It has been investigated that an open-channel flow with a relatively large-scale side cavity exhibits water surface oscillations in spanwise or streamwise directions. Such oscillations, once occurred in actual river installing a side cavity zone as a water-friendly facilities in the urban areas, may cause flooding, resulting in a large damage in the residential area. In order to investigate the flow features associated with such surface oscillation, the authors have developed a 3D LES model that utilizes a density function for detecting air-water interface. With the developed model, it becomes possible to simulate time-dependent water surface variation with a reasonable accuracy as compared with the experiments. In this paper, local flow features along the interface between main channel and side cavity zone are investigated by distributing virtual tracers following the 3D flow pattern.
In the present study, we developed the discriminator PIV and PTV systems (D-PIV&PTV), in which fluid tracers and sediment particles were discriminated reasonably by their occupied particle sizes, and thus, the velocities of particles and fluid could be measured simultaneously. As the results, we have investigated experimentally the sediment effects on coherent motion of kolk-boil vortices in suspended sediment-laden flows over sand dunes by using these D-PIV&PTV. In particular, it was found that the kolk-boil vortex has a significant relation with the local distribution of suspended sediments near the reattachment point behind the dune crest.
It is important in river environment and hydraulic engineering to reveal the hydrodynamic properties in vegetated open-channel flows, in which velocity profiles are largely changed in the vertical and spanwise directions. In particular, vegetated canopies generate coherent turbulent motions (such as sweeps and ejections) which promote erosions and depositions of sediment on beds.Therefore, it is needed to investigate these turbulence mechanism and coherent vortices in order to maintain the vegetations in actual rivers. In this study, we conducted turbulence measurements by using PIV technique, and revealed the turbulence structure in open-channel flows with vegetated canopies.
In Recent years, flood disasters are frequently taking place where relatively steep slope rivers meet in the mountainous area. The cause of the disasters is mainly due to the sudden rise of water level at a confluence, which sometimes accompanies a hydraulic jump in the upstream region. In this research, a numerical simulation based on the shallow water equations and the unstructured grid system is performed to investigate the effect of the discharge ratio to the flow patterns at a confluence. In order to simulate a river confluence in the mountains, the main channel slope is set at 1/80 with a tributary channel slope of 1/40. Laboratory experiments are also conducted to provide data with respect to water surface profiles. Water surface velocity distributions are obtained by an imaging technique, LSPIV, using a high vision video camera. It is made clear that general flow features calculated by the simulation model agree fairly well with the experiments including the location of hydraulic jumps.
The reflected light image method has been developed to measure unsteady wave height distributions. In this method, the gradient vector distribution of water surface height can be obtained through image analysis. And the wave height distribution can be reconstructed from the measured gradient distribution and a known height at one point. In this paper, we made the following modifications to measure the waves around a model ship :(i) Formulation errors in calculating gradient are modified, (ii) Random pattern and grid pattern are used as the reference images, (iii) A new technique to reconstruct height from gradient is applied. Direct cross correlation method is applied to image tracking. But in the case of a wave having large surface curvature, a point in the reference pattern corresponds to several points in the deformed surface image, therefore we used grid pattern as a reference image and tracked the grid points manually.
It is important to grasp water surface profile when we discuss various phenomena in coastal zone. For example, sediment transport and rip current are determined mainly by the spatial distribution of waves in surf zone. Measurement of sea waves using Euler's method is a general. However it is difficult to determine spatial distribution of waves. We had measured wave profile using experimental water tank without tracers or targets. We generated a few kinds of regular waves and took the pictures by two digital cameras and analyzed the azimuth difference in digital images by stereo matching method.
Pollutants such as biocides, ballast, exhausts and spilled oil and chemicals from vessels are investigated for marine environmental protection by many scientific techniques. We reported the environmental fate of booster biocide from antifouling paints and micro-analysis of particulate matter from diesel engine for environmental assessment. Photolysis of zinc pyrithione (ZnPT) was investigated by HPLC and xenon lamp. Photolysis is main degradation process of ZnPT. The HPLC study successfully identified the photo-degradation products which are Pyridine-2-sulfonic acid (PSA) and 2, 2'-Dipyridyl disulfide (DPS). Exhaust particle from diesel engine were analyzed by Scanning Microscopy and X-ray diffraction. Edge Particles include carbon and oxygen mainly and edgeless particles include CaSO4 were observed. These techniques for speciation were useful tools for environmental fate analysis and risk assessment.
Cloud formations and precipitation are highly-complicated phenomena, and the accurate modeling of them is a crucial subject for meteorological simulations. Recently, we developed a new algorithm, which enables the first-principle simulation of cloud formation process, by introducing a new numerical concept called "super-droplet". In this paper, we report about the visualization of the cloud formation-precipitation simulation using the super-droplet method. The technique to visualize the distribution of all droplets included in a cumulus cloud will be explained, and some application results of it will be also presented for the analysis of droplet size spectrum, cloud motion, and the optical property of cloud, respectively.
Volume rendering is one of the effective techniques for analysis of simulation results which have complex phenomena like as the volcanic smoke. We visualized the results of eruption cloud simulation using MovieMaker which is the high performance movie making software. Three dimensional structures of eruption cloud were become clear using volume rendering function of MovieMaker. In this work, we will report visualization results of large-scale eruption clouds simulation.
The ventilation efficiency by the pressure difference of tower inside and outside, which is generated by wake formed in the leeward side of the tower or by the Venturi effect, was researched by a wind tunnel experiment and a numerical simulation. The ventilation efficiency by wake increased with the increase of wind speed, but was unrelated to the number of open windows. The ventilation efficiency by the Venturi effect increased with the increase of wind speed and of Venturi width. The numerical simulation reproduced the ventilation efficiency of the wind tunnel experiment.
The confluence region downstream of the Katsura River, the Kizu River and the Uji River in Kyoto displays complicated flow patterns depending on which watershed undergoes larger precipitations. The flow characteristics at this location have not been clarified so far due to the complexity of the combining streams. In the present study, in order to obtain the flow features in normal flow conditions, surface flow measurement by using a helicopter is performed. The surface flow is visualized by biodegradable tracers and they are videotaped from a helicopter hovering at about 300 meter height following the cloud of tracers. A high-vision video camera is used for recording the images and the velocity of the tracers are analyzed by applying PIV with subtracting background movement. At the same time, distributions of temperature, pH, and other parameters related to water quality are measured by multi-purpose instrument installed on a boat. It was found that water quality of the Ktsura River is quite different from the other rivers and the longitudinal dispersion of tracers is evident at the location.
In the recent. development off topographical measurement method using laser beams shed from an airplane, high resolution ground data referred to as digital elevation models (DEM) have become available. DEM gives us ground 3D data with a resolution of an order of one meter in the horizontal direction and an order of centimeters in the vertical direction. With such a densely distributed topographical data, the accuracy of runoff analysis would become much better than the previous ones and a more sophisticated analysis would become possible. In the present study, a virtual tracer method is proposed in order to determine the catchment area for an arbitrary location within the river basin. A runoff analysis for a relatively small area in Kobe city is also performed by using the DEM data and locally distributed time-dependent rain zones.
GIS (Geographic Information System) is an effective tool also to visualize regional environment information in bird's-eye view. In this paper, some examples of the examination of the visualization technique to make our WEB site, "Osaka University Yodogawa Basin Project", more rational as an environment-information offer site. They are, (1) Display of the historical change as a diagnostic technique, (2) Selection standard of colors used for visualization, and (3) Display of the multi-dimension information by superposition of colors. Although the example which utilizes WEB-GIS for offer of environment information is predicted to increase from now on, the argument about the function required of environmental GIS has just started. From now on, the further examination will be required.
In this paper, we report monitoring results of water temperature in 24 stream sites of the Ibogawa watershed, Hyogo, Japan. The spatial distributions of the averaged water temperature in the whole watershed show that the temperature gradually increases form the upper stream to the river mouth. The spectrum analysis of temperature time series indicates that the fluctuation component with the period of 24 hour is predominant because of the solar radiation. From the comparison of the equilibrium water temperature with the observed temperature, not only the solar radiation but also other effects such as the heat advection. from the upstream may be important for water temperature prediction.
River bed is composed of movable material such as sand or grain and small or large scale vortices are generated at the bed, which are generally lifted upward making confliction with water surface. The confliction of vortices against the water surface yields surface ripples making water-surface configuration rather complicated. Although there are a large number of researches on rough bed flows, the interrelationship between flow and water surface has not been clarified so far. In order to investigate fundamental features of flows with rough walls, measurements are made for the flows with strip roughness. A numerical simulation by LES is also performed to compare with the experimental results, showing a reasonable agreement with the experiments.
The characteristic of roll-wave flow, which is a flow with high Froude number which appears on the steep slope, is hardly known at present. In laboratory experiment, it was difficult to measure the flow profile which is a thin sheet flow having the characteristic of a wave and a flow. In this study we measured the velocity field of the roll-wave flow using PIV technique. We also investigated the behaviors of the velocity field in each region separated into five parts of one wave length. As a result, the relationship between velocity field and the water depth in each part was clarified. It also appeared that the velocity profile is grater than a log-law profile at every region.
In the numerical analysis of the indoor thermal environment with windows through which solar radiation is incident, it requires much computational time to identify irradiated surfaces. This paper shows the fast algorithm to calculate the wall surface distribution of the solar radiation through the window using the CG technique for the purpose of a prediction of the indoor thermal environment. We developed the fast calculation method of the direct solar radiation using parallel images made by graphics hardware at high speed. The diffuse solar radiation can be calculated by applying PPM (Pyramid Projection Method) that is the fast calculation method of view factors. PPM that we developed before uses perspective CG images. The errors of this algorithm are mainly derived from digitization errors of digital images. It was verified that this algorithms had a possibility to become an effective tool for the analysis of the indoor thermal environments with solar radiation.
Bottleneck capacity is one of the important factors to determine a scale of traffic congestion on expressway. This study examines traffic detector's data to investigate capacity reduction due to sunset. The detector's data are observed at 450 sites on Hanshin Expressway through 2 years at 5-minutes intervals, so size of the data becomes very huge. Visualization approaches are considered as one of the efficient methods to analyse such huge data. To find the sites with capacity reduction and to understand the overview of the reduction phenomena, the diagram named "Traffic Contour Map" has been developed. The diagram is depicted for every observation site, and the sites with capacity reduction are selected. Then the causes of capacity reduction are analysed by the other diagrams named "Dynamic Flow vs. Density Diagram (D-QK diagram)". This paper provides how visualization approaches would be applied to the analysis of traffic flow.
Visualization plays an important role in the utility of satellite remote sensing. This work describes a procedure how to make an image processing system for satellite data using the visualized soft wear (named OpenDX). It is shown that our processing system is independent on the data format and the operating system (OS) of the computing. The visualized 3-D maps for vegetation and/or land coverage obtained from ADEOS/ POLDER & GLI and Terra & Aqua/ MODIS data look promising for environmental monitoring.
We visualized the clay flows of monolithic honeycombs in the extruded process 3-dimensionally with one parallel beam light source using several tools as follows. (1)Transparent clasp made of resin (2)Transparent silicon compounds instead of a real clay (3)Silicone carbide particles as a tracer Observing the real tracer and the shadow of the tracer simultaneously, we found that 1) Clay flows towards a center of a clasp from a edge of the one 2) Clay flows in parallel inside clasp 3) Clay moves from the die side to the clasp side as it flows towards a center of clasp
We have been developing fundamental software which supports to develop a conference system with virtual reality technology. OpenGL Fusion is one of technology that we have developed in the work. The techonology allows us to assemble two or more 3D graphics output in a virtual space. Therefore, what we should do is just to develop 3D graphics software, not need specializing to virtual reality. In this paper, we reports a test when a video avatar and animation software works in a virtual, space at the sametime.
In this study, we examined the effect of the 1/f fluctuation element in sound by analyzing the power spectrum of Heart Rate Variability (HRV) when listening to music. The 1/f fluctuation means the inclination degree of the power spectrum in music. The following four tunes were used in experiment. Sample A dose not contain 1/f fluctuation. Sample C is the reversal play of "Sample A". Sample B contains 1/f fluctuation. Sample D is the reversal play of "Sample B". We measured the HRV of each subject, in the following state. In State 1, the subjects seated with eyes closed under resting condition for 2 minutes without music. In State 2, the subject heard a sample tune for 2 minutes while keeping the condition of "State 1". In State 3, he recovered to condition of "State 1" again for 2 minutes after stopping the sample tune. As a result, The LF/HF values of the reverse-reproduction music were greater than the values of the regular-reproduction music. We confirmed that personal preference (acquired by experience, environment and familiarity) strongly influenced the subject's comfort level more than the 1/f fluctuation element for music.
A very thin water veil like a transparent thin sheet of vinyl has been produced by shaping a double-disk nozzle in such a way to accelerate the water flow inside the nozzle. Comparison of the simulated shape of the water veil with that of the experiment shows that they are almost identical. Human mind can be refreshed and relaxed by being inside of this water veil. In this paper, the application of water veil to healing of mind and body is examined. The analysis of the brain wave data using the emotion spectrum analysis method (ESAM) elicited that the water veil is very useful to recover the freshness and effective to healing of mind and body.
There is no useful method of inspecting the state of surgically amputated bone after an operation on internal organs. This paper proposes a noninvasive method for evaluating the state of fractured bone using speckle interferometry. The method measures the vibration of the skin surface of the body surrounding bone to know the recovering state of fractured bones. The performance test using an imitation bone, a skin and muscular test phantom show that there are detectable differences on speckle images between the cases with bone fracture and those without it.
The aim of this study is to estimate single motor unit action potential (sMUAP) firing time and muscle fiber conduction velocity (MFCV) by surface electromyogram (sEMG). We made the matrix surface electrode of 8×8 that got 56ch sEMG signals. The 56ch sEMG signals were recorded from the biceps brachii muscles during isometric contraction at 20% maximal voluntary contraction. We used Independent Component Analysis (ICA) and the template matching for the identification of sMUAP. By using the results of identification, we estimated sMUAP firing time. As sEMG is interference of many sMUAP, ICA is useful for making it easy to detect sMUAP train. Using the estimated sMUAP firing time, we calculated the averaged MUAP waveforms at each electrode. Finally we estimated MFCV by using averaged sMUAP waveforms.
Blood flow dynamics play an important role in the initiated and developed cerebral aneurysm. In particular, the wall shear stress (WSS) acting on an aneurysm surface is believed to be responsible for the cytological effect leading to the long-term growth of the aneurysm. The present paper describes in vitro measurement of WSS inside an aneurysm model that is generated from MRI and rapid prototyping. The WSS is evaluated from an in-plane distribution of three-component mean velocities measured with the stereoscopic PIV. A WSS evaluation technique applicable to complex three-dimensional geometry like aneurysm is proposed here and its accuracy and validity is discussed.
This paper presents CFD results of steady and pulsatile flow behavior in a cerebral aneurysm and their comparison with in vitro measurements taken with a stereoscopic PIV technique and a miniature pressure probe. A commercial CFD code based on FVM is utilized with a computational grid system that is defined from a 3-D shape of a patient's cerebral aneurysm. The aneurysm considered here has experienced the rapture in the tip of the main body of the aneurysm. Both a long entrance region and a fine mesh near the aneurysm wall are defined in the computational grid system in order to permit a direct comparison with the measurement. The CFD results obtained thus for steady and pulsatile flows show good agreement with the measurements. The CFD results are analyzed and discussed in detail to reveal the flow behaviors that are responsible for the wall shear stress and the wall pressure inside the aneurysm.
Color and luminance expression of artistic master paintings is investigated by a digital vector scope and a wave form analyzer working on the digital reproduction of the original paintings. Examples are taken from the representatives of the 19th century Rococo-romantic school, the Romantic school, the early and late Impressionist schools including the Pointism and Symbolism paintings. The results are then compared in terms of the hue and chroma distribution pattern as well as of the brightness characteristics between two or more paintings.
One of the well known cures for the aortic regurgitateon is a vascular grafting surgery using a composite graft as an artificial ascending aorta and an artificial valve. Although, almost all conventional grafts do not have Valsalva sinus at the aortic root, the influence of omitting the sinus have not yet been clarified. In order to understand the effect of the sinuses at aortic root on the valve characteristics and flow field around the valve and furthermore the coronary blood flow, the authors have fabricated some realistic models of aortic valve using 3D modeling machine, and have investigated the effect of the sinus existence by PIV. As the result, flow into coronary artery around the Valsalva sinus was smoothly than the straight wall model at early diastole. Consequently it was concluded from a standpoint of flow and valve characteristics that the sinus had an important role for the aortic valve and the inlet of the coronary circulation.
Patients who have operation for artificial valve substitution frequently suffer from brain embolism. Micro air bubbles are generated with opening and closing of an artificial valve in such a patient's blood. It is difficult to discriminate air bubbles from emboli by methods using ultrasonic wave. Hence, we tried to develop a new method for discriminating embolus from air bubble in pulsatile blood flow using ultrasound. We utilized the difference in motion of embolus and an air bubble when they are irradiated by ultrasound beam. It is considered that the difference in motion is caused from the difference in acoustic impedance and mass of them. As a result, we succeeded to discriminate emboli from micro air bubbles in pulsatile flows as well as in steady flow in the model experiments in vitro.
Surgery to relieve nasal hypertrophy is always performed without quantitative measurements of the effect on the airflow. In order to build up the objective measuring method of airflow in the human nasal cavity, the 3-dimensional numerical model in the human nasal cavity, concluding the nasopharynx was reconstructed from CT scans of a healthy nose. The airflows of the numerical model at inspiration and expiration as steady flow are analyzed by using finite element method (FEM). As a result, during inspiration, the most airflow in numerical model passed a middle meatus and an inferior meatus. The airflow at expiration also showed the same tendency as that of inspiration. During inspiration and expiration, the airflow in the superior meatus having the function of olfaction was small. Meanwhile, there were articulate differences between right and left nose in point of the velocity distribution and the wall shear stress distribution.
In this paper, a technique of speckle measurement has been developed for evaluating the wetting state on a surface of offset printing plate. The present method can provide not the amount of water supplied to a printing plate, but the information of the wetting state on the plate to automate the system for water supplying in offset printing machine. The experimental results demonstrate that the speckle intensity increases for the wetting state suitable for better offset printing as compared with that for short or excessive water supplying.
To establish a social consensus for disaster prevention, understanding of possible disasters is required. In this paper, we focus on smoke in case of fire and propose a realistic visualization method of volume data sets of smoke obtained from experiments or simulations. The proposed method realizes simultaneous visualization of both density and velocity of smoke by adding details to volume data based on systematic fluctuation reflecting time evolution of a velocity field. An implementation on a GPU realizes real-time visualization of dynamics of smoke.
This paper reports the experimental study on behavior and collapse of micro-nano bubbles to develop a new ballast water treatment technology. The experimental flow system is composed of flow channels, a cooler tank, a pump, a micro-nano bubble generator, and an ultrasonic wave generator. The inactivation effect of marine bacteria of this system is checked by the colony counting method. The effect is related with the collapse of micro-nano bubbles by ultrasonic waves. The schlieren method is carried out to observe the collapse phenomena of micro-nano bubbles in the flow channel. As a result, shock waves are observed around bubbles, and it is found that the collapse of bubbles contribute to the inactivation of the marine bacteria.
This paper presents the clustering algorithm for detected points of slender objects in 3D space using a self-organizing map(SOM) and its test results in numerical simulations. In the 3D measurement of slender objects using digital holography, a lot of object points are detected for each slender object. The present method can identify the detected points for each object to know the object information, such as shape and inclination. The clustering performance is checked in numerical simulations. The simulations employ two different models in which the detected points are isotropically and linearly distributed in 3D space. The test results show that this algorithm can successfully identify several target clusters in 3D space.
This report compares the measurement accuracy of off-axis holographic technique with that of in-line holographic one, in digital holographic particle measurement. Off-axis holographic can separately reconstruct a real image a virtual image and offset to easily measure the object position in 3-D space with accuracy. It is seen in numerical performance tests that the object position can be more accurately measured with off-axis technique than in-line one, and the measurement error is affected by increasing object size and object number density.
It is very important to visualize three dimensional shock shapes around hypersonic vehicles. However, in general, it is not possible to visualize complicated spatial shock shapes by optical systems, such as Schlieren method and so on. In this paper, the method called the electrical discharge method for visualizing such shock shapes has been reported with some examples.
To analyze the flow field around models it is very important to understand the streamlines around the models. However, it has been almost impossible to visualize such streamlines around hypersonic models. Because, the hypersonic flow obtained in laboratory is, in general, very high speed, low density, and short duration. However, methods for visualizing hypersonic streamlines under these experimental conditions have been developed by using the electrical discharge. The principle of the method and visualized hypersonic streamline are demonstrated in this paper.
It is important to visualize the boundary layer over hypersonic models for understanding the flow field phenomena around them. However, it has been very difficult to visualize such boundary layers. Because, the hypersonic flow obtained in laboratory is, in general, very high speed, low density, and short duration. However, a method for visualizing boundary layer over hypersonic vehicles under such experimental conditions has been developed by using the electrical discharge method. The principle of the method and visualized results are demonstrated in this report.
A concept of the new measurement of velocity in subsonic air-flow is shown. This method uses Schlieren method and PIV method using pressure wave image. In this method, the ordinary tracer particle is not necessary because the pressure wave, which propagates in subsonic flow is used as tracer image. This study aims to construct the principle and to mention the merits and demerits of this method. The experimental study in one dimension was done and it was appeared that the result agrees with the theoretical value and the difference is less than 10 percent in this method. We are going to try and evaluate this method in two dimensions.
Conventional PIVs are not always capable of measuring the entire field of two-dimensional flow in rivers and oceans as they often contain an insufficient amount of tracers. However, Gradient-Based PIV using Neural Networks is potentially able to perform these field measurements. In a previous study, we evaluated its usefulness using artificially generated images. Here we apply this method to surface velocity measurements of experimental open channel flow. The open channel was filled with water and its flow was 100mm wide and 40mm depth. The flow rate was kept at a constant value of 60cm3/s. Floating tracers were used to measure the surface velocity. Several images were taken with the tracer population ranging from 18% to 81% of the water surface. The obtained velocity data were compared with those produced by conventional PIVs. As a result, it was found that Gradient-Based PIV using Neural Networks is capable of observing two-dimensional flow even when the tracer population is 18% of the water surface.
In order to develop a calculation method using CFD, computational fluid dynamics, for estimating the hydrodynamic forces and moment acting on ships in manoeuvring motion, experimental data are needed for its validation. Especially, experimental data of flow fields around ships in manoeuvring motion are crucial for developing an advanced CFD code. In this paper, stern flow field data of a container ship model, equipped with a rudder and a propeller, measured by using an 8-hole Pitot probe are reported. The data clearly show wake distributions and vortices shed from the model ship hull in turning motion with oblique angle. The effects of turning rate on the wake and vorticity distributions are discussed. Uncertainty analysis results of the measured data are also presented and validity of the test data is examined.
This paper reports the study on behavior phenomenon of shock waves in water sealed with an aluminum container numerically and experimentally. In the numerical study, the propagation of shock waves in the container is calculated by LS-DYNA using the Johnson-Cook model and the Tait equation. We observe the propagation phenomena of shock waves generated in water part of the container by elastic-plastic deformation of aluminum using the schlieren method. From these results, we examine the complicated propagation of shock waves in the target container.
This paper investigates to what extent the landslides water depth, the velocity of submarine landslides and the landslide slope can change the size of tsunami generated by landslides according to the wave tank experiment using the triangular cross section model of submarine landslides when the volume of a submarine mass movement is constant. The streak lines are visualized by injecting the red ink at several fixed points into water continuously when the cross section model moves down along the slope. According these experimental results it is shown that there are the rising current sources and the tsunami wave height divided by the landslides water depth and landslides water depth divided by the uniform water depth and slope influence the tsunami wave height considerably.
Recently, data transfer rates of optical disc drives have been dramatically increasing. To obtain the high data transfer rates, disc rotation speed and laser power also need to be increased. Therefore, to develop the next generation optical disc drives effectively, enhanced cooling system of the optical pick-up unit which includes the laser diode is indispensable. The cooling performance of the pick-up unit is directly influenced by the inside airflow induced by the disc rotation. Tb maximize the effect of the airflow around the pick-up unit, we applied the combination of PIV (Particle Image Velocimetry) and CFD (Computational Fluid Dynamics) simulation. It was made clear that the tray opening near the pick-up unit increased the cooling performance effectively.
A new model turbo-fan engine for small aircrafts is being developed as a national project. Multiple slot cooling configuration that is a new cooling structure of a turbine blade will be adopted to the engine. Cooling performance of the configuration stays equal to those of traditional methods, but this structure is much simpler than conventional ones. So the cost to make turbine blades will decrease. The representative company in this project, Ishikawajima-Harima Heavy Industries Co., Ltd. (IHI) performed numerical simulation of flow field CFD in a turbine blade and measured cooling effectiveness of this configuration. In this study, cooling airflow in a turbine blade was visualized and flow velocity was measured with the particle image velocimetry (PIV). The purpose of the present study is to confirm usefulness of CFD and to find out some relationship between the flow field and heat transfer. Thus we made a comparison among experimental results and numerical simulation.
In the quenching process, heat transfer behavior will is very complex due to boiling, generation of the bubble by the boiling in the quenchant, flaking off of steam film in metal surface. In this research, the behavior of steam film in quenching process was investigated with high-speed video camera by visualization method. The behaviors of the boiling bubbles including generation and movement as well as the breaking during stirring quenching process were clarified. The flow velocity fields around the quenching parts at no stirring and stirring quenching with various flow velocities on nozzle were investigated. In order to identify the heat transfer coefficients by using of the measured cooling curves of surface temperature. Effects of stirring and oil temperature on breaking the steam film were confirmed.
The quenching of steel products is a heat-treatment technology that improves durability and fatigue strength. In order to control distortion and strain due to quenching, recently, a new technology of gas quenching such as nitrogen gas was developed in mobile car industry. We developed the gas cooling evaluation device that it was possible to be visible of a thermal flow around a specimen during gas quenching at the same time to measure cooling ability of gas to use for cooling. In this paper, the gas flow velocities have been measured in situ using a PIV method (laser imaging method) and compared to gas locations in the cylinders.