Several methods of flow measurement and flow visualization rely on the use of particulates to mark the fluid and make its motion visible, thereby rendering it amenable to optical study. In comparison to molecular markers like dyes, particle offer the unique capability of marker very small points in space which remain small and do not diffuse. In general, particle-based methods such as laser Doppler velocimetry (LDV) and particle image velocimetry (PIV) have been developed to a high degree, and they are used widely, especially for quantitative measurements. The properties of the particles must be managed correctly if the particle-based measurements are to be of the highest quality. The particles must follow the fluid motion accurately, they must scatter adequate light to produce high signal-to-noise ratio, and they must produce uniform, repeatable.

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Numerical Simulation is used for the aerodynamic design and flight analysis of re-entry spacecrafts, HOPE and HYFLEX. Several hundreds test runs are made to determine optimum configuration of HOPE. Real gas effects are also estimated by using non-equilibrium Navier-Stokes code and code validation are continued by comparing numerical results with conventional HWT, high enthalpy wind tunnel, and flight measurement data. CFD activity of enormously enlarged hypersonic flow simulations by Reentry spacecraft developments, enforces large scale parametric studies and parallel computations by NWT at NAL can correspond to these demands.

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This paper describes an image processing technique for detecting abnormal equipment conditions using temperature distribution pattern by an infrared camera. A thermal power station monitoring is performed to ensure reliability and to improve availability. Inspection task is composed of 60 percents judgment using eye and 30 percents judgment seeing temperature.
In the newly developed method, to recognize an abnormal equipment condition, a temperature distribution images are compressed keeping a feature of sharps. Abnormal condition detection method compares compressed image of thermal pattern with normal condition compressed image.

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A new method for diffused gas detection and location in an open space using photo-acoustic technique is proposed. When a laser pulse tuned to an absorption line of the gas is irradiated, an acoustic pulse is generated due to the collisional relaxation between excited gas molecules and other bodies. As to photo-acoustic effect in an open space, the signal has a frequency of about 40kHz and propagates perpendicularly to the laser axis. Array microphones and 2-dimensional laser scanning system are used for detecting the gas distribution. In the feasibility test, range resolution is better than 50mm with a probable maximum range of 3.2m. A methane gas distribution blowing up from small diameter nozzles is 3-dimensionally visualized using volume-rendering method. In the visualization result, the two nozzles could be clearly distinguished.

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This paper presents adaptive filter applied to gradient vector fields. Distribution of gradient vectors reflects specifically shaped objects. In other words, it is possible to detect them by examining the distribution of gradient vectors. In this paper, filters to detect rounded convex regions and curvilinear convex regions are proposed. They are the function of only orientation of gradient vectors, and therefor, those with weak contrast can be enhanced.

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In this paper, we propose a new method of extrating heart wall contours using the Active Contour Model (snakes). We use an adaptive contrast enhancing method, which made it possible to extract both inner and outer contours of the left ventricule of the heart. Experimental results showed the efficiency of this method.

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We have aimed to improve safety of ship navigation at night and studied appropriate passage routes on ship handling simulator taking Kanmon Passage as an example.
As we enhance recognition of the passage route, we prepared several ways such as changing character of light buoys or corresponding/cascading buoys lighting. We have represented lights of aids to navigation such as buoys and lighthouses accurately in our ship handling simulator and executed simulator experiments to test those ways. To represent accurate representation of lights, we have made several CGI objects based on their colors, their luminosity and luminance of CGI on screen. A buoy chooses appropriate object automatically from them according to its own luminosity and a distance between the buoy and a viewpoint. Besides we have added equations of atmospheric transmittance to our program and realized visibility of light on our simulator. We discuss those methods in this paper.

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Electronic Navigation Research Institute (ENRI) had started to construct a total air traffic control (ATC) simulation facility in 1993. An airport tower ATC simulator and a flight simulator have been developed and ENRI is now carrying out several experiments and simulation. In this paper, a coupling method of three or more virtual reality spaces for creating a larger ATC simulator is mentioned and some basic ideas of the coupling method are also explained.

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A visual sense is an important information source for aircraft pilots. In a modern flight simulator, the image made by computer graphics is used as a visual information. Several equipment which artificial visual information are used as a flight simulator visual system. First, we present display systems for a flight simulator. Next, the half dome type display system which is installed to the National Aerospace Laboratory is explained. Finally, the evaluation results and its application is described.

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An experimental study on the transient downward solidification of a binary solution in the rectangular container cooled from its top wall is reported in this paper. An ammonium chloride aqueous solution was used as a binary solution. Dual wavelength holographic interferometry was used to visualize the transient temperature and concentration field an d to measure the transient local heat and mass transfer rates at the mush/liquid interface. The experiments were performed varying the initial concentration from 5 wt% to 25wt%.
As a result, it was clarified that heat transfer rate is promoted due to the rejection of solute.

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To study the macro-characteristics of high dispersion sprays were analyzed using laser sheet and high speed camera. The injection pressure was 24.5 MPa, the chamber pressure was 0.098, 0.98 or 1.96 MPa, where the amount of injected fuel was 28.5 mg per cycle, and the injection frequency was 8.3 Hz. The spray dispersion rate was defined and used to evaluate the spray. As a result, at atmospheric chamber pressure, the conical spray and grooved-slope nozzle spray both have a conical pattern, but at high chamber pressure, the sprays become three dimensional. Also the sprays don't have a liquid core, they have an air region in the center of the sprays. The penetration of the grooved-slope nozzle spray was 25% stronger than that of the conical spray.

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Three-dimensional void fraction distributions of a steady air-water two-phase flow in a 4x4 rod-bundle with circular ferrule type spacers were measured by neutron radiography using a CT method. High flux neutron radiography system at JRR-3M in JAERI, was used. The thermal neutron flux was 1.5x108n/cm2s. Visualization with high spatial resolution of 0.18mm was carried out by using a cooled CCD camera. Projections in 250 directions were obtained and were reconstructed by a filtered back projection method after some image processing. Animations were made to show the two-phase flow behaviors in the rod bundle near the spacer.

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Liquid metal flows were visualizaed by using neutron radiography. Single-phase lead-bismuth eutectic flow was visualized by a tracer method. High speed visualization of water evaporation behaviors in lead-bismuth-tin alloy was carried out. Thermal neutron radiography system at JRR-3M in JAERI was used. It was shown that neutron radiography was applicable to visualize single-and two-phase flow of heavy metal.

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The turbulent shear flow around a rotating cylinder in a quiescent flow is a simple case of rotating turbulent flow field, where centrifugal force works and an instantaneous fluctuation velocity is affected by Coriolis force. Two different power law mean velocity distributions exist in this flow field. One is Uα1/γ and the other is Uα1/γ2, where γ is a distance from the surface of a cylinder. Velocity fluctuation are invetigated by the wavelet transform using Mexican-hat, French-hat, antisymmetric and Morlet Wavelet. Contours of the wavelet transform in the (a, b) parameter space are found to be similar for the four wavelets if the aand b-axes are properly translated., where a is the scale and b is the temporal location of the center of the wavelet. The Morlet wavelet yields the most detailed multi-scale structure of the velocity fluctuations among the four wavelets.

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Air velocity distribution in solid-air two phase flow model has been clearly obtained from particle velocity distribution by discrete inverse wavelet transform. The particle velocity distribution of solid-air two phase flow consists of the exact air velocity and random noise velocity caused by the wake behind the particles. The discrete inverse wavelet transform extracts the exact air velocity from the particle velocity. The discrete wavelet transform collects the vector data of particle velocity in the vicinity of the mother wavelet spectrum. A matrix consisting of the spectrum data near the mother wavelet spectrum is inversely transformed. The matrix reduces the noise data, resulting in the exact air velocity data.

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In thispaper, in order to reveal the coherent structure of a turbulent bounded jet in both Fourier and physical spaces, the wavelet transform and local wavelet Reynolds stress are used to analyze the large eddy motions and the secondary flow structure over a measured frequency-physical plane. The experimental fluctuating velocities at various positions in the near field are used for the analyses. From wavelet analysis, the frequency and the time of the large-scale structure inthe shear layer and of the secondary flow near the wall can be determined. The branching structure of multi-scale eddies in the wall shear layer becomes more complex than that in the free shear layer. Due to the effect of the secondary flow the scales of eddy and entrainment process become small.

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In this paper, the continuous and discrete wavelet transform are applied to the velocity signal of a plane turbulent jet, in order to estimate the eddy motion in the dimension of time and frequency. First, a review of the definitions of the continuous and discrete wavelet transform are described. Then, from the experimental velocity signal of a jet on the centerline, the eddy motion is analyzed in terms of instantaneous frequency and time.

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In recent years, research and development activities for next generation supersonic transport are being carried out actively by the world aeronautical communities. In a supersonic air-intake, a cavity with bleed plays an important role in the control of normal shock wave under the cavity/shock wave interaction. The supersonic air-intake flow tends to be unstable due to the shock wave/wall boundary layer or the shock wave/shear layer interactions occurring close to the leading edge of the cavity. In the present study, the effects of cavity/shock waves interaction on the pressure oscillation in the cavity were investigated experimentally in the case of the flow Mach number 1.75 at the cavity entrance and the characteristics of oscillation in the cavity were analyzed using the wavelet transforms.

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It is well known that the wavelet transform has a new possibility in data analysis on not only frequency but also time/spatial domain. Continuous wavelet transform is effective for the signal of which the frequency is changing in time, such as turbulent velocity data. This technique is applied to the visualized image here as a edge detection method. In order to analyse image data, the discrete wavelet transform must be a effective technique. New image analysing method would be derived from the relationship between the wavelet transform and the multi-resolution analysis. The maxima analysis on wavelet domain is shown as an example.

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The purpose of this paper is to reduce edge tone generated by flow of a jet-wedge system. An attempt to reduce the edge tone has been carried out by attaching projecting objects to the nozzle exit. It is found that the edge tone is reduced even though a pair of projecting objects is attached to the nozzle exit. In addition, the flow patterns of the jet oscillation are visualized by the color tracer injection method.

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The mechanism of the discrete frequency noise generation from the symmetric airfoils was investigated in transition Reynolds numbers. The following results are obtained. At the transition Reynolds numbers the boundary layer separate from the airfoil surface upstream of the trailing edge and the wake vortices form just at the trailing edge with inducing the shear flow fluctuation when the discrete frequency noise(DFN) generates. But the boundary layer flow attached up to the trailing edge and the wake vortices form at a downstream of the trailing edge. Then the shear flow do not fluctuate at the trailing edge and the discrete frequency noise little generate. that is, the formation of wake vortices does not always generate the DFN and the location of the wake vortices formation is closely relating to the discrete frequency noise at transition Reynolds numbers.

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The aerodynamic sound generated from the high speed train under progress of speed up program is now a great issue. This aerodynamic sound radiating from a half-cylindrical train model with a quarter spherical front nose and the behaviour of an air-flow created around this model are measured in a low-noise wind tunnel. This paper presents a study of an appearance of generated sound referring to the graphical flow pattern. The case that there is a quarter sphere at the tail part of model is compared the case that there is none. If the cylinder is long, the presence of the tail part or none will have a small influence on the generated sound. On the other hand, if the cylinder is short, the sound without the tail part is bigger than that with it.

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Separated shear layers are highly receptive and unstable to external disturbances. In this experimental study, shear-layer instability waves/vortices are excited by acoustic forcing for two typical separation bubble flows; one is a flow separating at a convex corner, and the other is a separation bubble on a NACA0012 airfoil. The visualization photographs and movies as well as hot-wire measurements clearly show that when the acoustic forcing is applied, discrete vortices are excited around the separation point and they can suppress the development of separation bubble.

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In this paper, sound field around the exit of a cylindrical duct which is protruded from a flat wall was investigated experimentally and analytically. Distributions of sound pressures and sound intensities were measured by the sound intensity microphones and calculated numerically by using the finite difference method. Sound field transits from the plain wave mode to the non-plain wave mode when the ratio of the duct diameter to the wavelength exceeds a critical value. Also, according to the amount of protrusion length, the sound fields exhibit very complicated distributions.

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A spatially evolving shear layer of axisymmetric compressible jet has been studied by accurate numerical simulations, where the fourth order upwind scheme is used to reduce numerical dissipation. Mach numbers simulated are 0.5, 0.8, 1.0 and 1.5, and the Reynolds number is 10⁵. At M=0.5 the effect of compressiblity is not remarkable and the flow has almost the same features as incompressible jet. However at M=1.5 the structure of vortex is rather different, where the shock waves are generated around vortex rings and the pressue waves are emitted in the direction with some angle from downstrea jet axis, which might seem to represent or lead to acoustic wave. This pattern was clearly captured by systematically increasing the number of grid points.

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Strong acoustic intensity radiates at the upstream direction during jet screech. An evidence of this property has been found by a sound intensity mapping.

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Experimental measurements were made of the frequencies of discrete tones emanating from high subsonic jet of air issuing from a circular nozzle and impinging on a slender circular cylinder placed normal to the jet axis.
Schlieren photographs of the flowfield along with the near-sound field were taken. Close investigation of these photographs has shown that one strong sound wave is emitted near the cylinder and two large ring vortices are produced near the nozzle exit during one cycle of the feedback loop. These two large ring vortices merge together in a later stage of the loop.

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A theory of vortex sound formulated in the form of multipole expansions is applied to the oblique collisions of two vortex rings with various angles. Using the theoretical formula, the coefficients of the multiple modes of the far-field wave pressure are estimated by the numarical data of computer simulation. Time evolution of the vorticity field is obtained by solving a viscous imcompressible vorticity equation with a vorticity-potential method. Numerical simulations are carried out for 23 different collisions of two vortex rings with the same core and ring parameters but the different initial angles θ between the axis of rings(0° ?? θ ?? 66°). The results show that the far-field acoustic pressure is strongly related to the stretching phenomena of vortex tubes.

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A particle mask is of a typical brightness pattern of a particle image, which is called a template in pattern matching. The proposed particle mask correlation method calculates a cross-correlation coefficient between the particle mask and a particle image plane. The following are evaluated:
(1) the dependence of the cross-correlation coefficient on the shape of a particle image, and
(2) the separation of a particle image from a closely-located lineament.

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In Particle Image Velocimetry (PIV), the cross correlation tracking technique is widely used to analyze the particle images. The actual flow fields may have some distorted motion, such as rotation, shear and expansion. When the distortion of the flow field is not negligible, the fluid motion can not be tracked well using the cross correlation technique.
The author proposed a new particle tracking technique, based on the particle cluster matching using linear Affine Transformation. The deformation of the cluster pattern is expressed by the linear Affine Transformation. The parameter of the transformation can be determined using the least square technique from the particle positions. The effectiveness of the tracking techniques, including 3D cross correlation, Spring Model and Affine Transform, were evaluated with synthetic data of three-dimensional flow field. The 3D cross correlation technique could be applicable to the small deformation cases. When the deformation of particle pattern between two images are very large, the pattern deformation could not be expressed by the Affine Transformation, i.e., linear transformation, resulting in the miss-tracking. While, the Spring Model technique was found to be more effective even in the larger deformation condition, because the Spring Model does not assume the linear transformation.

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Cross-correlation coefficient used in the binary image cross-correlation method for PIV has been used without mathematical strict proof, although the method is thought to be convenient and efficient to analyze the particle images due to the high speed algorithm for particle identification. In the present study, the basic equation of image cross-correlation coefficient and its extension to Delaunay tessellation method are derived from mathematical foundations, and the generality is discussed.

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Cross-correlation coefficient used in the binary image cross-correlation method for PIV has been used without mathematical strict proof, although the method is thought to be convenient and efficient to analyze the particle images due to the high speed algorithm for particle identification. In the present study, the basic equation of image cross-correlation coefficient and its extension to Delaunay tessellation method are derived from mathematical foundations, and the generality is discussed.

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The change of luminance of visualized image is caused by the motion of tracer particles or dyne transported by fluid, and it is expressed by a governing equation using the Lagrange's derivatives. The so-called spatio-temporal derivative method is well known as an image measurement technique which has a high spatial resolution. The technique also has disadvantages such as small dynamic range and the unsteadiness for the image noise. In the present paper, the principles of the measurement techniques based on the spatio-temporal derivatives are explained, and the applications are shown. The spatio-temporal derivative method would have much wide application field.

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The present study quantitatively analyzes changes of flow patterns occurring in unsteady horse-shoe vortex systems, using a flow visualization and spectral analysis for fluctuations of velocity, u', measured by PIV. Experiments were performed for flows around an obstacle (prism or cylinder) mounted on a flat plate in a water channel. As a result, it was proved that the changes of flow patterns in the transient process enable to clarify quantitatively, using the results of the auto-correlation, the power spectrum and the cross-correlation.

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Skin friction reduction devices for ships have been studied, but a reliable device has not been found. The authors are experimentally investigating one of the devices, which is Microbubbles. The microbubble-is a more effective device for reduction of local skin friction, but the reduction mechanism is not made clear.
We successed in visualizing the microbubbles in a boundary layer of a high speed flow, U=10m/s, in a small high speed water tunnel using PIV and two YAG lasers system. The shape and the distribution of microbubbles in a boundary layer are found by photography. Next target is to measure the velocity distribution with microbubbles in a boundary layer.

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For the structural feature of the Box-shaped Very Large Floating Structure(VLFS) with shallow draft, the VLFS may be subject to the large slamming load when its bottom happens to emergence in the state of the severe sea condition. Therefore, the safety of the VLSF against the slamming load has to be fully examined on its design stage.
This paper describes the flow measurement using PIV concerning the deck wetness around the comer of VLFS in rough seas and the slamming due to the emergence of its bottom.

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Recently an effective energy management technique becomes important in an OA machine design for accumulation of several parts and compact size. Especially, heat control of the machine is necessary to keep the good quality of precise image in copier or printer. PSU(Power Supply Unit) is one of the highest temperature parts in the copier.
Thermal plume of the natural convection from the PSU is analyzed by the thermal vision using infrared light with an aid of the wire-net method. Also, the flow field of the thermal convection from the PSU is visualized using smoke-wire technique, PIV method is applied to these images to determine the quantitative flow velocities for various setting conditions. The compared results between them show a good agreements.

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Two-color dual sweep PIV has. been used in an engine to obtain quasi-instantaneous two-dimensional velocity data. The particle-seeded flow field was illuminated by scanning beams(blue and green) of Ar laser. The illuminated particles were photographed at TDC compression with 1.7×magnification, resulting in paired particle images distinguished by color. In this way, this PIV succeeded to evaluate complex turbulence flow including counter current like tumbling flow, and also the spatial resolution achieved was adequate to resolve the few-mm turbulence integral length scales.

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In analysis of combustion in IDI diesel engine, high-speed shadowgraph photography was applied to investigate the combustion flame motion in main chamber. For more exact analysis, quantification of flow field in the flame is necessary. Therefore, a cross-correlation method was applied to calculate the velocity distribution in the combustion flame and the accuracy was improved. From the calculated velocity distributions, the effect of double leaves (main chamber) configuration on flame separation was investigated quantitatively.

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Aiming at an implantable artificial heart, flow visualization measurements were conducted to eliminate stagnaiton areas, standing vorteces, and high shear regions, which mihgt lead to blood clotting or destruction of blood cells. The detail flow patterns in the centrifugal blood pump under development were clarified using a 3-times scale-up model, and 4-time particle tracking velocimetry software.

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Many types of 2D-PIV system have been come onto the market, and there are various techniques for the calculation of velocity vectors. In the present paper, a bench mark test for the calculation technique of PIV was tried. Four pictured images of a real flow were distributed through internet as digital image files. The flow in the problem was that induced by an oscillating flat plate and the 2D relative flow was pictured using a CCD video camera moving with the plate. The calculation was pursued without any information on the flow. Then, the evaluated results of velocity vectors were compared with each other. The problems to utilize images of a real fluid flow as a standard image of bench mark test were also discussed.

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Particle Image Velocimetry (PIV) offers many advantages for the study of fluid flows. Lots of PIV technique and PIV system had been developed. However, there are no standard tool for the evaluation of the PIV system effectiveness and accuracy. To popularize the PIV for practical use, the PIV system should have some standard. The PIV has two processes, i.e., the image capture with visualization and the image analysis. In order to evaluate the image analysis system for the PIV, the standard images were proposed. Using the images, the evaluation of the effectiveness and accuracy for the PIV system will be carried out. The requirement of the standard images and the computer graphics technique for the images were investigated. The developed PIV standard images are distributed using the Internet, (http://sap.gen.u-tokyo.ac.jp/).

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The standard images are analyzed, and the obtained velocity fields are compared and examined. The different type of PIV systems, four-step PTV, spring-model and spatio-temporal derivative methods, are applied on the standard images which are offered by the authors.
In the first report, the generating process of the standard images which. aims to evaluate the effectiveness and accuracy of the systems, are explained. Fine particle images are generated using a numerical flow data calculated by three-dimensional LES. The images cover wide range of parameters such as particle diameter, concentration, displacement length etc. Applied three systems show different tendencies through the parameter changes. Furthermore, simple performance test is applied on the obtained velocity fields. Present study is the first step for the construction of a standard evaluation code for PIV systems.

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Air change rates in a cross-ventilation model were measured from decay curves of video image signals by the step down method under the perfect mixing assumption. From the wind tunnel experiments, the following results were drawn. 1) The proposed calibration method could measure the air change rates with a precision accuracy of more than 73 % even for the low dynamic ranges of cameras to adjust black balances of images. 2) For oil mists as tracer, the laser power of more than 0.5 watt was enough to visualize the mist movements in the model for the air change rates. 3) The air change rates, obtained by the video image method was proportional to the reference velocities. 4) The maximum image signals in the case for the smoke liquid mists was lower than those for the oil mists due to the smaller particle diameters. 5) The results of air change rates measured by video image method could have good agreements with those derived from decay curves by the tracer gas method using a high-speed hydrocarbon analyzer

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In this paper we visualize "Comfortableness" in thermal environments by using PMV(predicted mean vote) and MRT(mean radiant temperature). Velocity and Thermal fields in thermal environments are simulated by using High-Speed GSMAC FEM method with improved k-ε turbulence model. PMV and MRT are calculated from the results of the simulation.

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Flow fields in a pulverization device of toner, which pulverizes chip of toner and produces fine powder from it using a mechanical mill, are studied experimentally as well as numerically. This device consists of co-axial double cylinders, both of which have the surface groove-cut, and chips injected by pressurized air are pulverized due to mechanical and fluid dynamic impact with the grooved surface, and then ejected out at the other end of the cylinders. Using a model of pulverizer made from acrylic material, the flows were simulated by water with aluminum powder as tracer, and was observed by video system equipped with CCD camera. Various kinds of the groove shapes were tested and the flow patterns observed, which were compared with the numerically simulated results.

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This paper deals with the study on flow patterns for the steady axisymmetric laminar flows around the flanged type poppet valve for the convergent flow. In this study, the stream function ψ and vorticity ζ are calculated numerically applying the up-wind difference method for the change of geometrical dimensions; valve seat length, valve opening, vertical angle of valve and flange diameter, and they are compared with flow patterns photographed using 3CCD camera.
As a result, even though small flange diameter, it is useful to suppress the separation at the valve seat corner, and result visualized by tracer method shows comparatively a similar tendency with the calculated flow pattern.

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Visualization and noninvasive concentration measurement using a photochromic dye are used to investigate the turbulent mixing caused by a travelling sphere in a still fluid in a circular pipe. Visualized dye patterns indicate the presence of large-scale motions to mix the dye. The concentration distribution deduced from the dye image using Lambert-Beer's law shows rather isotropic mixing in longitudinal direction. Turbulent diffusion coefficient calculated from the concentration distribution reveals its interesting time-dependency that has not known previously.

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