We have developed hybrid pattern gas channel consisting of high and low pressure gas channels for polymer electrolyte fuel cells (PEFCs). The pressure difference between them gives rise to inplane flow in the gas diffusion layer (GDL) under the rib. This hybrid pattern gas channel allows to configure both parallel and serpentine gas channels for the high pressure channels. The low pressure channel is a serpentine gas channel to improve water exhaust ability by its large flow velocity. By taking advantage of the hybrid pattern gas channels, stability of the cell voltage is improved by increase in the flow velocity of the high pressure gas channel when it is switched to the serpentine gas channel. Moreover, atmospheric air introduced into the low pressure gas channel without humidification can dry and exhaust product water extruded to the GDL under the low pressure gas channel. However, flow rate of this air should be optimized to avoid output voltage drop due to the drying of the membrane electrode assembly.

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We have developed hybrid pattern gas channels consisting of high and low pressure channels for polymer electrolyte fuel cells (PEFCs). The pressure difference between them gives rise to in-plane flow in the gas diffusion layer (GDL) under the rib. The high pressure channel is an interdigitated gas channel and the low pressure channel is a serpentine gas channel having smaller cross-sectional area than that in the 1st report of this work. An in-house separator is used for the cathode to vary the air flow velocity in the low pressure channel. By taking advantage of the hybrid pattern gas channels, maximum current density and stability of the cell voltage are significantly improved by an increase in the flow velocity in the low pressure channel. In contrast, a decrease in the flow velocity in the low pressure channel leads to a decrease in the current density at which sudden rise of IR overpotential due to the drying of the membrane electrode assembly occurs.

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It has been clarified that malted rice solutions cause the drag reduction phenomena in turbulent flow range. The drag reduction is classified in the Type-B for the friction factor of a circular pipe flow because of biopolymer solutions. Although it is an important problem to be solved saving energy for the hydraulic transportation of a pipeline system awaiting solution, some problem lays in the practical application for it. In this paper, we clarified the effect of the culture condition on the drag reduction phenomena by using a pipe friction measurement system.

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Recently, many Japanese suffer from paranasal sinusitis also known as empyema. One of the medical attendances for the paranasal sinusitis is a nebulizer treatment. The effectiveness of the nebulizer treatment has been confirmed until now. However, there are few researches that evaluated the treatment quantitatively, i.e., how many medicinal mist droplets deposit on inflammation areas inside a nasal cavity. This paper focused on a case-adult male, deflected septum, chronic paranasal sinusitis in left nasal and endoscope sinus surgery-and analyzed flow field inside a nasal cavity using computational fluid dynamics techniques. In addition, the paper also implemented medicinal mist droplet transportation analysis using gas-liquid two phase flow numerical model. From the analysis results, it is clear that (1) deflected septum significantly influences on medicinal droplet transportation, and then the effectiveness of nebulizer treatment, (2) narrow nasal cavity due to deflected septum reduces nasal cavity passage rate of medicinal droplets, and (3) air flow in the nasal cavity and transport phenomena of medicinal droplet is controllable by nebulizer inlet angle.

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The boiling water reactor (BWR) in the Quad Cities Unit 2 Nuclear Power Plant experienced a dryer failure under extended power up-rate conditions. The cause of the dryer failure was considered as flow-induced acoustic resonance at the stub pipes of safety relief valves (SRVs) in the main steam lines (MSLs). We have started a research program on BWR dryers to develop their loading evaluation methods. Moreover, it was also desirable to evaluate the dryer integrity of BWR-5 plants which are the main type of BWR in Japan. In the present study, we used 1/10-scale BWR tests and analysis to investigate the flow-induced acoustic resonance in SRV stub pipes and propagation of fluctuating pressure from SRVs to the dryer through the MSLs. We demonstrated that acoustic resonance occurred in SRV stub pipes at higher velocity flows than in the normal operation and fluctuating pressure propagated from SRVs to the dryer. The amplitude of the fluctuating pressure due to several stub pipes was much larger than that in one stub pipe because of interaction between them. The flow-induced acoustic resonance occurred for Strouhal number below 0.6 in the MSLs system of the BWR-5. Results of the tests were compared with those of acoustic analysis. The acoustic analysis could well predict the dryer loading.

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A Large-eddy simulation (LES) was developed to predict a visible plume region from a mechanical-draft cooling tower. This numerical model solves the equations for conservation of mass, momentum, energy, vapor and liquid water. It is assumed that the visible plume is generated whenever the instantaneous liquid water mixing ratio is existed. To estimate the accuracy of the present numerical model, the predictions of visible plume length and height are compared with observations. The results show the visible plume length and height are in good agreement with the observations. Furthermore, we investigate the basic behavior of the visible plume and temperature emitted from the cooling tower under severe metrological condition. It is found that whether the visible plume reaches the ground or not mostly depends on the wind angle to the cooling tower, and temperature emitted from the cooling tower has little influence on atmosphere environment on the ground.

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In this paper, a cylindrical particle method to simulate squeezing flow in a high aspect ratio domain is proposed. In a high aspect ratio domain, the scale of the vertical direction is incomparably smaller than that of the plane direction. It is practically impossible to simulate such a domain in three dimensions because a large number of calculation points are necessary and it takes too much time. A high aspect ratio domain is represented by a two dimensional model and particles are regarded as cylinders. Sizes of particles change according to the height and the pressure term is calculated so as to make the fluid incompressible. As a result, fluid flow in the two dimensional plane is calculated. Three dimensional viscosity resistance is calculated so that viscosity in simulation is accorded with that in an experiment. Simulation results agree with the experiments qualitatively.

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Stability of a drop in a pin-to-plate electrohydrostatic system was examined both theoretically and experimentally. With this static model, the mechanism of electrostatic ink jetting process was estimated. The basic equations are the augmented Young-Laplace equation for drop shape and the Laplace equation for electric field. These coupled equations were solved by the Finite Element Method. By the initial condition of its shape, a drop could be deformed into anomalous shapes, such as "nipple" and "dog bone," as well as conical shape, often referred as Taylor cone with the increment of non-dimensional electric field. The concentration of electric field around the corner of a nozzle was the cause of these anomalous shapes. By this stability analysis, it was demonstrated that the electrostatic ink jetting modes, dripping mode and the onset of cone-jet mode, were governed by the force balance between forces from surface tension, pressure and electrostatic field.

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The near pressure field formed around a high-speed train causes a vibration problem such as window rattling in railside residential areas. This paper investigates the effect of a wall along a track on the near pressure field both theoretically and numerically. The potential flow model of a flow around a train shows that the pressure fluctuation is reduced by the velocity field of the doublet generated on the wall. From the result with the panel method, we also find that the pressure reduction by the wall is a function of the ratio of the wall height to the distance from the train and is independent of the wall position.

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Direct numerical simulation (DNS) of a feedback-controlled turbulent channel flow at Reτ=640 is carried out. In order to seek a possibility of employing fewer sensors and actuators of larger sizes for real applications, the control performance is assessed through either the small scale or large-scale components of wall-normal velocity fluctuation, of which threshold is defined to be the spanwise wavelength of 300 viscous wall units. The present numerical results reveal that the control of small scale fluctuations generally leads to larger drag reduction than that of large scale fluctuation. In the former case, the contribution of small scales to the friction drag is reduced, while that of large scales remains unchanged. In contrast, when only the large scale fluctuation is damped, the contribution of the small scale fluctuation to the friction drag is found drastically increased due to the reduced pressure strain correlation, which acts as a major destruction mechanism of the Reynolds shear stress.

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In an attempt to improve the accuracy in direct numerical simulation (DNS) of fully developed incompressible turbulent channel flow using the finite difference method, the fourth and eighth order central compact schemes with 'spectral-like resolution' have been introduced to the viscous terms, which play an important role in the dissipation range in the near-wall turbulence. The DNSs using the conventional second and fourth order central difference schemes are also conducted for comparison. The results are compared with those obtained by the spectral method. The results show the improvement in accuracy by the introduction of the compact schemes. The remarkable improvements in the power and dissipation spectra are also confirmed in the dissipation range.

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High-speed two-phase mist flow is very important in developing the ejector of a refrigeration cycle and in the total-flow system of a geothermal power plant. Two types of sound speed in two-phase flow can be created because of the inter-phase transport phenomenon. One is equilibrium sound speed in which the inter-phase transport in the flow is in complete equilibrium. Whereas, the other one is frozen sound speed in which the inter-phase transport is completely frozen. Usually, the fluid velocity is higher than the equilibrium sound speed but lower than the frozen sound speed because the equilibrium sound speed is very low. The existence of the supersonic oblique shock waves is not certain because the fundamental equations of two-phase flow are controlled by the frozen sound speed. This paper shows that the oblique shock wave could appear at some conditions even though the frozen Mach number was less than unity. As the reference length became bigger, the inclined angle of the oblique shock wave reduced to the angle of the equilibrium one. The thickness of a shock wave is directly proportional to the product of the relaxation time and the inlet velocity. Then, the fronts of the shock waves for large relaxation times reached up the inlet. All of the flow area corresponded to subsonic state and the oblique shock wave could not exist anymore.

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Molecular dynamics study of equilibrium system of an argon nanodroplet and surrounding argon vapor is carefully carried out to address a fundamental issue whether the thermodynamic description is applicable to the nanoscale inhomogeneous system. The numerical result is sufficiently reliable so that it can identify the smallest droplet standing stably over 200ns. The validity of the Laplace equation for nanodroplet is proved by a purely mechanical argument on the basis of directly computed normal and tangential pressures in the transition layer. Furthermore, it is demonstrated that the chemical potentials of liquid and vapor phases are not equal when a droplet is so small that the number of molecules consisting the transition layer may be comparable to that in the droplet. The Kelvin equation does not hold in such a case.

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To explore a reliable technology possibly applicable to the inactivation of micro-creatures in ship ballast water, this paper reports a result of a primary experimental and analytical study. We obtained 10μm bubbles in averaged diameter by using a swirling flow type micro-bubble generator. We exposed a shock wave generated by a micro-explosion of a 10mg silver azide pellet to the water containing micro-bubbles filled in a 10mm wide parallel test section. Observations were carried out with a high-speed camera, and the corresponding rebound pressures of bubbles were measured with a fiber optic probe pressure transducer. We confirmed micro-bubble motion with higher temporal resolution and found that micro-bubble collapse arose in several hundred nano-seconds after the shock loading. The peak pressure generated by bubble collapse was over 200MPa at the distance of 20mm from the explosion center. These experimental results were consistent with those analyzed on the basis of the measured pressure data. The presence of such high impulsive pressures upon bubble collapse clearly indicated that the rebound pressure would be effectively applicable to the inactivation of micro-creatures in ship ballast water.

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In this study, process of vorticity decay caused by viscous interaction in a separated shear layer was investigated based on velocity measurements and flow visualization of the separated shear layer in the very vicinity of the separation point of a test body. A right isosceles triangular prism with two 200mm long isosceles sides was used as the test body, and the experiment was carried out at the fixed Reynolds number of 19000. As the results, following aspects were clarified about the vorticity decay. i) A part of the vorticity decay in the separated share layer behind a body was caused by viscous interaction associated with transition of velocity distribution from boundary layer like shape to free shear layer like shape in the very vicinity of the separation point. ii) The Reynolds shear stress associated with turbulent dissipation does not take part in the vorticity decay process in the very vicinity of the separation point. iii) Since the Reynolds shear stress about an intermediate size vortex produced by coalescence of smaller vortices was considerably large, the flow field becomes turbulent and three dimensional by the coalescence of the smaller vortices.

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Lift and drag characteristics of a symmetric NACA 0012 airfoil in a low Reynolds number range have been investigated when miniature electromagnetic actuators attached on the airfoil have been operated in order to control the flow separation and the stall. Flow visualizations including PIV method have also been made to examine the flow separation structure of the airfoil. At a small attack angle just after the stall, the periodical actuation generates the vortex in phase. This induced vortex flows near the surface of the airfoil and noticeably decreases the dead water area so that the maximum lift coefficient increases by 25% and the angle of stall increases by 3 degree with the actuation. At a relative large attack angle, among the several types of the actuation patterns tried, only the in phase actuations with selective frequency can suppress the abrupt drop of the lift force owing to the generations of a large-scale vortex and its strong downward flow toward the airfoil near the trailing edge, although this large-scale vortex no longer contributes to reduce the dead water area.

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The specific aim of this work is to develop a new technique to control vortex excitations of a circular cylinder by utilizing interference of a downstream strip-plate in cruciform arrangement. In the previous paper, it is shown that the two longitudinal vortices, trailing vortex and necklace vortex, shed in the vicinity of the crossing of a fixed circular cylinder/strip-plate system. In this paper, the circular cylinder was supported elastically so as to allow cross-flow motion and influence of the strip-plate on vortex excitation was investigated with the same wind tunnel apparatus. The strip-plate suppresses Karman vortex excitation more effectively compared with a downstream circular cylinder. A wider strip-plate has a larger suppression effect. The trailing vortex induces vortex excitation when gap-to-diameter ratio s/d less than 0.3. When the strip-plate width w is equal to the upstream circular cylinder diameter d, the velocity range for longitudinal vortex excitation is 5 times wider than the case of the downstream circular cylinder. The necklace vortex excitations dose not occur for strip-plates with w/d≥0.75, as expected from the fixed-cylinder experiment. Longitudinal vortex excitation by downstream strip-plate occurs over a wide velocity range, and it can be easily controlled by s/d adjusting.

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While a train is running in a tunnel, a pressure wave (we call it "tunnel outside continuous wave") is radiated from both end portals to the outside space. Though some characteristics of the tunnel outside continuous wave are revealed from previous researches, the relation between the tunnel outside continuous wave and the pressure wave in a tunnel has not been obtained yet. A pressure wave measured at a fixed point in a tunnel is the superposition of two waves (the incidence wave and the reflected wave) propagating in opposite directions. Therefore, in order to investigate the relation between the tunnel outside continuous wave and the pressure wave in a tunnel, it is necessary to separate the incident wave or the reflected wave from the measured pressure wave. In this paper, we propose a method of extracting the incident wave or the reflected wave from the pressure waves in a tunnel propagating in both directions in a tunnel. The validity of this method has been confirmed by numerical and experimental investigation.

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Acoustic cavitation has an important role in ultrasound applications, such as HIFU (High Intensity Focused Ultrasound) therapy. Control of the growth of the cavitation bubbles is one of the important factors to control the effects of the cavitating bubbles. Several researchers have shown that a dual-frequency excitation method can enhance the growth of the bubbles due to rectified diffusion and consequently enhances the effects of the cavitation. In this study, the growth of an oscillating bubble in an ultrasound field due to the rectified diffusion is numerically investigated. In the model, we consider the compressibility of the surrounding liquid, mist generation inside the bubble, and the heat and mass transfer through the bubble interface. Mass transfer is calculated by solving the gas diffusion equation in liquid phase with the boundary condition at the bubble interface. The results reveal that the dual-frequency excitation method can enhance the rectified diffusion in certain cases and it can be useful to control the growth of the cavitating bubbles.

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The Lattice Boltzmann Method (LBM)is used to study the propagation of high amplitude progressive sound wave radiated from a piston in a duct. The discretised Boltzmann equation for the 2D21V thermal BGK model is solved using a second-order Runge-Kutta scheme in time and a fifth-order upwind difference scheme in space. The formation of a shock front and the development of saw tooth waves are simulated for the dimensionless distance x^^- up to 3. The Fourier component amplitudes of computed waveforms are obtained. The simulations are compared with the solution of Burgers' equation, The results show good agreement with Burgers' equation for non-linearity factor Γ〜O(1). For Γ>>1 i.e. when the effect of non-linearity is strong relative to thermo-viscous dissipation, the feature describing the occurrence of acoustic streaming in the direction of wave propagation after shock formation is observed. These results suggest that the LBM is useful for studying a wider range of nonlinear acoustical problems than Burgers' equation.

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The choking phenomenon of a convergent nozzle flow has been experimentally investigated using four nozzles with the same diameter but different boundary layer thickness at the exit of the nozzle. It is observed that the pressure ratio across the nozzle when the flow is just choked depends on the boundary layer thickness at the nozzle exit, and both the choking pressure ratio and the choked mass flow rate decrease with increasing boundary layer thickness. The main flow at the exit of the nozzle when the flow is choked is supersonic, and the Mach number increases with increasing boundary layer thickness.

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The pressure-sensitive paint (PSP) is very useful and easy way to obtain the pressure distribution on surfaces. Usually the pressure distribution by the paint shows good agreement with that obtained by other methods, like a pressure tap. Here, in this study, we discuss on the property that the paint really shows, especially in high Knudsen number regime. In this regime, it is well known that a pressure tap shows good agreement with surface pressure, and not gas pressure. Therefore, a PSP experimental result is examined with a DSMC numerical result, and shows good agreement with surface pressure. To argue against the suggestion that "PSP measures pressure, not density" [Bell, J.H. et al., Annu. Rev. Fluid Mech., 33 (2001), 155-206.], a temperature sensitivity is investigated in detail. From these arguments, it is suggested that the PSP measures a number flux toward a surface.

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The effect of an inhomogeneous part in a blood vessel on pulse wave has been investigated by using a one-dimensional lattice model associated with the material nonlinearity of the arterial vessel wall. In the present study, from the viewpoint of mechanics, a certain part of blood vessel, which has the different configuration and mechanical properties of the arterial vessel wall, is regarded as the inhomogeneous part by a generalization. The stability of the solitary wave is applied in order to obtain the reliable results by the numerical analysis of the pulse wave which propagates through the inhomogeneous part in the blood vessel. As a result, the behaviors of the pulse wave which propagates through the inhomogeneous part are shown. The factor which has the effects on the propagation of the pulse wave is revealed. Moreover, the relations between the behaviors of the pulse wave and the properties of the inhomogeneous part are clarified.

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In the present study, the wobbling motion of a single-flagellated bacterium was analyzed assuming that the bacterium consists of a cell body of prorate spheroid and flagellar helix, the axis of which is inclined to the major axis of the ellipsoid, and observed by using a dark field microscope. We investigated that the effect of body shape on swimming behavior such as propulsive velocity and wobbling frequency for various inclined angle of flagella about cell body major axis. As a result, it was found that the aspect ratio of cell body in which propulsive velocity becomes maximum are determined by the resistive force acting on the cell body and rotation frequency of flagella which vary with aspect ratio of cell body.

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Multi-Objective Genetic Algorithm (MOGA) optimization was developed for a small and high efficiency blood pump without hemolysis. The outer diameter of impeller and hydrodynamic efficiency were chosen as objective functions, and the rotational speed of impeller was chosen as a constraint condition. The measured pump performance of the GA optimized pump showed good agreement with the required one. Unsteady RANS calculations presented that the GA optimized pump can suppress higher shear velocity in the blood pump. As the result of the present study the GA optimization is found to be effective for the design of blood pumps.

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A horizontal axis wind turbine installed in the open air experiences the wind field which is nonuniform in space and unsteady in time. The resulting yaw misalignment and wind shear bring about periodic fluctuation of aerodynamic loads on the rotor, and turbulence causes complicated load fluctuations. For the fatigue design of the rotor blades, it is imperative to predict the aerodynamic load fluctuation depending on various inflow conditions such as yaw misalignment, wind shear, and turbulence. The present paper describes a numerical method for calculating the aerodynamic loads for combined inflow condition and shows several numerical results. The turbulent wind field is simulated with the Mann model, which is based on a Fourier synthesis method. For the calculation of aerodynamic loads on the rotor blades, an inviscid aerodynamic model based on the asymptotic acceleration potential method was adopted. For the fatigue load analysis, each of the simulated time series of the aerodynamic load was processed with the Rainflow counting algorithm. The calculation results show that the effects of each inflow conditions on fatigue loads have nonlinear relations among each other. Therefore fatigue loads should be calculated on the combined inflow condition, by the model which can consider unsteadiness and non-uniformity of the each inflow condition, simultaneously.

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In centrifugal pumps for artificial hearts, a magnetic drive and lightly loaded journal bearing system are often used to avoid leakage and to minimize the damage on blood cells. In such system, the rigidity of the shaft support part is so small and the impeller usually rotates over the critical speed. For such cases, the rotordynamic fluid forces play an important role for the stability of operation. In the present study, the characteristics of the rotordynamic fluid forces on the shaft support part are examined. The destabilizing fluid force which encourages the whirling motion of the rotor occurs in the positive whirl speed region and the destabilizing region is decreased as the flow rate is increased. The destabilizing region is influenced by the pre-swirl at the inlet of the shaft part and the destabilizing region is increased in the positive whirl speed region as the pre-swirl is increased. The fluid forces with static eccentricity are also measured. Finally, the flow visualization around the rotor is carried out and a Taylor-vortex structure is observed.

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In centrifugal pumps for artificial hearts, a magnetic drive and lightly loaded journal bearing system are often used to avoid leakage and to minimize the damage on blood cells. In such system, the rigidity of the bearing is small and an impeller usually rotates over the critical speed. For such cases, rotordynamic fluid forces play an important role for the stability of operation. The present paper reports about the results of numerical studies on the rotordynamic fluid forces on the shaft support part. For the numerical calculations, a commercial code based on RANS and a bulk flow model have been used.

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Critical heat flux was measured for saturated pool boiling of 2-propanol/water mixture (9.4wt%) on a 12mm diameter horizontal disk at pressures of 5kPa to 100kPa. The CHF of the mixture was 1.5 to 2.2 times greater than that of water over the whole range of pressures. To examine the mechanism of the CHF improvement in the mixture, liquid-vapor behaviors close to the heating surface were measured using a conductance probe under atmospheric pressure. It was found that for boiling of the mixture, radial distributions of the void fraction and contact frequencies of the probe tip with vapor have a distinct peak near the periphery of the heating surface. This means that vapor generation is suppressed at a central area and enhanced near the periphery of the heating surface. The thickness of liquid layer beneath the vapor mass determined for the mixture at a center of the heating surface becomes considerably thicker than that of water. The formation of this thicker liquid layer is likely to be one cause of the CHF improvement in the 2-propanol/water mixture under atmospheric pressure.

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The theoretical and experimental study was conducted to investigate the critical condition at which a liquid droplet starts to move on a rotating disk. Based on the force balance between the surface tension and the centrifugal force, the critical rotation speed was theoretically calculated in the similar manner to the preceding report. The critical rotation speed was experimentally measured for each combination between three kinds of test plates and test liquids. The movements of droplets were judged from the careful observation of infinitesimal motion of the three-phase contact line. The calculated rotation speeds agreed well with measured ones for any contact angle when the droplets were set on the plate. The three-dimensional surface profiles of droplets were calculated from the approximate Laplace equation in which the contact line was assumed as the combination of two ellipses with different ratio of measure to minor axis. The measured profiles on the rotating disk were approximated well by the method proposed in this study.

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We developed a method for designing the thermal properties of an optical head for a Blu-ray^<TM> Disc (BD) apparatus. This optical head contains two laser diodes for BD and DVD compatibility, and the higher the operating temperature at which the laser diode emits a beam of light, the shorter its life-time becomes. Therefore, reducing the temperature increase of both laser diodes is necessary to obtain high reliability. First, we expressed the temperature increase of a laser diode as a summation of the products of the following three terms. The first term is the power dissipation of an electric component. The second term is a ratio of the amount of heat flow into the laser diode from the electric component to the total amount of its power dissipation. The third term is the summation including all thermal resistances between the laser diode and the ambient on the whole heat transfer paths from the electric component to the ambient via the laser diode. Then, by taking this interpretation into consideration, we designed the position of the laser driver IC, which dissipates the largest amount of electric power in the optical head. As a result, there was a 1/3 decrease in the amount of heat flow into each laser diode from the laser driver IC compared to that of the conventional optical head, and the calculated temperature increase of the laser diodes for BD and DVD were 10K or less and 15K or less, respectively.

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Gasification technology is recognized as one of the candidates to utilize the biomass effectively. From this viewpoint, this study focused fundamentals on woody biomass gasification, using a labscale packed-bed. In this experiment, pellets of black pine are gasified, using air as the gasification agent. The gasification tests were carried out under both updraft and downdraft conditions. The temperature distribution inside the gasifier and the compositions of gasified gas were measured and analyzed during gasification by thermo-couples inserted from a furnace wall and a micro gas chromatograph, respectively. The produced gasses before cooling were also sampled to analyze amount of tar generation in the gasses. As a result, the lower heating value of the produced gas under the downdraft condition was higher than that under the updraft condition. It was easier to operate under the downdraft condition than under the updraft. Under the updraft condition, bridging phenomenon happened. Amount of tar generation under the downdraft condition was lower than that under the updraft. This is because tar passes through a partial combustion zone or higher temperature zone in the downdraft gasifier.

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In this study, effect of fuel properties on diffusion combustion of kerosene was investigated experimentally. Five types of kerosene, which distillation and composition properties were different, were used as the test fuel. Laminar diffusion flames of kerosene were formed by using wick combustion burner. Fuel consumption rate, flame temperature and flame luminosity of each flame were measured. As the results, fuel consumption rate proportionally increased with decreasing volume average boiling point, and both temperature and luminosity decreased as the aromatic content in the fuel increase. To investigate the effect on soot formation of fuel properties, concentration distributions of polycyclic aromatic hydrocarbons (PAHs) and soot were measured by laser-induced fluorescence (LIF) and laser-induced incandescence (LII). Both PAHs-LIF intensity on wick and LII intensity of soot emission increased with the content of aromatic compounds in the fuel became higher.

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To realize thermal recycling of waste plastic resin as one of alternative fuels, detailed microscopic observation is made of the multiphase process in a micro spherical PET particle under abrupt heating. It is observed that multiple internal micro bubbling occurs within the micro PET-droplet independent of its initial diameter and is triggered by flash vaporization of thermally decomposed products of PET resin. Internal random explosions of micro bubbles follow and blow up multiple irregular micro jets from the micro droplet. The latter forces the micro droplet to move around irregularly on the fine wire, while micro diffusion flames are randomly established behind them. Based on the observation results, the key factor to such a violent burning process of PET particles as to exceed that of well-known volatile liquid fuels can be attributed to the internal multiple micro bubbling due to the flash vaporization of thermally decomposed products.

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It is very important to control the fly ash properties for effective utilization of fly ash. The influence of combustion conditions (particle size of pulverized coal, two-stage combustion ratio) and coal properties on the fly ash properties (particle size, Blaine, particle density and particle shape) are experimentally investigated by use of a pulverized coal combustion test facility. Particle size of pulverized coal strongly affects the fly ash properties. As the particle size of pulverized coal decreases, the particle size of fly ash also decreases. The particle density of fly ash increases and the shape of fly ash particle approaches spherical. The effects of the two-stage combustion ratio on the fly ash properties are weaker than particle size of pulverized coal. The coal properties also have little influence of the fly ash properties. The particle size distribution of fly ash is, however, affected by the fuel ratio.

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In a polymer electrolyte fuel cell (PEFC), current density through polymer electrolyte membrane (PEM) would be distributed along the electrode on membrane electrode assembly (MEA). To increase the electric power density of a PEFC, it is needed to find out some low-current-density areas where electric power generation decrease due to a lack of hydrogen, flooding and so on. Therefore, a monitoring method of local current density in PEFC is required to achieve higher current density operation of a PEFC. We developed the new method to estimate the spatial distribution of current flowing through MEA in a PEFC using Nuclear-Magnetic-Resonance (NMR) signal detector. The magnetic field strength induced by the current through MEA generating electric power is acquired as the frequency shift of the NMR signal by NMR signal detector. The one-dimensional spatial distribution of frequency shift changing along the MEA was measured. In order to verify the method, under the assumption that the current through MEA was uniform, magnetic field strength induced by the current through GDL in a PEFC was analyzed theoretically. And then, the frequency shift at the each NMR signal detector was calculated as functions of the geometry of GDL, current and the position of the NMR signal detector. In these studies, the experimental results agree with the theoretical results.

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This paper investigates the performance, combustion characteristics, and emissions of a small single cylinder DI diesel engine with biodiesel fuels derived from unused rape oil, soybean oil, and palm oil. Compared with gas oil, all the BDF showed slightly higher brake thermal efficiencies and considerably reduced smoke densities while the NO_x emissions were somewhat higher. The rape oil BDF and Palm oil BDF used in the tests are mainly composed of Methyl Oleate (OME) and Methyl Palmitate (PME). Therefore, the combustion characteristics were examined using neat OME and OME-PME blends. As a result, the neat OME and OME-PME blends showed good ignitability and combustion stability like that of gas oil operation. To discuss the influence of PME addition on evaporation, ignition, and combustion characteristics, basic experiments with single droplets were also performed. The results showed that the ignition delay and combustion duration tend to decrease when PME is blended with OME.

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In order to clarify the effect of heterogeneity of distributions of temperature and oxygen concentration in a combustion chamber induced by EGR on the soot and NO emissions from the diesel engine, the combustion characteristics of diesel spray flame achieved in a rapid compression and expansion machine (RCEM) at various patterns of temperature distribution in the chamber are investigated. The distribution of surrounding gas temperature in a chamber is controlled by changing the location, phase, and duration of EGR gas injection with multi-port intake system. The multi-port intake system can make the circler distributions of gas temperature with different gradient. NO and soot emissions are measured at different temperature distributions. Results indicate that the NO_x and soot emissions from diesel combustion are governed mainly by the amount of enthalpy entrained into the spray upstream the ignition region, when the temperature distribution in a chamber is changed with keeping the oxygen fraction at constant.

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Engineered tissue of digestive organ requires high cell density around 10^7〜10^9cells/mL. For the production of such a high cell density engineered tissue, namely a bioreactor, microstructured scaffold and the flow system supplying oxygen to the cells, should be designed systematically. For this purpose, the plate type hepatic bioreactor, which was optimally designed to support 10^8cells/mL cells, was produced to estimate the flow characteristics and oxygen mebolism. The microstructured scaffold which is composed of aligned square pillars, was designed to allow hepatocytes to attached on the surface of microstructures in cell density of 10^8cells/mL. The designed scaffold with microstructures (pillar hight: 109.6μm, channel: 33.1μm) was fabricated using PDMS. The flow resistance of fabricated scaffold was measured at flow rate from 0.46 to 2.0mL/sec. Thereafter, hepatoma cell line HepG 2 were cultured in the scaffold with open culture to compose bioreactor of high cell density around 9.7×10^7〜1.9×10^8cells/mL. Finally, the bioreactor was closed for perfusion cell-culture, which simulates in vivo circulation system. Oxygen concentration of inlet and outlet of the bioreactor in perfusion cell-culture were measured under the perfusion flow rate from 0.3 to 2.2mL/min. The result showed that there is a certain flow rate, under which the bioreactor consumes maximum oxygen. Nevertheless maximum cellular oxygen metabolic rate in the bioreactor is far lower than normal cellular metabolic rate. This trend explains the diffusion resistance on cellular surface and the detachment of cells from the surface of bioreactor at high flow rate.

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A high-ash coal is fired in a pulverized coal combustion test furnace (thermal input of coal: 760kW). A/C (mass ratio of primary airflow rate to coal feed rate [kg/h]/[kg/h]) and two-stage combustion ratio are changed, and blends of the high-ash coal and a bituminous coal are also fired. The emission characteristics of NO_x and unburned carbon in fly ash are investigated in detail. A/C affects the emission of NO_x and unburned carbon in fly ash on the high-ash coal combustion. It is desirable that primary air flow rate on the high-ash coal is almost same with that on the bituminous coal. The high-ash coal has an influence on the blended combustion.

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