[in Japanese]

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It is very important to optimize the shape of the flow passage in order to minimize the pressure drop through it. The typical examples are observed in the designing of air duct inside the automobile, the external flow passage around the car, the flow passage inside the pump, etc. We have developed a new method to predict the optimized shape of the flow passage. It is implemented into the specialized CFD code called Shape-Designer. The code is very unique in the sense that it does not require the candidate of the optimized shape to the user. It automatically predicts the shape by itself.

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In recent years, technologies to manufacture high cost performance products in shorter periods of time have become considerably necessary in the manufacturing industry in general, to meet drastic changes in the market needs and the reduction of development cost. In response to this trend, our corporate facility actively makes use of computational fluid dynamics (CFD) analysis in studying fluid flow in turbomachinery such as pumps, which are our mainstream products. This report introduces an examination of prediction of the pump cavitating performance by using CFD code.

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The numerical method for analyzing a floating type of wave energy conversion device fixed on the water surface is described under the condition that the linear water wave theory is applicable. The method is proposed in order to calculate the device characteristics of an air chamber. It uses the flow rate and the gauge pressure in the air chamber directly, because the interaction between oscillating water column and the turbine is controlled only by the flow rate and the pressure drop through the turbine in this system. It is confirmed that the solution gives good agreement with the experimental data

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We developed the wave power converter set up at the bottom of sea. The two air tanks were set away from each other about a half-wave length and they were connected with a pipe and a wave energy converter was set between them. In this paper experiments were performed in a model tank and thin tubes were used in place of a converter. On the other hand, computer simulations were performed and their results coincided with those of experiments. It became clear experimentally not only hard tank but also flexible one could be used. We applied our simulation to the actual model set at the bottom of sea. The efficiency of the wave power converter was calculated as 30%, and 20kW of power was gained when the diameter of tank was 10m and the wavelength was 80m and wave height was 2m. As a result, we concluded that the wave power converter set up at the bottom of sea would be useful, and it would make it possible to reduce the cost of production of wave power converter systems.

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