We have studied the flow of a fluid contained between concentric rotat-ing cylinders (the circular Couette system), in which the inner cylinder rotates faster than, but in the same direction as, the outer cylinder. The flow was visualized by polymeric flakes and an inner and an outer conical mirror were used to observe the flow all around the cylinder at all times. There found three patterns of the vortex boundary dislocations, where a Taylor vortex does not close itself, but instead joins with another vortex. Furthermore, a new flow regime has been found where the wave number of Taylor vortex changes in the axial direction.

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Transition of the flow between a rotating cone and a casing is studied by using a flow visualization technique. The cone vertex angle used in the present experiment is 60°. Observations of the flow have been made for several clearance ratios s/R from 0.016 to 0.184, where s is the clearance and R is the radius of the rotating cone. Characteristics of spiral vortices which appear at first in the transition region are clarified. It is found that three different types of instabilities may occur at large clearance ratios ; one of those is a centrifugal type and the others are similar to those observed in the Ekman boundary layer. The effects of throughflow on the behavior of the spiral vortices are also investigated.

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In the simultaneous spectral and flow-visualization measurements, the flow pattern is visible using a suspension of small aluminium flakes that align with the flow and the intensity of laser light scattered by the aluminium flakes is simultaneously measured. The vortex structure is analysed and the fundamental frequency of the velocity fluctuation is identified by comparing the results of the visual observation and the spectral analysis of the scattered-light intensity.
The present method using simultaneous spectral and flow-visualization measurements is applied to analyse the spiral Tay-lor-G ?? rtler vortex, the travelling azimuthal waves, the shear waves and the modulated travelling azimuthal waves appearing in the laminar-turbulent transition of the Taylor-G ?? rtler vortex flow in the clearance between two concentric spheres with only the inner sphere rotating.

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The flow pattern at the later stage of the laminar-turbulent transition in a flat plate boundary layer was visualized in a water channel by hydrogen bubble technique, and wave forms of velocity fluctuations were recorded by a coated hot-wire probe, also the in-stants of taking pictures were recorded below the wave forms. The comparison between the flow patterns and the wave forms showed that the so-called spikes in wave forms occurred due to the induced velocity of hairpin eddies of small size, which were generated through the instability of the high shear layer at about a half depth of the boundary layer, and that the hairpin eddies increased in number in the streamwise direction. Eventually, a local turbulent flow was observed in a similar way to the experiments by Nishioka et al. in a plane Poiseuille flow. The local turbulent flow had, however, not the same features as a so-called turbulent spot generated by local large disturbances in a laminar boundary layer.

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The development of the Karman vortex street due to natural convection in the opposing flow was discovered and has been clarified by means of the numerical simulation by Noto & Matsumoto. A flow visualization is carried out to verify the numerical prediction on the development of the Karman vortex street. As a result, the numerical simulation results are in good agreement with the flow visualization results. The validity of development of the Karman vortex street due to natural convection is verified by flow visualization. The flow without vortices is really varied to the Karman vortex street, the large vortex street and the natural convective vortex by natural convection as predicted by numerical simulations.

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The natural convection of water in vertical narrow annular gaps is visualized by using polystirene particles and tempera-ture distributions of a inner wall are measured. The following results are obtained. (1) The flow pattern, the temperature distribution of a inner wall and the critical Rayleigh number are established again. (2) Local velocities of circulating flows are measured and the values of mean velocities increase with Ra number.

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Quasi-stable multicellular natural convection is induced in a vertical slot filled with glycerin-water solutions and examined by visualizing the flow field and measuring the thermal field. In the experiment, a three-dimensional traverse equipment is controlled by a micro-computer and the thermal field in the vertical slot is measured by a thermocouple attached on the traverse equipment. During the measurement the flow field is observed with aluminum tracer in a light sheet and the measuring points are monitored by a video-camera. Moreover methylene blue solution in a glycerin-water mixture is continuously injected in the convection field through a thin hypodermic needle, and the multicellular convection field induced in the vertical slot is revealed.

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Isotherms and stream functions of the natural convection in a square cavity have been obtained numerically and compared with the results of the thermal field visualization by the liquid crystal capsule method and of the flow pat-tern by the pearl pigment particles.
The use of the half domain with the central point symmetry drastically saves computational time while maintaining the accuracy of the solution. The calcu-lated results with a given large Prandtl number for the silicone oil explain well the experimental results of the silicone oil cavity.

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The flow around a van-type vehicle passing through cross wind is visualized to analyze its cross wind stability. The vehicle is driven at 120 km/h across a 45m long cross wind generator which blows crosswind of 15m/s. Several hundred tufts are attached onto the side panel of the vehicle and their motion is taken by a high-speed video tape recorder. The results show that a strong vortex is generated on the leeward side while passing through crosswind in the case of the original vehicle. This is why a considerable value of the yaw-rate is observed with it. On the other hand, in the case of the vehicle with some aerodynamic attachments, the flow on the leeward side is separated and the suction pressure there is reduced and the yaw-rate value is reduced considerably. It is concluded that the changing of the vortex on the leeward side into the separated flow is effective in improving the crosswind stability.

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Recently the high performance of the road vehicle in high speed including the improvement of its fuel economy is strongly desired. In this paper the effect of rear body shape on the wake structure behind the vehicle and on its aerodynamic characteristics under a blockaged test section is clarified, considering that the aerodynamic characteristics of the vehicle strongly depends on the condition of the wake. Three different rear body shapes, with the same front and center body shape, are used. The flow condition in the wake is observed by the fluorescent taft grid method. Total pressure distributions in the wake are measured. The relations between the rear body shape and the wake structure are also discussed.

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In order to reduce particulate and NOx emission from the direct injection diesel engine, most researchers have been expecting the utilization of higher injection pressure and injection rate for improvement of diesel combustion. In the case of pump-line-nozzle system, the injection pipe line is very important with regard to the higher injection pressure. Namely, the pipe line must he able to resist not only high pressure but also cavitation erosion.
In this paper, the effect of sharp cutting at the end of fuel injection for change of fuel injection rate is discussed along with the visualization of cavitation bubbles in the injection pipe line. And the countermeasure of cavitation erosion is also described.

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The variation of the flow around an O ₂-sensor element due to the difference in the shape of a protective tube of the sensor was examined by the visualization experiment. Sensor models with the shape of four kinds of the protective tube were used in the experiment. The soots of exhaust gas does not adhered on the element in 4-slits model since the strongly circulating flow is not directly touch the element. But the soots adhere on the element in 9-slits model compared with 4-slits type. Two stream are observed in the plover model, also the turbulence in this flow is strong.

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This study was performed in order to investigate flow patterns around a control rod and flow-induced vibration characteristics of that in HTTR (High Temperature engineering Test Reactor). The control rod used in the experiment is a full-sized partial model of HTTR and consists of four control rod elements and a shock absorber. The simulated control rod was suspended vertically in circular duct. The experiment carried out up to Rein=22000 using water. Water flowed downward inside and outside paths of the simulated control rod. Flow patterns were visualized by the pearl pigment method and vibration amplitudes were measured by a noncontact displacement sensor. Fundamental flow characteristics around the control rod were observed, such as a counter flow in narrow passage and an oscillory flow in outer channel.

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It is necessary to estimate air flow and temperature distribution in rooms before designing air conditioning systems. In this paper, we present the visualization with color graphics EWS for the result of three dimensional nonisothermal turbulent flow analysis with k-ε model.

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Flow visualization was numerically carried out for some internal flowfields. The configurations dealt with in this simulation include high bypass fan blade rows and a circular cross sectioned S-duct with two circular arc bends. These flowfields were first analyzed by viscous flow solvers, and then visualized by simulating surface oilflow patterns, streamlines, etc. The flow visualizing programs were developed in National Aerospace Laboratory in order to represent the results of three-dimensional numerical flow analyses. Additionally, these phenomena were much more clearly visualized with the assistance of animation techniques.

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A new technique for the particle tracking of two dimensional turbulent flow was developed using the image processing technique, The motions of fine particles are extracted automatically by the tracking algorithm in which the correlation method for the estimation of the detecting area of the particle tracking is included.
This algorithm is applied to the flow field behind a turbulence promoter and the applicability to turbulent wake flow is examined.

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A new algorithm has been developed which enables automatic 2D-velocity measurement within a very short time. The algorithm consists of a high speed calculation of cross-correlation between two pictures, and new methods of removing erroneous vectors.
The method is examined to measure a rotation of a turn table, a natural convection in a tank and a sudden expansion flow in a channel. The typical analysis time which depends on analysis conditions and pictures, is 2-4 seconds to obtain 100 vectors from a couple of 200×240 bi-levelyzed pictures.
The programs coded in C runs on a simple 16bit peraonal computer system with a image capture board.

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Structures of two interacting free jets with different source pressure are Studied by flow visualization. Angles between jet axes are set at θ=45° and 180°. Experiments are carried out for various source pressure ratios and various ratios of the source pressure to the pressure in the expansion chamber. For θ=45°, many types of flow field appear with respect to the source pressure ratio and the structures of these flow fields are classified into four patterns according to their shock systems. For θ=180°, structures of the flow field are divided roughly into four types depending on the condition of the source pressure and the pressure in the expansion chamber. Specifically, stable and unstable flows in the interacting region are found for the equal pressure ratios.

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CAFV(Computer Aided Flow Visualization) system for the gas dynamics has been developed and is applied to analize three dimensional structures of the flow field that is visualized using laser induced fluorescence of I ₂ seeded in Ar. The flow field is visualized by many laser sheets and photographed two dimensionally by a high sensitive vidicon camera. These image data are stored up in a personal computer in order to record three dimensional information on the entire flow field. For the purpose of suppressing the noize, an image datum is an average of many frame data. From the image data, the visualized pictures at arbitrary cross sections (CT; Computer Tomography) are reproducted on the monitor by the personal computer. The propriety and effectiveness of this system are verified through the results applied to two flow fields, i.e., the free jet expanding into the vacuum chamber and an interacting flow field between the skimmer and the free jet.

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The flow fields of supersonic free jets are visualized by the laser induced fluorescence method. The local fluorescence intensity is also detected by a computer aided high sensitive photomultiplier and 3D-stage system. The entire flow field is well observed, but the fluorescence intensity depends quantitatively on the population fraction and quenching effect of I ₂ .The measured intensity is corrected in consideration of these dependences, and the corrected one is well related with the density of flow fields.

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The vapor-screen method is a simple and practical method of flow visualization for high speeds. In the present paper, it has been applied to shock waves generated in a supersonic nozzle, and the photograph has been compared with that of shadowgraph method. As the result, it has been demonstrated that this method is very useful to visualize shock waves.

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Interaction between a detonation and blockages positioned in a channel is experimentally observed with the use of conventional visualization techniques: (1) Emission trajectories of triple shocks included in the front structure of the detonation are taken by the open shutter photography, and (2) for capturing of the detonation front propagating with a supersonic speed (Ms=8) is utilized the pulse-laser Schlieren photography. By means of this experiment, propagating configurations of disturbances in the coupled or uncoupled detonation are observed, and the instabilities of detonation are discussed.
A combustible test gas used in this study is an equi-molar oxyacetylene gas mixture.

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An infrared radiometer has been used for detecting and visualizing surface cylindrical and conical pinholes of metal and graphite. The image of surface pinhole can be displayed on the CRT under a remote sensing condition by using the infrared radiometer, Two dimensional distribution of radiation energy emitted from the cracks shows an isothermal line image on the CRT by radiation cavity effect. The diameter and depth of surface pinholes can be measured with increase in the radiation temperature.

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In this paper we consider an analytical method by fluie flow mapper for axisymmetric three dimensional electrostatic fields in complex dielectric substances. The method of visualizing the axisymmetric three dimensional electrostatic fields is based on the fact that a potential equation in electric fields is identical to a pressure equation in fluid flow mapper. This method has great advantage that the potential fields are able to be observed continuously.

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Mouth breathing is considered as one of the important predisposing factors in periodontal disease. Generally palatal and lingual tension ridge and labial. mouth breathing line are common clinical findings among mouth breathers. But until today, no experiments have demonstrated the association of mouth breathing with the above. The present experiment is undertaken to further clarify the above findings using three-dimensional artificial model. The components of three-dimensional model were consisted of the plastic plates which were stabilized in water tank made of glass. The stream of detailed flow patterns were carried out using a hydrogen bubble technique. Constant water flow of same volume as human inspiratory phase was continued to observe the flow patterns. As the result of this experiment, the main inhalation flow pattern viewed from the sagittal direction went into the oral cavity along the upper incisors, and clashed against the palatal gum-margin and then ran into the throat alongside the hard palate. And the same inhalation flow pattern viewed from the horizontal direction was concentrated on the central area of the palatal gum-margin and ran into the throat alongside thehard palate. Then, the inhalation flow patterns stagnated with the circulations on both sides of the upper arch, and ran into the throat. These phenomena maybe thought one of the reasons why inflammation is conspicuous in this region.

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For the flow of a fluid at low Reynolds numbers around a circular cylinder, some experimental and theoretical investigations have been made up to the present. But the clear photographs of the flow patterns which serve as a verification or guidance of the theories seem to be in relatively lack. The low Reynolds number flows around a circular cylinder were photographically investigated using the aluminum dust flow visualization technique. From many photographs of the flow patterns at Reynolds numbers from 0.35 to 12.8 were investigated the variation of flow patterns with Reynolds number, the critical Reynolds number for the appearance of standing twin-vortices behind a circular cylinder and the effect of the Reynolds number on the growth in size of the standing twin-vortices.

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Flows around a circular cylinder which is stationary, rotating, or oscillating in a uniform flow have been visualized by hydrogen bubble techniques. The photographs of the flows are taken in a long exposure time in order to make clear the timeaveraged characteristics of the flows. The shapes of the streamlines near the stagnation point and the separation points of the cylinder can be determined accurately by analyzing these photographs. Time-averaged patterns of the near wake of the oscillating cylinder are obtained and the relation between these patterns and the drag of the cylinder is discussed.

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Some flow visualization experiments have been made on a two-dimensional NACA 0012 airfoil pitching with large incidences at Reynolds numbers ranging between 10³ and 10⁴. Additional numerical calculations have been made in parallel with a view to comparing the results and to assuring the following flow analysis. The object of this study, a continuation of our preceding report on an elliptic airfoil(1), is to examine more precisely the development of the deep dynamic stall occurred on a more realistic airfoil body. Another aim of the research is to investigate the effect of the pitching axis to which the foregoing authors have not paid so much attention. It will be shown that this parameter plays a very important role at the highest pitching frequency.

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The purpose of this study is to understand the flow pattern in a rotating centrifugal blower impeller by flow visualization. The flow pattern in an impeller was visualized by spark tracing method. The stationary image of the flow pattern in a rotating impeller was observed using the rotating image stopping processor, in which a triangular prism rotates at a half of the outlet of an impeller was observed in detail using the spark tracing method, in which needle type, and, line and needle type electrodes were used.

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When a swirling flow enters a centrifugal pump, the flow inside the impeller passages is subject to a rapid change due to the interaction of the vortex core and the impeller blades. Using pressure transducers, the instantaneous pressures on the blade surface were measured and the pressure fluctuation due to this vortex core was analyzed.
In order to visualize the collapse of the vortex core inside the passage, a small quantity of air was introduced into the suction pipe and photos of air bubbles inside the impeller passage were taken by detecting the circumferential position of the eccentric vortex core. The nature of the pressure change was found to depend upon the direction of the swirling flow component.

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It is known that the multiple jets issued parallel from a number of two-dimensional nozzles, interfere with each other.
In this report, the flow patterns of the three and four two-dimensional parallel jets were investigated experimentally.
In the three and four jets, the two outside jets set up a dual jet flow with an associated reverse flow. When the inside jets are introduced, the flow field of the three and four jets are largely affected by the ratios of the inside jet velocity to the outside one. In order to examine the effect of varying the ratio of the velocities in the inside and outside jets on the flow pattern, measurement of the flow by a tandem type hot-wire anemometer and flow visualization by oil film were carried out.

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We investigated a flow due to a vortex pair confined by parallel flat plates by smoke visualization. In this paper we focused our attention particularly to the effects of aspect ratio of a rectangular nozzle, through which air was puffed, as well as the Reynolds number on the flowfield. Some new facts were found concerning temporary change of visualized. flow patterns, distortions of a vortex pair, and behaviiors of an induced vortex near the plates.

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In this paper we treated a flowfield due to an arch vortex generated by puffing air from a circular orifice to which a flat plate was set perpendicularly. The arbitrary orifice of a circular arch could be made by simply setting the plate at a proper location against the surface of the circular orifice. We investigated characteristics of three kinds of arch vortices obtained by using three kinds of orifices set as mentioned above. Arch vortices travelled touching their both ends on the plate. Their motions, distortions, and interactions with induced vortices, generated on the wall, were clarified extensively by the method of smoke visualization.

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The correlation between the flow patterns visualized and the results obtained from the hot-wire probe was investigated with the wakes both behind a circular cylinder and a flat plate at zero incidence in a low speed wind tunnel.
The flow patterns for both cases seem to show the downstream increase in the size of vortices, but not always their growth. The vorticity in each vortex diffuses and its circulation decreases downstream in the wake of a circular cylinder. On the contrary, the vorticity concentrates and the circulation increases downstream in the wake of a flat plate.

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