The hybrid carbon/glass composite rod (the hybrid composite rod), which consisted of a CFRP rod and a 16-braided GFRP shell of the core-sheath type, have been developing. In order to apply the hybrid composite rod for infrastructure use, its reliability should be ensured with respect to its effects under various environmental loads. In this study, the uniaxial compression test, which disassembled it as a CFRP rod, a GFRP shell and a hybrid composite rod, respectively, was carried out using a tensile/compression testing machine. The mechanical failure characteristic for the hybrid composite rod, which was subjected to an uniaxial compressive load, was clarified by comparing with the strain-stress curves.

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The hybrid carbon/glass fiber composite rod consist of CFRP and GFRP is attractive for structural applications because of their high specific modulus and strength as a substitute for steels. In order to evaluate the interfacial mechanical properties between CFRP and GFRP bundles the fiber push out test has been examined by using different sample thickness under the constant displacement mode. The debonding process and shear sliding behavior at the CFRP/GFRP interface were revealed by load displacement curve during the push out test.

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Much attention has recently been given to poly(lactic acid) (PLA) because it is degraded to nontoxic lactic acid through non-enzymatic hydrolytic degradation in the body. As one of the methods to improve mechanical properties of PLA, orientation of molecular chains by drawing has been investigated. In this study, PLA screws were made of drawn PLA rod to obtain high mechanical properties. Immersion in phosphate buffered solution was conducted to forecast mechanical properties of screw which inserted in the body. Weight measurement during the immersion suggested that degradation ratio of drawn screw is slower than undrawn screw. Shear test on screw after immersion showed that stiffness and strength of screw decrease by the immersion. Shear strength of screw increased by drawing and the maximum strength of 110 MPa was achieved at extrusion ratio 2. Shear strengths after immersion were 80 MPa at extrusion ratio 2 or more, while was 60 MPa at extrusion ratio 1. The result showed that the increase in shear strength by drawing is maintained after immersion.

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Halloysite is a naturally occurring aluminosilicate in the form of nanotubes, also known as halloysite nanotube (HNTs). This has been focused as a functionally effective material in order to mechanical strengthening by restrictive matrix dislocation movement. Especially, there are studies showing that adding HNTs to plastic improves tensile strength, impact resistance, fire retardancy and gives the added advantage of improved cycling time in production by injection molding. In the current study, we established the optimal dispersion condition of HNTs using ultrasonication, and analyzed the impact properties of nanocomposites based on HNTs and unsaturated polyester resin (UPR). Also the sructural changes of HNTs by heat treating at various temperatures was evaluated. The ultrasonic homogenization is used in the production of nano-size materials, dispersions and emulsions, because of the potential in the deagglomeration. Additionally, the reinforcement effect of HNTs was studied as well.

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Carbon fiber reinforced thermoplastics (CFRTP), which is expected to reduce the weight of transportations and stainless steel (SUS304) were joined in the form of lap joint by a semiconductor laser (3kW, CW(continuous wave), 0.8-1.2m/min) using insert materials of thermoplastic elastomer sheet. When the irradiation speed is 1.0m/min, the shear strength was the highest showing cohesive failure at the joining area. While, 0.8m/min and 1.2 m/min specimens were lower values than 1.0m/min specimens showing the interfacial failure. The fatigue strength was very similar results to the tensile shear strength. These laser-joint specimens were lower shear/fatigue strength than adhesive-joint specimens. From the results of thermo-elastic stress analysis using the thermography, the stress concentration was observed at the joining area just before the fatigue failure. From the characterizing energy dissipation and degradation evaluation, the 1.0m/min laser-joint specimens showed higher value than the adhesive joint specimens during fatigue tests. It can be assumed that the laser-joint specimen accelerated the process of failure as compared with the adhesive-joint specimen.

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This study aims to reveal the heating behavior of CFRTP composites by induction heating method. The material used is UD-CF/PPS and woven CF/PPS laminates. The effects of geometry of coils, coil distance, heating time and the carbon fiber reinforcement on heating behavior of CFRTP composites in induction heating were investigated. The experimental results revealed that the surface temperature of UD-CF/PPS and woven-CF/PPS laminates was increased with increasing the heating time. Moreover, the surface temperature was increased with decreased the coil distance remarkably.

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Cross-ply carbon fiber reinforced plastics (CFRP), which is expected to reduce the weight of transportations, was cut by a CW (continuous wave) fiber laser (λ=1.06μm, 2.0kW or 3.3kW) and machining with milling. Although the high-power laser cutting processes make it possible to improve cutting rate of CFRP, the laser-cut specimens clearly showed a thermal damage with a heat-affected zone (HAZ) identified by a micro X-ray CT analysis and infrared thermography. These specimens were lower tensile strength and fatigue strength than milling-cut specimens. In laser-cut specimens, specimens cut by the 2.0 kW fiber laser exhibited the lowest strength of all processes because of large HAZ extension. While, the 3.3 kW CW fiber laser (6 m/min), which is the highest cutting speed, was minimized the HAZ extension. It could be resulted of preventing the degradation and reduction of strength.

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This paper presents machining quality of circular piercing hole produced by punch press in CFRP laminates under low-velocity impact load. A piercing hole was produced by using a punch with flat surface under low-velocity impact load and quasi-static load. After piercing process, damages and burrs on the surface and cross sections of the specimen were microscopically observed. Internal damages were then observed using X-ray radiography. In addition, roundness of a piercing hole was examined using three displacement diagrams. It was proved from X-ray radiography and roundness evaluation of the hole after the piercing process under high impact energy that the least amount of internal damage was generated and the roundness was high compared to that at the piercing process under quasi-static load. It was found that the clearance between the punch and die was one of the most important parameters to amount of internal damage.

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Nowadays, rapid prototyping (RP) technology has gained great interest in manufacturing applications due to its advantages such as simplicity, low cost production, short manufacturing cycle time and increasing competitiveness. However, the physical properties of material is main problem for RP and become an obstacle to the application on industrial. Halloysite nanotube (HNT) has high specific surface area, chemical stability and other characteristics. In this research, we investigate the effect of the addition of HNT in mechanical properties. The specimens were fabricated using photopolymer as matrix materials and HNT as reinforce materials. The surface adhesion were improve by using silane treatment. We proposed the addition of HNT as reinforcement in polymer matrix composites and improved the properties produced by RP. As the result, Compared with neat photopolymer, tensile strength is decreased 21.7% because the HNT had poor interfacial adhesion. Silane treatment of HNT using 3-Aminopropyl triethoxysilane has succeeded to improved tensile strength of lower phr of about 31%.

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It is well known that grafting carbon nanotubes (CNTs) on the reinforced fiber surface modifies fiber/matrix interface adhesion. In this study, the mechanical properties of unidirectional FRP using the CNT-grafted pitch-based carbon fiber were investigated. CNTs were grafted on the pitch-based carbon fiber surface using thermal chemical deposition (TCVD) method at 750℃. First, the single fiber tensile tests were conducted to examine the mechanical properties of the CNT-grafted carbon fibers. From the results, the mechanical properties of the CNT-grafted carbon fiber were decreased compared with as-received fiber. This degradation was caused by an exposure of the carbon fiber surface and a dissolution of iron particles into the carbon fiber surfaces under the high temperature condition of TCVD method. Moreover, static tensile tests were performed in unidirectional CFRP to investigate the mechanical properties of the CNT-grafted unidirectional CFRP. For these tests, specimens with fibers oriented at longitudinal (0°) or transverse (90°) angle from the load direction were prepared. From the results, the mechanical properties of the CNT-grafted unidirectional CFRP were decreased in longitudinal direction compared with as-received CFRP due to the degradation of the mechanical properties in CNT-grafted carbon fibers. On the other hand, it was revealed that the mechanical properties of the CNT-grafted unidirectional CFRP were increased in transverse direction compared with as-received CFRP. This enhancement was mainly due to a relaxation of stress concentration at the edge of carbon fiber by the constitution of CNT/epoxy nanocomposites around the carbon fibers.

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Cellulose nanofiber composites cause less damage to the environment, but poor strength is a major drawback. Therefore we focused on the orientation of nanofibers as a way to strengthen the composite material. By unidirectionally orienting fibers, mechanical properties can be improved as reported in previous studies. This study examined the effect on mechanical properties caused by cellulose nanofibers extension. Specimens consisted of cellulose nanofiber and polyvinyl alcohol. The experimental set-up consisted of a modified vice with aluminum jigs to fix the specimens for extension. Wet specimens were extended several times (1, 5 and 10 times) by 2% strain at every extension cycle. Due to large extension exerted at once broke the specimens, a cyclical extension was carried out instead. As a result, 5 times-extended specimens reached the highest tensile strength and Young's modulus at 157.3 MPa and 18.2 GPa, respectively. Compared to non-extended specimens, tensile strength increased 32% and Young's modulus increased 16%. Consequently, cyclical extension of specimens led to the nanofibers orientation, producing stronger composites without causing fracture.

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In the conventional PVA composites reinforced by cellulose nano fibers (CNF) obtained by film casting, it is considered that resin rich layer is formed because of differences in their densities. This research aims to increase the strength of the composite material by preventing the formation of a resin rich layer using a CNF sheet as a reinforcing material. A method for manufacturing composite materials is proposed introduced where CNF sheet was soaked in PVA solution, dried and hot pressed to fabricate the composite sheet. On top of that, the CNF sheet was directly soaked in PVA solution without being dried after filtration (named as composite A). The tensile strength of conventional PVA/CNF composite was 113 MPa, whereas the tensile strength of composite using CNF sheet was 154 MPa and composite A was 178 MPa. From these results, the high strength of composite material is achieved by using CNF sheet.

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FRPs are widely used in many engineering fields due to their high specific stiffness and specific strength. Nanofibers have 1-1000 nm in diameter and their lengths are 100 times more than the fiber diameters. The nanofibers have superior properties such as a high specific surface area, a nano sized effect and a supramolecular effect. The aim of study is to apply the nanofibers to FRPs in order to improve their mechanical properties. In this study, the nanofibers were generated from PA6 by using an electro spinning apparatus and the PA6 nanofibers were used in the FRPs composed of glass fibers fabrics as the reinforcement and UP as the matrix. In order to confirm the effects of the nanofibers, the tensile tests of GFRP without and with PA6 nanofibers were carried out. As a result, the tensile properties were almost the same.

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Creation of repeatable healing function is one of the most interesting topics in self-healing materials. As a solution of this problem, we aimed to develop a principle to realize repeatable healing using microcapsules with stress-activated channels. In this study, we evaluated the effect of pH of MC preparation environment on membrane thickness of microcapsules prepared by coacervation. Here, pH of MC preparation environment was set as of pH3.5, pH3.4, pH3.3 and pH4.5. Moreover, we observed repeatable leakage behavior of core material from microcapsules prepared by coacervation and removal of glass micro beads as secondary phase. The experiment was carried out at the acetic acid concentration of 40[wt%] and 60[wt%]. As results, the membrane thickness of microcapsules increased with increase of acetic acid concentration. In addition it was confirmed that microcapsules prepared using beads with diameter of 10 μm stope leakage of core material after unloading. These results indicate that the closing function actuated in case of channel diameter of 10 μm.

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This study examines the interlaminar shear strength and self-healing of carbon fiber/epoxy laminates containing graphene oxide. Healing is accomplished by incorporating a microencapsulated healing agent and catalyst within an epoxy matrix. Self-healing is demonstrated on short beam shear specimens and healing efficiency was evaluated by the strain energies of virgin and healed specimens. The damaged area of the specimens was also examined by an optical microscope.

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For many applications, the advanced self-healing plastics that can attain the complete strength recovery are valuable; because these are anticipated to exhibit actively ensure the structural integrity. In the present study, employing the composite consists of continuous aramid fiber having thermal contraction ability and epoxy resin in which microencapsulated dicyclopentadiene (DCPD) as healing agent and Grubbs catalyst are dispersed as typical model of the self-healing plastic attaining complete strength recovery, the exothermal behavior of self-healing reaction and the crack closure due to thermal shrinkage of aramid fibers were discussed.

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Self-healing materials are anticipated to be attractive candidates for wide applications. The most important feature of self-healing materials is to activate the chemical reaction in use. Therefore, self-healing materials cannot be exhibit large advantage compared to ordinary materials without materials design to select adequate chemical reaction for the service condition. Furthermore, the present author proposes the selection of the adequate chemical reaction by considering the life time of the application. Especially for the short life time component, the self-healing function should compose the degradation reaction. In the present study, the first attempt to develop the advanced self-healing ceramics for short life time application will be introduced.

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In this study, we develop the constitutive model to analyse the self-healing ceramic materials within the framework of FEM. The isotropic damage and self-healing constitutive model for ceramic materials can describe not only the damage process under a certain boundary condition, but also the self-healing process under arbitarary high-temperature and oxygen pressure condition. The damage process is formulated based on the fracture mechanics, while the self-healing process is formulated based on the kinetic model of self-healing time and velocity. We then apply the proposed model to analyses of alumina/SiC nanocomposites.

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The self-healing fiber-reinforced ceramics (shFRC) is a new functional material. When a crack propagates in this material, self-healing occurs due to high-temperature oxidation. Then, the strength of the material recovers to its initial state because the crack is re-bonded. However, to effectively realize this self-healing function, crack bifurcation phenomena have to be controlled. The strength of shFRC is suddenly decreased if the fibers are broken by crack propagation. Therefore, the optimal structural design, in which the crack is induced in the interface of the fiber, is one of the key factors for developing shFRC. In this study, we investigated the crack propagation using the Finite Element Analysis (FEA). Then, we introduced a cohesive-zone model of the matrix, fiber, and the interface to express crack propagation. Using FEA, we analyzed optimized condition with respect to the composite ratio under varying dimensions of the matrix, fiber and non-oxide layers, and energy release rates.

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Interfacial fracture toughness is an important property for layered materials. However, the evaluation technique for the toughness is generally difficult. Vickers indentation test is easy, and can provide the fracture toughness using the length of a generated crack and the indentation load. In this study, we proposed sharp indentation test for fracture toughness of multilayered material with high adhesive. The possibility was experimentally confirmed using a TBC system specimen. Following results were obtained: The sharp indenter can generate a longer crack rather than using a Vickers indenter, and the generated impression was smaller. As the smaller impression, the size did not over the thickness of intermediate layer. Consequently, the force was accurately applied to the interface. Finally, the obtained toughness was confirmed to be accord with the results of DCB tests.

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In order to evaluate the influence of nano-wires formed at interface on delamination strength of SiC films, the nano-wires were formed on high-speed steel substrates by a plasma discharging method, and the SiC film was deposited on the substrate using a sputtering apparatus. The delamination strength was evaluated using the convex edge indent method, where a diamond indenter was indented to the specimen with convex edge using a nano-indenter. The result showed that abrupt increment of the displacement of the indenter occurred at the film delamination. The interfacial fracture toughness of the specimen with the nano-wires was around three times higher than that without the nano-wires. The interfacial fracture toughness decreased with increasing normalized base area of the nano-wires due to cracking of the film.

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In this study, interfacial feature and bonding strength of ultrasonic bonded Al-Cu joints was investigated. A pure aluminum A1050-H24 and an oxygen-free copper C1020 were used. These dimensions were the width of 9mm, the length of 30mm and the thickness of 1mm. Several kinds of Al-Cu joints were produced using an ultrasonic metal bonder with different bonding condition, such as the order of laminating Al and Cu, and the indentation of the horn. The bonding strength by the peer testing, the cross-sectional microstructures and the interfacial features exposed by the chemical treatment were investigated. It was found that the bonding state differs depending on the position at the interface.

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In the present study, singular stress fields in three-dimensional dissimilar material joints are investigated at a vertex and along a free edge (a singular line) of an interface. The conservative integral formulation based on Betti's reciprocal principle is extended for analyzing the intensity of singularity at a point located on the singular line of three-dimensional bi-material joints. Models of difference angles between side surfaces are used to investigate the influence of the angles on the stress singularity characteristics. Finally, relationship between the intensity of singularity at the vertex and that at a point located on the singular line is discussed.

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This paper described the joining phenomena and joint strength of friction welded joint between Ti-6Al-4V and low carbon steel (S15CK) . When the joint was made with a friction pressure of 30MPa, the adjacent region of the weld interface reached to about 1,075 ℃ at a friction time of 8.0s or longer. This joint had the intermetallic compound layer (IMC interlayer) at the weld interface, and the joint efficiency of 100% was not achieved. It was demonstrated that the joint inhibited the generating of the IMC interlayer on the weld interface by increasing friction pressure, because the temperature at the weld interface was able to estimate a propensity to decrease with increasing friction pressure. Then, the joint, which was made with a friction pressure of 120MPa, a friction time of 7.0s or longer, and a forge pressure of 330MPa, had the 100% joint efficiency and it fractured from the S 15CK base metal with no cracking at the weld interface. This joint did not have the IMC interlayer on the weld interface. In conclusion, the joint should be made with the opportune high friction pressure and opportune long friction time for it without IMC interlayer with the high forge pressure for completely joining of the weld interface.

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Dissimilar materials joining between type 304 stainless steel and polycarbonate (PC) was carried out with fiber laser. Local interfacial strength was higher in the center of weld region. Bubbles might be formed in the center of weld region according to the temperature distribution. However, position of the maximum bubble size observed was not always in the center, but was nearby the edge of weld region in case of the joint with lower strength. The bubbles might move with flow of molten PC. It is considered that position of bubbles has significant effect on strength of the joint. Moreover, it is also speculated that distribution of interfacial strength and change in mechanical property of PC due to thermal degradation also can affect strength of the joint as a secondary effect to change crack propagation behavior.

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The use of adhesive has recently been expanding in many fields such as automotive and aircrafts. An adhesively bonded joint, however, has a high stress concentration at the ends of the bond-line and that causes strength reduction. A uniform stress distribution along the overlap is appropriate for improving the load bearing capabilities. As a method to realize the uniform stress distribution, functionally graded adhesive joints have been proposed by a few researchers. The proposed manufacturing method of functionally graded adhesive joints was, however, difficult to control the properties of adhesive such as moduli, elongation and strength. This study presents a novel method to control the properties easier than previous ones. By changing continuously the mixing ratio of two types of adhesive: soft and hard second generation acrylic adhesives (SGA), the adhesive mixture was applied on a substrate. The adhesive layer has graded moduli after the curing at room temperature. In order to evaluate the mechanical properties of the adhesive mixture, bulk specimens were prepared and examined by static tensile tests. Additionally, the hardness distribution of a property graded adhesive layer was measured by the nano-indentation test to confirm the accuracy of the mixing ratio control.

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Singular electric displacement fields occur around the vertex of interface in piezoelectric material joints under loadings. Concentrated electric displacement is useful for engineering and singular electric displacement fields should be further investigated. In the present study, some characteristics of singular electric displacement fields in a piezoelectric material joint are investigated using 3-dimensional finite element analysis. Influences of loading conditions and geometric factors on singular electric displacement fields are discussed.

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Microstructures of laminated foils bonded using an ultrasonic metal bonder were investigated in order to clarify an influence of bonding conditions. Several kinds of specimens, such as laminated Cu foils bonded on a Cu tab sheet, laminated Al foils bonded on an Al tab sheet and so on, were produced with different bonding conditions. The indentation and the frequency of the horn were changed as bonding process parameters. The cross-sectional microstructures of the laminated foils parallel or perpendicular to the vibration direction of the horn were observed using SEM. It was found that microstructural features of the laminated foils were strongly dependent on the conditions of the indentation and the frequency of the horn. The increase of the indentation extended the bonding time and promoted the bonding of laminated foils. On the other hand, the well bonded areas of the laminated foils bonded at a low frequency were larger than that at a higher frequency.

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In this study, friction stir process (FSP) was applied to fabricate composite material between high density polyethylene (HDPE) and bamboo fiber. A new fabricating method to providing reinforcement from inside a FSP tool was proposed. The composite material was fabricated with lower heat input in the new proposed method compared to conventional fabricating method by using a groove. The maximum temperature measured during the FSP process with a new method was lower than the melting temperature of HDPE and also the temperature inducing degradation in mechanical property of bamboo fiber.

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Dynamic properties of particle distribution behaviors in the circulating fluidized bed with rolling motion have been clarified by both Electrical Capacitance Tomography (ECT) experiment and CFD-DEM simulation. A series of experimentals with a cold mode the rolling circulating fluidized bed is performed wihle the rolling amplitude and period varies. As a result, the particle distribution behavior at z'=300mm is dominated by the shear effect which is derived from the inertial forces and gravity in the radial direction of riser. Positive influence of rolling amplitude on the shear effect causes augmentation of particle volume fraction, but particle distribution becomes unstable and heterogeneous. Meanwhile, although the characteristic fluctuation frequency of particle volume fraction is dominated by the rolling period, little effect of the rolling period on the particle distribution behaviors can be recognized due to its little influence on the shear effect.

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The use of Savonius type wind turbines is effective for wind from variable directions as a result of its omnidirectivity. In the past research, the wake structure of Savonius turbine has been researched for enhancing the performance. Also, it has been reported that interaction of flow among multiple Savonius turbines realized extra power generation in particular configurations. As a further advanced approach, twisted Savonius type wind turbines is now ongoing issue while being spread rapidly. However, aerodynamic characterization of the wake structure of a twisted Savonius turbines has not been established yet. The interaction of multiple twisted Savonius turbines by applying the near wake field is one of the possibilities of increasing efficiency. In this study, we focused on the vertical movement of blades of twisted Savonius turbines, and obtained the velocity vector fields on vertical cross section of the wake behind of a twisted Savonius turbine by particle tracking velocimetry (PTV) technique, and interpolated the vector fields by means of Laplace equation rearrangement (LER). As a result, it was revealed that the flow field have vertical component definitely, and flow field itself moves to flow direction with turbine rotating. In addition, vortex shedding was occurred in the vertical cross section wake structure.

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Toward the improvement of performance of the air-cooled generator, design of the generator appropriate to heat removal is important. An air-cooled generator is composed of the pair of coaxial cylinders with the fixed outer cylinder (stator) and rotating inner cylinder (rotor). The present study experimentally and numerically clarifies the flow characteristics in rotating coaxial cylinders simulated a salient-pole rotor within the air-cooled generator. The flow behavior in the slot between the salient-poles was measured via PIV. The velocity fields were obtained by the numerical simulation. In flow visualization, we proposed a transformation method from absolute coordinate to rotational one in order to obtain the velocity fields in rotational coordinate. The vortex structure was observed in the slot on the rotor wall. In the numerical simulation, the same vortex structure as flow visualization was identified, and the numerical simulation was validated by comparing the velocity profiles obtained numerically and those obtained experimentally.

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To understand the flow characteristics around a wing in viscoelastic fluids, velocity vector field of 0.50 wt% polyacrylamide (PAA) solution around a wing was obtained with particle image velocimetry (PIV). According to the velocity vector data, flow separation was vanished in lateral part of wing surface in PAA solution. To identify the mechanism of this phenomenon, streamline, shear rate, and shear strain was derived. And then first normal stress difference and shear stress were estimated by means of Kelvin-Voigt model and Lodge and Meissner formula. According to normal stress difference distribution, on the lateral part of upper surface of wing, first normal stress difference (Ni) was enhanced. First normal stress difference implies the stress balance between stress along streamline direction and stress along normal direction of streamline. Therefore, it fulfills important role in deformation such as stretching and compression. In case of positive Ni, flow element is stretched along streamline direction and compressed along normal direction of streamline. And rebound pressure against the deformation works in opposite direction of this deformation; compressing pressure in streamline direction and stretching pressure in normal direction of streamline. Thereby in this case, flow is suppressed to upper surface of wing by stretching pressure in vertical direction of streamline, which results in vanishment of flow separation.

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We have invented a novel bubble generator with a vented hydrofoil for ship drag reduction. The hydrofoil has an air outlet on the top surface, and small air bubbles are generated by the negative pressure above the hydrofoil as the device moves forward. In order to understand the relationship between the local shear stress and the local projection void fraction under the ship hull, towing tank (100m) experiments using a 4m-long model ship made by transparent acrylic resin were conducted at Hiroshima University. The void imaging data obtained by a high-speed video camera revealed that the characteristics of the entrained bubbles (bubble size, bubble volume flux, etc.) depend on the towing velocity, angle of attack, and the arrangement of the vented hydrofoil. A large amount of air was introduced by this device when the hydrofoil was mounted at the non-inverted position with the angle of attack from 10 to 15 deg. On the other hand, the local drag reduction rate of the inverted hydrofoil setting was higher than that of the non-inverted one.

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The machine perfusion (MP) technique can expand the donor pool for organ transplantation. The MP technique is able to not only supply the organ with nutrition and oxygen continually through the preservation solution but also evaluate the liver viability. However, the perfusion machine that can evaluate liver viability is not yet established. In this study, the new evaluation technique using temperature visualization technique is suggested using porcine donated livers. This technique is visualized temperature distributions using temperature difference between preservation solution and the livers, and the temperature difference distribution in the liver can estimate flow condition in vessels. As a result, the temperature difference distribution in the liver and the transitions of the temperature at each measurement points can indicate the visualization of flow condition in vessels and liver viability at each point before implantation.

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In the field of flow visualization technique, various methods have been employed to practical use until now. The Background Oriented Schlieren (BOS) technique has been proposed as a new flow visualization method. The most significant point of BOS technique is that quantitative measurement can be achieved with simple setup, while conventional schlieren technique is generally used as qualitative measurement. Besides, the BOS technique requires only camera and background, while other quantitative measurements require a lot of optical elements, time and effort for precise measurement. We have been studying the Colored-Grid Background Oriented Schlieren (CGBOS) technique which was improved from BOS technique using random-dot pattern. In the CGBOS technique, two different colors are used for vertical and horizontal stripes, and displacements in both directions can be obtained from one image. We tried acquiring quantitative four-dimensional density distribution by CGBOS technique using high-speed camera. The CGBOS measurements of supersonic cross flow/lateral jet interaction field were carried out in supersonic wind tunnel at JAXA/ISAS.

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The Colored Grid Background Oriented Schlieren (CGBOS) technique is applied to the measurement of the natural convection flow above a candle flame. Twelve digital cameras are employed to realize the simultaneous multi angle observation of the unsteady phenomena. The normal digital cameras are used to construct the multi-angle CGBOS measurement system with low-cost. To realize the three-dimensional (3-D) measurement of unsteady density field with CT (Computed Tomography) technique, simultaneous measurement system is necessary. The prospect of the measurement system is discussed and the measurement results are described.

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This paper introduces a novel method for imaging the temperature fields in water with a small heated sphere. This method is based on the temperature dependence of the absorption coefficient of water at the wavelength of 1150 nm. When a 1 mm diameter steel sphere in water contained in a rectangular glass cell with a light path length of 10 mm was heated inductively by a 760 kHz magnetic field, the absorbance images at this wavelength were acquired by using a near-infrared imaging system. The images showed that the absorbances around the sphere increased, corresponding to the heating power levels, and that a circularly symmetric distribution was formed by thermal conduction in a certain initial period and subsequently upward flow occurred by free convection. To the circularly symmetric distributions, inverse Abel transform was applied, and radial temperature distributions were reconstructed.

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The plenoptic camera provides information about how a scene would look like when viewed from a continuum of possible viewpoints bounded by the main lens aperture. By extracting information about both horizontal and vertical parallax the depth information can be estimated simply with improved reliability than in a binocular stereo system. In this paper, results of depth measurement of some fixed 3D targets and PIV results of particles are presented using "Lytro", a consumer plenoptic camera. An optimized calibration equation for the camera is proposed which is then utilized to perform PIV analysis on particle images taken by the camera.

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In this paper, unsteady forces of wet-steam flows through real steam turbine low pressure final three stages developed by Mitsubishi Heavy Industry are numerically investigated. Compressible Nervier-Stokes equations coupled with nonequilibrium condensation models are simultaneously solved. The SST-model is also employed for evaluating the eddy-viscosity. Time-dependent pressure distributions on three-stage stator-rotor blade surfaces at constant spans are plotted to show the magnitude and the variation of unsteady forces locally. And then, the flow mechanism, how such unsteady forces are generated from the wet-steam flow through the multi-stage blade rows, is predicted.

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In this study, we examined accuracy of the flow simulation over a turbine blade on Cartesian grid using virtual flux method. In the simulation, we used 2-dimensional compressible Navier-Stokes equation for governing equation and set Hodson's linear cascade for the simulation model. For the first stage of this study, Reynolds number is set for Re = 1.0 × 10^4, which is lower than that of the actual flow around the turbine blade. We evaluated accuracy of the flow simulation by comparing pressure coefficient distribution and Mach number distribution on a turbine blade's surface with respect to grid resolution (100 and 200 cells for a chord length). As a result, we got accurate pressure coefficient and Mach number distributions from the flow simulation in the order of Re = 10^4 on Cartesian grid (200 cells for a chord length). However, since the order of Reynolds number of the actual flow around the turbine blade is Re = 10^5〜10^6, higher grid resolution is required to simulate the actual flow field such as boundary layer accurately. To simulate the flow field near the turbine blade, we apply multi-block method to the flow simulation and set higher grid resolution in future work.

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The increase of turbine blade loading is the effective means to improve the perfomance of gas turbine. The increase of turbine blade loading by the increase of blade turning angle can enhance the torque obtained from single stage, and consequently decrease the size and the weight of gas turbine by reducing the numbers of the blades and stages. However, because the increase of turbine blade loading increases the pitchwise pressure gradient in the blade-to-blade passage and also the pressure difference between the pressure and the suction surfaces at blade tip, both of the passage and the tip leakage vortices became stronger. Therefore, in order to develop the practical turbine blade with the high turning angle, it is necessary to clarify the effect of the increase of blade turning angle on the secondary flow behaivor and the loss generation. In the present study, the measurements of the blade surface static pressure and the internal flow field were carried out by using the 5-hole Pitot tube for the ultra-highly loaded turbine cascade (UHLTC) with turning angle of 160 degree. The experimental results clarified that the increase of the size of tip clearance strengthened the tip leakage vortex and moved its starting point at the suction surface of blade tip toward upstream, and consequently increased the associated loss.

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This paper treats three dimensional unsteady CFD simulations of two types of supersonic turbines with different configurations, i.e. a full admission turbine and a partial admission turbine configurations respectively, for a future rocket engine. The CFD results are compared with each other from the point of view of the turbine flow pattern, loss distributions, loss mechanisms and turbine efficiency in order to determine which configuration is preferable. It is found that entropy value at the axial gap is higher in the partial admission turbine stage than that of the full admission turbine stage due to the partial admission losses. However, in the full admission turbine stage, rotor leading edge shock waves cause large separation on the rotor suction surface and large amount of entropy is created. Then, the turbine efficiency in the partial admission stage is higher than that of the full admission stage.

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The numerical simulation of turbulent supercritical water flows is presented. In the present method, the supercritical-fluids simulator is coupled with the building-cube method because of its simplicity and efficiency, and a meshless method is implemented as a wall boundary treatment because of its flexibility and adaptability. The implementation of the SST turbulence model has been accomplished to deal with the turbulent supercritical-fluid flows. The supercritical water jet submerged in a subcritical water environment is simulated, which is a typical process of supercritical-fluid flows in the hydrothermal spallation drilling application. First, turbulence model implementation verification is proposed with the classical case of zero pressure gradient flat plate. Then, the effects of temperature and pressure on the behavior of the supercritical water jets are investigated.

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The most dominant secondary flow generated in an axial turbine cascade is the passage vortex. An enhancement of turbine blade loading by the increase of blade turning angle makes the passage vortex stronger. On the other hand, a flow acceleration by the convergent channel as in a reaction turbine cascade suppresses the development of passage vortex by reducing the boundary layer development on the passage walls. In the present study, flows in the curvature duct, which is considered to be a basic model for the generation of passage vortex, were analyzed numerically in order to examine the influences of the curved angle and the changing rate of channel width on the passage vortex and the associated loss generation. The computed results showed that the increase of curved angle promoted the development of passage vortex, and the increase of changing rate of channel width suppressed the developments of the passage vortex as well as the boundary layer by the reduction of the pressure difference between the inner and the outer walls.

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The present study investigates a periodic wake passing induced boundary layer transition on a flat-plate subjected to favorable and adverse pressure gradients. The aim is to exploit unsteady effects in order to design a turbine blade without increasing the profile loss, as has been achieved for low pressure turbine blade. Detailed boundary layer measurements were conducted using a hot-wire probe. A passage-contouring device was employed to generate on the test model a pressure gradient which is typical to that generated by a turbine blade. A wake generating squirrel cage was used to create periodic wakes in front of the flat plate. It was found that the effect of turbulent spots due to the wake passing was confirmed distributions of raw velocity signals measured at y=0.2mm under the influence of a passage contouring device.

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This paper details experimental and numerical studies on the effectiveness in controlling boundary layer separation with the performance of dimples on a low-pressure turbine airfoil. The profile loss due to boundary layer separation in LPT has a significant contribution to its overall loss, especially in a high stage loading condition. Hence it becomes important to study methods to control the boundary layer separation. A linear cascade test facility is employed to investigate the aerodynamic performance of the airfoil by use of a miniature Pitot probe. LES simulations are also carried out to gain a better understanding of the flow field around the airfoil. The Reynolds number based on the chord length was varied in the range of 40,000 to 170,000 in order to simulate a typical flight condition. It is found that the proposed methods have a capability to reduce the profile loss and result in improvement of cascade performance.

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In this study, we focus on supersonic impulse turbine designed for rocket engine and investigate feature of high efficiency turbine using Computational Fluid Dynamics (CFD) by exploring a design space which in the present study is the distance between the Nozzle and the Rotor (Nozzle-Rotor Gap). Four grids with increasing mesh densities were used for estimating the Grid Convergence Index (GCI) in order to quantify the uncertainty of the numerical results. We calculated five conditions of Nozzle-Rotor Gap which are set to 50%, 75%, 125%, 150% of the reference Nozzle-Rotor Gap. The trend of the influence of the Nozzle-Rotor Gap on T-T efficiency was obtained although the GCI uncertainty analysis showed that the trend falls within the uncertainty range. Hence an addition of another level of grid refinement is preferred in order to ascertain the presence of the trend.

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Needs for low noise turbo machineries have been increased. To extract the pressure fluctuation dominant to the noise, proper orthogonal decomposition (POD) was applied to unsteady computational fluid dynamics (CFD) results of a centrifugal blower in a vacuum cleaner. We extracted a time series of static pressure distribution in the diffuser, applied the POD to these data and compared the results of a measurement. The result was that the first six POD modes made a 99.4% contribution in terms of the L_2 norm. In the scope of this research, the first six modes were revealed to surrogate the pressure fluctuation sufficiently. Also, the data storage was reduced to less than 2.0% of one of the original unsteady results. Next, frequency spectra were obtained by applying discrete Fourier transform (DFT) to the expansion coefficients. The spectra of the expansion coefficients had a peak near whole-number multiples of the BPF. The noise, the frequency of which is BPF, causes the majority of the noise that occurs in the diffuser. Therefore, we found using both the POD and DFT that we could both reduce the dramatic data storage and extract the pressure fluctuation dominant to the noise.

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Supercritical CO_2 has been recognized as an attractive new method for power generation. In this system, Supercritical CO_2 is compressed and heated beyond the critical pressure and temperature. In this study, transonic flows through a compressor cascade are investigated under the supercritical pressure condition by our numerical method. A detached bow shock is found near the leading edge and a normal shock is captured between the blades. The results are compared with those of the atmospheric condition.

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