Can the economic growth by industrialization and the environmental preservation be achieved at the same time? Japanese industries have worked hard to meet this challenge through severe lessons. During 60's, pollution caused by industrial waste and emission brought environmental degradation and even public health hazard. The development of new technologies and the. implementation of strict regulations have mostly overcome these problems. Drastic energy saving in manufacturing was also achieved prompted by oil crisis in 70's. These achievements, however, have been limited in plants as a whole. Now manufacturers have to pay more attention to 3R (Reduction of energy and resource consumption, Reuse, and Recycle) of each product and its components on the one hand and environmental problems in global scale such as carbon dioxide emission on the other. Radical redesign of products and its manufacturing processes based on PLCA (Product Life Cycle Assessment) is going on. As examples in office automation industry, the life cycle of photosensitive drums and the recycle of copied paper will be mentioned.
Molecules such as ethyl alcohol emit radio waves and cool interstellar gas and cause the gas cloud to contract and finally to form stars. Stars produce heavy atoms to form molecules to emit radio waves. Wine makes stars and stars make wine in the sky. This grand circulation of matter is the fundamental process in the evolution of matteer in the Universe.
A flow field in a gap between two crossed circular cylinders was visualized by the use of tracer particles, and was analyzed by the image processing. The Reynolds number was kept at about 500 for all experiments. The profile of velocity vectors in a gap flow was measured by the particle image tracking vclocimetry. As the results, the characteristics of the vortex structure in the gap was clarified. In the case of smallest gap, there are none of vortices in the gap. In the middle gap between G/d=0.269 and 0.385, the quasi-steady necklace vortex or the periodical necklace vortex is formed. In the critical gap of G/d=0.7-0.8, the quasi-steady twin vortex is formed.
The three-dimensional particle tracking velocimeter (3-D PTV) is a powerful tool for measuring the instantaneous three-dimensional distributions of the velocity vectors. Despite of its significant ability, it can be applied only to the flow field in a simple geometory, because of its complex camera calibration procedure. Although there have been made some modifications that handle the refraction at the glass walls implicitly in the camera parameters, but their applications are still limited to the case of parallel planes. Presently, a new method is proposed that calculates all the refractions at any surface explicitly. Thus, one can avoid the complexity in the camera calibration and can measure any flow field in the complex geometry, if the shape of which is known by the numerics. The principle of the new camera calibration technique and the procedures for the practical mesurement in a circular curved pipe is shown in this study.
Velocity measurement technique through digital image processing of airflow images visualized by smoke particles is applied to the real space. In a measurement of indoor airflow, a laser light sheet is used as the light source and an optical filter is attached on the camera lens to reduce the effects of obstructive light. In a measurement of outdoor airflow, colored smoke particles are used to make tracer image separation easy.
This paper describes SFM(Spatial Filtering Method) which is image analysis velocimetrp for measuring the particle velocity of solid-air multiphase upward flow like that in the riser of CFB. For image analysis as SFM, there are some difficult conditions such as the high particle density and the high particle velocity. This time we developed in the image processing and image analysis program, further repairing in the number of image frames per time. The results also depended on selection of tracer particle which indicated us offering the good image pictures. We reconfirmed that SFM was successful method for measuring particle velocity.
Two or three cameras are generally used for 3-D PTV. But, it is very difiicult to arrange the cameras at indivudual observation points. In general, such a sysytem is complex. So, we discuss the simple system com-posed of one camera and a mirror in this study. And we then propose a measurement method of the position of particles. The present method is as belows; At first we set up the theoreticale quations of optical path using the space coordinates system composed of camera, particles and a virtual image of particles in a mirror. We expand it in a series subsequently and correct it in order to adapt an actual condition. Although it has several coefficients and some correction values which are contained in them, we can calculate easily without the oth-er parameters.
This paper focuses on a quantitative flow analysis around a human body which is based on a flow visualization and a digital image processing. The natural convection induced by a human body was visualized by a smoke method and a technique of laser light sheet (LLS). The quantitative velocity data were carried out from the flow visualization images using simplified density correlation method. Influence of a strong upward natural convection due to the presence of the human body is an important factor in the design of a room ventilation.
A measurement system of wave height distribution using visualized image data has been developed. The light scattering of water and air are usually different, and the difference is obvious when small bubbles or tracer particles are in water. The position of free surface is identified as the boundary of bright and dark part of laser sheet which is given under the free surface. Wave height distribution around high speed craft was measured in circulating water channel. The measurement was much easier than that by conventional equipments.
In the safety analysis of the High Temperature Gas-cooled Reactor, it is important to investigate the density stratified flow field caused by air ingress into top cover filled with helium after primary tube rupture. Three-dimensional density distribution can be reconstructed using tomography technique from interferogram images. Conventional tomography techniques have low accuracy with a few interferogram images. To improve the accuracy of the reconstruction, a new tomography technique is proposed. In the present method, density distribution is assumed to be mainly effected by diffusion processes, and to be expressed as the summation of elementary density distributions. The tomography is carried out as the optimization of the arrangement of elementary density distributions. As optimization technique, genetic algorithm is introduced. With the present method, high accurate density distribution is calculated with a few interferogram images.
The characteristics of a steady flow along a coaxial cylinder with the front step was investigated by means of the pressure measurement on the cylinder surface and the visualization technique of the smoke method at the subcritical Reynolds number. Measurements were carried out with the front step all length vary in size between -10 mm and 20 mm. The negative pressure distribution acts to turn in the step wall for the separation flow from the front edge of an axial cylinder. The pressure distribution of the cylinder surface was compared with respect to the step size ratio. A minimum wake section area of the model with annular step is one half with the no step, then the pressure on the step part is twice negative values of the total pressure at the optimum step.
This study eluidates the onset of wake oscillation and the generation process of the oscillating bubble behind a circular cylinder by visualizing computed results obtained by solving numerically the two-dimensional, time-dependent Navi-er-Stokes equations at the low Reynolds numbers. The zero-streamline begins to oscillate near the rear stagnant point at Re=1-4. A bubble composed of two standing vortices adhered to the cylinder certainly begins to oscillate at Re=5.60-5.6 2. Instability generated by motion of the zero-streamline and the bubble is not transported into the downstream and is the absolute instability, since the flow outside the neighborhood of the rear stagnnant point is completely steady and symmetric at Re≤16.
From the view point of safety and maintenance simplicity, the development of high performance gas cooled gas insulated transformer has been desirable. In this type of transformer, the coolant gas is circulated in the gap between the coils to cool it. The flow pattern of coolant in the flow path strongly depend on its configuration formed by the coil. Therefore, in order to achieve high cooling efficiency of coils and at the same time to reduce the pressure loss, it is important to have sufficient knowledge about the flow behavior in the coil flow path. In the present work, in order to decide appropriate flow path configuration formed by the coil foi its efficient cooling, flow visualization study based on numerical simulation was performed. This study led to the understanding that for the standard coil flow path configuration there occurred recirculating flow covering a region of stagnation which caused increase in coil surface temperature and in efficient for cooling. In order to prevent the occu ?? ence of recirculating flow, a modified flow path configuration is proposed to have efficient cooling.
The wake configuration of a rotating sphere with smooth surface in axial flow was visualized by means of smoke wire method in a low-speed vertical wind-tunnel at Reynolds number of 2600. The test was conducted using the sphere with rotational speed ratio of 0, 1.19, 3.57, and a shedding vortex and a three dimensional wake motion behind the sphere was observed.
Flows around a flat wing with a pitching motion in a uniform flow are investigated numerically and experimentally. The pitching motion is one cycle of oscillaion with constant angular velocity. The flow patterns are visualized by the tracer techniq using Al-pouder. A vortex is generated when the maximum attack angle is larger than 20°. A pair of vortices is found when the maximum angle is larger than 70°. Numerical analysis is carried out and the Navier-Stokes equations are solved using body-fitted grid with moving boundary system. The experimental results show good agreement with the numerical results.
In the low-speed vertical wind-tunnel, flow patterns around the rotating rectangular flat plates with aspect ratio of 1.5, 3.0 and 8.0 were visualized by means of smoke wire method. Then, separation bubble flow near the leading edge of the plates was recoginized clearly, and such flow was compared with the pressure distribution for each plate.
In order to observe the limiting streamline on ship hull surface, the so-called oil film method has been applied by many people. This method always gives clear line on the body surface. In the experiment in circulating water channel, however, a number of small air bubles attached on the hull affect the limiting streamline. This causes misunderstanding of the physical phenomena. This paper discribes a new method for obtaining the limiting streamline on hull surface using image measurement technique, spatio-temporal method, to the oil film on the wall surface. This method also enables to measure the wall friction distribution.
A simple method to estimate skin friction on two-dimensional bodies using both wake survey based on momentum theory and measurement of oil dot streak due to skin friction is proposed. For thin and streamlined two-dimensional bodies like wing sections, drag measured by wake survey can be assumed as skin friction drag. It is experimentally recognized that oil dot streak distribution is resembled that of skin friction and area enclosed oil dot streak distribution represent skin friction drag. Therefore, relation between streak length and skin friction can be obtained easily.
The explanation of the influence of the exit divergent angle of nozzle on the subsonic jet noise is very important. It was found that the jet issuing from the divergent angle nozzle of 10°-30° produced a powerful screech contained the discrete frequencies. To clarify the mechanism in the generation of powerful screech, a flow visualization was carried out by means of the instantaneous schlieren photograph method. It is proved that there is a series of dynamic eddies moving with jet flow near by the exit of nozzle, and it is due to the self-excited vibration occuring in the dynamic eddies region that the powerful screech is produced.
Pulverization devices of toner were studied experimentally as well as numerically in the point of view of fluid dynamics. Supersonic flow, into which raw toner powder is poured through an injector, is injected against a flat plate or a coneshape obstacle. After passing through a shock wave formed in front of the obstacle, the raw toner powder is produced. Based on the flow visualization study together with numerical analysis of the flow field, the velocity field and the pressure and the density distributions are determined. As the results, the optimum shape of the obstacle and the flow conditions are found.
Numerical approach for supersonic mixing flow field with the ramp injection is examined. It is said that ramp injector configurations can enhance mixing efficiency in combustor of ram/scram jet engine, by use of the formation of axial vortex. One of ramp injector types, which consists of alternate compression ramps and expansion troughs, has been studied by I.A. Waitz et al.. Calculation is conducted comparing with the result of the experimental study and calculated flow field was visualized by using particle traces. As a result of this numerical simulation, it was observed that the pattern of shock wave obtained by calculation agreed with experimental results. The formation of a counter-rotaing streamwise vortex pair and vortical roll-up of the jet were captured clearly as same as experimental observation. According to these results, it can be said that the CFD code used in this study has an ability to capture vortex structure formed by ramp injector and that the streamwise vortex generated by the injector is the one of key factors for enhancement of fuel-air mixing in scramjet combustor.
Holographic interferometric visualization was made of diffraction of shock waves using a diaphragmless shock tube. The diaphragmless shock tube, instead of using a conventional rupture diaphragm method, employs a consistently repeatable rubber membrane for separating the high pressure chamber of the shock tube from the low pressure channel, enable to generates shock waves with the very low scatter of shock Mach number ± 0.25%. Making advantage of this shock tube performance, diffraction of shock waves passing through a sharp 90°comer for Ms=1.10, 1.50 and 2.0, was visualized Emphasis was given to the case of Ms=1.50. It is well demonstrated that holographic interferometric visualization together with a reliable diaphragmless shock tube can provide quantitative measurement of entire processes of shock wave diffraction over a sharp 90° comer.
An automated technique for measuring an instantaneous, two-dimensional temperature distribution in water has been developed with a digital image processing system. The thermal field is visualized by laser-induces fluorescence of Rhodamine B. The fluorescence of Rhodamine B decreases with temperature increase. A normalized calibration curve, which is not affected by laser intensity, concentration of Rhodamine B and optical configuration, can be obtained. Uncertainty intervals associated with the present technique are systematically evaluated. A steady temperature field in a rectangular enclosure is measured by the present technique. The instantaneous temperature profile measured shows good agreement with both the analytical solution and the result measured by thermocouples within the experimental uncertainty. An unsteady temperature field is also measured. The mean temperature profile is in good agreement with the result of MIYATA (1978).
For an analysis of supersonic flow, visualization of the flow field structure using LIF of tracers has been employed. In this study, the capability of imaging of supersonic flow using O2-LIPF (Laser-Induced Predissociative Fluorescence) is examined. Since oxygen is one of main component of air, O2-LIPF may make it possible to visualize the air flow in the high speed wind tunnel without the tracer. However, because the visualization of the flow field below the room temperature using O2-LIPF is very difficult, ithas been applied only to the high entalpy and combustion flow, not to high speed flow with low temperature. In this study, the supersonic oxygen flow is visualized by O2-LIPF, using an ArF excimer laser and a high-sensitive CCD camera. If long exposure time (1200 seconds) of the CCD camera is set and the scattered laser beam is suppressed sufficiently, the supersonic oxygen flow below the room temperature using O2-LIPF can be imaged successfully.
To investigate the transonic three-dimensional flow-field with complicated shock wave-boundary layer interaction, the laser-induced fluorescence (LIF) method was developed. This diagnostic system was based on the argon laser with seeded iodine as fluorescence material, and was applied to the rectangular duct with a swept-back bump. The temperature distributions in the duct were obtained, and the structure of the flow including the curved shock wave and the boundary-layer separation was clarified.
Vortex structure and bed pressure fluctuation in a plane impinging jet are investigated by the flow visualization and the pressure meseurement. For the visualization of the cross-sectional view, the laser illuminated fluorescent dye method were adopted. Observations by visualization make clear that a vortex structures hardly change by flow impingement. And the simultaneous observation of visualization and pressure shows that the movement of vortex explicitly contributed to the pressure fluctuation.
Visualization of boundary layer for diffusion system was made experimentally. A sheet that was pasted by Cobalt-Chloride was set vertically near a horizontal absorptive plate. Humid air was flowed along the plate and the sheet. Cobalt-Chloride was changed from blue to white gradually while it absorbed vapor in the air. Since Cobalt-Chloride located near the absorptive plate was remained blue, diffusive boundary layer was visualized in blue color.
The wire deformation and flow behavior of model liquid within the cavity of a transfer molding process were studied with flow visualization experiments and image processing measurements. The flow pattern within the cavity was found to be a laminar flow. The pressure drop and flow rate during filling from a pot to each cavity was different in each cavity. The wire deformation is proportional to flow rate and the distance of the cavity from the pot. The correlation between the deformation and the flow rate has been also made clear through the measurement experiment.
The visualizing technique using infrared radiometer, which is useful in estimating a two-dimensional temperature distribution on a surface, has been attractive. It is important to establish a simpler and more general measurement technique in estimating various engineering problems. In the present study, the measurement technique of temperature using infrared radiometer was newly proposed to estimate heat transfer and was applied to a few temperature fields. We confirmed its applicability and accuracy throughout a series of experiments and error analyses.
We have measured successfully the transition point of a 2-D LFC airfoil in transonic, high Reynolds number wind tunnel flow with the aid of liquid crystals. We first describe details of the test procedure and then show the results of the transition points with a discussion of the effect of stagnation temperature variation in the settling chamber on the choice of proper liquid crystals in the test.
This paper presents the experimental results on the negative surface buoyant jet discharged on the sloping bottom. Different results has been reported by many researchers on the hydraulic conditions of plunging point. The purpose of this study is to clarify the cause of this difference by flow visualization technique. Fow visualization revealed to be able to classify into four flow types from the configurations of density interface of plunging point and strong dependence of bottom slopes and densimetric Froude number at outlet on hydraulic conditions of plunging point was found. Flow mechanism of each types were investigated experimentally. Finally, this paper concluded that the different results on hydraulic conditions which has been reported by several researchers were caused by different experimental conditions.
Recently, submerged water-jets are very often applied for cutting, peening and cleaning. In such a jet-working-capacity, the shedding of cavitation clouds and the vortex cavitation around the jets are the most important factor. In order to clarify the mechanism of the shedding around the jets, we systematically observe the aspects of the jets, by means of a highspeed-video-camera, whose maximum framing rate is 40500 per second, by using a laser-light-sheets. And the digital images taken by the video camera are stacked to a stereoscopic display to examine the jets behavior changing with time. The cavitation clouds and the vortex cavitation are stereoscopically displayed by the digital image-processing-technique.
A numerical simulation is applied to a two dimensional unsteady natural convection environment with smoking interaction. The coupled continuity, momentum, energy and mass transfer equations are solved in the present study by an iterative procedure.Both of the effects of mass and heat generation at smoking site are considered. As the result, the time dependent behavior of the smoke as well as other information about flow and temperature fields are obtained. It is found that the smoking generated micro particles and gaseous contaminants are transfered both by the indoor natural convection and the rising flow due to buoyance force above the smoking site, rather than the diffusion due to the local mass concentration gradiant. 77te heat generation effects upon mass concentration, temperature and velocity distribution are found to be quite significant.
Film Coating is one of the most widely used techniques for producing photo-sensitive materials, magnetic tapes, etc. The curtain coating process is one of those techniques utilizing a free falling liquid curtain between a pair of guide plates. This method has several merits such as less consumption of coating liquid, post measuring and non-smell process, etc. It is most important to analyze precisely the velocity field of the curtain in order to keep the whole process stable. In this study, curtain coating is analyzed using hydrogen bubble method. From the timeline of bubbles, the velocity field and acceleration together with the boundary layer along the guide plate are measured. The influence of liquid viscosity on these parameters are mainly considered.
Biological morphology of marine organisms has been measured and observed with preserved specimen. Especially, specimen of molluscan Octopus is a type which deformed and shrinked, we cannot see the original form. Then, I tried to apply non-invasive medical imaging techniqhes to marine biological morphology. I selected Octopus vulgaris as the first target. Ultrasonography was the most successful method for visualization of its organs in motion and water flow by jetting. Inner organs as ovary, heart, gill, intestine, liver, baccal mass, brain case and mantle-funnel complex in respiration were clearly observed. It is demonstrated that ultrasonography is so useful in marine biological morphology and fishery biology.
Spawning behavior of Octopus vulgaris has been known as the mystery in marine biology. Because mother octopus makes fine egg masses in the underwate and narrow space, we could not observe this behavior with naked eyes. Especially how to form each egg mass is in interest. We used endoscopy (Olympus Video Imagescope IV-11D2-30) designed for industrial use to observe this phenomonon. It was successful that Octopus spawning behavior in the octopus pot was clearly recorded in detail. A few eggs with egg stalks were ejected through its funnel in one jetting. Eight small suckers around the mouth caught the eggs, and twisted their stalks. It is certified that " egg mass forming part" is the just around the mouth. Imagescope visualized spawning behavior of benthic animals, then this method would be the powerful tool in marine biology and fishery science.
In one of the proposals for a classifier, an injection port is mounted at the suction mouth, and sand ( relatively large particles) and muddy deposits ( relatively small particles ) which are deposited under a body of water are fluidized before the particles are collected. The maximum diameter of the particles lifted up is determined only by the suction velocity of water. It was clarified from the results of flow visualization in the vicinity of the classifying region that good separations are achieved for several combinations of spherical glass beads. By analyzing the image of the visualized region, the effects of the injection on the classified volume and the effects of small bead diameter on the classified time could be discussed quantitatively.
In this paper the authors discuss a numerical technique for simulating a formation process of electric discharge path by means of a percolation process. Since the theory of percolation process issued for treating the connection of superstructure points, this technique gives an explanation that the simulated discharge path is permeating in the electric fields. The application of this technique to electlic fields is considered by analyzing the distribution of discharge path glowing at the surface of a dielectric plate. Finally, it is concluded that the distribution of surface discharge is analogous to the geometric patterns created by the percolation process.
Flow pattern on inside and opening region of an open cavity for the following shapes of an open cavity is experimentally studied by means of tracer technique in the range of Reynolds numbers from 2×10 3 to 6.0×10 4: the range of depth-to-width ratio H/L is from 0.2 to 3.0. Flow pattern inside an open cavity is significiantly influened both Reynolds number and the depth-to-width ratio of an open cavity. Flow pattern on an opening region of an open cavity in the range of Reynolds numbers from 1×10 4 to 6×10 4 is unsteady with chaotic movement of parts of fluid in different direction superimposed on the external main stream, that is to say, turbulent flow on the opening region of an open cavity is observed.
The flow in the intersecting region in which confluent and branching flows exit continuously is complex due to combined consequence of the ramming phenomena and the centrifugal force. In this study, both the symmetric and asymmetric flows in the intersecting region are investigated by the methods using elastic pole and LDV. The intersecting angle and flow rates are varied to determine their effects on flow behavior. The mechanisms of secondary flow generated downstream in the intersecting region are disclosed.
Experiments are performed to investigate the vortex formation in and near the intersecting region. The particle tracing method using potato starch is applied to observe streamlines. Both the symmetric and asymmetric flows between the different confluent and branching angles are investigated. Flow rates are also varied to determine their effects on flow behavior. The vortex formation is found to be different due to a change in the intersecting angle. It is also disclosed that the fluid control in the intersecting ducts with the confluent angle of 60°and the branching angle of 30° is easier than those with other angles.
A numerical analysis has been performed for developing turbulent flow in a 180°-bend tube with straight inlet and outlet sections by three turbulent models. The calculated results of these models are compared with the experimental data available. These predicted results are in a good agreement with the experimental data of time averaged velocity and fluctuating velocity. As a striking feature of the flow, it has been pointed out in the experiment of 180°-bend tube that the cross-stream flow undergoes a second reversal in its sense of motion and is redirected toward the pipe inner radius. Each of three turbulent models is able to predict this occurence of the cross-stream flow reversal in the bend. Judging from the comparison the calculated results with tile experimented data, the great discrepancies among near-wall turbulent models are not confirmed.
Analysis of flow in a multi-blade fan is required for improvement of efficiency and for noise reduction. This paper describes experimental investigation of flow in a multi-blade fan by qualitative and quantitative visualization. Intake flows of the fan are qualitatively visualized by means of laser-light-sheet technique and velocity distributions in the scroll of the fan are measured by processing of images obtained by dual-beam-sweep illumination technique. The results obtained show that the intake flow pattern changes with flow rate and the velocity in the scroll at large angle is larger than it at trailing edge of the blades.
In the case of using the resistance-type virticai-axis wind rotors as a water wheel, the Savonious rotor shows the worst efficinsy. Then in this paper, the reason of these experimental results is tried to investigate by visualizing flow fields around rotors without a rotation. In the visualization, the smoke of Japanese short piece is used for the reason that the continual time is comparatively long and the smoke is thick. The sharp pictures are obtained and it can be thought from these pictures that the factors affected on the efficiency are not only the flow blown throuth between the blades but also the disturbances created behind the rotors.
The effect of concave curvature on turbulent boundary layers are analyzed by expe-riments and numerical calculations, considering influences of longitudinal voltices which caused by amplification of turbulences. In experiments, velocityprofiles and some turbulent characteristic profiles are measured. For the numerical calculations, the Reynolds stress model by LRR, limitting as a high Reynolds number type, is adopted, and then the concave boundary layer characteristicsunder consequences of longitudinal vortices are analyzed, introducing coefficients ; RF. The characteristics of boundary layers analyzed by the numerical calculations are compared with experimental data, and the accuracy of analysis are confirmed.
The effect of Karman vortices generated by a circular cylinder, which was placed in the upstream side of a regular pyramid diffuser, on the flow at outlet of the diffuser was studied. The circular cylinder was placed at L/W = 0.25 ( L: distance in the direction of flow; W: width of inlet ) perpendicular to the flow. The total divergence angles of the diffuser used in the study were 2 ?? =0°, 2°, 4°, 6°. The effect of the circuler cylinder was greater for diffuser with greater total divergence angles.
In order to clarify the phenomena of bubble growth and coalescence, we studied the growth and release behavior of bubbles formed at a nozzle tip, the coalascence of two bubbles formed at a dual-nozzle tip, the coalescene of many bubbles in a liquid, and the flow behavior of bubble groups. We also studied the conditions at the onset of bubble coalescence in terms of a hypothesis, derived from the earlier observation results, that bubble coalescence is strongly affected by the degree of swing in the paths of the bubbles.
An air bubble separation and removal system is necessary, especially in space, for fluid processing devices. We have been developing a new bubble separator for microgravity environments in which bubbles are pushed through a hydrophobic membrane by electromagnetic body forces. Our ground experiments using the separator model confirmed that air bubbles can be removed efficiently by an electromagnetic force. Subsequently, we carried out microgravity tests of 10 second duration in a drop shaft. In these tests, the effect of the electromagnetic force on bubble behavior was visually investigated and successfully recognized.