A numerical evaluation of erosion on a surface of a pipe with double elbows was carried out. The flow field was estimated by the k-ε turbulent model. And, particle motions were estimated by Stokes equation and bouncing coefficient by Tabakoff et al. The erosion rate was estimated by a new erosion model. The main results as follows : (1) A clear roping structure was seen at the elbows. (2) Due to the roping structure, the large magnitude of the erosion at the elbows was occurred. The numerical magnitude of the erosion was in good agreement with experimental results.

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To predict the efficiency of the heatpipe and the coolability of the debris bed, it is important to presicely estimate the flow pattern and the temperature distribution in the porous media of complex geometry. It is, however, very difficult and time consuming to generate such a complex geometry in the numerical scheme such as porous debris bed in usual macroscopic numerical simulation technique. In the present study, as a first step of the mesoscoipc numerical approach tc analyze the multiphase flow through porous media, fundamental numerical simulations with the lattice gas automata method are demonstrated for the single-phase natural convection through porous media. The flow pattern and the temperature distributions are successfully calcurated with the lattice gas automata methd as a function of porocity. It was clarified that the lattice gas automata reasonably simulates natural convection through complex geometry like porous media including critical Rayleigh number.

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A numerical method for more realistic prediction of the pressure fluctuations due to rotor-stator ; interaction in a diffuser pump was developed, in which time-dependent inlet flow was supposed to, change with the total hydraulic head according to the resistance equation of pumping system. The unsteady flow was calculated for a diffuser pump with 5 impeller blades and 8 diffuser vanes by using vortex method, in which a new procedure that vortices shed from solid boundary was proposed from the basic governing equation. A new scheme was proposed to improve the unsteady pressure evaluation by boundary integration method in rotor-stator interaction problem. The calculated time varying flow rate, total hydraulic head, and pressure fluctuations in vanes diffuser passage, were compared with those measured and calculated by other methods. Calculated unsteady pressure fluctuations in vaned diffuser passage showed good agreement with the experimental data and the CFD calculated results.

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In the present study, we observed motion of the bacterium, Vibrio alginolyticus, which swims rotating a single flagellum, using a dark-field microscope with a CCD camera system. Then, we took measurements of the speed and the rotation rate as well as the size of the individual bacteria. Also, we employed the boundary element method to analyze the bacterium motion and predicted the swimming speed. Then, we compared the predicted speed with the observed one. They agree well qualitatively and quantitatively. Furthermore, we evaluated the torque of the flagellar motor coupling the computational and the experimental results. It is estimated at the order of 0.1∼1 pNμm.

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The DNSs of the incompressible flows around a circular cylinder are performed by using the Cartesian grid approach with virtual boundary method. In the virtual boundary method, the body surface is expressed by a set of plural points, and the velocity components on virtual boundary are feedbacked to the momentum equations as the additional forcing terms. As a validation of this method, the steady flows around a circular cylinder are computed in order to investigate the dependence of virtual boundary points on flow characteristics. Then, this method is applied to the unsteady flows. The results show that the present method is very promising for the DNSs of the incompressible complicated flow.

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We performed two-dimensional DEM simulation to investigate the effcts of pulsating gas injection on the flows in dense gas-solid fluidized bed. Geldart D particles were assumed as the solid particles. The effects of the mean gas velocity, the frequncy and the amplitude of the gas injestion were examined. To evaluate the effects quantitatively, we analyzed the transport properties of the predicted granular flows, such as granular convection energy or fluctuating energy of particles. The present simulation showed that the pulsation promotes the granular convection for moderate pulsation frequencies and the predicted flow properties saturated for the variation of the pulsation frequencies in the high frequency region. We proposed an equation to estimate the relaxation time scale of the beds for the fluctuation of gas velocity based on Ergun's equation. The estimated relaxation time scale agreed well with the predicted saturation frequency of the bed.

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In order to develop a phase separation technique under microgravity condition, the method of a Y-junction by utilizing the difference of inertia force between gas and liquid phases is proposed. The experiments for phase separation in the impacting T(θ=90°) and Y(θ=60°, 30°) junctions of 10.5 mm ID set in a horizontal plane were carried out under normal gravity condition. Air and water were used as the working fluids in the range of the liquid superficial velocity, j_L1, of 0.05 to 0.5 m/s and the gas superficial velocity, j_G1, of 0.1 to 7.0 m/s. The phase separation performance is improved by the decreasing of the angle θ between the inlet and the side branch. For the Y-junction (θ=60°), about 82% water could be extracted from the inlet two-phase flow at j_L1 =0.5 m/s and j_G1=7.0 m/s.

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In the vertical upward gas-liquid two-phase flow, churn flow is a distinctive flow pattern that appears in the intermediate region between annular and slug flow. To clarify the flow characteristics of churn flow, simultaneous measurements of spatio-temporal characteristics of gas-liquid interface and pressure gradients are conducted at low liquid flow rate conditions. Flow reversal of the liquid film and large wave formation are found to be characteristic features in this regime. The decrease of gas flow rate makes the flow oscillation more violent, which induces a breakdown of the continuous gas core by bridging of the liquid film, and eventually leads to the flow pattern transition from churn to slug flow. The effect of flow structure of churn flow on the frictional pressure gradient is also investigated. It is found that the negative slope and the drastic decease in the frictional pressure gradient are attributable to the propagation of large wave and the formation of the developing slug flow, respectively.

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Lift force on a slightly deformed bubble rising near a plane wall was measured experimentally. We developed an experimental apparatus in which a CCD camera with a microscope follows the rising bubble. We used it to precisely measure the bubble radius (R), the rising speed (U), the distance between the bubble and the wall (L) and the deformation of the bubble, and then estimated the lift force including the effect of both the inertia and the deformation. We also analytically estimated the deformation and the lift force due to the deformation under the Stokes approximation. We compared the analytical solutions with the experimental results. The results show that the deformation can be expressed as a function of the Capillary number defined by the R, the U, the L and the surface tension and the experimental and analytical values are in the same order. They also show that the lift force estimated by the analytical solutions is smaller than the force estimated by the experimental values.

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Particle laden water jet have been analyzed by means of a laser Doppler anemometer (LDA). Glass spheres of 389μm in mean diameter were loaded into the injection water by a particle mixer and after then injected into still water bath. The particle/water jet injectors were made by brass pipes of which diameters were 5 and 8 mm. The mean velocities of the center of the jet were set as 1.8 and 1.5 m/s for 5 and 8 mm pipes, respectively. The initial volume fraction was set as 0.087% in all experiments. The results of vertical relative velocity between particle and water indicate that the particles have same velocity as water at the outlet of the jet however particle velocities are larger than that of water at the expanded jet in downstream. From the results of the transverse relative velocity, it is considered that the particle can get larger velocity than water at a certain downstream from the outlet. These features are well explained by using local Stokes number defined by local time scale of the turbulence and particle time constant as well as Saffman's lift force.

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An experimental study on the behavior of wake flow behind an obstacle, square cylinder, in a gas -liquid vertical two-phase flow especially the effects of blockage ratio, is examined. The results showed that Karman vortex was shed regularly under certain flow conditions for various Reynolds number, void fractions and blockage ratios. Two uniform experimental equations were shown to describe the vortex shedding frequency f and pressure difference ΔP between the front side and the back side of the obstacle for various blockage ratios. A new measuring method by f and ΔP for the flow rate of gas-liquid two-phase flow was shown.

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Turbulence-induced vibrations of a circular cylinder were measured in a water cross flow at supercritical Reynolds numbers. Turbulence intensities of the incoming flow were varied from 1% to 13% in order to investigate the effect on the power spectra of fluctuating forces. The power spectra of the fluctuating lift above the Strouhal number agreed with those of the fluctuating drag. Normalized spectra of the fluctuating lift above the Strouhal number were independent of Reynolds numbers and moved toward higher frequency with increasing turbulence intensity. Empirical expressions of the normalized spectra of the fluctuating lift for each turbulence intensity were given to estimate the displacement due to turbulence-induced vibration. The calculated displacement agreed with the measured one with a standard deviation of 30%.

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An experimental investigation was made to clarify the unsteady characteristics of the cavitation on an oscillating hydrofoil. The behavior of the cavitation affected by the hydrofoil oscillation is discussed based on the measurement of the pressure fluctuation upstream of the hydrofoil and the visual observations using the high-speed video recording. Concerning the response of the cavity to the pitching motion of hydrofoil, the amplitude of cavity length fluctuation and the phase difference between the angle of attack and the cavity oscillation were measured. In addition, the amplitude and the phase angle of the inlet pressure fluctuation were measured. And furthemore, the correlation between the pitching oscillation of hydrofoil and the self-oscillation of cavitation was investigated.

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The instability of the flow through a mixed-flow-type vaneless diffuser system was examined experimentally. An unsteady flow was observed when the angle of the flow at the diffuser inlet became small, and it was concluded that the unsteady flow was based on rotating stall occurred in the vaneless diffuser. The effects of the diffuser width and inlet pipe on the rotational speed of the stall cell were observed. Rotating stall measured in this study was different from that reported for radial vaneless diffusers. The rotational speed of the stall cell, however, is nearly equal to that measured for the radial vaneless diffusers. The flow condition in the vaneless diffuser at the initiation flow rate of rotating stall was discussed based on the velocity distributions measured and those obtained from a turbulent flow analysis.

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Coherent structures or large scale motions in a turbulent boundary layer on a rotating cylinder in a quiescent fluid are considered by various conditional sampling procedures. As it is clear from previous investigations that the coherent structures are depending on the conditional technique of sampling, here we discuss some dynamical aspects of them. Several conditional sampling procedures are adopted here, and also the variable interval time average (VITA) technique is modified with a reasonable assumption. Turbulent velocity signal and a random process generated by a Langevin equation are analyzed by these techniques. With comparing these results, we found that statistial properties of the coherent structure are well modeled by the Langevin equation as far as the conditional sampling is assigned.

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The perforation mechanism of a radial liquid sheet, which depends on the Reynolds number, is clarified. The radial liquid film flow is generated by a water discharge through a small gap formed between the end of a nozzle and the flat surface of a disk. The liquid film flow spreads radially outward on the disk, flowing from the edge of the disk into the air as a liquid sheet. Sudden laminar-turbulent transition occurs in the liquid sheet when the Reynolds number exceeds a critical value. The transition begins to result in perforation. In this study, the authors formulate a stochastic relation between a void fraction at a reference point and a rate of perforation generated upstream of the point. The radial distribution of the peforation rate is calculated from the void fraction which is measured with a perforation sensor at each radial position. The calculated perforation rate revealed that while the perforation occurs at far downstream of the transition point at relatively low Reynolds number, it does immediately after the transition at extremely high Reynolds number.

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Generation and growth of an isolated turbulent puff and slug in the initial stage of a transitional pipe flow were investigated by LDV measurement, wall pressure measurement and flow visualization. The LDV measurement was carried out using the straight glass tube of diameter D=5.02 mm and i total length L=2576 mm, and the wall pressure measurement was done using the glass tube of D= 2.61 mm and L=1527 mm. Manipulative disturbance necessary to produce the puff and slug was provided by several kinds of ring-shaped roughness elements, installed at downstream locations of 40D, 77D and 120D from the entrance of the tube. Visualization photography of the puff and slug was synchronized with the LDV signal or the wall pressure signal. The critical Reynolds number, which was defined at the initiation of generation of the puff or the slug, changed abruptly in a range of 1 to 2 of the ratio of the momentum thickness at the location of the roughness element to the height of the roughness element. Propagation speeds of both the leading and trailing edges of the puff and slug could precisely be detected by the wall pressure measurement.

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This paper describes the fluid force acting on the two-dimensional oscillating circular cylinder in the locking-in region. The experiment was carried out in an N. P. L, blow-down type wind-tunnel with a working section of 500 mm×500 mm×2000mm, and with the Reynolds number of 1.9×10⁴. The cylinder was then forced to oscillate sinusoidally in the lift direction. The power spectrum of the fluctuating velocity in the wake behind a circular cylinder was measured to show the locking-in region in the present experiment. The time-mean pressure distribution and fluctuating pressure distribution on the circular cylinder were measured for the displacement in the vibration. Consequently it was found that the mean drag and fluctuating lift increase and become maximum in the locking-in region, while, the base pressure in the rear surface (θ=180°) of the cylinder becomes low and attains minimum.

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We have improved a laser trapping method to control bubble positions without contact. In this method, we use an empty laser cone obtained by focusing a laser ring. Bubbles of the order of 10 micron in diameter have been trapped and manipulated successfully using a dry objective lens with large working distance. We have also evaluated the optical force acting on a bubble both experimentally and theoretically. It is shown that the axial force is about 90 pN when the net laser power is about 110 mW. The thinner the thickness of laser curtain becomes, the stronger the optical force becomes. The trajectory of a rising bubble is calculated by taking the optical force into account. The result shows that the predicted trajectory is in good agreement with experimental data.

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Transverse optical force for the laser trapping of microbubbles is evaluated experimentally and theoretically. We simulate the trajectories when a trapped bubble escapes from the trapping region in the uniform flow field. It is shown that the simulation is in good agreement with experimental results. The trajectories of an escaping bubble are significantly dependent on the bubble location where it is trapped. The trajectories are classified into two types. When a bubble is trapped below the location of the peak of the transverse optical force, the trapped bubble escapes from the laser trap after it is repelled downward by the optical force ; this trajectory can be seen for relatively smaller bubbles. In this case, the transverse optical force increases nearly in proportion to the square of a bubble radius. On the other hand, when a bubble is trapped above the location of the peak of the transverse optical force, the bubble escapes from the laser trap without being repelled downward by the laser beam.

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The purpose of this study is to investigate flow pattern around a mosquito's wing while it is beating. Reynolds number and Strouhal number when mosquito was flying were calculated by an analysis of pictures from a high speed video camera and a microphotograph. Beating motion showed three types ; a flapping motion in which wing was moved up and down, a lead-lag motion in which wing was moved back and forth, and a feathering motion in which wing was twisted. Those motions were observed using the high speed video camera. An enlarged scale model testing was carried out using a very low speed wind tunnel under the condition that Reynolds number and Strouhal number were set to be equal to those of real mosquito. Phenomena of periodic vortex growth and its release from a wing model moving up and down were visualized with a smoke method. By changing wing's attack angle, vortex pattern was changed. The vortex was analyzed and the circulation was calculated from visualized pictures.

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The variations of the vapor concentration of water-ethanol mixture during saturated nucleate pool boiling were studied. The temperature changes of vapor in the generated bubbles measured at several different positions near the boiling surface by using thin thermocouple having high responsibility. The superheat of bubbles were initially higher in the superheated liquid layer near the heat transfer surface and then approached the bulk temperature with moving upwards. It was clarified that the temperature and the concentration differences of the bubbles from the bulk almost disappeared at the height of 3 to 5 mm from the heat transfer surface and within 20 ms after the appearances. As a result, the former result of the liquid-vapor equilibrium at the bulk condition was confirmed.

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The critical heat flux (CHF) in subcooled boiling is theoretically predicted by using the microlayer model. The enhancement of heat transfer for subcooled boiling is mainly contributed by the augmented convection caused by the periodical forming and collapsing of individual bubbles. For uniform temperature surface, the CHF increases with the liquid subcooling, while the CHF approaches a constant value at high subcooling region for uniform heat flux surface. The evaporative heat transfer becomes small and the total heat flux is mainly contributed by the periodic transient heat conduction outside the evaporating area as the subcooling is increased. At low subcooling, the mechanism of CHF is the same as that in saturated pool boiling, which is due to the local dryout of microlayer. However, at high subcooling, the mean wall heat flux reaches to its maximum (CHF) because the duration of bubble condensation rapidly increases with the wall superheat.

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Basic experiments using molten aluminum and sodium have been conducted to investigate the possibility of fragmentation of molten metals for instantaneous contact interface temperatures sufficiently below the boiling point of sodium (881°C) . Aluminum was heated to the temperature from 898°C to 1073°C in a crucible by using an electric heater and dropped into a sodium pool at the temperature of around 275°C. Recovered aluminum fragments were sieved to measure particle size. The degree of fragmentation increases with higher initial temperatures of molten aluminum. The fragmentation process is closely related with the formation of pot-like shape from aluminum drop. Even though the instantaneous contact interface temperature is sufficiently lower than the boiling point of sodium, an efficient fragmentation is caused by a high pressure produced rapidly due to the thermal interaction between the molten aluminum and the sodium entrapped into the molten aluminum.

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Fluid flow and heat transfer characteristics in a turbulent combined-convection boundary layer in air along a vertical heated plate have been investigated with normal hot and cold wires. The measured heat transfer rates and turbulent quantities show that the turbulent transition moves downstream with a slight increase in freestream velocity. Then, the heat transfer rate rapidly decreases to about 40% of that obtained in the turbulent natural-convection boundary layer, and velocity and temperature fluctuations become smaller in amplitude and change from random to harmonic at a specific frequency. Thus, the characteristics of the turbulent combined-convection boundary layer differ in several respects from those observed in both natural and forced convection. Based on the experimental results, the regimes of boundary layer flows are classified as a function of local Reynolds and Grashof numbers.

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An experimental study was carried out to investigate the natural convective oscillatory flow of air caused by a line heat source placed eccentrically along the axis of a horizontal rectangular chamber. The frequency of the oscillatory flow and the initial condition under which the oscillation commences were compared with the previous investigation for the concentric axis. It was found that the generalized equations of non-dimensional frequency of the oscillatory flow for the concentric axis are applicable to the eccentric case. The visualization of the flow showed that there are two typical oscillatory flow patterns which result in the existence of two generalized equations of non-dimensional frequency. The transition of oscillatory flow pattern is dominated by the aspect ratio of the upper space of the heat source and the expansion number.

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In this paper, we proposed one method that considers static pressure distribution of refrigerant for predicting capacity of a heat exchanger. Thermal Network Method is modified by adding Equivalent Heat Generation term into heat balance equation that is connected with calculated 1-D static pressure distribution of refrigerant. Experiment was performed with a 2 rows-2 passes heat exchanger for velifying accuracy of the present method. As a result, error of predicted capacity was less than 1% for a evaporator, and less than 2% for a condenser.

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The hysteresis phenomena of solid-liquid contact angles were investigated theoretically by using the result of the preceding report that the hysteresis is caused by the irreversibility of energy change of wetting behavior between liquid advancing and receding on the solid surface. The energy was calculated for the system composed of a meniscus attached to a vertical solid plate with three-dimensional random roughness and heterogeneity. The irreversible movement occurs in the different manner between advancing and receding, which causes the difference of the system energy change. The contact angles calculated from the thermodynamically stable condition showed that the advancing (receding) contact angles were maximum (minimum) ones among those which locally satisfies Young's equation. The contact angle hysteresis can be expressed by the sum of the energy dissipation occurring at the advancing and receding.

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In internal combustion engines, lean-burn is particularly attractive for minimizing pollutant emissions, in particular NO_x, with a concomitant improvement in fuel economy. A Pulsed Flame Jet (PFJ) has a great potential to enhance ignition reliability and burning rate in lean fuel-air mixtures. In this study, two-dimensional images of OH radical in the jet of PFJ were obtained using a Planar Laser-Induced Fluorescence (PLIF) technique. The effects of equivalence ratio of the mixture in the cavity, cavity volume, and orifice diameter on the variation of OH fluorescence area in the jet and their intensity were revealed quantitatively.

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This paper has dealt with direct contact heat exchange characteristics between ice water slurry (average ice particle diameter : 3.10 mm) and hot air bubbles. The hot air bubbles ascending in the layer fluidized the ice water slurry layer, and the bubbles were cooled down directly by the ice water slurry. The following results were obtained from the experiment. In case of ice water slurry layer, the hot air bubbles fluidized the layer in earlier stage and heat exchange performance was higher than using only ice particles layer. The maximum temperature efficiency increased as Reynolds number Re increased because fluid in the layer became active and kept at the fixed value in the region of Re >__=900. Dehumidity efficiency increased as modified Stefan number and Re increased since the heat capacity of inlet air and heat transfer coefficient increased. Some empirical correlations for temperature efficiency, dehumidity efficiency and the completion time of latent cold heat release were derived in terms of various nondimensional parameters.

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Fundamental characteristics of the catalytic combustion of vaporized kerosene spray were studied experimentally. Palladium catalyst supported on the cordierite honeycomb monolith was used. Inlet temperature was elevated up to 700 K to evaporate the kerosene spray. Premixed gas of air and kerosene vapor was introduced into the catalyst. The catalytic combustion and gas phase reaction after catalyst were observed in this combustion system. The lean limit of the catalytic combustion was not affected by the space velocity and equivalence ratio of the mixture, but it was greatly affected by the inlet temperature. The parabolic shape blue flame that was supported on the catalyst was formed when the supplied mixture was not completely burned in the monolith. To clarify a reaction process in an combustive gas between the monolith and the blue flame, CO, HC(C₁∼C₇) and NO were analyzed. When the blue flame was observed after the catalyst, the HC and CO were formed from the unburned composition of fuel and they were burned as the blue flame. The NO emission level of the catalytic combustion was very low compared with the gas phase reaction of lean mixture.

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The Lewis numbers of lean heavy-hydrocarbon fuels are larger than unity, and hence, their flames are prone to extinction in a shear flow, which occurs in a turbulent combustion. Here, propane is used as a representative fuel of heavy-hydrocarbon fuels because the Lewis number of lean propane/air mixtures is larger than unity, and an attempt to improve its combustion characteristics by hydrogen addition has been made. A counterflow premixed flame burner is used to evaluate its improvement, since a flat, streched flame is established in the burner. The results show that with hydrogen additon, the fuel concentration, the flame distance and the flame temperature at extinction are reduced and combustion characteristics are imporved. However, it is found that the effective equivalence ratio at extinction for propane flame cannot become so small as that of lean methane/air mixture, which has a Lewis number less than unity. The CO concentration in the burned gas increses when the flame distance becomes smaller than 4 mm, and the burned gas temperature under than 1000°C.

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Direct numerical simulations of hydrogen-air turbulent premixed flames propagating in two-dimensional homogeneous isotropic turbulence are conducted to investigate the effects of turbulence intensity on the structure of turbulent premixed flames. Detailed kinetic mechanism including 12 reactive species and 27 elementary reactions is used to simulate H₂-O₂-N₂ reaction in turbulence. DNS are conducted for the cases of turbulent intensities of 10.0, 20.0 and 30.0 times of the laminar burning velocity. Turbulent burning velocity increases with the increase of turbulence intensity. The flame fronts for the case of lowest turbulence intensity can be classified in the regime of 'wrinkled laminar flame', whereas those for the cases of higher turbulence intensities show the characteristics of 'distributed reaction zone'. The mean flame thickness increases and the mean heat release rate decreases with the increase of turbulence intensity. However, for the higher intensity cases, variances of local flame thickness and heat release rate become large where the minimum local flame thickness decreases and the maximum local heat release rate increases with the increase of turbulence intensity. The local flame thickness and local heat release rate are well correlated with the tangential strain rate at the flame front.

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The local chemiluminescence emissions intensities of OH^*, CH^* and C₂^* were measured to study local flame front characteristics such as flame propagation speed, flame thickness and local A/F (air/ fuel) ratio. An engine of 548 cc (four stroke, port-injection) was used for measurements at 1 200 rpm for various A/F ratio. The results show that the measured flame propagation speed for both lean and rich was faster than that at a stoichiometric condition, while the speed was almost constant at 3.6 m/s for A/F ratio of 14 to 18. Although the flame thickness both in lean and rich condition was small about 2 mm, the maximum flame thickness was measured at A/F=16 which is over 8 mm. The chemiluminescence intensity ratios of CH^*/OH^* and C₂^*/OH^* were examined to show the A/F under different conditions in comparison with the A/F value measured by O₂ sensor. It was found that the local A/F ratio at the flame front can be estimated by the chemiluminescence intensity ratios of CH^*/OH^* and C₂^*/OH^*.

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Spray behavior of gasoline fuel injected into a N, gas vessel through a swirl nozzle with narrow spray cone angle were studied by means of a Schlieren photograph observation and a fuel vapor concentration measurement by Rayleigh scattering method, using Ar ion laser as a light source. The pressure and temperature inside the vessel were changed up to 0.6 MPa and 200°C respectively. A low volatility gasoline and iso-Pentane of very high volatility were also studied. As a results, under the higher volatility condition appeared such features as the stronger gradient or sharp skeleton in the shade of the spray photograph at break up, the more accelerated penetration of the spray tip after break up, the wider region where Mie scattering dose not interfere the Rayleigh scattering, the wider region in the outside of the spray edge observed where fuel vapor concentration is detected. A simple break up theory was considered and the experimental formulas were made for the spray shape behavior.

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Hydrogen has higher burning velocity and shorter quenching distance than hydrocarbons, and combustion characteristics of hydrogen in internal combustion engines are different from hydrocarbons. Authors have reported influencing factors to thermal efficiency in a hydrogen fueled spark ignition engine, and shown that heat release rate is very important in the thermal efficiency analysis. Error factors in calculation of heat release rate were analyzed in this research. Results show that hydrogen combustion with higher burning velocity than hydrocarbons has faster change in specific heat during combustion period, and it is better to include the term of d_k/d_θ especially in evaluation of cooling loss ratio. Influences of coolant temperature and engine speed on thermal efficiency were also analyzed in this research.

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For improvement in thermal efficiency of steam injected gas turbines for electric power generation, Partial Regenerative Dual Fluid Gas Turbine System (PRDF) was proposed in the previous paper. In this paper, heat recovery processes of PRDF and steam injected gas turbine are evaluated in view of exergy loss. It has been shown that decrease in exergy loss in the heat recovery process can contribute to improvement in thermal efficiency. Extended systems of PRDF for further improvement in thermal efficiency were also proposed and evaluated : one is a Partial Regenerative Dual Fluid Reheat Gas Turbine, and another is a combined system of PRDF with NH₃ bottoming cycle.

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The current BWR fuel assembly has seven spacers for maintaining a constant gap between fuel rods. Spacer design has a significant effect on the thermal hydraulic performance of a BWR fuel assembly. The purpose of this study is to develop an accurate method for predicting the effect of spacer shape on critical power. The critical power prediction method combining the CFD code of droplet deposition rate and the conventional subchannel code was verified by the critical power data of 4×4 rod bundle with various spacer shapes. From the verification, this method was found to be effective for predicting the critical power change with the change of the spacer shape.

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The purpose of this study is to clarify whether microencapsulated cells have an advantage over suspended cells in cryopreservation. Rat pheochromocytoma (CP 12) cells were selected for test biological cell and microencapusulated in alginate-polylysine-alginate membranes. Microencapsulated PC 12 cells were frozen with differential scanning calorymetry (DSC) at a cooling rate of 0.5 to 10°C/min. Their latent heat were measured in freezing process over the temperature range 4 to -80°C. The post-thaw viability was evaluated with dopamine release and trypan blue exclusion assay. As a result, latent heat of encapsulated cells were lower than that of suspended cells at a cooling rate of 0.5 and 1°C/min. This is because extra-capusle was frozen and intra-capsule unfrozen, as ice crystals forms in extra-capsule space. The post-thaw vability of microencapsulated PC 12 cells was improved at 0.5 and 1°C/min compared with that of suspended cells. Therefore, in microencapsulated PC 12 cells, acievement of intra-capsules unfrozen condition during freezing leads to reducing the solution effect and improving the post-thaw viability.

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