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A mixing flow in a cylindrical vessel agitated by a bubbling jet is measured quantitatively applying the binary cross correlation method, which is one of the particle tracing methods. With this method, not only flow patterns, but also quantitative measurements such as instantaneous velocity distributions, velocity fluctuations and particles paths can be obtained easily in a short time.

PIV system now available are mostly large and painstaking to deal with. In case of precise experiment, it is inevitable. However, in an engineering section of a factory, it does not always need such an accurate system. This time, we formed simple type PIV measuring tool for the purpose of this kind of requirement. In this report, we took a circuit board model needed for cooling as its test sample. We visualized flow by forward lighting and applied PIV analysis to the obtained picture. Comparing with numerical analysis, we found that this tool is useful for rough evaluation in field use.

Behaviors of bubbles in liquids have been one of the most important target to be studied in many engineering fields. Recently, two powerful techniques are successfully introduced into the study. The one is PIV whole field measurement technique, the other is the numerical analysis. Studies using one of the techniques are successful, but so far only a few results are compared each other. This paper aims to obtain data for comparison to existing numerical results. In the experiments, velocity distributions and trajectories are measured simultaneously with deformations of bubble shape.

Experimental conditions of bubbling jets were chosen in the intermediate gas flow rate regime where the size and the shape of bubbles are mainly determined by nozzle size and gas flow rate. The velocity of liquid in bubbling jets were measured by making use of LDV (Laser Doppler Velocimeter). The radial and axial distributions of them were related to the behaviour of rising bubbles. The empirical expressions for the mean velocity and root mean square value of velocity fluctuation on the center-line were presented as functions of gas flow rate. Also, water jets in the same vessel were measured to confirm the applicability of LDV system and to clarify the effect of side wall on the confined jets.

In the previous report, velocity vectors and vorticity contours of an unsteady viscous diffusing free doublet flow field were analyzed using a digital image processing system based on the correlation method. In it a serious problem was pointed out oncerning the identification of the tracers using the correlation method for the flow patterns with sharp gradients of velocity and great vorticity. The purpose of the present study is to propose a quantitative limit of the applicability of the digital image processing system using the correlation method. Some experimental simulations were carried out employing the analytical solution of the same doublet flow field as a flow model. The effects of the correlation region size on the erroneous vectors due to the sharp gradient of velocity and great vorticity were discussed in detail.

The object of the present study is to establish a new method for the automatic measurement of unsteady slow flow field with vortices, using a digital image processing system. The flow patterns of viscous diffusing free doublet are recorded on VTR. The two pictures of visualized flow at small time intevals Δt are stored in an image acquisition board. After bi-level quantitation, each image of objective tracer between the two pictures is identified by a new coorelation method. The velocity vectors and vorticity contour curves are dipicted, and the flow mechanism of doublet is explained like that the fluid arround a doublet convected with otherwise uniform flow is rolled and engulfed in it and that it diffuses gradually.

A new concept of the pictures for the particle tracking method is introduced, and it is applied to estimation of the optimum size of correlation area. The estimation is found to be adequate for two different examples. A fast algorithm for rotating pattern matching method are developed, and the algorithm enforce the perfornance of the correlation method.

Velocity and turbulence around a sphere made of synthetic resin submerged in water and bubbling jets in a cylindrical vessel with bottom blowing were measured by making use of Laser Doppler Velocimeter (LDV). The melting process of an ice sphere was recorded by video camera. The local Nusselt number Nuθ of the ice sphere was determined from the initial change of the local radius. The mean Nusselt number Nu was calculated from Nuθ by numerical integration over the surface of the sphere. The effects of velocity and turbulence intensity on Nuθ and Nu were investigated. An empirical expression for Nu was proposed as a function of Reynolds number and turbulence intensity. A method of predicting the complete melting time of an ice sphere was presented.

A new method to measure a velocity distribution through the analysis of the visualized image of a flow is developed. The method ischaracterized by two points. One is the very high speed performance. The other is its very simple and economical analyzing system. Using the system, it takes only 45 see. to analyze a couple of 256*256*8 bit images and to obtain a set of velocity vectors. And it should be noted that it enables to evaluate the reliability of the measurements quantitatively by using correlation coefficients.

A new optical system for a modified shadowgraphy is developed to study the evaporating process of a sessile droplet on a plate. The shadowgraph enables to observe the changes in both drop shapes and internal flow structures.Drops of pure acetone, cyclohexane and the mixture of the two are observed.

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.

In a particle tracking method, a few percentages of errors are included. In order to process them, two kinds of indices, which enable the quantitative evaluation of estimated pairs are newly difined in this paper. The effectiveness of these indices showed in measurment examples. And it is confirmed that these indices are useful to expand the applicabilities of the binary image correlation method, and measure velocity distributions efficiently and automatically.

Characteristics of three visualization techniques are examined through visualizing a pulsating jet in a sudden enlargement. The pulsation has relatively long period and large amplitude. The flow field consists of four characteristic parts which are laminar jet, laminar recirculating flow, turbulent flow and reverse transition flow. These techniques are chosen for better realization of these flows. They are1) Particle suspetion method(a) Particle 1 (aluminum flakes)(b) Particle 2 (polyethylene particles)2) Streak line method (fluorescein)