Jet mixing noise radiated from turbo-fan engines is dominant during take-off of civil aircraft. Simple and available empirical models to predict the jet mixing noise under several engine conditions are required for developing the suppressors of the jet mixing noise. To improve the accuracy of noise prediction, especially in coaxial jet configurations, a Four-Source concept has been applied in place of the former noise models such as SAE AIR1905. The Four-Source concept, allocating four types of noise sources behind the nozzle, is originally coupled with ESDU, the data base having difficulty in accessibility. This study thus proposes a simpler combination of the Four-Source concept with an available model, the SAE ARP876. The authors compared the proposed noise model with the experimental data. From the agreement of the noise model with the experimental data, it was confirmed that the proposed combination is practical in predicting jet mixing noise as well as the original model that is a Four-Source concept with ESDU.

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Underwater glider is the glider to use for environmental researches in lake and sea. The Reynolds number of flow around underwater glider is between about 10⁴ ～ 10⁵ and the research for the aerodynamic characteristics of such low Reynolds number region is not so much. So in this study, we investigate the aerodynamic characteristics for various airfoils of under-water glider at low Reynolds number by the towing water tank experiment and 3-dimensional numerical analysis using STAR-CCM+ by IDAJ co. ltd. As results of experiment, the lift-drag ratio of airfoils with camber become larger than those of flat plate. As results of numerical analysis, the effect of maximum camber ratio and maximum camber position and thickness ratio on aerodynamic characteristics and optimum cross-sectional shape of wing for underwater glider are found.

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In the photoresist stripping process of semiconductor manufacturing, the cleaning method with the ozone water and a disk-shaped nozzle is proposed in authors' previous studies. Moreover, it is suggested that the three-dimensional flow structure of the ozone water between a rotating silicon wafer and the disk-shaped nozzle affects photoresist stripping rate. The purpose of the present study is to reveal this flow structure. In order to reveal this flow structure, the visualization experiment with dye, stereoscopic micro-PTV measurement and CFD analysis are conducted. As a result, the injected dye forms contrasting density, and a high concentrated area is indicated near the disk end. On the other hand, CFD analysis is conducted with 5 models ; laminar model, k-ε model, Lam-Bremhorst k-ε model (1981), Launder-Sharma k-ε model (1974) and Lien-Leschziner k-ε model (1999). The result suggests that Lien-Leschziner k-ε is the most appropriate model for the present study. It is cleared that there is a transition radius of flow structure. It is suggested that the transition radius also depends on the balance between the inertial force and the force caused by the adverse pressure gradient. Furthermore, the photoresist stripping rate increases where the wall shear stress is strong. As a result, it is suggested that the wall shear stress affects the rate of photoresist stripping.

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In the photoresist stripping process of semiconductor manufacturing, the cleaning method with the ozone water and a disk-shaped nozzle is proposed in authors' previous studies. Moreover, it is suggested that the three-dimensional flow structure of the ozone water between a rotating silicon wafer and the disk-shaped nozzle affects photoresist stripping rate. The purpose of the present study is to reveal this flow structure. In order to reveal this flow structure, the visualization experiment with dye and stereoscopic micro-PTV measurement are conducted. As a result, the injected dye forms contrasting density, and a high concentrated area is indicated near the disk end. From this result, it is cleared that there is a transition radius of flow structure. The transition radius is different corresponding to experimental conditions. Nevertheless, it is suggested that the transition radius depends on a dimensionless number Re_Ω / Re_s which is the ratio of rotational Reynolds number Re_Ω and Reynolds number Re_s. From the result of stereoscopic micro-PTV measurement, it is cleared that the backward flow exists along r-axis. Furthermore, the backward flow keeps already reacted ozone water between two disks. As a result, it is suggested that the concentration of ozone water decreases near the circulation area.

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Control of flow separation over stator vanes with backward-facing step applying synthetic jets (zero net mass flux) is investigated using particle image velocimetry (PIV). The stator vanes are fixed at an angle of -10° to the main flow with Reynolds number of 2.7×10³, which is produced by a small ducted fan. Without synthetic jets, the flow separates at the edge of the step and the shear layer glows in width along to the downstream, the flow reattachment is achieved at near the trailing edge. In contrast, with synthetic jets actuating on Cμ =4.5×10^-2 and F⁺=1.46, high momentum and high actuation frequency for conventional backward-facing step flow control, the flow is directed immediately to the lower step near the synthetic jet orifice and reattachment length is shortened by 53% of no-flow control case. Phase-locked data shows the vortices of synthetic jets dominate the flow filed of upstream and downstream of the step. The shear layer is completely overcasted with the strong vortices of the synthetic jets, and furthermore, the recirculation bubble is controlled by the separated vortices of synthetic jets resulting recirculation region smaller.

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Drag-reducing flow owing to polymer additives in wall turbulence is investigated by means of numerical simulations. A spring-damper chain element model is employed to express a spatial concentration and flexible motion of the polymer in a turbulent flow. The model consists of some beads linked by springs and dampers. The influence of the model's length upon the turbulent flow is mainly focused. As lengthening the model, the skin-friction drag decreases since the turbulent contribution to the skin-friction coefficient decreases while the body force term due to the model increases. The behavior of the model and the energy transport process in the drag-reducing flow due to the model are discussed to clarify the mechanism of the drag reduction.

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Heat removal in the exothermal of electric vehicle (EV) motors has been studied. Improvement of efficiency of EV with arranging thermal-hydraulic characteristics in the motor is required. However, the flow field in EV motor is not clarified. The aim of the present work is to clarify the flow characteristics of the narrow gap between an inner high speed rotating cylinder and a stationary concentric cylinder. In the present study, the gap between the inner rotating cylinder and the stationary concentric cylinder is visualized with experimental apparatus which simulates the geometry of an EV motor. Water is adopted in order to simulate the actual status of flow characteristic in the EV, where air flows as working fluid, by the Reynolds analogy. In addition, Reynolds number is applied as one of the experimental parameters and is changed in the range of 247 ≤ Re ≤ 2510 at intervals of about 65. The flow structures in the gap and the rotor end part are observed with mixing Kalliroscope flakes and nylon particles in the water. As a result, distinguishing stripe pattern which seems to be the Taylor vortex was observed. Furthermore, the flow regimes changed to different way such as azimuthally waves appear to stripe pattern by changing Reynolds number, finally it transited to complicated flow. The flow field of the rotor edge part observed from the stator end face also transited to complicated flow with increase of Reynolds number. However, flow direction turned from the circle of stator edge face to the central shaft and it does not change with increase of Reynolds number. The fluid in the gap did not actively move over to rotor edge part before Re = 383, but it moves obviously beyond Re = 584.

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The motion of a liquid pouring from a beverage can is experimentally and numerically studied. First, we measure pouring motion for sixteen examinees and find that the can motion in pouring consists of three stages; tipping stage, filling stage, and returning stage. In each stage, the angular velocity of a can is nearly constant, and its average velocity is obtained. A liquid flow from a can rotating at the average angular velocity is visualized with high-speed cameras and is also numerically simulated with the Volume of Fluid (VOF) method. At the beginning of pouring, the liquid from a can opening is once blocked by the rim of a upper lid and then flows over the rim. It falls from the can forming a V-shaped surface, which converges few centimeters below the rim expanding the liquid surface in the direction perpendicular to the V-shaped surface. This results in a wavy pattern of the liquid surface. The computational result agrees with the experiment.

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This paper reports on the performance evaluation of a rapid opening valve assisted by magnetic force for a new diaphragmless shock tube. The movement direction of the piston valve in the driver section of the present device crosses the axis of a shock tube at right angles so that the piston valve is accelerated before the shock tube is opened. In addition, a permanent magnet installed in the high-pressure chamber increases the pressure difference between both sides of the piston valve. The opening time of the shock tube inlet and pressure variations in the shock tube are measured experimentally. Detailed driving process of the present device is investigated using a one-dimensional theoretical calculation. The experimental and computational results show that the opening time of the shock tube inlet can be shortened about 30% when magnetic force is applied to the piston valve. The theoretical results suggest that the performance of the driver section is under better condition.

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The opening delay of a discharge reed valve for compressors caused by the oil film in the clearance between the reed and the valve seat is investigated. The coupling calculation model which consists of the reed deformation, the gas flow and the oil film flow is developed. The two-dimensional reed deformation is expressed by expanding natural modes that are obtained by the finite element method using shell elements. The gas flow is expressed by the thermodynamic model under the assumption of the internal reversible process. The two-dimensional oil film pressure is obtained by solving numerically the Reynolds' equation through the finite volume method. In addition to the case in which cavitation in the oil film is not taken into account, two cavitation models are tested; the static cavitation model (Reynolds' condition) in which the minimum oil pressure is set to absolute zero and the dynamic cavitation model in which the bubble expansion is directly simulated. Comparisons between calculation results and the experimental result show that the dynamic cavitation model in which the oil film pressure can fall to the absolute negative (tensile in the liquid) is required to reproduce accurately the opening delay time in the experiment.

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The opening delay of a discharge reed valve for compressors caused by the oil film in the clearance between the reed and the valve seat is investigated. The developed simulation method which couples the reed deformation, the gas flow and the oil film flow is applied to simulate delay times on two types of seats with different contact areas. Three models for cavitaion in the oil film are tested; no-cavitation model, the static cavitation model (Reynolds' condition), and the dynamic cavitaton model in which the bubble expansion is directly simulated. The calculaion through the dynamic cavitation model reproduces well experimental results with regard to the delay time and oil film behaviors of cavitation and blow-by (oil film rupture). The result also shows that the growth of cavitation bubbles occupies the change in the oil film volume and prevents the oil film pressure from falling. The rupture mechanism based on the calculation results is that the increase of the oil film thickness directly causes the oil film pressure recovery leading to the blow-by flow, and both cavitation and the smaller contact area promote the growth of the oil film thickness.

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The influence of transverse vorticity on the dissimilarity between turbulent heat flux and Reynolds stress was investigated by use of direct numerical simulation data for a channel flow. The theoretical relations regarding to Reynolds stress obtained from Lagrangian momentum equation shows that the correlation v(∂p/∂x) between wall-normal velocity v and streamwise pressure gradient fluctuation (∂p/∂x) has an important effect on the dissimilarity. The correlation v(∂p/∂x) would be negative near the transverse clockwise vortex in the flow field because v and (∂p/∂x) have a different sign to each other around the vortex. The numerical results of turbulent flow and temperature field demonstrate a strong correlation between the strength of dissimilarity (difference between turbulent heat flux and Reynolds stress), -v(∂p/∂x) and the transverse clockwise vorticity. The dissimilarity would be mainly caused by the reduction of Reynolds stress near the vortex region, where the streamwise velocity fluctuation of fluid particle is accelerated (or decelerated) on the ejection (or sweep) side due to the pressure field around the vortex. The strength of dissimilarity increases remarkably where the ring-shaped vortex stands up from the wall and bends to the spanwise direction in the lag-law region.

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Emulsification technique is used in broad fields, such as food, chemistry, and medical treatment, and the range of use has been spreading still more. A pressure type homogenizer consists of a plunger pump and a valve part with a narrow channel. It generates the effects of shear, a turbulent flow and cavitation at very short time, and then makes a homogeneous emulsification state. If the flow pattern in the valve can be solved in more detail, the more effective and stabilized emulsification will be attained. However, since the measurement of the size, the pressure and the flow velocity in a narrow gap space by experiments is difficult, the details of the mechanism of emulsification by the shear, the turbulent flow, the cavitation and a collision have not been clarified enough. In this research, the size of gap is first calculated from the theoretical equation assumed to be laminar flow, based on the Reynolds number of the gap flow. Next, the pressure, the flow velocity, shearing stress, etc. are calculated. Then, the emulsification mechanism of each part of the valve is clarified by expressing the droplet size as a function of the gap size, the shearing stress and the exit velocity.

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This study investigated the use of a coaxial dielectric barrier discharge plasma actuator at a nozzle exit for jet diffusion control. In order to achieve enhanced mixing of the primary jet flow, the influence of the input voltage and frequency to the plasma actuator was examined. In the case of continuous operating, the secondary flow by the induced flow using coaxial plasma actuator is able to adjust the velocity gradient of the free shear layer near the jet nozzle. Intermittent control using the plasma actuator was also attempted by varying the driving frequency and the duty ratio. Based on the results of a PIV analysis, the optimum conditions for jet diffusion control were found to be a driving frequency that matched the preferred frequency and a duty ratio at 50%.

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Instantaneous velocity and reactive concentrations are simultaneously measured in a planar liquid jet with a secondorder chemical reaction (A+B→R) by combining an I-type hot film probe with an optical fiber probe based on the light absorption spectrometry. Conditional statistics conditioned on the mixture fraction ξ are investigated experimentally. The results show that the reactive concentrations strongly depend on ξ . It is also shown that the conditional mean concentration is close to the concentration at the frozen limit in the upstream region of the jet, and in the downstream direction, the conditional mean concentration becomes close to the concentration at the equilibrium limit because of the reaction progress. The rms value of reactive concentration fluctuation is small compared with the conditional mean concentration. In the conditional moment closure methods, the conditional mean reaction rate is often approximated by using the conditional mean concentration of reactant species. The results show that the conditional mean reaction rate is well approximated by using the product of conditional mean concentrations of reactant species A and B. It is found that the conditional statistics measured in the downstream region is little dependent on the lateral position of the jet flow.

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Conditional scalar dissipation rate <N | ξ = η> conditioned on a mixture fraction ξ and mean scalar dissipation rate <N> in a planar liquid jet are experimentally investigated. Streamwise velocity and reactive concentrations are simultaneously measured in the planar liquid jet with a second-order chemical reaction A+B→R. <N | η> on the jet centerline is obtained from a conditional moment closure (CMC) equation and measured conditional mean values. To calculate <N | η>, we derive the equations which represent conditional mean concentrations by assuming that the ratio of the conditional mean concentration of product R and the conditional mean reaction rate does not depend on the mixture fraction. The conditional dissipation rate is obtained from the budget of CMC equation. The results show that <N | η> becomes small in the downstream direction. It is also shown that the profiles of <N | η> change in the downstream direction; in the downstream region, <N | η> has a local minimum value at η ≈ ξ_S, where ξ_S is the stoichiometric ratio in mixture. <N> can be obtained from <N | η> and the probability density functions of mixture fraction. It is observed that <N> on the jet centerline decays in the downstream (x) direction as x^-2.9, which is close to the -3 power expected from scaling arguments.

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The objective of this study is to investigate the unsteady aerodynamic response of road vehicles subjected to gusty crosswind, with the special focus on its shape dependence. Large-eddy simulation was used to predict the transient aerodynamic forces and surface pressure distributions acting on the vehicles and transient and three dimensional flow structures were extracted to explain the mechanisms of unsteady aerodynamics. The numerical method adopted was first validated in the stationary case by comparing its results with the wind tunnel data. Then it was applied to the gusty crosswind cases to investigate the dependence of upper and under body geometry separately. For the upper body dependence, sedan type and hatchback type vehicles were compared. On the other hand, for the under body dependence, the sedan type vehicles with flat or complicated under body geometry were confronted. In both cases, overshooting of yawing moment after the vehicle rushing into crosswind region was used to evaluate the crosswind stability. The results of the upper body dependence indicated that the hatchback type vehicle has better crosswind stability than the sedan type vehicle. It was confirmed that the rear pillar vortex at the windward with respect to the crosswind contributed to the difference of stability. Concerning the dependence of under body geometry, the complicated underbody showed better crosswind stability than the flat underbody. Its stability mechanism of the complicated underbody was explained by the difference of the side flow originated from the rear tire house.

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The laminar-turbulent transition of a mixing layer induced by oscillating flat plates at the exit of a two-dimensional nozzle was experimentally investigated. The mixing layer was formed between the jet, which issued from the nozzle, and the surrounding quiescent fluid. The plates oscillated vertically in relation to the jet. The oscillation frequency was two orders of magnitude smaller than the fundamental frequency of the fluctuating velocity. The oscillating amplitude was double that of a previous report. The oscillating frequency was pseudo-steady and the same as in the previous report, at 5 Hz, and unsteady at 15 Hz. Mean and fluctuating velocity components in the streamwise and normal directions were measured by hot-wire anemometers. As the flow proceeds downstream, the mixing layer entrains the surrounding quiescent fluid. This entrainment is affected by the oscillating frequency rather than the oscillating amplitude. The variation of the streamwise velocity with the oscillating phase is much affected by the oscillating amplitude rather than the oscillating frequency. On the other hand, the variation of the normal velocity is affected by both oscillating amplitude and frequency. For an irregularly fluctuating velocity, a linear region where the velocity grows exponentially first exists. The spatial growth rate in this region is the same between the streamwise and normal components, and does not differ with various oscillating amplitudes and frequencies.

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When a train enters a tunnel at high speed, an impulsive pressure wave, called a micro-pressure wave, is radiated from a tunnel exit portal. Because it is one of the important wayside environmental problems in high-speed railways, many studies about its countermeasures have been conducted. The principal countermeasure applied to the Shinkansen on the ground side is a tunnel entrance hood. The necessary length of the tunnel entrance hood increases with the increase of a train velocity, and some of them installed in recent years have over 40 m length. The reduction rate of micro-pressure wave by extending the hood length decreases in case the hood length is long. In this paper a new countermeasure to install a tunnel exit hood to reduce the micro-pressure wave has been proposed. While the tunnel entrance hood is installed at tunnel entrance portal, the tunnel exit hood is installed at tunnel exit portal from which the micro-pressure wave is radiated. The tunnel exit hood has an inside partition which divides the inside of the hood into two parts in the vicinity of its mouth with the end of one part closed. Its reduction rate of the micro-pressure wave has been estimated by an acoustic analysis and verified by model experiments.

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A linear cascade wind tunnel was developed to verify starting characteristics of supersonic inflow and outflow turbine cascade. Under the present near sonic conditions, the wind tunnel in itself is susceptible to become unstarted due to the blockage effect of the wind tunnel wall boundary layer. Hence, the present wind tunnel has special bypass flow passages, which were properly designed so as to remove the boundary layer without affecting the cascade flows. In addition, supersonic cascade flows may be affected by shock reflection stemming from the wind tunnel wall surface. Numerical simulations indicated that it is impossible to remove shock reflection just by sucking flows through a perforated wall surface if the incident shock wave is strong. In the present study, the wall surface was shaped wavy according to the flow turning induced by the incident shock wave, which shape was determined from the blade wake line predicted by numerical simulation of infinite linear cascade. The designed wind tunnel and non-reflective wall shapes were actually tested in the experiment, and shock patterns were visualized using Schlieren techniques. Test results indicated that the tested turbine cascade can be started as originally planned, and that shock reflection on the wind tunnel wall surface was clearly attenuated. The design methodology of supersonic turbine blade shape is confirmed to be valid regarding the starting characteristics at the designed inlet Mach number. Moreover, the wavy porous wall with suction is found to be effective to give the adequate cancellation of the reflected shock waves.

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Lift and drag of a symmetric airfoil with miniature electromagnetic actuators have been measured in the low Reynolds number region from 3 × 10⁴ to 1× 10⁵. It was found that the coefficient of the maximum lift increased as the Reynolds number was increased. The actuation made the maximum lift larger than that in the no-actuation case for each Reynolds number, although its effectiveness was the largest at the lowest Reynolds number of 3× 10⁴ and became smaller as the Reynolds number was increased. Even in the case of the wind speed decrease, it was demonstrated that the actuation was effective to avoid the stall. Feedback control using increase/decrease of angle of attack was also effective to maintain the high lift in the case of the wind speed decrease and the additional feedback operation of actuators worked well to suppress the abrupt decrease of the lift.

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In order to increase the capacity of renewable energy in power systems, it is necessary to reduce power fluctuations. In this paper, the potential of gas engines (GEs) is evaluated by means of dynamic simulation in hybrid power systems consist of GEs and photovoltaic cells (PV) supply power to a large grid. First, basic characteristics of gas engines were investigated for load changes. The small gas engine, its maximum output is 9.9kW, shows quicker response of output and lower generating efficiency than the gas engine of 350kW output. The load response of both engines is influenced by the amplitude and the frequency of the output demand, and not by the bias load. Next, the simulations were implemented using the real power profile of PV. As a result of simulations, 9.9 kW GE is very useful to compensate PV power fluctuation because of its quick response for the load change. The efficient system to use GEs to achieve both the suppression of the PV's power fluctuation and the higher efficiency of the system is also discussed. By combining a larger scale GE with small scale GEs, the system to control preferentially the small GEs shows higher system efficiency at the same output response condition.

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Molecular dynamics (MD) simulations are performed to study the liquid-vapor interface structure of a group of carbon chain molecules: butane (C₄H₁₀), octane (C₈H₁₈) and dodecane (C₁₂H₂₆) in this paper. The effects of the chain length and temperature on the liquid-vapor interface structure, molecular evaporation/ condensation behavior and the orientation of the liquid-vapor interfacial molecules in equilibrium systems are investigated. It is found that the condensation/ evaporation coefficient of carbon chain molecules primarily depends on the translational energy and the surface temperature similar to simple molecules like argon and water. The MD data of carbon chain molecules agree well with the theoretical expression based on the transition state theory. Also, it is found that the chain ordering at the interface depends on the molecular structure but there's less effect on the condensation/ evaporation behavior at liquid-vapor interface. We conclude that the condensation/ evaporation coefficient can be predicted by the translational length ratio of liquid to vapor in general even for the chain molecules.

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The objective of this study is to understand the effect of cavitation inside the injection nozzle on spray atomization for various nozzle geometries and injection conditions. In this paper, it was focused on the influence of impulsive acceleration derived from cavitation phenomenon on liquid jet ejected from test nozzle, which was magnified 25 times based on actual nozzle size and made of acrylic for internal flow visualization. The result from this study represents that the energy spectrum of impulsive acceleration with low frequency becomes large with increase in injection pressure, and it has relationship with surface fluctuation frequency of liquid jet ejected from nozzle exit. On the other hand, it looks no distinguished difference in cavitation length and width of liquid jet with increase in dissolved air concentration in test liquid under the same injection pressure condition, whereas the energy spectrum peak appears at different frequency range among each injection or dissolved air concentration. Therefore, it concludes that the impulsive acceleration energy by cavitation bubble collapse inside the nozzle hole has less effect on width of liquid jet.

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This study investigated the characteristics of the HCCI combustion process in detail by means of in-cylinder visualization of the entire bore area and ultraviolet absorption spectroscopic measurement in the combustion chamber. Special attention was focused on the influence of the equivalence ratio and ignition timing on the degree of local dispersion of autoignition and resultant rapid combustion. The results made clear the relationship between the production/consumption of formaldehyde (HCHO) in the autoignition process and flame development behavior in the combustion chamber. Additionally, it was found that changes in the equivalence ratio and/or ignition timing significantly influenced the degree of local dispersion of the autoignited flame in the combustion chamber. As a result, some cases showed rapid combustion accompanied by in-cylinder pressure oscillations.

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Thermal power plants are the biggest source of global warming because they emit huge amount of CO₂. CCS (Carbon dioxide Capture & Storage) system that separates CO₂ from boiler flue gas by using CO₂ capture solvent is expected for remarkable reduction of CO₂ emission from thermal power plants. This paper describes chemical absorption method of CCS for thermal power systems, especially the results of our research and development in refinement of amine solvent for CO₂ capture using ion exchange treatment. Sulfur oxides such as SO₄ and nitrogen oxides such as NO₃^- are contained in boiler flue gas as impurities. These impurities block the adsorption of CO₂ and cause the significant performance degradation of CCS system. Adsorption and desorption behaviors of SO₄^2- and NO₃^- by ion exchange resin are studied here in terms of small scale experiment and numerical analysis. The obtained results explain that two types of impurities such as SO₄^2- and NO₃^- , in which SO₄^2- has larger adsorption energy onto ion exchange resin than NO₃^- , show the temporal excess of NO₃ concentration in amine solvent after ion exchange treatment. It is concluded that knowledge acquired here can be extended for design of ion exchange resin tower for boiler flue gas of CCS plant operation.

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In this study, in-cylinder flow has been measured using high speed PIV to investigate turbulent characteristics of in-cylinder flow and to give a guiding principle for optimization of intake port and combustion chamber for down sized boosted engine. To clarify turbulence characteristics which will affect combustion process in engines, decomposition method of turbulence component from instantaneous velocity are investigated. Since velocity spectrum in 1 cycle from intake to compression stroke has a specific frequency where slope of the spectrum changes, a time filtering method for turbulence decomposition is proposed using this specific frequency as a cut-off. A characteristic of turbulent kinetic energy extracted by the proposed method well represents the expected flow characteristics at each test condition and shows good correlation with combustion characteristics such as burning speed and geometry of flame front. The obtain results show that turbulent intensity is high at a vortex center of tumble flow, which suggests that a control of tumble flow was very important in design of a boosted engine.

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Styrene-butadiene rubber (SBR) and natural rubber (NR) blend with 30 mm thickness was press cured in a metal mold by heat conduction. Peroxide and D-nitrosopentamethylenetetramine (DTP) were used as the curing and blowing agents, respectively. The heating surface temperatures of 413 K and 423 K were adopted and heating time was ranged from 180 minutes to 480 minutes in nine steps in order to study the effects of heating conditions on the relation between the curing and blowing characteristics. The other side of the rubber was set to be adiabatic condition. Typical temperature field of one-dimensional, transient heat conduction was observed in the rubber. The degree of cure ε changed depending on the heating conditions and the distance from the heating surface, showing lower values for lower heating wall temperature with increasing distance from the heating surface. Observation studies for the foaming characteristics showed that the cell structure changed depending on both the distance from the heating surface and the heating conditions, and two extreme cell structure, open-cell foam and closed-cell foam, were clearly observed. Results of the image analyses of the cell structure can be well related to the degree of cure. The open-cell foam was found in the region ε < 0.05, the closed-cell foam in the region 0.14 < ε and the two types of cells coexisted in the region 0.05 < ε < 0.14.

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This paper investigates water transport phenomena in PEM (Polymer Electrolyte Membrane) electrolysis cell. Experimental result showed that the cell voltage is less affected by the concentration overpotential even at quite high current densities, although significant amount of produced gas is observed in the water flow channels. Impedance measurement indicated that water content in the membrane increases with an increase in current density. The water flux measured at the cathode exit was almost identical to the osmotic flux in the membrane with saturated water content. In order to discuss the mechanism of the enough water-supply under the high current density conditions, numerical analysis was conducted on the water transport in the anode catalyst layer and the membrane. The result showed that the order of the water hydration rate into Nafion ionomer is greater than 1×10^-4 m/s, and sufficient amount of water is supplied from pores in the catalyst layer to the ionomer surrounding catalyst particles at the anode side. This water supply mechanism results in the membrane water-content close to the saturated state, and the water in the membrane is mainly transported by osmotic force. It was also shown that water content in the membrane at the cathode boundary has little influence on the water flux and overall water distribution through the membrane.

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Effect of engine operating conditions on nanostructure and oxidation reactivity of soot particles from diesel engine was investigated experimentally. The soot nanostructure, i.e., the graphitic crystallite size and the amorphous carbon content in the soot particles, was characterized by Raman spectroscopy. Oxidation reactivity of soot was evaluated by temperature-programmed oxidation (TPO). The soot Raman spectra showed that the size of graphitic crystallite in the soot increases with increasing exhaust temperature resulting from the increase of the engine load. In addition, the graphitic crystallite size of soot obtained during lower engine speed was slightly larger than that of higher engine speed of same exhaust temperature. The results of TPO indicated that the oxidation reactivity of soot decreases with the increase of graphitic crystallite size.

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This paper presents a numerical solution to multi-objective shape optimization problems of steady heat-convection fields. In previous study, it has been dealt with a shape optimization problem for total dissipated energy minimization in the domain of a viscous flow field and a shape determination problem of temperature distribution prescribed problem in sub-domains of heat-convection fields. In this study, a multi-objective shape optimization problem using normalized objective functional is formulated for the total dissipated energy minimization problem and the temperature distribution prescribed problem in steady heat-convection fields. In addition, another multi-objective shape optimization problem is formulated for the temperature distribution prescribed problem, while the total dissipated energy is constrained to less than a desired value, in the steady forced heat-convection fields. Shape gradients of these multi-objective shape optimization problems are derived theoretically using the Lagrange multiplier method, adjoint variable method, and the formulae of the material derivative. Reshaping is carried out by the traction method proposed as an approach to solving shape optimization problems. The validity of proposed method is confirmed by results of 2D numerical analysis.

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We have developed a novel nanoscale patterning method of self-assembled monolayer (SAM) using near-field light. This method utilizes the thermal desorption of constituent molecules of a SAM (e.g. the desorption temperature of Octadecanethiol on Au is 130～230 °C) through the irradiation with near-field light, which can make noncontact and noncontaminating patterning of the SAM at nanoscale. In this paper, the near-field photothermal effect is numerically analyzed by the finite difference time domain (FDTD) method, and the electromagnetic field intensity and temperature distributions are estimated. The sample consists of Au thin film as a bonding layer with thiolated molecules of SAM, Ti thin film as an adhesion layer for Au, and SiO₂ substrate. In the analysis, the shape of the near-field optical fiber probe and the thickness of the thin film layer are considered. In the case of the thick Au layer with a double-tapered near-field optical fiber probe, the temperature of the fiber-tip becomes higher than that of Au surface. The strong heating of the probe tip causes a fatal damage of the coating metal of the fiber, therefore it is difficult to couple the high intensity laser into the near-field optical fiber probe in order to reach the desorption temperature. On the other hand, the desorption temperature can be achieved with the 10 nm-thick Au thin film. Moreover, in order to gain high optical intensity enhancements, the triple-tapered near-field optical fiber probe is utilized. Our simulations confirm extremely high temperature distribution on the sample surface by using the triple-tapered near-field optical fiber probe with 10 nm-thick Au thin film layer on 50 nm-thick Ti membrane.

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This paper describes a novel method for estimating the thermal conductivity of soft materials and liquids using a thermophysical handy tester. A thermophysical handy tester utilizing a point-contact method is a fast, non-invasive and in-situ device for measuring the thermophysical properties of a material. This device has been applied to various industrial materials for deterioration diagnosis and quality inspection. However, it cannot be applied to soft or liquid materials precisely. In this study, an inverse analysis of this device was conducted to make it applicable to the measurement of the thermophysical properties of these materials. In the proposed inverse analysis, a real coded genetic algorithm (GA) was used to minimize the objective function. First, a calibration experiment of the device was conducted by using agar-gelled water (0.5 wt%) to determine the apparatus constant. Then, this method was validated by measuring the thermal conductivity of some materials such as glycerol and ethanol. It was found that, the estimated thermal conductivities show good agreement with the reference values. Moreover, estimations of thermal conductivities of various materials including biological materials such as fat and muscle of pig were carried out, and reasonable values could be obtained by a proposed method in this study. However, it was revealed that there were the upper and lower limit in the measurable range which is 0.14 - 1.3 W/(m·K). Thus, a proposed method has a possibility to be effective for the measurement of thermal conductivity of the biological tissue, because the range of that is generally 0.2 - 0.6 W/(m·K).

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Carbon capture and sequestration (CCS) is part of the global challenge to mitigating global warming and climate change. Geological sequestration of carbon dioxide (CO₂) is an immediately available and technologically feasible method for achieving a substantial reduction in carbon dioxide emissions into the atmosphere. Because injected CO₂ migrates upward in an aquifer owing to the buoyancy force, a highly impermeable layer is generally employed to prevent CO₂ leakage from the storage reservoirs. For these reasons, assessment of the storage site, leakage risks, and storage costs are one of the main issues in CO₂ geological sequestration. The intent of the present study is to clarify the fundamental mechanism of buoyancy driven CO₂ in a porous media. The behaviour of liquid CO₂ in water-saturated silica packed bed was observed using high spatial resolution X-ray computed tomography. As the result, CO₂ migration in porous media was visualized with 20 μm resolution, and it was found that the CO₂ migration speed was mostly dominated not by the viscous resistance of CO₂ itself but by that of the surrounding water.

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Natural convection heat transfer from upward-facing horizontal heated surface which a heated cylindrical pipe is placed above is estimated experimentally. The purpose of this study is to determine the relationships of the heat transfer from the horizontal heater to the flow characteristics around the heated cylinder. The parameters considered were the distance of between the heaters, the heat flux and the aspect ratio of the heated cylinder. The results showed that flow characteristics had three distinctive patterns: non flow reversal, flow reversal occurred only in the heated cylinder and reached the horizontal heater. The necessary conditions determined the flow field were discussed. Heat transfer from the horizontal heater was enhanced by placing the heated cylinder above. In the case of no flow reversal and flow reversal occurred in the heated cylinder, Nusselt number increased with increasing the modified Rayleigh number. On the other hand, in flow reversal to the horizontal heater, they decreased generally with increasing that.

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From the viewpoint of safety design of nuclear reactor and an economic terms, It is important to clear the mechanism of post boiling transition heat transfer and to estimate correctly the fuel rod wall temperature. So, in this research, we proposed a calculation model of post boiling transition heat transfer and developed a method to predict the axial variation of the fuel rod wall temperature. Furthermore, we evaluated the prediction accuracy and validity of this prediction method by comparing the prediction results with experimental data for a circular tube measured by Bennett et al⁽¹⁾ under the actual BWR's operating conditions. From the results, it was concluded that under high pressure (7MPa) and for a wide range of conditions, the method developed in this research was able to predict accurately.

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In this study, a renewal planning problem of energy supply system is formulated as a large scale mixed-integer linear programming problem, in which the objective function to the minimized is the average value of annual total cost during system's evaluation period. By adopting the programming language AMPL and CPLEX solver, a numerical study is carried out for a hospital, where electrical(e.g., heat pump) and gas(e.g., gas engine cogeneration) systems are compared together with arbitrary combination one, which is composed of electrical and gas driven pieces of equipment, by focusing particularly on the influence of initial system's difference. The main results obtained are as follows: (a) If the initial system is gas one, it is better to renew it to the electrical one as soon as possible due to relatively low energy efficiency of gas utilizing pieces of equipment, the high price of gas input energy and so on. (b) If the initial system is electrical one, the optimal renewal year becomes relatively later year, because it is economically better to use the initially installed high efficiency system as long as possible. (c) Theoretically, the arbitrary combination system is of course the best renewal one. However, there is no economic difference between the arbitrary combination system and the electrical one.

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The melting behavior of a rotating ice cylinder inside a cylindrical cavity containing calcium chloride aqueous solution was investigated experimentally. The cylindrical cavity was inclined at prescribed angles. We visualized the behavior of the melted ice using a shadow graph technique to elucidate the changes in the melting mass fraction from the ice cylinder resulting from variations in the cylinder rotation speed and the cavity inclination angle. Melting behavior depends strongly on the inclination angle of the cylindrical cavity. Given a large angle of inclination, the ice cylinder mass melting is inhibited by rotation. The melting front is smooth despite the rotation. For a large angle of inclination, observations revealed that the ice cylinder and melted ice rotate together because of viscous forces. A low concentration gradient is thereby created near the melting front, reducing the mass of melting ice and producing a smooth melting front.

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