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Many kinds of ducts are employed in many places for such purposes as water supply and drainage, inhalation and exhaust of gases, electromagnetic wave guides, and transmitting sound. In this paper the dependence of sound propagation in a finite unflanged circular duct and sound radiation from the open end of a duct on duct length and sound frequency is discussed. The sound pressure at the central duct axis, amplitude and phase of the sound pressure at the open end, and the radiated sound pressure directivity were measured. From these values, the end correction, radiation impedance at the open end, and attenuation value were obtained and compared with similar values in other references. The experimental results were explained from the general theory of sound. As shown in table 1 the experimental values are much the same as in other papers and, in cases with different characteristics, they are similar.

The bubble behaviors on the basis of experimental results were considered in detail and the experimental correlations were reported previously on the subcooled-boiling heat transfer with forced convection under the atmospheric pressure. The bubble behaviors were complicated by fluid motion in the neighborhood of nucleate sites. In this paper, it is discussed that the heat transfer of nucleate boiling under forced convection is related with the mechanism of the bubble movements as a simplified model. This mechanism of boiling heat transfer is not analysed microscopic, but the analytical results agree well with the experimental values.

In the previous reports, the experimental results of frictional pressure drop in channels with rectangular cross section were discussed to compare with the correlations of frictional pressure drop in pipes with circular cross section in air-water two-phase flow. The frictional pressure drop and the flow behaviour in two-phase flow were inquired into the effects of the geometric shapes of the cross section and the inclined angle of test section.In this paper, the experimental results of the frictional pressure drop and the flow behaviour in channel with rectangular cross section which has larger aspect ratio are added to the preceding results. The correlations of frictional pressure drop in two-phase flow are investigated experimentally in detail.

Finite difference schemes for the convective term of the governing equations of fluid flow have a great influence on the computational time, accuracy and stability of the numerical solution. In this paper, Up-Wind, Hybrid, PLDS, QUICK, Optimal and Approximate LODA Schemes are used tocompute the turbulent flow in a 3-D room. The computational time consumptions to reach the convergence of the flow are compared with each other. Several time steps are set to the Schemes to get faster convergence.The results are as follows :(1) The computed flow patterns are reasonably coincide with the experimental results.(2) Quick Scheme and New Quick Scheme have the higher accuracy with shorter computational time.(3) The selection of suitable time step for each Scheme can greatly decrease the time consumption for the computation.

There were some correlative equations on the apparent coefficient of viscosity and the apparent coefficient of kinematic viscosity of gas-liquid two-phase fluids, in the past reports by several investigators. The purpose of this paper is to make clear the qualitative characteristics of their equations,because the gas-liquid two-phase fluid takes a complicated behavior of flow.

In the preceding paper, the author reported on the correlations of the subcooled-boiling heat transfer of pure water with and without forced convection. In this report the author treats with the subject materials as extended from water to organic liquids. Thus from the same point of view, he gets an experimental formula which can apply for any organic liquids. Compared with other researchers' formulae and data, this formula has shown a favorable agreement.

In the previous paper, the experimental results were reported on the breakup pattern and thecontinuous length of the disintegrating liquid jet and on the period, the amplitude, the wave lengthand the propagating velocity of the surface wave of axial symmetric liquid jet.The author analyzes experimentally in detail the results on the variation of the thickness and thecontinuous length of liquid jet, and considers to correlate their experimental results in this report.

In the foregoing paper, the authors reported on the correlations for the subcooled-boiling heat transfer and the saturated-boiling heat transfer with forced convection. These correlations are insufficient for the transition region that lies between the end of the region of subcooled-boiling and the start of the region of saturated-boiling. The author makes an experiment at the transition region and obtains the correlation for the nucleate boiling heat transfer with forced convection.

To analyze the mechanism of boiling heat transfer varlous behaviors of bubbles must be studied in detail. This paper reports on the relations between the bubble rising periods and the diameters of bubble departing from heated surface, under nucleate boiling. The author translates the mechanism of boiling heat transfer into a simple model and analyzes it theoretically. As the results the author has got the formulae expressing the relations between the bubble rising periods and the bubble diameters. These formulae show qualitatively a good agreement with experlmental data reported by researchers hitherto.

There are many correlations on the pressure drop for two-phase, gas-liquid flow in channel, but it is necessary to reconsider the method which has been used. In this paper, the experimental results on the flow pattern, the void fraction and the pressure drop in the vertical rectangular channel (cross section 30mm×15mm, aspect ratio 2) are reported and the correlation based on the experimental data is proposed. The values of the ratio of the frictional pressure drop of the air-water two-phase flow to the water single-phase flow take some difference about it as compared with the horizontal pipes.

In the foregoing paper, the author reported on the correlation of the subcooled-boiling heat transfer under forced convection. The boiling heat flux in this correlation was observed not affected by velocities and subcooling, while it was found dependent on the system pressure. Then，the boiling heat flux was applied to the correlation of the subcooled-boiling heat transfer under natural convection. The results of the applied correlation were found agreeing with other investigators' data obtained from their experiments.

The present work was performed to elucidate the mechanism of turbulent jet diffusion flames from a circular nozzle by using a high speed video camera. The visible images present an instantaneous display of the turbulent flames. This paper gives information on the turbulence of jet diffusion flames, analyzed from the flame shape which was recorded every 2 milliseconds. An image processing method was employed to visualize the flames shape. In order to obtain the external length and area of flame, a binary image was made from the gray scaled images. A quasi-periodic fluctuation appears in the external length of the flame, and in the area of flame, based upon examination of 300 sequential frames of binary images, in the case of Reynolds number 500. Resulting from an increase in the Reynolds number, the periodic fluctuation graduallydisappears, and a high frequency component appears. Its amplitude becomes high. there is a similarity between the external length and area of the flame. Analyzing the binary image of a flame can reveal the physical characteristics of turbulentdiffusion flame behavior.

The aim of this paper is to clarify flow and heat transfer characteristics behind circular cylinders. Our main attention is focused on the examination of the validity of heat transfer correlations, which have already been proposed by serveral authors. Heat transfer at the rear stagnation point and streamwise velocity were measured under the condition that free-stream turbulence and blockage factor are maintained considerably lower level. The examined range of the Reynolds number was from7000 to 22000.In the relatively high Reynolds number heat transfer coefficients are predicted by means of the existing correlations, while their prediction accuracy is insufficient in lower Reynolds number cases.A corresponding experimental result of the separated shear layer shows that the laminar-to-turbulent transition region is shifted in the upstreamwise direction, as the Reynolds number increases. It was found, therefore, that the transition of the separated shear layer has a significant effect on theheat transfer behavior.