In the present paper, the authors discuss the large scale structure and mechanism of turbulent bubbly flows in a rectangular-vessel-type bubble column (RVTBC).In the experiments, two different size-scale bubbles, mm-scale and sub-mm-scale bubbles, were injected into the water. The mm-scale bubbles were injected into the liquid phase from a sintered metal bubble generator set at the center of the bottom. The sub-mm-scale bubbles were injected uniformly from the bottom of RVTBC. Furthermore, a superficial liquid-phase velocity was added. The 3D profiles of the liquid-phase velocities were measured using a two-component LDA. The profiles of void fraction, diameters, velocities and number density of the mm-scale bubbles were measured using an F-TOP (Four-Tip Optical-fiber Probe). A large scale liquid-phase circulation was formed between the center and the corners by the upward and downward flows.

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Objective in the present study is to examine effects of a horn attached to a circular nozzle on the coherent structures in the near field of an axisymmetric jet. Experiments have been conducted to compare two flow fields issued through a plate nozzle and horn nozzle in a water channel. Reynolds numbers of these flows were low enough to visualize the flow patterns with the dye-injection method and to capture the coherent structures by using an ultrasonic velocity profile (UVP) monitor. Images were reconstructed from the visualized photographs along the line of x/d=20, and from these images for the horn nozzle, a large scale structure was found out. Instantaneous velocity profiles were obtained in the radial directions with UVP, proper orthogonal decomposition was applied to these dataset.

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Vortex ring migrating with background rotation is analyzed experimentally. The rotation field is given by rigid rotation whose axis is parallel to the migrating direction. The transverse velocity and the internal flow structure of the vortex ring are measured by ultrasonic velocity profiler (UVP) with changing the stroke and the velocity of piston-type vortex ring generator. The results show that the transverse velocity decreases with the rotation but keeps its original value when the stroke is long. This trend is explained by the time scale of fluid circulation inside the vortex ring.

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In this study, experiment was carried out for Taylor-Couette vortex flow(TVF) with a small aspect ratio. TVF is generated with two concentric rotating cylinders; a rotating inner cylinder and a fixed outer cylinder. Two test section sizes with radial ratio of 0.375 and 0.667 were applied. Aspect ratio and gap between inner and outer cylinder were kept constant 3 and 25 mm respectively. Successive instantaneous and mean velocity profiles were obtained by using an ultrasonic velocity profiler (UVP). The spatiotemporal velocity field was analysed by two dimensional Fourier transform. In this case, the characteristics of Wavy Vortex Flow (WVF) and Modulated Wavy Vortex Flow (MVF) transition are confirmed. Furthermore, the bifurcations between each cell modes namely the N-2Cell, N-4Cell, A-3Cell and A-4Cell modes are clarified. The flow was much cmplicated compared with the one observed in η=0.667.

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In this study, our purpose is to obtain instantaneous and mean velocity profiles in a Taylor-Couette vortex flow(TVF) by using a pulser receiver device based on a ultrasonic generator. The experiment was carried out with a small aspect ratio where the Ekman boundary layer was not neglected. The device has a radial ratio of 0.375,aspect ratio of 3 and the gap length between the inner and outer cylinders of 25. As the result, the velocity profiles and their absolute values were in good agreement with the ones obtained by the Ultrasonic velocity profiler (UVP), which results in well approximated in the vortex structures of Normal 2 and 4 cell modes. This measurement system was applied to the multi-phased flow as a solid-liquid flow experimentally, and well measured even in the dilute solution up to 2.0g/400ml.

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The discharge of the overflow at a dam is currently determined by applying an empirical equation estimated on ideal system to water level at the dam. However the real overflow on large scale has many uncertain factors and thus the estimated discharge has large errors, which may be order of several ten percent. Until now, we have studied an overflow measurement by using ultrasonic velocity profiler (UVP) to realize more accurate measurement of the discharge (Kashiwaguma, 2003). Cross-sectional velocity distribution over the weir setting in an open channel was measured by UVP and discharge calculated from velocity distribution was compared with discharge determined from the empirical equation. That system has slightly error because of rough detecting the position of free surface on measurement line. To reduce error in the measurement of the discharge, we must acquire the position exactly. In this study, we attempted to utilize the amplitude information of US echo which has not been used to calculate the velocity profile in conventional UVP. The velocity profile was measured in the vertical direction on the condition accompanying free surface in an open channel. The time evolution of the free surface displacement was measured by using the amplitude information of reflected ultrasound at the surface. The measured position was compared with an alternative measurement method based on the position meter fixed on the measurement line of UVP and then the accuracy of the present method was verified.

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The tracer particle is necessary for Ultrasonic Doppler Method (UDM) as the reflection body of the supersonic wave. Use is difficult in the measurement of the environmental flow place though the nylon powder is used as a reflection body in the laboratory. Therefore, the coverage of UDM is limited. Then, it thinks it has a profitable action like the water quality purification and the generation of the physiology revitalization of the aquatic life, etc., and the micro bubble with a good follow with the liquid phase is used for the flowing quantity measurement of the environmental flow place as a reflection body of UDM. Then, this research mixed the micro bubble with an open channel, and measured UDM. And, the relation between the bubble diameter distribution and the amount of the inhalation bubble and the flow velocity distribution was experimentally requested.

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A pulse ultrasonic Doppler method has been developed for a new type of flow metering system. This new system, which is under investigation, is a hybrid of time-of-flight (TOF) type ultrasonic flowmeter and ultrasonic velocity profile (UVP) type flowmeter, and it has the advantages of these two types. Our final purpose is to apply the hybrid ultrasonic flow metering system to an accurate flow rate measurement of feed- or recirculation- water in nuclear power plants. The pulse ultrasonic Doppler method (UDM) has the capability to obtain instantaneous velocity profiles along an ultrasonic beam. The principle of the UDM flow metering system is based on the integration of an instantaneous velocity profile over a pipe diameter. Hence, the system is expected to eliminate installation problems such as entry length, and also to follow transient flow rate precisely by increasing the number of ultrasonic transducers. However, it needs reflectors for receiving ultrasonic Doppler signals. On the other hand, the TOF ultrasonic flow metering system does not need any reflector, but it needs profile factors (PFs) which depend on velocity profiles. PF is one of the important experimental coefficients for the accurate flow rate measurement. Therefore PFs must be corrected according to the changes in flow conditions.

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Unit of Vector-UVP system, which is an advanced UVP system to measure three directional velocity components on a line by using multiple transducers, was developed. To optimize the Vector-UVP system, we attempted to determine an acoustic field generated by a focusing transducer, which can focuses ultrasound via acoustic lens mounted at the head of the transducer. The acoustic intensity was measured using a small hydrophone by scanning the sound field. It is also theoretically calculated by solving two-dimensional wave equation to validate the measured results, such as focal point of the ultrasonic beam. We also estimated the influence of an intermediate wall existing between target fluid and the transducer on the acoustic field. With the estimated results, the measurement volume and the measurement area were determined so that the system is optimized. The system was applied to the measurement of two directional velocity components of Karmann vortices in a wake of a circular cylinder to demonstrate the applicability to multi-dimensional unsteady flow. From the measured velocity vector profile, the two-dimensional vorticity distribution were validly detected using the present vector-UVP system after Taylor's frozen hypothesis was considered.

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Measurement of Lead Bismuth Eutectic (LBE) flow velocity profile was successfully realized in the spallation target model loop of Accelerator Driven System (ADS) by the Ultrasonic Velocity Profiler (UVP) technique. UVP is a powerful tool to measure an instantaneous space-time velocity profile especially on a velocity measurement of an opaque liquid flow, such as liquid metal. However, it has not yet been done well because both of its poor wetting property with stainless steel and of the difficulty in manufacturing probe at high temperature. We performed velocity measurement along the centerline of the ioop and confirmed basic performance of the loop. It was found that there were periodical releases of eddy from the re-circulation region formed near the wall surface of the inner cylinder. We made then a measurement for non-parallel directions with the centerline and observed 3-dimensional structure of LBE flow configuration.

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The dynamic behaviors of the two layers fluid in a laterally oscillating rectangular container under a vertical magnetic field were studied. The two layers fluid was a water-based magnetic fluid and a silicone oil. The frequency responses of displacement of free surface and interface were measured and their resonant frequencies moved to higher frequencies as the magnetic field intensity was increased. The velocity profiles in magnetic fluid and silicone oil were periodically measured during a sloshing cycle by using the ultrasound velocity profile system(UVP).

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The dynamic behaviors of the two layers fluid in a laterally oscillating rectangular container under a vertical magnetic field were studied. The two layers fluid was a water-based magnetic fluid and a silicone oil. The frequency responses of displacement of free surface and interface were measured and their resonant frequencies moved to higher frequencies as the magnetic field intensity was increased. The velocity profiles in magnetic fluid and silicone oil were periodically measured during a sloshing cycle by using the ultrasound velocity profile system(UVP).

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As a basic study for developing a two-phase flowmeter by means of ultrasonic velocity profiler(UVP), theoretical and numerical estimations of the phase distribution measurement are performed. The measurement accuracy depends on the number of ultrasonic measurement lines. When the azimuthal resolution is lacked, the error grows up for low void fraction conditions. Considering the relative resolution to radial direction, the sufficient number of the lines is concluded as 8. A practical measurement for a slug flow is also carried out to understand the internal secondary flow that affects on the flow rate measured by UVP.

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To measure the main parameter of the gas-liquid two-phase flow at the same time, the compound measurement system was developed. The compound measurement system is composed of Ultrasonic Time-Domain Correlation method (UTDC), Wire Mesh Tomography (WMT), and Digital Image Processing (DIP). UTDC and high-speed camera were introduced for a more detailed measurement of the gas-liquid two-phase flow. As a result, the monitor of the gas-liquid two-phase flow became possible. The bubbly flow adapts the compound measurement system in this research. Furthermore, the each parameter effects for bubbly flow structures are clarified using the compound measurement system.

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In this paper, the orientation of a long rectangular bar in still water was investigated. The inclination angle of the bar was analyzed based on Archimedes' principle and the conditions of the existence of a solution. The inclination angle φ of the bar are given by the widthlheight ratio of a section of a and the specific gravity a of the bar. The orientation of the rectangular bar is classified on the map of α-σ. The orientation of a long rectangular bar is illustrated.

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Sewage pumps are designed with a wide flow channel by, for example, sacrificing some efficiency and reducing the number of blades, in order to prevent plugging with foreign bodies. Authors have been proposing a new type of sewage pump impeller designed to further improve pump efficiency and performance in passing foreign bodies. This sewage pump impeller has a structure in which the suction flow channel of closed type non-clog pump is wound in a helical spiral. The focus of this research was to investigate internal flow and radial thrust in this single blade sewage pump impeller. The results clearly indicated the following facts. Internal flow of this pump is very complicated, and a state of internal flow largely changes when flow rate changes. As a result of having compared calculated results with experimental results, internal flow and radial thrust almost matched at the flow rate of design point.

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We propose a new type of propulsive equipment for a ship in this paper. It is directly driven by the high-pressure wave generated by air-propane mixture combustion. The propulsive equipment is a simple structure consisting of a combustion tube and a semi-open-type nozzle. In order to clarify the mechanism of thrust generation, we measured the pressure fluctuation on the nozzle wall and the thrust for various angles of ejecting the pressure wave, and also we observed the flow in the two-dimensional nozzle by using a high-speed motion camera. Water flow in the nozzle is accelerated momentarily by the pressure wave, and the bubble is exhausted to downstream while their expansion. It was clarified that the thrust strongly depend on the nozzle-wall angle, and the thrust for the nozzle-wall angle 4sdegrees is higher than others in this experiment. The thrust of the nozzle was 42N when 400kPa pressure wave driven with added oxygen.

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Performance improvement of micro gas turbine (MGT) by mist cooling was examined. Mist was injected at the compressor entrance, and the rotational speed was change. Gas turbine out put was calculated from the compressor inlet and outlet temperatures and the turbine inlet and outlet temperatures. The performance of the MGT was calculated by the simulation, where the mist flow rate and the air-fuel mixture ratio were changed. The calculation showed that mist did not evaporate completely at the experiment. However, it was demonstrated that mist is very effective for cooling of the compressor and the turbine. Mist has decreased the compressor input. Then, the output of MGT has increased.

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The authors conduct numerical and experimental investigations about the three-dimensional thermal convection in a cubic cavity heated below in the gravitational field. Frequency responses are analyzed numerically concerning global quantities such as spatially-averaged kinetic energy, spatially-averaged internal energy and the Bejan number. We assume incompressible fluid with a constant Prandtl number Pr=7.1 (water) and Pr=130 (silicone oil). Tested Rayleigh number Ra is varied from 5.0x10^3 to 8.0x10^4. A set of the full Navier-Stokes equations with the Boussinesq approximation and an energy equation are solved by a finite difference method based on the MAC method with a staggered computational grid. As a result, the authors find the existence of one optimum frequency where we get the maximum frequency response, and find the relation between the optimum frequency and Ra. In addition, experimentally, the authors check their computation, using thermo-graph technology at P =2500 (silicone oil).

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Radial flow phenomena in a disk-shape channel which simulate a disk-shape planar-type Solid Oxide Fuel Cell(SOFC) was investigated experimentally and numerically under the same condition. In the planar-type SOFC, a reduction of thermal stress is one of the important issues. A temperature distribution in the planar-type SOFC is strongly affected by the gas flow behavior, and hence we tried to clarify flow pattern at various mass flow rate by using Particle Image Velocimetry(PIV). In the present study, it was found that a uniform flow distribution in the fuel channel was attained in the case of the Reynolds number of about 7. On the other hand, non-uniform flow distribution was enlarged with increase of flow rate in the air channel. Results of numerical simulation were in close agreement with experimental measurements. These results suggest the necessity of improvement of the channel shape.

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The siphon phenomenon is widely used for the transportation system of water and it is very economical and easy on the environment because the natural energy is only used for the power source of the transportation system. In the present paper, the feature of a siphon phenomenon induced by a water jet was numerically and experimentally investigated. In order to investigate the influence of jet velocity and flow passage configuration, numerical simulations were carried out for three kinds ofjets and four kinds of tube configurations. From computational results, the jet velocity was strongly influenced for the appearance of the siphon phenomenon. The configuration of the flow passage was clearly influenced in the case of slow velocity of the water jet. When the orifice location was low, the appearance of the siphon phenomenon became early. The similar tendency was also obtained from the experimental results.

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The purpose of this research is to search a new method of dispersing heavy oil which gives detrimental effect to natural environment and ecosystem of sea. In this research, we compared the experiment that ejects water jet to the diagonal 45 degrees from the water inside to heavy oil (underwater jet) and the experiment that ejects water jet vertically to heavy oil on the water surface (in-air water jet). The present experiment showed that the latter is better than the former. The previous experiment showed that the scatter of data was large. We examined the effect of water jet again and confirmed reliability of the experiment. To examine whether the in-air water jet generates cavitation bubbles, the experiment to compare the pressure distribution of in-air water jet and the underwater jet impinging on a horizontal surface. The shape of the pressure distribution is obviously different. From this, when the water jet is ejected in air to the water surface, the cavitation is not generated. Heavy oil is dispersed and emulsified by shearing force of water jet and guide plate

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The diffusion of water vapor from semi-infinite flat porous plates has been studied by numerical analysis and experiments. The flow regarded as binary mixtures of vapor and dry air was assumed to be steady, two-dimensional and Boussinesq incompressible. Due to the temperature and the concentration differences between the pores and the ambient air, mass is transported by convection and diffusion. From the numerical and measured results, influences of the pore sizes and the spacing on the evaporation rates and the stream were discussed. Application of the results from plant leaves is demonstrated.

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Effects of ultrasonic vibrations on turbulent (Re=7000±50) square-duct flow were investigated experimentally by means of LDV. Ultrasound was introduced into the flow by Langevin PZT-type transducers attached to the trapezoidal horn. Three cases of horn arrangements were investigated: the horn is located at the sidewall near the bottom, at the corner between sidewall and bottom, and at the center of the sidewall. Driven frequency and power supplied to transducers were 45±2 kHz and mainly 20 W respectively. Results show that acoustic streaming varies the distribution of Reynolds shear stress, and its change is explained by conventional momentum transfer theory. The experiment varying ultrasonic power shows that the region of ultrasonic vibration can be adjusted in case that the horn is located at the sidewall near the bottom, since this case is less affected by inertia of main flow compared with other cases.

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Recently, it's necessary for saving energy of air-conditioner to reduce fan noise. In this study, the new type of cross flow fan is developed, which has pretty high performance of noise reduction. That new fan is called "saw-edged blade fan" whose blade has a lot of cutouts. In this paper, PIV (Particle Image Velocimetry) measurement is carried out to analyze the flow structure of blade passage of the fans, and it's found out that the decrease of wake by saw-edged blade effects the noise reduction of the fan.

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A numerical simulation is conducted to clarify the mechanism of total temperature separation in the vortex tube. The supersonic jet flow simulation is performed to validate the numerical simulation code. The flow structure and the acoustic characteristics of the oscillation modes for supersonic jet are in good agreement with past experimental resuts. Multiple computational domains are created for complicated geometries of the vortex tube, and the flow field is solved using the zonal mehod. The flow structure in the vortex tube can be successfully captured in this simulation. The existence of the acoustic streaming was clarified and the temperature difference caused by the total temperature separation in qualitatively good agreement with that of the experiment.

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