Fluid noise is what always happens in the windmill. Therefore, the purpose of this study is to analyze the fluid noise induced around horizontal cylinder using numerical simulation. The tubulence models used in the numerical simulation are SST k-ω model，LES (Large Eddy Simulation) model and Dynamic-LES (Dynamic-Large Eddy Simulation) model. The acoustic model is FW-H model. The caluclation target is the cylinder. Characteristics of the fluid noise is revealed by the FFT analysis and wavelet analysis.

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Studies on small HAWTs has been attempted because not only their mechanical performance but also acoustic noise becomes important issue. This paper presents simulation results of the NREL phase VI wind turbine and the MEXICO model wind turbine. The rotor of the NREL Phase VI is horizontal-axis, 2 blades, 10.058m in diameter and 72rpm. And the rotor of the MEXICO model has horizontal-axis and 3 blades, 4.5m in diameter and 424.5rpm. The SST k-ω turbulence model is used in both simulations in the wind speed is 10m/s. The number of volume mesh elements amounts to 6.19 million in the NREL Phase VI, and 7.28 million in the MEXICO model. They show the comparisons of CFD results with experimental results about pressure on a blade. And also they show the aero-acoustic simulation results, especially AM sounds, with the FW-H equation at the receivers based on JIS C 1400-11. The pressure coefficients of NREL simulation results agree with those of the experimental results, and the pressure data on the blade of MEXICO simulation results roughly agree with those of the experimental results. AM sounds of NREL Phase VI have peaks which derive from the BPF and its turbulences, and those of MEXICO have peaks which derive from the BPF. The differences are caused by blade length and rotation speed.

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Microbubbles have various characteristics due to their fine size, and are expected to be applied not only to the field of engineering but also to various fields. As one of these characteristics, it is known that the bubble surface is negatively charged. Therefore, bubble behaviors when the bubble surface was charged are analyzed. In order to investigate how the charge amount on the bubble surface affects the bubble growth and shrinkage behavior, we set up the equation of motion of the bubble wall considering the electrostatic tension of the bubble surface, and numerically analyzed it. The numerical result shows that the shrinkage time of the bubble extends with increasing the charge amount on the bubble surface.

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Wetting behavior of liquid state resin material before curing is an important design factor for component and process designs of resin products. Resin material before curing consists of monomer, filler, etc., and those components affect the wettability of a whole droplet. However, behaviors of them are still unclear and difficult to reveal in experiments. An effective analysis method which covers molecular level interactions and wetting behavior of a droplet is nessesary for material developments. In this study, coarse-grained molecular dynamics (CGMD) simulations are performed, and wetting behaviors of droplets consisting of monomers and fillers are revealed. In the simulations, monomers adhere to a solid surface and spread along that. Fillers also spread, however, some fillers are vertically piled in the droplet. In the simulations performed by the droplets of the small filler ratio, piled fillers decrease and then the whole droplet show the low contact angle. Wetting behavior of a droplet is sucessfully observed by the CGMD simulations.

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It is well known that nylon 6 possesses water absorbability and hygroscopicity, affecting their mechanical properties such as Young's modulus and yield strength. This study aims to investigate the effect of water content on the mechanical property of nylon6 using experiment and molecular dynamics (MD) simulation. First, uni-axial loading and micro indentation test were conducted against nylon sample having different water contents. Here, the water content was changed by heat aging and then we evaluated Young’s modulus and yield strength as a function of water contents. It is found that their mechanical properties strongly change, dependent on the water content. Next, to elucidate the deformation mechanism of nylon 6, molecular dynamics (MD) simulation was conducted. We constructed MD simulation cell for semi-crystalline structure of nylon 6 and water molecular was inserted in the simulation cell. Two models (with and without water content) were constructed, and mechanical loading was applied to this cell. We discussed the deformation mechanism of nylon 6, which is influenced by water content.

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The Tohoku earthquake (March 11, 2011) has made us pay more attention to tsunami disaster than before. One of the most important things in the tsunami is an immediate evacuation from it. While we should conduct a tsunami evacuation drill in order to enhance our decision, it is impossible for us to experience a tsunami directly. For training as many people as possible, especially children and old persons, we have been developing a portable tsunami virtual reality (VR) system using three key technologies; the head-mounted display (HMD), the laptop computer and the tsunami CFD simulation. Our previous studies used the particle-based methods for CFD, because the methods are suitable for such a large deformation of free-surface as Tsunami. However, the particle-based method cannot change the particle size in one simulation, and the front edges of the first wave of the computed Tsunami becomes thicker than those of the real Tsunami. In order to solve the problem, we apply a mesh-based CFD code, ANSYS, for Tsunami simulation. Since the mesh size is easily variable in the mesh-based method, the thin front edges of the first wave of the Tsunami can be simulated.

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Massive damage in the Tohoku earthquake (March 11, 2011) made us more conscious of tsunami disaster. In the case of tsunami, it is important for us to judge the risk and run away from it as soon as possible. For improving the judgment, actual trainings are effective, but we cannot get training in real tsunami unlike earthquake. Earthquake can be experienced in an earthquake simulation vehicle. For training as many people, especially children and old persons, as possible, we have been developing a portable tsunami virtual reality (VR) system using three key technologies; the head-mounted display (HMD), the laptop computer and the tsunami CFD simulation using SPH method. In our Tsunami simulation system, the GPU is used for accelerating the simulation since the target regions are large and require much computing resources. In this study, we have permitted larger-scale simulation by improving the computational efficiency of the SPH code. We have at first reduced the SPH computing time by 1/8 by improving the memory access efficiency in GPU computing. Furthermore, we have also reduced the required memory by expressing wall boundaries with polygons instead of particles. Through such improvements, we can perform such a large-scale simulation as that with 5x10 7 particles within practical computing time.

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Establishment of design method of the macroscopic stress-strain relationship of open cell foam have been investigated because of its complicated microstructures. In this study, a material design method of mechanical behavior of the open cell polyurethane foam using the voxel finite element analysis is proposed to consider microscopic structure and matrix properties. The finite-strain hyperelastic model was applied to matrix of the polyurethane foam. The MooneyRivlin model was adopted for the potential energy function of the hyperelastic model. Microstructures of the open cell polyurethane foam were given by the CT-scanning system. Finite element models constrained by the original microstructural configurations were applied to numerical simulations. The periodic finite element models based on the modified microstructural configurations of which relative density were same as the original models, were applied to the simulation. From the numerical results, design performance of the simulation code for open cell polyurethane foam were performed. The simulation results were reasonably consistent with compression loading test results up to plateau region.

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The implant overdenture has some difference of fixed attachment system. Each system has different characteristics. Now, many dentists decide to use which system based on their experience. So, it is still debatable which systems to use for patient. In this study, two CAD models of the implant overdenture, using the locator and the kugel hook, were made by CAD software. The CAD models of fixture and abutments of the locator and the kugel hook were made by scanning original. The vertical load (100N) was applied on the artificial tooth and the stress distribution was calculated using FEM. When comparing analysis models using locator and using kugel hook, the jawbone of analysis model using locator has high stress level better than the jaw bone of analysis model using kugel hook. Because the kugel hook has clearance between the female and the abutment. In the analysis model using kugel hook, when the vertical load was applied on the artificial tooth, female move along the clearance.

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The focus of this study is to clarify effects of the interface edge shape on bonding strength of ceramic to metal joint. Each silicon nitride to nickel joint plate with arc-shaped free surfaces edge was produced by Electric Discharge machining after bonding process. The dependence of the bonding strength on the edge angle was experimentally clarified in silicon nitride to nickel joint with arc-shaped free surfaces. The result shows that changing the edge angle from right angle improves bonding strength since it decreases residual stress near the interface edge. It also shows that secondary machining, which cuts both edges into optimum geometrical conditions after bonding, can improve bonding strength.

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This study provides an estimation method of surface crack depth of electric conductive Zirconia induced by wire-EDM. The fracture dynamics model was used for this analysis. The crack depth was evaluated experimentally by two different methods. One of them was derived from ground removal amount of the wire-EDMed surfaces fracture strength recovered. The other was derived from the rest of the crack depth and ground amount of the wire-EDMed surface. These estimated values were compared each other to clarify the surface crack depth induced by wire-EDM. The surface crack depth was predicted based on experimental results and the residual stress measured by X-ray analysis each machining condition. It appears effects of wireEDM condition on the crack depth.

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This study provides that effects of interface edge configuration on distributed stresses near the edge of the interface on ceramic to metal joint system based on numerical thermal elastoplastic analysis, using finite element bonded dissimilar models consisting of elastic material as ceramics and elastoplastic one. An elastoplastic model was used in this numerical analysis, assuming silicon nitride/nickel bonded at high temperature condition. Dependence of thermal elastoplasitic behavior on geometrical interface configuration was also clarified numerically by using FEM models with interface edge configurations. Results of the numerical analysis are compared with dependence of bonding strength on the interface edge angle of the silicon nitride to nickel joints system with the same interface shape condition as the analytical models. It is clarified that the improvement mechanism for bonding strength by changing interface edge configuration and relationship between the stress distribution near the edge interface and the bonding strength.

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This paper provides effectiveness of using ECR ion shower device for evaluating fracture toughness of single crystal silicon. Removing the residual stress should be required on CSF method for evaluating the fracture toughness of brittle materials after indentation crack induced. It attempts to clarify the effects by using ECR ion shower devise which can control the removal amount with micro meter order. Fracture toughness of cleavage plane of single crystal silicon was evaluated by CSF method. Effects of removal amount and crack shapes on the fracture toughness were evaluated by using ECR ion shower device. The validity of the fracture toughness value was considered by comparing both results of CSF and IF methods. Dependency of surface removal amount and crack shape on fracture strength and fracture toughness value fracture toughness was clarified.

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This paper provides effects of temperature environment conditions on fracture toughness value of cleavage plane in single crystal silicon based on controlled surface flaw (CSF) method. Evaluating system for four-point bending strength of small specimens under high temperature environment was constructed. This system can provide fracture strength under high temperature condition for the small specimen cut from single crystal silicon wafer. Removing the residual stress on the surface, which indentation crack was introduced, should be required on CSF method. Ion shower was applied for removing the surface. It confirmed that appropriate removal amount of the surface experimentally based on effects of removal amount of surface on the fracture toughness values in room temperature conditions. It experimentally provides that effects of temperature conditions on the fracture toughness of the single crystal silicon based on the above results.

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Bamboo does not break even if it bends greatly due to wind or its own weight. Its mechanical properties are characterized by tapered hollow cylinder, nodes, anisotropic material and functionally graded material. These features are thought to have been obtained by adapting to changes in the environment over the years and optimizing themselves. For this reason, it is very important to clarify these properties. In this study, we will carry out a cantilever test of bamboo, and determine the Young’s modulus distribution using cantilever deflection measurement test and inverse analysis method with axially functionally graded material and taper. Next, we compare the deflection in experiment, theory and finite element method (FEM). We also clarify the validity of identification method of axially functionally graded materials based on deflection of multiple points.

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This study aims to evaluate the interfacial fatigue strength of the surface coatings using Laser Shock Adhesion Test (LASAT). This method uses strong ultrasonic wave induced by repetitive pulsed laser irradiations. For this irradiation, grease layer is foamed on the back surface of substrate and a pulsed laser is irradiated, so that ablation occurs in the grease layer, inducing strong elastic wave. The elastic wave propagates from the back surface of substrate to the coating surface, and tensile stress acts on the coating/substrate interface. In this study, repeated pulsed laser irradiations are conducted to cause the coating delamination. In parallel, the out of plane displacement is measured by using a laser ultrasonic interferometer. The timing of delamination can be detected by the correlation coefficient calculated with a series of the out-of-plane displacement velocity waveform. We evaluate the number of repeated laser irradiation up to coating delamination, so that it may estimate the interfacial fatigue strength. Furthermore, computation of elastic wave propagation is carried out using FDTD (finite difference time domain) to estimate tensile stress developed at the coating film/substrate interface. Based on the above results, the interface fatigue strength is estimated.

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Mechanical characteristics of polymer foam materials are determined by the interaction of microstructure and matrix. In this study, mechanical properties of polymer foam materials were evaluated to consider the influence of microstructure and matrix properties. Tensile tests of three kind of specimens were performed in order to get mechanical properties of matrix. Stress-Strain relationships of the tests were different each other. The Mooney-Rivlin model was adopted for the potential energy function of the matrix. Material parameters were identified by approximating the potential energy function to the tensile loading test results the of solid specimens. Two models containing microscopic structures of polymer foam were obtained from the CT scanning data. These models were applied to FEM analysis. The material parameters obtained from tensile loading test results were introduced to the FEM analysises. The FEM analysis showed different results depend on the matrix properties. In addition, the strain reaching the plateau region were resulted from not only microstructure but also matrix.

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In this study, we developed a fatigue life evaluation technique for multilayer bellows and got the following conclusions. (1) The fatigue life of the multilayer bellows is roughly in agreement with the fatigue life of the single layer bellows which can be evaluated with the best fit curve of stainless steel material. (2) The fatigue life of bellows should be evaluated taking into consideration that the fatigue life decreases due to the high-temperature atmosphere and the initial stress in the actual equipment mounting environment. (3) By deriving the relationship between the initial stress and the allowable stress using the stainless steel best fit curve, it is possible to evaluate the breakage of the bellows in the actual machine mounting environment.

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In a previous study, we had proposed a buckling evaluation method for plate structures, in which the buckling strength is given as the product of the Euler buckling force and buckling coefficient, and the buckling coefficient is obtained from size and material for adjoining plates at both ends of buckling plates. In this paper, we derived a buckling coefficient for adjoining plates under the condition of compressive forces and extended the buckling evaluation method. For confirming the effect of the extended method, a buckling analysis was executed to solve buckling forces for a plate structure. By comparing the buckling forces between the buckling analysis and the proposed methods, it was found that the extended method can predict the buckling force within an error -3.6 % and be more accurate (6.1 %) than the previous method.

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Analysis of near-field spray, that is a core of spray structure, is important because it is essential to understand spray structure detail to improve thermal efficiency of internal combustion engines. The conventional optical equipment, such as LED light source, cannot be used to capture the detailed structure of near-field spray due to its inability to penetrate the spray core and thus the inner structure of the spray cannot be captured. By using a high-intensity and a high-energy X-rays generated by synchrotron X-ray facility, it is possible to capture spray structure detail in a high fuel density area. In this study, X-ray phase-contrast imaging, which can image the interference of X-rays at different density boundary, was used to visualize the structure of gasoline spray with 10MPa of injection pressure and 9, 83kPa of ambient pressure. Furthermore, this study also investigated the spray characteristic in the flash-boiling condition. From the captured X-ray images, the near-field spray observation and radial velocity distribution analysis were performed. As a result, a significant increase of radial velocity in flash boiling spray was confirmed.

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To investigate the choked flow in DME (dimethyl ether) injector nozzle, numerical calculations of two-dimensional steady state multi-phase flow was carried out in the range of injection pressure 30-60 MPa. Numerical results were compared with experimental ones of a previous report to examine validity. The degree of void generation in the nozzle under various differential pressures were investigated using numerical simulations. The results suggested that choke flow occures due to the decrease in effective cross section and the increase in velocity.

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Addition of hydrogen is effective for expanding the lean stability limit to improve the thermal efficiency in internal combustion engines, because hydrogen has high burning velocity. In this study, hydrogen production characteristics of exhaust gas fuel reforming of dimethyl ether (DME) fueled engine was investigated by chemical equilibrium calculation. As a result, DME reforming can produce more hydrogen compared with gasoline reforming, while it has lower energy recovery than gasoline reforming.

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In this study, formation process of deposit adhering on an EGR simulated sample line was investigated using attenuated total reflection-Fourier transform infrared spectrometry (ATR-FTIR). Exhaust gas of a diesel engine passing through diesel particulate filter (DPF) was introduced into the sample line. Time-resolved infrared absorption spectra of the deposit were obtained for 6 hours from the beginning of the experiment including water condensation and evaporation process. Absorption peaks of C=O, C-H, and C=C were observed after condensed water has disappeared, and those absorption peaks increase with increasing the deposition time. The change of the ATR-FTIR spectra was not observed in formation process of the deposit. These findings suggest that EGR deposit were simply formed by condensation or adsorption of hydrocarbons having functional groups such as C=O, C-H, and C=C in exhaust gas.

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In this study, exhaust gas components emitted from spark ignition engine were analyzed using a comprehensive two-dimensional gas chromatograph (GC×GC) with a time-of-flight mass spectrometer (TOFMS). N-hexane and 1-hexene were used as fuels. As a result of the analysis, it was found that reaction products in the exhaust gas were influenced by the molecular structure of the fuel.

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In recent years, new measurement and inspection techniques using infrared camera are being applied in various research and development fields. The advantage of infrared camera is the ability to measure time series two-dimenstional surface temperature distributions without contact. In this report, various special resin materials, which representative infrared transmission is stronger than germanium and the price is low, are selected to devise a new method to obtain the infrared transmission from the theory of thermal radiation by applying an infrared camera at different temperature. Experimented results shows that the transmittance of ITF05, ITF10, PET05, PMMA10 is 45~65 %, 35~5 %, 0~3 %, 0~1 %, respectively. Although the transmittance of these special resin materials are smaller than Ge20, which transmittance for both visible light and infrared light. During the data processing, uncertainty analysis is also applied to analyze the uncertainty of measured transmittance for all materials.

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Decay heat removal system (DHRS) by using the natural circulation without depending on the pump as the mechanical equipment is recognized as one of the most effective methodologies for the sodium-cooled fast reactor from the viewpoint of the safety enhancement. The numerical estimation method which can predict thermal hydraulic phenomena in the natural circulation under the plant cooling process by operating the various DHRSs including the severe accident is nessesarily required. In this paprer, the numerical results of the preliminary analysis for the sodium experiment condition with the apparatus of PLANDTL-2, in which the core and the upper plenum with a dipped-type direct heat exchanger (DHX) were modeled, were discussed, in order to establish an appropriate numerical models for the reactor core including the gap region among the subassemblies and the DHX.

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In order to develop an automatic driving system, it needs to examine the effect of cars in a line on the flow around a car. The related phenomenon is slip stream where the drag force of a car is reduced. The objective of the research is to clarify the drag force on car models in a line arranged linearly at a certain inter-vehicle distance. Therefore, the drag force acting on the models in a wind tunnel was measured by using a load cell. In the experiment, we compared with the effects of attaching or not attaching skirts on a car. Drag force reduction of the following car model was observed only at very short inter-vehicle distances, and the drag force increased when the inter-vehicle distance increased.

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To develop a system that measures the flow rate of several nl/min with 1% uncertainty by acquiring the moving speed of the liquid meniscus in the capillary using image processing, we performed a fundamental verification of the measurement method by creating an image processing program that determines the position of the liquid meniscus in the capillary and calculates the flow rate. We recorded the meniscus moving inside a glass capillary (inner diameter is 2 mm) using a high speed camera and tracked the meniscus by the image processing program we created. Although the meniscus can be tracked, the accuracy of themeniscus position obtained is unclear because the shape of the meniscus is yet to be considered. The major factors of flow rate uncertainty are the time and spatial resolutions of the camera, as well as the uncertainty of the inner diameter of the capillary. When the time resolution is 0.02 second, the spatial resolution is 0.1328 mm, and measurement time is less than 500 seconds, with a capillary of inner diameters of 0.1 to 2 mm, it is impossible to achieve a 10 nl/min flowrate measurement uncertainty of 1% or less. In order to achieve that, it is necessary to improve the spatial resolution of the camera by narrowing the capturing range.

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An air turbine handpiece is a dental abrasive device that rotates at high speed and uses compressed air as the driving force. It is characterized by its small size, light weight, and painless abrading due to its high-speed rotation, but as compared to an electric handpiece driven by a motor, there are problems such as low torque and high noise level. We conducted a CFD analysis and investigated the internal flow which changes as the impeller rotates, and it became clear that the blade phase angle and the torque are closely related. Therefore, in this study, we investigated by experiment and numerical analysis for the purpose of elucidating the turbine performance and the internal flow due to the difference in the number of blades of the dental air turbine.

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The purpose of this investigation is to develop a new quantitative flow visualization technique based on quantum dots (QDs), which can be applied as both the temperature probe and tracer particles. This technique can be applied to hydro-mechanical micro-electro-mechanical-systems (MEMS) system to simultaneously determine instantaneous temperature and velocity distributions in such micro- or small-scale flow field. In this report, the temperature dependency and the emission features of QDs is measured. It is showed that the temperature tendency and the emission features of QDs measurement method and theory for small-scale flow field based on QDs, the temperature distribution inside a Y-shaped micromixer during the mixing process is are mixed with each other at the junction of the micromixer, and the temperature in this region is obtained.

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Heat exchange system with two heat storage containers filled with phase change materials having different melting points were set up and were experimentally investigated to develop a cascaded heat storage system which enables us to use low level thermal energy for an ambient temperature range. We focused on lauric and myristic acids which are some of fatty acids as a heat storage material. These acids are also harmless to the human body. The heat transport mechanisms pertaining to the melting and the solidification processes were analyzed using an appropriate visualization and heat transfer experiment.

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A vertical counter-flow heat exchanger with mist injection is newly designed and made in a vertical double cylinder in order to reuse waste thermal energy discharged from various environment, such as factories, commercial facilities and houses, as effective resources. In the present study, the performance of the prototype is elucidated using a series of parametric heat transfer experiments and flow visualization. Through several kinds of comparative experiments with different flow regimes (falling liquid film, 50 μm of mean-particle-diameter, 500 μm of mean-particle-diameter) at the hot water inlet section of the heat exchanger, it is obvious that the thermal exchange effectiveness (or temperature efficiency) becomes maximum for the case of the finest mist even though the heat exchange flow rate is small at the hot water section of the heat exchanger.

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In the decommissioning of nuclear power plants, the long-term management of radioactive waste of fuel debris is necessary. In the process, hydrogen which is the flammable gas is generated by the decomposition of water by radiation. Therefore, reducing the concentration of hydrogen gas.is important to ensure the safety of the waste storage container. Then, it was considered that the generated hydrogen and the existed oxygen in the container are recombined with the passive autocatalytic recombiner (PAR) installed in the storage container and returned to water. The objective of the present study is to confirm experimentally and numerically the effectiveness of the waste storage container with PAR on reduction of the hydrogen concentration. In addition, the hydrogen behavior in a container with PAR is clarified and then reflected to the design of the optimum container structure.

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A liquid mercury target for high-power pulsed spallation neutron sources is installed in the Materials and Life science experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC). The pressure waves are generated by the rapid thermal expansion of mercury due to the high-intense pulsed-proton beam bombardment. The pressure waves induce cavitation, and the cavitation causes severe erosion damage on the mercury enclosure vessel made of stainless steels. Therefore, the cavitation is a major issue to realize a high-power stable operation. Gas microbubbles injection into mercury is one of the effective techniques to suppress the pressure. A swirl-flow bubble-generator has been developed and installed in the mercury target at J-PARC. In this study, dependencies of the vane angle and reduction rate of the Venturi were parametrically investigated through the water experiment in order to optimize the swirl-flow bubble-generator for decreasing the aspiration pressure without increasing pressure drop at the bubble-generator. The result showed that the swirl-flow bubble-generator was aspirated more air gas volume as increased in the Venturi reduction.

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We have been developing the liquid mercury target system for a megawatt-class spallation neutron source. In the system, cavitation induced damage at the beam window of the mercury target vessel is a critical issue to decide lifetime of target. In this study, the cavitation bubble behaviors of the growth and collapse under water flow field were investigated by using the combination of a spark discharge for bubble formation and a high-speed photography in order to be clarified the mechanism of mitigating cavitation damage in narrow channel. Relationships between the shock waves due to the cavitation bubble collapsing and the flow velocity was examined. The bubble shape just before collapsing in the flow was also compared with that without flow through the image analysis. The results showed that the shock waves that correlated with the cavitation intensity is mitigated by flowing.

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Because that a sewage pump is used for the transportation of liquids containing solids and fibrous foreign bodies, it is necessary to prevent blockage by foreign bodies. A single blade centrifugal pump can form a large passed particle size (the minimum particle size for the flow channel in a pump); thus, it is commonly used as a sewage pump. The internal flow of the single blade centrifugal pump is very complicated. Explication of the flow is extremely important in improving efficiency and reducing the fluid force acting on the impeller. CFD analysis were performed to investigate the flow structure in casing of a closed-type single blade centrifugal pump. In addition, we investigated the relationship between flow structure and hydraulic loss. The instantaneous static pressure by experiment and CFD analysis were in good agreement. Vortices generated from three points near the start of volute winding accumulate near the end of volute winding to form two large scale vortices and lower the total pressure. Moreover, the mixing loss inside the casing is thought to be caused by vortex generated near the start of the volute winding.

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A gravitation vortex type water turbine is a water turbine which generates power by the gravitational vortex. Although this water turbine can be generated by a low head and a small flow rate, the flow field is a complicated thing which has a free surface. Moreover, although we have investigated the performance and flow field of this turbine, the mechanism of loss generation is not clear. In this study, we analyze the free surface flow of the gravitation vortex type water turbine and propose a loss analysis method based on the analysis result. Then, this loss analysis method was applied when the rotational speed of the runner was changed, and its validity was verified. We also examined the cause and mechanism of loss. As the results, the following facts were clarified. From the analysis result at the time of the rotational speed change, the effective head calculated directly and the effective head calculated from the loss analysis agree well. By the loss analysis method, the dominant loss of the gravitation vortex type water turbine was found to be the loss in the tank and the loss at the tank outlet. Also, the loss in the tank, which is the maximum loss, decreased as the rotationalspeed increased.

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We have developed an axial flow hydraulic turbine with a collection device that aimed at high power by collecting and accelerating the flow of shallow open channel such as agricultural waterway and small river. However, the flow rate of the actual open channel flow changes from moment to moment. Therefore, it is necessary to investigate the performance characteristics under various flow rate conditions. In this study, we investigated the influence of the flow rate on the performance characteristics of an axial flow hydraulic turbine with a collection device in a shallow open channel by performance test and numerical analysis considering free surface. As a result, the power coefficient increased as the flow rate through the open channel increased. This is because although the loading coefficient decreases, the increase of the diffuser pressure recovery coefficient increases the inlet velocity ratio, the input power coefficient increases, and additionally the turbine efficiency increases.

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Vortex hydro turbines capable of generating power in small rivers and irrigation canals are used in Japan and abroad. The water guided to the casing swirls along the side walls and generates a vortex towards the drain hole provided at the bottom portion and is drained. The energy of this swirling flow is taken out as rotational energy by the runner to generate electricity, and the amount of power generation depends on the strength of the swirling flow. In this type of hydraulic turbine, the relation between runner shape and performance and the relationship between flow rate and power output have been studied and reported. In these reports, it is also reported that the swirling flow velocity and the free surface height are nonuniform in the circumferential direction. In this study, we investigated the relationship between casing shape and swirl flow velocity by gas-liquid two-phase flow simulation. As a result, we showed that the casing circumferential direction uniformity of swirl flow velocity and the free surface height is improved by using the eccentric casing.

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Pouring air bubbles from nozzle is used for the industrial field, such as stirring, separating from the past to now. Therefore, many studies on dynamic characteristic of the shape change and detachment of air bubbles were reported. On the other hand, it is a few that studying mainly about surface wettability that have an effect on bubble detachment. In this study, we blow air under constant flow conditions by using super water repellent nozzle such as over 120-degree contact angle for evaluating surface wettability influence bubble detachment process. Consequently, the detachment frequency is smaller, and the bubble volume is larger in case of using water repellent nozzle because it requires a longer time to release the bubble. Moreover, the water repellent nozzle can be applied to the existing correlation formula by taking the outer diameter that is equivalent to wetted perimeter in nozzle surface.

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Boiling and condensation is the most widely used heat transfer form and is used in various industrial equipment such as boilers of thermal power plants and heat pipes. Liquid industrial plant piping including boiler causes intense blowout in the pipe immediately after saturated boiling due to difference in tube diameter. Due to this phenomenon, there is a possibility that the liquid splashes out of the equipment and the equipment is damaged by water hammer Phenomenon. In our laboratory, we introduced a working fluid into a device composed of a boiling vessel and a glass tube simulating industrial piping and heat it directly. Then, we investigated the jetting condition and jetting cycle of working fluid experimentally. In addition, we changed the input power and the initial water level and conducted the experiment. We focused on the pressure fluctuation during subcooled boiling during the eruption. First, the temperature rise per second was investigated for each experimental condition. It was found that it increases as the input power and the sub plenum temperature increase. Next, the difference between the maximum value and the average value of the pressure ΔP^∗_max was obtained. It was compared with the temperature rise per second. As a result, it was found that ΔP^∗_max increased with increasing temperature rise per second.

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This paper describes the forming limit in burring processing of large diameter steel pipe. The pipe in this paper is SGP pipe. The large diameter pipes such as Φ165.2 mm are used for a plant as a flow channel of gas and liquid. A burring process of pipe is generally for forming the branch. The burring process is achieved by drawing of die from prepared hole. And the branch pipe is welded to the formed pipe. This process has some problem. One is the forming limit of pipe, and the other is needed to machining the end surface to be welded. Therefore, in this study, the forming limit of SGP pipe was estimated by FEM analysis of burring process. The pipe used in this study is an SGP pipe with a diameter of 165.2 mm and a wall thickness of 5 mm. The parameters used for criteria for forming limit are the maximum shear stress and the equivalent strain. As a result of comparing the analysis result and the experimental result, it was judged that the maximum shear stress is 350 Pa and the equivalent strain is around 0.8 is the forming limit of the 150 ASGP pipe.

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Twin roll strip casting of aluminum alloy A7075 using commercial scale machine was operated. Twin roll casting process is able to produce a strip from molten metal directly. Thus this process has a possibility to reduce total cost of sheet making comparing to conventional rolling process. Strip casting process has some disadvantages. Casting speed depends on the material properties. It is difficult to determine the casting conditions. Aluminum alloy A7075 has high tensile strength, and it is known as a material for aerospace application. The sheet is manufactured in small quantities comparing to the other sheet aluminum alloy. It is supposed that the demand of high tensile strength aluminum sheet such as A7075 is going to increase for weight saving of structural material. The aims of this study is to investigate the effect of roll speed on the strip. Strip could not be produced continuously at roll speed of 10 m/min, so the load limit of this experimental apparatus was exceeded. However, a good strip without cracks was produced. Continuous strip was produced at a roll speed of 20 m/min. The strip was consisted of a mat part and a metallic luster part. However, cracks were observed in the white mat part of the board. Continuous strip was produced at a roll speed of 30 m/min. However, rolling cracks were observed at the edges of the strip. It is necessary to control the solidification distance by installing the nozzle.

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Spinning is one of forming method which forms the flat metal into cylindrical metal by pressing tool such as roller. This method is used to neck form, the high-pressure hydrogen storage container which is mounted in FCV. Liner of the container is applied the 6000 series aluminum alloy. Both of the ends of container are formed by hot spinning. It is impossible to remove die from the container after forming, so the container should be formed without forming die. In this case, there is issues that the forming defect may be introduced at the inner surface of container after neck-forming. Further, there is a possibility that the defect may lead to gas leak. In cold spinning, forming die is able to suppress the occurrence of defect such as inner surface defect, changing of thickness. On the other hand, the high-pressure hydrogen storage container is formed by hot spinning. Thus, this study evaluates effect of die on hot spinning of the 6000 series aluminum alloy.

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In recent years, saving energy of transport equipment is demanded from the viewpoint of solving environmental problems such as global warming and depletion of fossil fuel resources. To fulfil this demand, applying a promising lightweight structural material for next generation to transport equipment such as railway vehicles is expected. Thus, flame-resistant magnesium alloys are paid attention to. However, in the previous study, hydrogen embrittlement was found to occur in flame-resistant newly developed AZX 811 and commercially available AZX 611 magnesium alloys by means of slow strain rate technique tensile test in humid air environment. In the slow strain rate technique tensile test, after a crack becomes of a certain size, stress will concentrate at the crack tip and then the local strain rate will sharply increase. This will cause insufficient supply of hydrogen to the crack tip. Therefore, extent of hydrogen embrittlement may not be assessed accurately by means of the slow strain rate technique tensile test. In the present study, we have adopted humid gas stress corrosion cracking test, and assessed the extent of hydrogen embrittlement of the two flameresistant magnesium alloys by means of humid gas stress corrosion cracking test, where a certain stress intensity factor is loaded for long term in humid air environment. The load has also been applied in dry air environment to examine fundamentally the resistance to humid gas stress corrosion cracking in these alloys.

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It has been found that peculiar behavior with low elastic modulus and high strength is achieved by cold working in a betatype titanium alloy, Gum Metal. It is considered that the origin of this peculiar behavior is attributed to its unique deformation mechanism, which has not been clarified yet. Therefore, we pursue the goal of catching a clue of its deformation mechanism. In this study, we report results of Vickers hardness test and nanoindentation test in cold rolled specimens of Ti-18%Mo alloy, which is used as a material for comparisons with Gum Metal.

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In this paper, cold plastic forming of ABS plastic pipe was operated for the purposes of improving productivity and lowering manufacturing cost. The parts of ABS plastic pipe is generally produced by injection molding of hot working. The processes need the cooling time, and it takes much time. In addition, expensive mold die is needed for each application. Thus, cold plastic forming of ABS plastic pipe was proposed. Product ability of cold plastic forming is higher than the injection molding or hot working. And the punch and die shape is simple comparing to these process. In this study, pipe expansion process at room temperature was operated. The ABS plastic pipe has a 10 mm diameter and 1 mm thickness. At first, true stress and true strain curves at any strain rate were measured by ring compression test. Obtained flow stresses was used to FEM analysis. Experimental device for pipe expansion process was made by Dip Inc.. Objective inner diameter was 10 mm. FEM analysis was operated to clarify the deformation behavior such as load-stroke diagram. It was possible to produce the expanded ABS pipe. The whitening of worked pipe was observed. Analysis result was indicated the good agreement comparing to experimental result in load-stroke diagram. Heat treatment was effective for reduction of whitening.

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Twin roll strip casting of aluminum alloy ADC12 using commercial scale machine was operated. Roll diameter is 1,000 mm and the width is 240 mm. Roll material is SKD61. The aims of this study is to investigate the possibility of strip casting for aluminum alloy. The effect of the gap between the rolls and the roll speed on the strip surface condition was researched. ADC12 strip was able to be produced continuously at the conditions of pouring temperature 590 ℃, initial roll gap 1.0 mm and roll speed 10 m/min. Strip surface had a metallic luster. Flakes were created with the roll gap of 2 mm. At the roll gap of 3 mm, the molten metal passed through without solidifying at the roll gap portion. The strip was able to be produced continuously at the conditions of initial roll gap 1.0 mm and roll speed 20 m/min.

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Al-Zn-Mg and Al-Cu-Mg alloys have been known to be susceptible to stress corrosion cracking, which is based on intergranular cracking. The crack propagation mechanism depends on alloy system. In Al-Zn-Mg alloys, the crack propagates due to hydrogen embrittlement. In Al-Cu-Mg alloys, anodic dissolution along grain boundaries is suggested to be the crack propagation mechanism, not to be hydrogen embrittlement. It has reported that the peak-aged Al-Zn-Mg alloy showed a loss of elongation resulting from hydrogen embrittlement when tensile testing was performed in humid air at a low strain rate, while the peak-aged Al-Cu-Mg alloy did not show a loss of ductility. To reveal the mechanism of high-resistance to hydrogen embrittlement in the Al-Cu-Mg alloy is important for the elucidation of the hydrogen embrittlement mechanism in aluminum alloys. In this study, an Al-Cu-Mg alloy was subjected to the artificial aging where the aging temperature was lower than usual condition in order to obtain fine and high-density distribution grain boundary precipitates. Hydrogen embrittlement sensitivity was evaluated by means of the slow strain rate tensile testing in humid air and fracture surface observation with a scanning electron microscopy.

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This paper presented the technical process of the robot roll hemming which was used for the automobile industry. Hemming is the metalworking process in which the edge of outer panel is rolled over onto the inner panel. Although the process of hemming has developed fast, the study of it lack of relevant research, indeterminate numbers of bending, bending angle and pressure. When a 6-axis multi-joint robot is used, the bending trajectory becomes complicated since it can be moved in all three directions. In this study, we propose a system for the position coordinate and acceleration through double integration, and an acceleration sensor is mounted on the tip of the robot. In the further study, we need to improve the accuracy of the acceleration sensor and accurately locate the position coordinates.

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