|Budget Amount *help
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2004: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2003: ¥2,400,000 (Direct Cost: ¥2,400,000)
To control the anoxic water occurring in the bottom layer of Ariake Sea, two seawater exchange systems were developed in this study. One is to utilize the lower pressure caused by the different velocity between upper layer and bottom naturally in Ariake Sea. Another is screw system.
1)The pumping test utilized the lower pressure carried out with pipes of three types of diameter (φ=0.2m, 0.3m and 0.4m). In this experiment, the pumping velocity was started to observe, after the approaching velocity at the upper side of pipes reached at 2.6cm/s or more.
2)The application level of the model was tested using the underdrainage pipe (φ:0.6m x 5m).
At the result of the test, it was observed that the maximum rates of the approaching velocity and the pumping velocity toward bottom side were 38.2cm/s and 35.4cm/s, respectively. Thus, it was considered that the pumping velocity in the pipe was mainly influenced by the significant wave height, but not by the approaching velocity at the upper site of pipe. As the aspect obtained hi this test was new, further experiments were required to reveal the relationship between the pumping velocity and the significant wave height.
3)The instrument with the screw system was newly constructed to transfer the surface flow toward bottom side.
As the result of test by the instrument composed of two types of screw (φ:0.3 m at upper site and φ:0.1m at bottom site), the screw of upper site was designed to get moving with the speed of 0.5m/s, however, the actual speed was 0.3m/s. Thus, it was identified that the movement of the bottom site screw coupled with upper site one allowed the flow at bottom layer with the rate of 18m^3/s.