ハイドロジェット艇とプロペラ艇の水中音について
スポンサーリンク
概要
- 論文の詳細を見る
The underwater sound from the boat driven by hydrojet was compared with the one driven by propeller in order to verify whether the hydrojet propulsion system is acoustically suitable for fishing boat.The underwater and airborne sound measurements were made in Negishi Bay, Kanagawa Prefecture.The Results of the experiments may be summarized as follows.At a low engine speed of 1,000 rpm, the overall sound levels in the water from the both boats nearly coincide with the background noise level in the sea, but the level of any boat and the level difference between the both boats increase with the increasing engine speed. For example, the level from the hydrojet boat is observed to be about 20 dB lower than the one from the propeller boat at engine speed of 3,000 rpm.The underwater sounds from the propeller boat have most of energy at high frequencies above 1.000 cps and in some engine speed the passage frequency of the propeller blade and its harmonics are observed in the low frequency range below 100 cps.The singing of propeller was experimentally observed only for the propeller speed of 1,200 and 2,400 rpm.In contrast to the spectra mentioned above, in the case of the hydrojet boat, they have little energy at high frequencies and predominantly high level conponents in the frequency bands which contain the rotor blade passage frequency of the pump.The methods of the underwater sound reduction were compared between the boats on the basis of the sound transmission paths from noise sources to the point of the observation in the water. It was found that in the hydrojet boat, the attenuation of the sound increase additionally by the means of both the resilient amount of the unit of engine and propulsion system, and the intake silencer of the pump.Studies on the auditory sense of fish are reported in several literatures and it is said that fish will be caused to go away by the sound which is predominatly high level above the background noise of the sea in the frequency range from 1,000 to 6,000 cps.Considering the experimental results as mentioned earlier and these published ones, it will be concluded that the hydrojet propulsion system is acoustically advantageous to fishing boats, although the problem of the differences of the underwater sound between the tested boats remain to be solved.This propulsion system may be effective when low underwater sound level is required.
- 社団法人日本船舶海洋工学会の論文
著者
関連論文
- ハイドロジェット艇とプロペラ艇の水中音の比較
- バルブノイズ
- 振動レベルと振動速度の関係に関する考察
- 公害振動の測定について
- エネルギー和の効用
- 航空機地上試運転時の騒音対策
- ディーゼルパイルハンマの騒音について
- ハイドロジェット艇とプロペラ艇の水中音について
- 船の騒音測定法に関する考察
- 機械騒音と騒音評価値の関係 : (2) 空気機械の騒音について
- 機械騒音と騒音評価値の関係 : (1) 艦船の騒音について
- 舶用内装材の音響的性質について
- 船の騒音について
- 騒音源のパワーレベルと使用上の注意点