In friction stir technologies (FST), the friction stir processing (FSP) is expected to be a promising microstructure refinement method for crystalline materials. In this study, we have applied the friction stir processing to a ZK60 magnesium alloy as a grain refinement method. In this paper, the distance between the tool centers of adjoining FSP passes, d, is discussed. The effects of d and the direction of FSP pass on mechanical properties are compared and discussed. Then, the effects of annealing temperature on relaxation of texture are discussed. We compared the annealed materials with the mechanical properties

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Friction stir welding technique possesses a lot of features such as the formation of a fine-grained microstructure in the welded zone. Therefore, the friction stir welding process is expected to be a microstructure refinement method for crystalline materials. Many researchers have been paid attention to this as a microstructure control method for variety of alloys ; it is now called Friction Stir Processing (FSP). We have applied this joining method to 7075-T6 alloy as a novel microstructure control method. It was found that initial microstructure was altered considerably by the process; in particular, grains in the stirred zone were refined to very fine and equiaxial ones. We discussed a probable mechanism of the microstructure evolution with the present experimental results.

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A high-strength 7475 aluminum alloy subjected to severe plastic deformation through hot equal channel angular extrusion (ECAE) with and without isothermal rolling (IR) was studied in tension at strain rates ranging from 2.7×10^<-5> to 5.6×10^<-2>s^<-1> and temperature of 〜450℃. It was established that IR slightly affect the superplastic ductilities. The alloy subjected to ECAE exhibited the maximum elongation of 〜720% at a temperature of 450℃ and an initial strain rate of 5.6×10^<-3> s^<-1>. Superplastic elongation of 〜660% was recorded at strain rates higher than 10^<-2>s^<-1>, in isothermally rolled 7475 aluminum alloy.

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Structural ceramics are used under severe conditions such as those at high temperatures, in corrosive gas environment and for the parts for which high wear resistance is required It has become clear that some structural ceramics show superplasticity, i, e., very high ductility Fine-grained tetragonal zirconia containing 3 mol.% yttria polycrystals (3Y-TZP) is a typical superplastic ceramics, which shows very high ductility at elevated temperatures. When actually using it, a good grasp of mechanical characteristics is necessary and indispensable. Recently, variation of Vickers hardness values of neutron irradiated 3Y TZP was reported for different indentation loads. In this study, the effects of evaluation method on mechanical properties are discussed in some detail.

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Zirconia based fine ceramics have a mechanism to improve the strength and the fracture toughness due to the stress induced phase transformation (the t-m phase transformation). They are expected to be used as a candidate material of the high heat resistant structures with complex shapes such as the core barrel and the upper shield block in high-temperature gas cooled reactors. Detailed data of the fatigue characteristics of zirconia based fine ceramics, however, aren't sufficient at high temperatures yet. In this study, the fatigue strength properties of 3mol% yttrium-stabilized tetragonal zirconia polycrystals (3Y-TZP) are estimated by 4-point bending fatigue test at high temperatures. The changing of the crystal structure of 3Y TZP after the fatigue test is also evaluated by the X-ray diffraction analysis. In the fatigue test, the fatigue limits of the 3Y TZP are 500 [MPa], 300 [MPa] and 250 [MPa] under a condition of a ratio of the minimum and the maximum stresses of 0.1 at 523 [K], 773[K] and 873 [K], respectively. And the most important cause to determine the fatigue strength finds to be the phase transformation due to the cyclic stress and the test temperature.

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Japan Atomic Energy Agency (JAEA) has started to study and develop ZrC coated fuel particles for advanced high temperature gas cooled reactors. The ZrC coating layers were fabricated with bromide process at JAEA. We report in this study the microstructures of the ZrC coating layers deposited in the second year of the project. We already reported the microstructure of the one deposited in the first year of the project last year. The ZrC coating layer deposited at lower temperatures contains less free carbons. The crystal grains of ZrC were columner in shape, small and oriented in the region containing less free carbons. The orientation was different from the one reported in the last year. The fibrous carbon structure is observed at PyC/ZrC boundary when the ZrC layer is deposited at higher temperature but not when ZrC layer is deposited at lower temperature. In addition to the stoichiometry of the ZrC layer, the microstructure of PyC/ZrC boundary also depended on the deposition temperature.

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Minoridai, Matudo, Tiba High temperature gas reactor's (HTGR) can produce high temperature gas. The graphites will be used as an important structural material for the HTGR, but they may be subjected to oxidation under practical use. In the present study, accelerated oxidation experiments were carried out for an isotropic graphite (IG-11) and a fine-grained isotropic graphite (IG-110) under various stresses to examine effect of stresses on the oxidation. As a result, both of the isotropic and fine-grained isotropic graphites were found to deteriorate by the oxidation. In particular, the oxidation was accelerated under tensile stress. On the other hand, compressive stress restrains the oxidation. The microstructures of the specimens were observed by means of SEM and an optical microscope. In each case, the occurrence of various kinds of micropores, which may affect mechanical properties and so forth, are found.

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Recently, the fuel cell has been observed from the environmental problems such as global warming and air pollution. Especially, the solid oxide fuel cell (SOFC) is promising, because it has the highest power generation efficiency among SOFC's. Zirconia-based ceramics have been often used as a SOFC electrolyte. Superplasticity has been found in many kinds of zirconia-based ceramics. To produce thin films or complex forms of the electrolyte by using a superplustic phenomena is, therefore, very promising. A bonding of ceramics using superplastic ceramics as an interlayer has been reported such that the joint has a bonding strength almost equall to the strength of the ceramics itself. In this study, experiments to bond the electrolyte and cathode using superplastic ceramics 5ScSZ powder as an interlayer was carried out. We used 10mol% scandia - lmol% yttria stabilized zirconia (10SclYSZ) as the electrolyte materials and LSM (La0.8Sr0.2MnO3) as the cathode material. We observed the bonding states of the joint and then discussed briefly the bonding process and so forth.

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Tungsten materials are particularly expected to be used as a target material of the Japan Proton Accelerator Research Complex (J-PARC) and a plasma facing material of the International Thermonuclear Experimental Reactor (ITER), since they have high heat resistance, high thermal shock resistance, high thermal conductivity and excellent erosion resistance. On the other hand, they are low fracture toughness and hard workability, and the joining technique with cooling structures is not established yet. In this study, a new working technique by using of the superplasticity and a joining method with a cooling structures are researched for the improvement of their weak points. The Superplasticity of tungsten materials are evaluated by tensile test at high temperatures. And the thermal responses of the tungsten joining models are also examined.

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Microstructural factors such as texture, substructure (dislocation structure and density) and intergranular stresses affect the mechanical properties of materials and they are expected to determine as macroscopically averaged values. Neutron diffraction enables us to measure these values for cm-ordered bulky specimens. In this study, texture measurements and profile analysis were simultaneously performed to determine the above microstructural factors.

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A powder eutectic coating using Al, Ti and Fe powder on Fe substrate is successfully performed by laser scanning method. Heat stress resistance and oxidation resistance of coated layer were estimated by oxidation tests.

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Liquid mercury target system for high power spallation neutron sources is being developed. When high intensity proton beams are inj ected into the target, pressure waves are generated by the thermal shock in mercury and pitting damage will be imposed on the target vessel. Bubble injection into mercury is effective to mitigate the pressure waves, In this work, we propose a method of fabricating mesa-nozzle for bubbles inj ection. The method is based on powder metallurgy by inserting thin glass fibers into a metal powder matrix to create a green compact, followed by sintering at a temperature between the melting points of the powder and the fiber. SUS316L and molybdenum powders were used as the nozzle matrix materials. In order to investigate optimum sintering condition, experiments were performed at different combinations of pressing load and sintering temperature. We found that a pressing load of 392MPa and sintering temperature of 1875℃ for molybdenum provide high relative density and straight hole with circular cross section.

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An attempt has been made to manufacture a recursive mirror for the optical measurement of soundness of a mercury-target vessel that is to be installed in the J-PARC project at the JAEA. The mirror is comprised ofdozens of reentrant pyramids as large as about 100μm in length. In order to make such a micro shape directly on a stainless steel substrate, we modified a pulsed Nd:YAG laser with 1.06μm wavelength to achieve resolutions of 10μm in width and 1μm in depth for the laser ablation. Its feasibility has been confirmed by manufacturing a small triangle as large as about 50μm in width and about 1μm in depth under the conditions of a scanning speed of 1mm/min, a voltage of 272 V, and a hatching width of 2μm.

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Peculiarities of the structure of metal foams, which can be produced by Sacrificial Template Method, are discussed. To analyze an evolution of pores with different radii during the sintering process, the Continual Theory of Sintering was used. Final results are formulated in terms of time dependences for the change in content of each type of pore without considering the specific sintering mechanism. The equations for each type of pores evolution as well as the effective viscosity coefficients are determined by unit cell analysis.

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In the case of loss of sight sense due to the sight function trouble, user meets the difficulty for capturing surrounding information and doing self-walking. Up to now, our research group has enabled the indoor walking assistance by extracting distance information from a surrounding situation and converting it into the sense of touch signal. However, it was pointed out not to be able to understand a surrounding situation because a existing walking assistance system transmitted only distance information (obstacle contact information), and to give mental uneasiness to the user. This research proposes the system that feeds back and transmits information that classifies the situation and the object roughly by using the stereoscope as surrounding situations other than the distance. This presentation reports the technique for improving the estimated distance precision by setting error level that is included the fluctuation for the image noise in this presentation.

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Healthcare in daily life plays a significant role in preventing lifestyle-related diseases. We have been developing a health care robot which measures vital signs, meal consumption, physical activity to manage human's health. A three dimensional (3D) reconstruction method based on multiple images treatment with a reference object is proposed to measure the meal volume as consumption. The robot records multiple images of the foods and measures the meal volume by using the 3D reconstruction method. Following results are obtained in this study. Firstly, the increasing number of treatment images, from five images to twelve images, reduces the reconstruction error from 5 mm to 4 mm. The multiple images treatment is good to reduce the reconstruction error. Second, the reconstruction error due to the reference object's angle widely ranges from 4 mm to 45 mm. The image angle of the reference object affects the reconstruction accuracy significantly.

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In this paper, we describe a technique to improve the reliability of a vision-based position sensing for a safety control which enables the cooperative work of a human and a robot. We improved the reliability of a position sensing with a light-marker-sensing system using the combination of a floodlight and a reflection marker. Also, we propose a technique to detect and recover sensing errors by using the light patterns which is encoded in consideration of the standard, EN50159. We have constructed our proposed system, and conducted an experiment to prove that the system can recover the errors caused by an occlusion of the light marker.

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In recent years, the opportunity to touch a human robot is increasing. When touching humans, the system which does a dialog and operation gentle to humans is needed for a robot. Therefore, the system which operates while a robot detects human feeling and feeling is called for. So, in this research, brain waves are used and the technique of detecting human feeling is proposed. The feature of brain waves is found out and it sets it as the last purpose to formulize it. By this report, a pleasant sensation and the sound considered to be unpleasant were subjectively told to the subject, and it was examined using the power-spectrum analysis by FFT (Fast Fourier Transform) what kind of feature brain waves would express relatively.

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Magnetic levitation systems require multiple displacement sensors. These sensors cause several problems; high sensor cost, interference between adjacent sensors, installation space and non-collocation of sensors and actuators. To overcome these problems, self-sensing technique has been proposed. In this paper, self-sensing control is applied to IPM(Interior Permanent Magnet) type self-bearing motor. The nonlinear outputs of the differential transformer type displacement estimation are analyzed. Then the nonlinear characteristics of differential outputs can be approximated as a bivariate polynomial. A nonlinear compensation method using the bivariate polynomial coefficients identified by least square method is proposed

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We have developed a circulatory system simulator which reproduces hemodynamics, which means change of pressure and flow rate, to evaluate a circulatory therapeutic device such as magnetically suspended artificial hearts. The simulator consists of eight chambers, an air compressor, two pinch valves and four check valves. The circulatory system simulator simulates the hemodynamics of a patient with left heart failure by changing several parameters. Left ventricular assist circulation is performed using the simulator and a radial type magnetically suspended pump developed in our laboratory. Developed simulator reproduced hemodynamics suitably. Stable range of the magnetically suspend pump and its sufficient ventricular assist performance was confirmed.

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Maglev technology realizes long lifetime and better biocompatibility for centrifugal blood pumps by eliminating the mechanical parts from the device. A new hybrid magnetic bearing with a double biased magnetic flux was invented as a high performance magnetic levitation system for blood pumps. The magnetically suspended motor with the hybrid magnetic bearing and a maglev pump was constructed and evaluated its performance. A levitated rotor-impeller is set between the magnetic bearing and a motor stator in the maglev motor. Maximum pressure head and maximum flow rate are 146 mmHg and 12.4 L/min, respectively. The maglev motor was miniaturized by three dimensional finite element method. The diameter of the rotor is reduced from 72mm to 50mm and miniaturized maglev motor indicates sufficient magnetic suspension performance as a result of simulator.

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Heart transplantation is reliable way to patients with severe cardiac failure. The limited number of available donor hearts promotes the establishment of alternative treatments for these patients. An artificial hearts has been used for such patient and has shown reliable results as a bridge to heart transplantation. However, direct contact between the material and the blood causes embolism from thrombus. Blood pressure is maintained by pushing the heart. The place which must be helped in the patient of severe congestive heart failure is contraction of the heart. The purpose of study is to develop a myocardium assist device that compresses the dysfunctional heart from its surface.

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The final medical treatment of respiratory disease, such as COPD, is a lung transplant. However, it has stood by the transplant in many cases for a long time because of donor failure. Therefore, the demand of respiratory support and an artificial implantable lung bridge to lung transplant is increasing. However, when an affection of the lungs is caused, assistance of the heartbeat is essential. Because a cardiac disease is supervene with in many cases. Then, we devised integrated the oxygenater and the blood pump with right ventricle assist. The blood pump used Cross Flow Pump. The Cross Flow Pump can obtain a wide outflow and uniform flow to oxygenator that was able to have high gas exchange ability, an anti-thrombus and small space. In this paper, we describe the trial manufacture and performance evaluation test of integrated the oxygenator and blood pump.

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We have developed a centrifugal blood pump with hydrodynamic bearings. To investigate the loss of pump head, flow visualization experiment was performed. As a result, tangential velocity in the vane/casing gap when the impeller is apart from the casing was found to be lower than that when locating in the vicinity of the casing. Impeller displacement measurement and hemolysis test showed that the more the vane/casing gap expanded, the lower the hemolysis level become. We found that expansion of the vane/casing gap is effective to reduce hemolysis but that too much expansion of the gap causes to lose pump head

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Numerical method simulating blood flow was presented using combination of SPH method and Grid method. In the method, we solved the plasma as continuous fluid by CIVA-based finite volume method and the red blood cell (RBC) as a particle by SPH method. The drag and lift forces were introduced here for considering interactions between particle and fluid. In order to confirm the validity of the method, we numerically analyzed a three-dimensional blood flow in blood vessel, and reproduced the axial migration of RBCs and formulation of plasma layer.

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We have studied the relationship between shear stress generated by surface roughness and hemoiysis to develop blood compatible artificial hearts. In order to measure the shear stress due to surface roughness, we used some different viscous glycerol solutions in a rotational shear stressor, with roughed inner cylinders. The surface roughness were added to a inner cylinder surface with 0.4-0.8[μ mRa]respectively. The viscosity of glycerol solution were 3.0-12.0[mPa・s]. The stressor was rotated at 3750[s^<-1>]for 1 min and measures the torque as a function of shear stress. As a result, the torque was increased 2.4%between 0.6 and 0.8[μmRa]with 12.0[mPa・s]glycerol solution. These results were similar to results for hemolysis test with bovine blood. Therefore we consider that shear stress was generated due to surface roughness, subsequently cause hemolysis.

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Diamond-like carbon(DLC)and fluorinated diamond-like carbon(F-DLC)films were prepared on polymer substrates using radio frequency(RF)plasma enhanced chemical vapor deposition (CVD)by changing the ratio ofcarbon tetrafluoride(CF4)and methane(CH_4).Raman spectra and XPS spectra were measured. The contact angle ofaqua destillata droplet on polytetrafluoro-ethylene(PTFE),DLC and F-DLC film were measured. Wear resistance of DLC and F-DLC film were measured by ball-on disk test. As a result, C-C bond decreased and C-F bond increased with increasing F incorporation. The maximum contact angle was 98.1±3.1°at CF_4-40%.Wear resistance ofF-DLC film also improved with increasing F incorporation.

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Hydroxyapatite(HA) film was prepared on stainless steel(SUS316L) plate using radio-frequency magnetron sputtering and treated by the hydrothermal method. The hydrothermal treated HA film was characterized by an X-ray diflractometer(XRD) and a scanning electron microscope(SEM). Adhesion test of HA film performed pullout test. Adsorption of albumin on HA film was measured. The XRD results showed high crystallinity. The crystal growth of HA was observed by a SEM. Adhesion test results of HA film indicated that bond strength of HA film was improved by the hydrothermal method. Adsorbed albumin on HA film increased with hydrothermal treatment times.

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An impact cutting tester was developed to clarify cutting phenomena under ultra high-speed cutting conditions where cutting speed exceeds speed of plastic wave of a workpiece material. The tester composed of three elements: a projectile launching and accelerating system, a cutting processing chamber and the projectile decelerating and collecting system. Pressures of the chamber can be controlled from the atmospheric pressure to the vacuum pressure so that influences of cutting environments on cutting phenomena can be investigated. The flow of the operation of the tester is as follows: a small projectile with built-in a small cutting tool is accelerated by a compressed air, the tool cuts a workpiece that fixed on a dynamometer in the chamber, the chip is captured in the projectile, the projectile is decelerated by a compressed air after finishing cutting process and stopped in the collecting system. This report discloses the tester developed

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In the field of the ultraprecision cutting, die machining can be processed mirror finished surface with lathe. Recently the demand for processing of complicated shape has been increasing, but the traditional processing system is difficult to process then. In this study, the processing machine with X,Z,and C-axis is used to process the complicated shape, and a new processing method which can achieve to create the asymmetric shape are proposed. Then, effective of the proposed method is confirmed.

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In this study, a metal-free electro-conductive resinoid bonded wheel made of waterweed carbon as the conductive material was experimentally built to reduce metal ions in the grinding fluid and metal contamination of the work piece in the aim to develop environmentally-friendly ELID grinding techniques. At the same time, characteristics of initial electrolytic-dressing and grinding were also investigated. The results showed that the prototyped metal-free electro-conductive resinoid bonded wheel consisted of a layer of oxides with high oxygen level formed on the wheel surface by electrolytic dressing. The layer generated by electrolytic dressing was found to wear more easily than the matrix composition and in addition have a high frictional coefficient. For the purpose of checking the difference of #1200 and #8000 waterweed grinding wheel's effect, mono-crystalline silicon was ground with ELID, and grinding performance was measured. Using the wheel with ELID, high quality surfaces of 50nmRy were successfully achieved.

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As finishing techniques for silica glass substrate, the free abrasive processes are able to offer a better surface roughness, but sacrifice profile accuracy. On the other hand, the fixed abrasive process or grinding is known as a promising solution to improve accuracy of profile geometry, but always introduces damaged layer. In order to simultaneously achieve both surface quality and profile accuracy, this research has proposed a novel chemo-mechanical-grinding (CMG) process by effective use of chemical reaction in the grinding process

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SEM (scanning electron microscope) is used for semiconductor device production and observation of the microstructure in the MEMS technology. However, there is a problem that information is not provided at all about the height of the object. In this study, we used technology called the Means of Binocular Stereopsis which restored height information from the 2D stereo pair images. The matching technique to find the corresponding point of the object between stereo pair images is necessary. We used shape based pattern matching and performed 3D measurement and shape reconstruction of SEM images. And measurement result with proposed method is compared with the result with the laser microscope.

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The aim of this study is to explore the possibility of applying ultra-short pulsed Laser into cleavage-cutting of silicon wafer. Unlike the conventional Laser machining which transforms the power into heat energy to remove the materials, ultra-short pulsed Laser removes materials by a behavior called "ablation" if the incoming Laser power is big enough. "Ablation" is able to directly break off the chemical bonding of the materials by multi-photon absorption without introducing heat effect. In this study, tension tests and three-point bending tests are performed after irradiation with different conditions to acquire the fundamental data for Laser cleavage-cutting.

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The demand for the superior performance and the size reduction of semiconductor devises are becoming severer with increasing the integrity of integrated circuits. However, the semiconductor lithographic process using the ultraviolet ray has met the limit to the produced pattern for the constraint of the wavelength. The nanoimprint lithography is one of the newly developed techniques to produce the nano-patterns easier than the MEMS process. Under such circumstances, this study aims to produce nano-patterns using the probe anodic oxidation method to support the nanoimprint mold production. In this report, the influences of anodic oxidation conditions and probe wear on produced nano-patterns were evaluated, and the formation of an island structure were also performed.

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It is known that the oxidation-reduction reaction occurs when a TiO_2 film absorbs ultraviolet rays, and such a phenomenon is widely utilized to many products. TiO_2 films are coated using several kinds of methods, however, they include problems, such as low cost efficiency, high environmental load, low-quality and so on. In this study, the functions and the mechanical characteristics of TiO_2 films produced by the spray method at room-temperature and the thermal spray method are investigated. As a result, it was confirmed that TiO_2 film produced by the spray method at room-temperature showed good wettability, antifouling property, mechnical strength and wear resistance.

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This study aims to clarify the possibility to achieve the line patterns generation on a silicon wafer surface at nm order by means of nano-scratching. This paper reports on the results obtained through several nano-scratching experiments by two types of diamond probes with radiuses of 50 nm and 120 nm by using an atomic force microscope (AFM). After several nano-scratching experiments, the shapes transcriptions were examined. As a result, the formation of scratch grooves with less than 100nm deep and several hundreds nm wide can be generated by present diamond probes. And, it was also confirmed that the importance to sharpen the probe tip to obtain smaller scratching grooves.

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A surface model with bending elasticity and in-plane share elasicity is studied nu-merically on triangulated spherical surfaces. We find that the collapsing transition is of first-order and is slightly strengthened by the in-plane elasticity.

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A meshwork model is numerically studied on triangulated spherical surfaces. We find four distinct phases including the smooth spherical phase and the smooth planar phase, and almost all two neighbouring phases are separated by a first-order transition.

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We analyzed the adhesion energy of metal and polymer interface by using molecular dynamics simulation. We showed that the polymer skim structure on the metal film is related to the character of adhesion. By using nano-scale simulation, in this way, we can predict the adhesion properties and suggest the best materials of micro electro devices.

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Numerical fluid simulation based on voxel mesh method was applied to 3.5-inch hard disk drives and the results were compared with the experimental results obtained by PW (Particle Image Velocimetry) system. The results showed that the velocity distributions agree well and this method is useful for such a complicated geometry as hard disk drives.

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We have been developing a dynamic simulation system of mechanisms with impulsive force. A mechanism is modeled as a set of rigid bodies connected with pair-axis motors. We defined linkage inertia, pair-loop matrix and velocity dependent torque to formulate equation of motion for mechanisms. The equation determines directly the relative angular accelerations on each pair-axis. This paper describes the simulation of running bicycle. The contacts between wheel and ground are represented as a series of collision and micro collision. By several experiments, it was confirmed that the length of trail greatly influences the mileage of bicycle until the tumble.

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We have been developing a dynamic simulation system for variety of cam mechanisms. A cam mechanism is composed of three parts connected with three pair axes. Pair axis, velocity, acceleration, momentum and force are represented as a motor. Velocity function and acceleration function derived form cam-diagram are prepared as input data to determine the cam-follower pair axis. Mushroom cam, swinging cam and translation cam are modeled to simulate the motion of cam, follower and supporting link.

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This paper presents a new algorithm to obtain principal stress trajectory grid. Grid points are calculated as the intersections of two mutually orthogonal contour lines in 2D domain of direction functions which are evaluated from the result of FEM. Misalignment with 2D pattern is solved by partitioning the triangular mesh with a line passing through the singular point where the maximum shear stress reaches the minimum value. The magnitude of principal stress is indicated by the line density of equal force grid and the brightness of line color.

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This paper presents a new algorithm to obtain principal stress trajectory grid. Grid points are calculated as the intersections of three mutually orthogonal isoplethic surfaces of direction functions which are evaluated from the result of FEM. The system to form equal force flow grid is developed, where the line density corresponds to the magnitude of principal stress. The line density of the principal stress trajectory which occurs subsidiarily from free boundary it faces to free boundary does not correspond to the magnitude of principal stress. Then, attenuations of the principal stress in the vicinity of free boundary surface are denoted by darker color of trajectories.

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We are developing an algorithm to generate NC-programs for regrinding ball end mill whose cutting edge are located precisely on a spherical surface. For this purpose, this paper presents a simulation program to evaluate the curve of cutting edge by a currently used NC-program. The curve is figured out as the intersection of two surfaces, R-gash and R-2. The patch object of each surface is computed as an envelope surface of a tool(grinding wheel) driven by an NC-command.

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A high-power liquid mercury target system for spallation neutron source is being developed in Japan Atomic Energy Agency. Cavitation will be induced by pressure waves which are caused by high intense proton beam injection into mercury. Injection of microbubbles in mercury with 50 to 200 gm in diameter may be effective to mitigate the cavitation. The effectiveness is dependent on bubble size and population. To investigate the behavior of bubble formation in mercury from a nozzle and develop microbubbles injection technique, numerical simulations on bubble injection in stagnant and flowing mercury were carried out using a Computational Fluid Dynamics (CFD) code. The simulation in stagnant showed that bubble grew around the outer wall of the nozzle. Bubble computed under flowing condition was smaller than that in stagnant due to the drag and shearing forces induced by mercury flow.

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CFD is expected to have a major role to play in optimizing the design of fluid machineries. However, it is very difficult to simulate hydraulic phenomena in fluid machineries, because it contains various kinds of problems such as complicated geometries, intermingling of compressible and incompressible fluid, multiphase flow. Therefore we structure an analysis scheme for multiphase flow based on T-CUP method and We call the analysis code CRIMSON. In this paper, the purpose is to add new functions and models to CRIMSON for refine the accuracy of numerilcal analysis by using CRIMSON. So, we tried to adapt Two-Fluid model to CRIMSON code.

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