Melting of ice in cylindrical capsules by natural and forced convections in outer region was studied by experiments including flow visualization technique and numerical calculations. When a cylinder diameter was small, natural convection melting was well simulated by axisymmetric heat conduction analysis. In case of a cylinder with large diameter, surface temperatures were affected by the effect of natural convection in a cylindrical, capsule. Melting time became smaller by the natural convection in the cylindrical capsule for natural convection melting. In case of forced convection melting, surface temperatures were considerably scattered and the stagnation temperature showed the highest value. The shape of the solid liquid boundary became asymmetric. Non-uniform distribution of heat transfer coefficient should be considered in treating melting with large size capsules.

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When condensation occurs in a supersonic flow field, the flow is affected by the latent heat released. In the present study, a condensing flow was produced by an expansion of moist air in circular bump models and shock waves were occurred in the supersonic parts of the fields. The experimental investigations were carried out to show the effects of initial conditions in the reservoir and nozzle geometries on the shock wave characteristics and the turbulences in the flow fields. Furthermore, in order to clarify the effect of the condensation on the flow fields with shock waves, Navier-Stokes equations were solved numerically using a 3 rd-oder MUSCL type TVD finite-difference scheme with a second order fractional step for time integration.

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The interaction of a strong vortex ring with a premixed flame was experimentally studied in order to understand how the flame is affected by an element of intensive turbulence. The interaction could be observed by sequential schlieren photographs and instantaneous OH-LIPF and CH-LIF images. As a result, two types of interacting behavior have been observed: One is that the flame becomes a mushroom shape, a pocket of unburned gas forms, and finally the pocket disappears by combustion. The other is that the flame becomes a mushroom shape but the mushroom flame intrudes into the burned gas region without entraining the unburned gas.

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Pattern tracking algorithms using the gray level difference (GD) as a similarity index of correlation area and the successive abandonment (SA) method were evaluated quantitatively through the application to the artificially generated images visualized with particulate or smoke tracers for a three-dimensional impinging jet flow.
The performance of both algorithms for smoke images is inferior in general compared with the performance for particulate images. However, the performance for smoke images with high spatial frequency of concentration change is expected to approach the performance for particulate images. The introduction of the safety factor of 2 or 3 to the threshold, which is used in SA and obtained with our statistical model, improves the performance of SA.

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A new vortex excitation of a circular cylinder placed in an otherwise uniform flow was reported in earlier papers by the present authors. This excitation is induced by longitudinal vortices which are originated by setting another cylinder downstream of the first one in cruciform arrangement with a gap less than one half of the cylinder diameter. In this work, the configuration and shedding frequency of the longitudinal vortices causing the excitation were investigated through flow visualization experiments in a water tunnel and quantitative measurements in a wind tunnel. The visualized configurations of the two types of longitudinal vortices, the trailing vortex and the necklace vortex, correlated well with their corresponding contours obtained from pressure-velocity cross-spectrum measurements in the wind tunnel. Strouhal numbers of the longitudinal vortices were also investigated over a wide range of the Reynolds number Re, by using both a wind tunnel and a water tunnel. While the Strouhal numbers for the two longitudinal vortices are practically independent of Re for Re>10000, they increase appreciably with an increasing Reynolds number in the range of Re<10000.

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