer coefficients. This means that the effects of circumferential and longitudinal wall conduction on the heat transfer of the patchily heated tube may be independent. Making use of the concepts of "pseudo-fin", the amount of heat conducted to both the circumferential and longitudinal unheated regions and the apparent heat transfer coefficients of the heated region were analytically predicted. These results agree well with the numerical ones whatever the shape of the heated region.

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Fully developed laminar forced convection heat transfer in curved rectangular ducts rotating at a constant angular velocity about an axis through the center of curvature of ducts is studied. Thermal boundary conditions of fluid flow are assumed to be subject to uniform wall heat flux. Navier-Stokes and energy equations are solved by the finite-difference method for Pr=0.7. The case for the positive rotation of a duct is considered. Velocity and temperature fields are obtained for various rotation rates and Reynolds numbers. A double-vortex secondary flow appears at a low to moderate rotation rate and Re number. It is found that an additional pair of vortices appeared and disappeared for a higher range of Reynolds numbers under the influence of centrifugal and Coriolis forces. The friction factors and Nusselt numbers are also obtained. The numerical results in regard to the friction factors are in good agreement with experimental results obtained by other researchers.

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An opposing flow of turbulent combined forced and natural convection along a vertical flat plate heated with a uniform heat flux was investigated experimentally. The local heat transfer coefficients along the vertical direction were measured at high Rayleigh and Reynolds numbers. It was found that the heat transfer rates in the combined convection region became much larger than those for both the pure forced and the pure natural convection. The natural, forced, and their combined convection regions are classified in terms of the non-dimensional parameter, ζ=(Grx^*/NuxRex^2.7). These results are then compared with those for the aiding flow.

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Measurements of the heat transfer and the visualization of the flow are carried out on vertical closed and open thermosyphons using water and ethylene glycol as a working fluid. The sizes of the closed thermosyphons are 10 and 20 mm in radius and 300 mm in length, and that of the open thermosyphon is 20 mm in radius and 150 mm in length. The present Nusselt number and flow pattern of the closed thermosyphons are compared with those of the open thermosyphon and the experimental and theoretical Nusselt numbers of the closed thermosyphon by Bayley et al.. The Nusselt number of the closed thermosyphons significantly decreases for the predominant flow of the conduction mode and the weak flow of the convection mode in the coupling region. The fraction of the flow of the convection mode is usually small and sensitively varied with the change of the tube diameter and the Rayleigh number for the range of diameter from 20 to 50 mm. This is the reason that the present Nusselt number of the closed thermosyphons is quite small, as compared with that of an open thermosyphon, and smaller than the other sources of data.

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An experimental study was made in order to clarify time-mean and instantaneous heat transfer performances near the separation point upstream of a forward facing step. In the case of the laminar boundary layer, the separation point was found to fluctuate almost in accordance with a normal distribution by small velocity fluctuation in the free stream. The Reynolds analogy law between the local shearing stress and heat flux was also found to be not applicable at the separation point for both laminar and turbulent boundary layers. For turbulent boundary layers, the position of the separation point is found to be very close to the step and its fluctuation region is very wide and has normal distributions.

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An experimental study was conducted to examine the heat transfer enhancement in forced convective channel flow by means of the ionic wind induced between the plate wall and plural negative wire electrodes, which were put at the center line of the channel. A theoretical analysis was also performed on electric, flow, and temperature field taking account of the interactions among these fields. Firstly, the combined flow field where the cellular secondary motion occured owing to the field's interaction was characterized in conjunction with the bulk flow velocity and the electric field strength. Secondly, the enhancement of convective heat transfer rate was recognized, especially under low Reynolds number, and its mechanism was clarified. On the basis of these results, the heat transfer performance was shown in connection with the amount of electric power and pumping power.

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High temperature horizontal platinum filaments have been dipped into subcooled water to simulate a new rapid solidification process, and forced convectional boiling heat transfer has been examined. A vapor film first collapsed at the edges of the filament and the collapsing sites propagated towards the center at rates ranging from 0.25∼2 m/s. The propagating rate of the collapsing site increased with increasing subcooling. A minimum heat flux point did not appear clearly in the boiling curve, and a variation of the heat flux corresponded to that of the propagating rate. Epstein and Hauser's expression of the convection film boiling of a sphere or cylinder could be applied for that of the filament during water quenching.

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An experimental study was made on a fully developed turbulent flow of air at a Reynolds number of 6000, entering a rectangular duct with an aspect ratio of 6 with uniform fluid injection through the bottom porous wall at two injection rates : 0.01 and 0.004. Measurements were made of the streamwise and transverse velocity distributions by means of a Laser Doppler Velocimeter. The following conclusions were drawn : (1) Close to the porous wall, the absolute value of <uv>^^- decreases rather sharply around the starting point of injection, and the flow tends to be locally laminar. This is caused by the change of mechanisms of both the turbulent production and the redistribution of turbulence. (2) Close to the upper wall, the absolute value of <uv>^^- decreases gradually as the flow moves downstream, and the flow also tends to be laminar. The tendency is caused by the flow acceleration and by the change of the redistribution mechanism of turbulence.

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The heat-mass transfer and pressure drop performances during the dehumidification of moist air flowing between plate fin and tube heat exchangers which are mainly used in air conditioners were investigated experimentally. The experimental results revealed the following. The heat transfer performance with condensation was equal to that without condensation, in consideration of dehumidified water on the surface of a heat exchager. The analogy between heat and mass transfer under dehumidification was not completely substantiated. The mass transfer coefficient is smaller than that of theoretical analogy.

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Experimental and analytical investigations are conducted on flow instability in a vertically installed liquid nitrogen shell & tube type heat exchanger. The experiments are carried out by making use of water steam as a secondary fluid and it is observed that flow instability occurs in the range of small inlet flow rate. Mode analysis of the flow instability oscillation reveals that there exists a fundamental mode and its higher harmonics up to the fourth. As the period of the fundamental mode is nearly equal to the transit time for a fluid particle to travel through the heated tube, it is suggested that this flow instability is of the density wave type. It is shown that the amount of exchanged heat, as well as the pressure drop, decrease when unstable flow oscillation occurs. An analysis of the static heat transfer and pressure drop characteristics can simulate the experimental results in the stable region. Linear stability analysis is also carried out to yield the stability map as well as the period of flow oscillation, which proved to agree with the experimental data qualitatively.

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The renewable energy laboratory of Kitami Institute of Technology is a facility for the research of space heating, cooling and hot water supply using solar energy and underground water heat by means of a solar system and a heat pump system. Measurements for two types of combination of series-and parallel-solar heat pump systems has been carried out during the last five years. In this study, based on the measured data of the solar heat pump systems, a simulation program is produced to estimate the thermal performance of the systems, and the results calcuated by a personal computer are compared with the experimental results. The correlation between two dimensionless factors of X_H(=COP_HPQ_EMAX/Q_TL) and Y_H(=F_W/F_WMAX) can be obtained in order to calculate easily the performance of a stand along heat pump system.

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This paper examines the flame development patterns after the propane-air mixture is ignited at double spark locations. The characteristics of the growth of double flames originate from the compression flow generated by the opposed flame. For simulating three dimensional flame development, the numerical method of analysis of this flow has been added to the space difference method. The effects of the ignition locations and spark time lag on the flame development are examined. The calculated results are in good greement with the measured ones, unless there is the generation of strong secondary flow.

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The characteristics of diesel spray and flame in a quiescent atmosphere were studied as a function of injection pressure ranging from 30 to 110 MPa. Measurements included the spray form and Sauter mean diameter of a non-evaporating spray, the liquid phase penetration of an evaporating spray and the visualization of sooting zone in a flame. Experimental results show that high pressure injection improves the atomization and air entrainment of a non-evaporating spray and that the liquid phase penetration of an evaporating spray is hardly affected by injection pressure, demonstrating a promotion of evaporation with injection pressure. Visualization of the sooting zone in a flame made it clear that high pressure injection is advantageous in reducing soot formation and shortening the combustion duration.

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The Authors inserted an optical fiber into the main chamber of a pre-combustion chamber engine. This fiber has excellent characteristics of transmittance in ultraviolet ranges. They found that the diesel combustion flames which originated from the multi-stage ignition phenomina in a main combustion chamber contained the band spectrum emitted from a radical of CH. The above investigation has given a glimpse of the chemical reaction in a diesel combustion.

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Velocity distributions of in-cylinder gas flow in a two cycle uni-flow type engine were measured under motoring conditions by a forward scattered LDV. Measurements were conducted in several planes along the cylinder axis so that the axial distribution and decaying process of swirl velocity in the whole combustion chamber could be investigated. The obtained results are as follows. (1) The initial profile of swirl velocity distribution like solid-body-rotation changes into a flat-top trapezoidal one during the course of the compression and the expansion stroke. (2) A complicated three dimensional flow structure exists in the early compression stroke. (3) The volume mean angular momentum of swirl velocity decays monotonously and maintains about 65% of the initial value when TDC is reached. It shows a similar decaying process in a pancake shaped constant volume bomb after the midway in the compression stroke.

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