ハイドロフォンの特性に関する水路実験 [in Japanese] Flume experiments to examine hydrophone characteristics [in Japanese]
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A hydrophone is capable of determining the number of pulses when the sediment rate is high. This study varied the grain size, sediment rate, length of pipe, location where the grains of sand collided, and sensitivity of the microphone, and examined the relationships between these parameters and the number of pulses to determine characteristics using a hydrophone. The flume experiment used a rectangular 9-m-long flume with a changeable inclination and a rectangular flume 20m long and 1.0 m wide, with an inclination of 1/50. L- and U-type steel pipes with circular cross-sections were used. The outside diameter was 27.2mm and the inside diameter was 25.2mm. With the U-type pipe, a microphone was positioned at both ends, and a filter made of sponge was installed on one side. The following results were obtained: 1) the channel that best detected the pulse differed with the grain size; 2) when the sediment rate was high, there was a high probability that the number of pulses decreased unless the sensitivity of the microphone was adjusted using a filter; 3) the length over which the sediments collided influenced the change in the number of pulses more than did the length of the steel pipe; and 4) when the sensitivity was decreased by placing a filter over the microphone, pulses were detected even in the high sensitivity condition. Based on these characteristics of the hydrophone, it is thought that it is possible to correspond by shortening length over which the sand collides, and decreasing the microphone sensitivity under the condition the pulse's large the amount of the sediment rate decreasing.
- Sabo Gakkaishi
Sabo Gakkaishi 60(5), 66-71, 2008-01-15
Japan Society of Erosion Control Engineering