In the partial admission stage of steam turbines, a flange is placed to separate the nozzle box. The flange makes a large wake which causes the partial admission loss and the ventilation loss. Additionally, it causes a rotor lift oscillation which gives an extra stress to rotors. This paper presents a numerical study of unsteady flows in a partial admission stage. Seven cases with a different flange thickness were simulated. Thicker flanges resulted in better total efficiencies.

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Unsteady 3-D flows through two-stage stator-rotor cascade channels in two steam turbine models developed by Mitsubishi Heavy Industry (MHI) are numerically investigated. In low pressure steam turbine cascades, steam flows generate water droplets mainly due to homogeneous nucleation. The mass generation rate for water droplets is modeled as a sum of the mass generation rate of critical-sized nucleus and the growth rate of a water droplet based on the classical condensation theory. The total pressure, the static pressure, and the yaw angle in span-wise directions obtained by the 3-D calculations are compared with the experimental data.

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Our research group has proposed a numerical method for supercritical fluids; Supercritical-Fluid Simulator(SFS). In this paper, supercritical carbon dioxide flows impacting on a flat plate through supersonic nozzle are calculated using SFS and the flow features changing inlet pressure, inlet temperature and the distance to the flat plate are comparatively investigated. Especially, it is noted that the density in the nozzle is rapidly changed and is deeply dependent to the inlet boundary conditions.

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Low pressure exhaust hood is one of the important parts in steam turbines, since the aerodynamic loss of exhaust hoods is nearly the same level of the loss of stator and rotor blading in low pressure steam turbines and there seems to be not little room remained for the enhancement of steam turbine efficiency. This paper presents the result of exhaust hood CFD analyses using last stage exit velocity distributions measured in the real scale development steam turbine as the inlet boundary condition to improve the accuracy of the CFD analysis.

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A new type of closed-cycle gas turbine which uses supercritical carbon-dioxide (SC-CO_2) as a working fluid was proposed and has been studied in these days. It is supposed that the behavior of SC-CO_2 will be different from that of perfect gas because the thermal properties of SC-CO_2 will change dramatically according to the slight changes of temperature or pressure in compressors. Analysis of the flow field in compressors is needed in order to operate compressors stably and to design blades optimally. In this paper, two-dimensional nozzle flow was simulated in order to confirm that the scheme can analyze the behavior of SC-CO_2 stably. Then the flow field of SC-CO_2 in a centrifugal compressor was simulated under several conditions. As a result, entropy generation was noticeable near the vortex induced by the tip leakage flow and this caused pressure loss. So it is assumed that pressure loss leads to the dynamic changes of thermal properties and to the shift to the low-density fluid locally.

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Effects of swirl brakes on the leakage flow in a centrifugal impeller shroud were investigated by using CFD simulations. Different types of impeller shrouds with or without swirl brakes were modeled and the leakage flow was simulated. Simulations showed that swirl flow strongly interacted with the swirl brakes and that the interaction resulted in rapid and effective loss of angular momentum of the leakage flow.

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In the present study, for the efficiency improvement of the centrifugal compressor for the turbo chiller in the part load region, the flow control device that had variable vane in the middle steps of the centrifugal compressor for the turbo chiller was developed. It was confirmed from the numerical simulation and experiment that the stall of the second stage impeller was suppressed and that higher efficiency was obtained in the part load region.

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In order to improve the performance and operating range of centrifugal compressors, it is indispensable to understand unsteady behavior of vortical flows. In this paper, the flow fields in a centrifugal compressor with single splitter blades have been investigated by Detached Eddy Simulation(DES). The simulation showed that the vortex breakdown occurred in the tip leakage vortex of full blade and discharged a part of the leakage vortex interacting with a horseshoe vortex around the leading edge of splitter blade. Moreover, the horseshoe vortex interacted with the leading edge of adjacent full blade periodically. It means that such unsteadiness of flow fields inside the impellers affects total performance characteristics.

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A low solidity cascade diffuser (LSD) shows features of a wide operating range and a high pressure ratio in centrifugal compressors and blowers. It was shown in the authors' previous steady flow analysis that formations of the stable and intense vortex in the shroud tip-groove and the secondary flow moving circumferentially along the shroud wall toward the impeller exit are the key factors for achieving a high LSD performance at small flow rates. In the present study, the effect of unsteadiness of the jet-wake flow on the formation of strong vortex in the tip-groove and the secondary flow moving circumferentially on the diffuser wall were investigated by comparing the simulation results between unsteady flow analysis and steady flow one. It is clearly shown that the lift force of the LSD blade fluctuates periodically with the blade passing frequency, however, the flow behaviors of the vortex in the tip-groove and the circumferentially moving secondary flow are little affected by the jet-wake flow.

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Grid generation technique and boundary conditions are studied to calculate accurately the flow fields for supersonic turbine cascades which have a low solidity and a high stagger angle. A structured multi-block structure is used with an offset periodic grid around a blade to reduce skewness of the grid for highly staggered blades. Nonreflecting boundary conditions based on two-dimensional characteristic theory proposed by Giles are applied for supersonic inflow and outflow to avoid spurious nonphysical reflections of shock waves at the boundaries. The effectiveness is confirmed for a supersonic aerofoil of a moving blade of the last stage of steam turbine.

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In a compressor and a turbine blade passages, there exist a number of vorticies such as horseshoe vortex and passage vortex. They lead to large loss. Tip leakage vortex is one of such vorticies, and accounts for about 30% of all loss in a turbine stage. In the present study, we perform numerical simulations for the flow field around a turbine blade with/without jet injection from the tip platform. The effects of injection on the blade performance are clarified..

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The measured thrust in the test facility is affected by secondary airflow and the thrust is different from gross thrust. Thrust correlation parameter between outdoor and test facilities is called cell factor. In this paper, CFD application for cell factor prediction has been investigated. Both overall test cell model and outdoor cell model are analyzed by CFD. The results are compared with measurement's aerodynamic parameters, which are cell bypass ratio and front cell depression, in the test cell and are agreed well. In addition, it is checked that CFD also predict cell factor precisely.

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A LES based on the FVLBM (Finite Volume Lattice Boltzmann Method) was applied to a simulation of the flow around a low-pressure turbine airfoil. The result was compared with the result from a conventional Navier-Stokes based LES as well as the experimental result. FVLBM- LES obtained the result comparable to the Navier-Stokes based LES, and provided a good agreement with the experimental result. FVLBM-LES succeeded in capturing the occurrence and behavior of vortices in laminar separation, transition, and turbulent reattachment processes.

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With increasing focus on global environment and energy, sustainability of aviation is becoming one of substantial challenges in world transportation, especially considering significant increase in future air transport demand. Firstly, this paper describes impacts on global/local environment and energy of aviation, then discusses about recent governmental and civil efforts to reduce such impacts, including studies on the use of alternative fuel. Overviewing some future civil air transport concepts, technical challenges in aerodynamics are addressed, emphasizing aerodynamic drag reduction techniques.

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The critical problems preventing a supersonic commercial transport going into service are the creation of sonic boom and poor fuel efficiency caused by large drag, both derived from shock wave. The "supersonic biplane theory" has been proposed to alleviate these problems. Previous research showed supersonic biplane wing can cancel out and reduce shock wave causing these problems. On the other hand, considering takeoff and landing, the low speed characteristics of the supersonic biplane is to be investigated. In this research, two-dimensional test was conducted to measure the lift and profile drag. The values were derived by integrating the static pressure measurements over the wing. Then the obtained results were compared with the computational results.

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This research focused on the "width of wind velocity", which is the standard deviation of wind velocity, as a new index for detecting Clear Air Turbulence (CAT) form the lidar measurement data with noise. In order to comfirm the detectability of the CAT by the width of wind velocity, it was compared with the time history of perpendicular acceleration that shows the shake of airplane. And, to expand the measurement range of the width of wind velocity, spectrum fitting method was applied to the measurement data and its effectiveness was investigated. As a result, width of wind velocity was confirmed as a valid index for detecting CAT and the effectiveness of spectrum fitting method to expand measurement range was proven.

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Airships with small horizontal cross-section and tall height are proposed. Such vertical airships have a remarkable advantage with respect to available locations for landing and mooring. Envelopes of vertical airships for flight experiments were manufactured and flight experiments were carried out. Aerodynamic characteristics of vertical airships are discussed.

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The noise from aircrafts at takeoff and landing has been regulated in all over the world airports. Now, aerodynamic noise from airframe such as a landing gear has been a problem. To analyze the aeroacoustic sound around a landing gear, we adopt aerodynamic/acoustic splitting method. We use a BCM three-dimensional incompressible solver as a flow solver and Curie's equation as aeroacoustic analogy and estimate the far field sound level. The present approach is then applied to JAXA-LEG model with the different components. The flow simulation and far field noise level is compared with experiments and numerical simulations to evaluate the usefulness and limitation for a future noise analysis around a landing gear.

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Conjugate heat transfer method was implemented in the unstructured-mesh CFD solver to predict the thermal loads of the two- and three-dimensional cooled turbine blades. In this simulation, the fluid domain and the solid domain are solved simultaneously satisfying the equality of the heat flux and wall temperature on the boundary of the fluid and solid. The results of the surface temperature and the external heat transfer coefficient distributions are in close agreement with the experimental data especially in the two-dimensional calculation.

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Wavelet analysis was applied to the prediction of flow separation from airfoil. Velocity fluctuations on the surface of the NACA631-012 airfoil at the attack angle of 5 degree were measured by a glue-on type hot-film probe in various chord positions. Morlet wavelet has the advantage to educe unsteady fluctuation over other signal analyses. The coefficient of the Morlet wavelet showed the change of the wavelet scale related to the precursor signal of flow separation. The result suggested that the wavelet analysis was a possible approach to predict and control of flow separation.

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The impulse density in wavelet space is derived from two-dimensional incompressible flow fields by a continuous wavelet transform. Furthermore, a sequence of dipoles is extracted from the impulse density by a recursive operation. Graphical representation of dipoles illustrates various flow structures. Results of dipole decomposition of two-dimensional turbulent flows include many columns of dipoles which illustrate jets.

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A compression method using discrete wavelet transform (DWT) is developed for CFD result data. DWT, quantization, and entropy coding are used for the compression. The DWT divides three-dimensional flow field data into eight areas; one is the approximation part and the others are the detail part of its original data. This compression method is applied to large-scale flow field data, obtained by the Building-Cube Method (BCM). The BCM is a block-structured Cartesian mesh solver, and the computational domain is composed of assemblage of various size of building blocks. In the quantization process, quantization bit rate is variable according to the approximation/detail part set by the DWT and the block size set by the BCM. The computational result are successfully compressed, keeping the quality of the data.

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In order to know the fluttering mode of the multi-articulated flat plate, the image processing technique was used. In that technique, wavelet transform was tried to apply to detect the moving body and focus points. In this study, Daubechies N2 wavelet was used for the detection. In this study, amplitude distributions and trajectory curves were investigated for the fluttering mode. From the result, the images by using wavelet transform show clearer distributions and curves than the composite images without detection. It was found that there were two modes in the fluttering mode of articulated flat plate. The trajectory curves of the articles and trailing edge showed the figure of eight.

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To reveal the flow characteristics of the jet flow issuing from circular pipe, affected by the reciprocal oscillating flow, the velocity measurement of the jet was performed by using PIV method. The reciprocal oscillating flows issue from two circular pipes placed at both side of the free jet. And these flows have the contrary phase each other. Moreover, in order to investigate the coherent structure of the jet flow the continuous wavelet transform was conducted using the fluctuating velocity obtained from the PIV. As a result, it has been clarified that the jet diffusion is promoted by adding the reciprocal oscillating flow. Moreover, it has been also found from the results of wavelet analysis that the adding effect of the reciprocal oscillating flow appears in the band of the relatively low frequency.

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As a part of study on the diffusion control and the direction one the diffusion of the jet flow issuing from the pentagonal duct with and without the synthetic jet actuator was studied by using the hot wire anemometer. As a result, it has been found that the width of the jet with synthetic jet becomes large, comparing with that of the normal pentagonal jet. Moreover, to investigate the coherent structure of the jet flow, the continuous wavelet transform was conducted using the information of the fluctuating velocity. As a result, it has been found that there exists the difference of the flow structure between the pentagonal jets with and without synthetic jet.

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The multi-scale structures of turbulent wakes generated by three kinds of body (circular cylinder, square cylinder and compound of cylinder and square cylinders) have been experimentally investigated in this study. Firstly, the instantaneous velocity fields and vorticity were measured by PIV technique in a circulating water channel. Then a two-dimensional wavelet multi-resolution technique was used to analyze the instantaneous vorticity measured by PIV, and turbulence structures were decomposed into a number of subsets based on their central frequencies, which are linked with the turbulence scales. Vorticity of various frequencies were examined and compared between the three generators.

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The present study focuses on the wings of dragonfly, by which dragonfly has sluggish speed of flight and high capability of flight. Actually the structure of dragonfly wings is not the streamline but the asperity. In the this study PIV is used to measure to flow velocity around the section model of the dragonfly wings, as to extract the effect of the surface structure on boundary layer. In addition, the section of the actual wing is quantitatively analyzed by wavelet transform. Three section models of wings, a streamline model, and the flat model are used. Based on the wavelet transform, it is found that the asperity of the dragonfly wings consists of large- and small-scale wave. From PIV, the asperity of the leading edge has strong effects on the flow and control the boundary layer.

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An optical fiber, which is widely known in optical networking, has a great and hidden potential for measurement. For example, an optical fiber probe is very useful and reliable in measuring bubble/droplet diameter and velocity. The single-tip optical fiber probe equipped with a micro groove processed by a femtosecond pulse laser is able to measure diameters and velocities of tiny droplets accurately. Furthermore, surface tension is easily measured by using the optical fiber probe equipped with a well-processed wedge shape sensing tip. The two-tip optical fiber probe equipped with a vapor deposit platinum layer measures droplet diameter, velocity and pH. In this paper, the author outlines these advanced optical fiber probes and their measurement principles.

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A Probe type PIV was developed in order to investigate behavior of liquid droplet in a steam turbine. Basically, this probe is composed from both a light sheet optics system and a bore-scope with purge function. The outer diameter of this probe is 〓48mm and length is 925mm. This probe can estimate particle size from relation between the gaseous phase velocity, the liquid phase velocity, and the liquid droplet size. This relation was derived by the wind-tunnel test. Furthermore, it was shown that the liquid phase velocity is measured with appling of the PIV probe to steam turbine, the gaseous phase velocity is measured using a pitot tube, and liquid droplet diameter can be derived. As a result, that the droplet size in main stream is larger than the droplet size atomized from trailing edge.

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To measure small size bubbles in gas-liquid two-phase flows, we have already developed a Single-Tip Optical fiber Probe (S-TOP). Our purpose of this study is to reduce the errors in a bubble measurement by the S-TOP, which is caused by random positions pierced by the S-TOP. To realize it, we pay notice to a pre-signal. This signal appears sharply, just before the S-TOP tip touches the bubble center region. Using this, we can easily detect the pierced position. The difference of chord lengths measured by the visualization and by the S-TOP was improved within 5 %. In this study, we conducted the experiment in which the S-TOP pierces bubbles under various conditions of the bubble orientation. We confirm that one can extract the signals that the S-TOP vertically pierces the bubble center region.

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Impedances are measured inside a container filled with only water, and filled up stationary particles by impedance spectroscopic method. The method uses alternating current with the renge of from 1kHz to 2MHz. An equivalent circuit from the relation ship between frequency and impedance is obtained by using the complex spectroscopic impedance method. The aim of this research is to investigate whether the resistance components such as resistances of a particle itself and water itself, a resistance of a particle interface, a resistance of a electrode interface are separable. Resistance particle is larger than the resistance of water. As, the distance between electrodes is increased, the resistance is increased. Because particle interface resistance is the capacitance, as the distance between measurement electrodes are increased, resistance decreased inversely. The electrode interface resistance is not concerned between electrodes, however both conditions become almost fixed values.

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We have conducted laboratory experiments on the flow past a circular cylinder moving beneath an air-water interface. The vortex street and the free surface profile are visualized for Reynolds number between 200 and 15,000 and for Froude number between 0.01 and 3.2. At large Reynolds number (> 10,000), the surface deformation becomes substantial in the downstream of the cylinder and bubble injection is observed. The Strouhal-Reynolds number relationship with gap ratio between 0.25 and 2.0 which shows the period of the vortex shedding becomes long when the gap ratio is small.

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Most of unintrusive velocimetry techniques utilize fine tracer particles to measure fluid velocity. The addition of tracer particles in multiphase flows induces not only errors due to their imperfect followability but also flow disturbance due to their accumulation at gas-liquid interface. Molecular tagging velocimetry (MTV) is one of recommendable methods to remove these difficulties. Some applications of MTV are introduced to demonstrate its advantages.

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Our purpose is to elucidate the relationship between the bubble motion (zigzag motion and shape oscillation) and its surrounding liquid motion (obtained from Stereo PIV). We examined a zigzagging ascent bubble of 2.9 mm in equivalent diameter. At first, the surrounding liquid motion of the bubble was obtained quantitatively via Stereo PIV. Second, tomographic measurement of Stereo PIV was carried out in order to obtain the 3-D structure of surrounding liquid motion. From the Stereo PIV results, the relationship between the bubble motion (zigzag motion and shape oscillation) and the surrounding liquid motion was discussed. From these results, at y-z plane, it was considered that the asymmetry of the shape oscillation resulted in the velocity difference between the right and left sides of the bubble. Therefore, the bubble changed its direction of the motion due to the liquid-phase velocity difference between the right and left sides of the bubble.

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The purpose of this paper is to investigate the relation between the acoustic streaming around a acoustically levitated droplet and the rate of mass transfer. External flow structure of a levitated droplet is measured observed by using PIV technique. We measure a external flow structure around a water droplet with several kinds of diameter at 162dB of sound pressure. Also, we observe the evaporation behavior of the levitated water and ethanol droplet. The droplet diameter decreases with d^2-raw and it is qualitatively in good agreement with the theoretical prediction. It is indicated that flow field around a droplet affects the rate of mass transfer.

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Bubbly flows are applied in many industrial applications. For the purpose of improving industrial bubble column reactors, a deep understanding of the large-scale structure of the flows is required. We have experimentally approached it by using a large-diameter vessel (380mm in diameter and 1500mm in height), Four-Tip Optical-fiber Probe and LDA. We carried out simultaneous measurements of point-wise void fractions and liquid-phase velocities at the same point. We quantitatively extracted the long-period fluctuations of both phases and characterized the flows in the large vessel. Furthermore, we measured spatial correlations to estimate integral scale. We quantitatively obtained a close relationship between the fluctuations in both phases.

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The electrostatic levitation is utilized as one of the containerless processing techniques. Some recent investigations focus on thermal property measurement of high temperature molten metals with an oscillating droplet method. For example, viscosity has been estimated from the damping constant. However, this method is limited to the low viscosity fluid. Thus, the purpose of the present study is to develop method of wide viscosity measurement on a levitated liquid droplet. In the present study, the droplets with kinds of viscosity were levitated by the electrostatic force. Droplet deformation was induced by applying rotation. The followings are obtained connection rotational breakup and viscosity. The observed dynamics indicated that it is possible to measure physical property of levitated droplet.

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Yearly, concerns on environmental problem of the earth are growing on. One of the typical issues is desertification. To inhibit harmful effects of desertification, the prediction methods which clarify mechanism of desertification are required. It is expected that numerical simulations are useful for the purpose. However, the numerical procedure and the physical models for predictions have not been established yet. Hence, our purposes are to construct the holistic simulation technique which reasonably reproduces a sand transfer, and to apply it to create an effective prevention method of desertification. The present target of our computation is wind tunnel experiments of sand transfer around a cube on the sand surface conducted by Tominaga (2007). Numerical results are compared with the experiments. In the computation, we confirmed that the results are quantitatively similar to the experiments, for example, the eroded sand height around the cube.

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In this study, the fundamental three dimensional particles manipulation properties with a dielectrophoresis (DEP) are investigated by a particle tracking method and a deconvolution technique between planar parallel electrodes in a minichannel. These properties are important to develop three-dimensional particle separation and classification systems for medical and industrial applications. As results, three dimensional particles behavior with a DEP force near planer electrode are observed and the effect of the electric field intensity and frequency on the particle velocities are clarified.

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The purpose of this study focuses on measuring the particle velocity and concentration characteristics in a horizontal pneumatic conveying. The test pipeline consisted of a horizontal smooth acrylic tube with an inside diameter of 80 mm and a length of about 5 m. The polyethylene spherical particles of density 978 kg/m^3 and 952 kg/m3 with diameters of 2.3 and 3.3 mm are used as conveying materials. PIV was first developed to measure the time-averaged particle velocity and was proven to be an efficient measurement technique in the pneumatic conveying. Then the particle velocity and concentration distributions of three locations were measured at mean air velocities of 12 m/s and 13/w/s and the solid mass flow rates of 0.45 kg/s and 0.43 kg/s. A comparison of the particle velocity and concentration profiles between the particles d_p=3.3mm and 2.3mm was performed. It is found that the higher particle concentration is observed near the bottom of pipeline at three locations. The particle velocity of d_p=2.3mm is lower than that of the particle d_p=3.3mm at three locations in the lower part of pipeline.

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This paper discusses the new role of Electrical Capacitance Tomography (ECT) in investigating the temperature distribution during phase transformation of the polycarbonate resins. The mean objective of this study is to measure the heat intensity and to track the temperature distribution during heating process of the said resins. The polycarbonate resins were placed inside the beaker with 12-electrodes array circumferentially mounted inside on it. The other ends of the electrodes were connected to the ECT. Heater plate was placed between beaker and heater to avoid cracking. Heat has been applied with 10 minutes allotted time. The electrical properties of the resins, relative permittivity in particular has been gathered through ECT and were fed to the computer where in images have been displayed that shows heat intensity and temperature level occurs to polycarbonate during phase change. The temperature value in a particular point radius has been calculated out of the relative permittivity using the Clausius -Mosotti equation. It was found out in this experiment that the relative permittivity greatly varies with temperature. ECT is not only suitably excellent in measuring electrical properties of a certain material(in this case polycarbonate) but it is also applicable to use in tracing the path of one of the most important thermodynamic parameters such as temperature.

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Wind tunnel experiments are carried out to investigate the interference effect of T-shape fin on the galloping of square cylinder with a side length d. As the T-shape fin, a rectangular-plate of spanwise width w=d and cross flow height l_d is fixed to the downstream side of the square cylinder at the mid span with a thin bracket plate. The gap between the plate and the cylinder is adjusted by the bracket length s. T-shape fin of l_d/d<2.0 effectively suppress galloping when 1.4<s/d<2. While, T-shape fin of 1.0<l_d/d<1.5 induce the large amplitude vibration when s/d<1.4. Maximum amplitude of this vibration becomes about 2.2 times of galloping at around s/d=0.3. The amplitude at s/d=03 increases divergently with flow velocity. This oscillation is called "Wake Body Interference Fluid Elastic Vibration (WBIFEV)" to be reasonable, because this vibration is caused by the fluid-elastic instability but not by a periodic vortex shedding.

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A crisscross arrangement downstream strip plate enhances Karman vortex induced vibration of a circular cylinder and a square cylinder under certain conditions (EKVIV). Wind tunnel experiments were carried out to investigate influence of the strip plate width w and length l_d on EKVIV. When w/d < 0.5 and l_d was enough long compared with the cylinder characteristic length d, KVIV of the circular and the square cylinder was enhanced, while wider plates can suppress KVIV. In addition, EKVIV occurs on the square cylinder when l_d/d &le; 6 though w is broad that is w = d. Spectrum peak values (S_u)_<peak> and spanwise cross correlation R_<12> of velocity fluctuation, which corresponds to Karman vortex shedding, were measured to reveal change in wake flow. When w/d < 0.5, (S_u)_<peak> increases in range of 0.4 &le; s/d &le; 1.4. When w/d = 0.5 and 0.8 &le; s/d &le; 1.4, R_<12> increases all over spanwise except the cylinder and the plate crossing.

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A noise becomes a problem for a Bernoulli type adsorption pad. Three improvement was carried out for the adsorption pad, and a noise reduction was carried out. To begin with, a diameter of a nozzle was changed. Next, a diffuser which slowed a speed of a flow was attached. Finally, a nozzle which eased a gradient of a shear layer was attached, and a noise was reduced.

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Pitching stability characteristics of land vehicle were assessed by conducting large eddy simulation of flow past the simplified vehicle models. Forced-sinusoidal-pitching oscillation was imposed on the vehicle models for the probing of their dynamic responses. Predominant flow structures around the real land vehicles, and the trend associated with pitching stability characteristics were successfully captured by the simplified vehicle models. The configuration of curved front pillar coupled with sharp-edged rear pillar produced a trend for unsteady aerodynamic force to restrain the pitching motion, while the presence of front pillar vortices, which is associated with sharp-edge front pillar configuration, resulted in a tendency for enhancing the pitching motion.

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