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Mechanism and performance of a hydrofoil bubble generator utilized for bubbly drag reduction ships
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| Title: | Mechanism and performance of a hydrofoil bubble generator utilized for bubbly drag reduction ships |
| Authors: | Murai, Yuichi Browse this author →KAKEN DB | | Sakamaki, Haruki Browse this author | | Kumagai, Ichiro Browse this author | | Park, Hyun Jin Browse this author | | Tasaka, Yuji Browse this author →KAKEN DB |
| Keywords: | Bubbly drag reduction | | Hydrofoil bubble generator | | Air lubrication | | Two-phase flow |
| Issue Date: | 15-Nov-2020 |
| Publisher: | Elsevier |
| Journal Title: | Ocean Engineering |
| Volume: | 216 |
| Start Page: | 108085 |
| Publisher DOI: | 10.1016/j.oceaneng.2020.108085 |
| Abstract: | Following the success of bubbly drag reduction for marine vessels by hydrofoil bubble generators (Kumagai et al., 2015), we conducted two kinds of experiments to specify and improve its working principle. Firstly, PIV measurement was carried out to elucidate the flow structure around a hydrofoil running beneath a free surface. Froude number dependence of the anti-stall characteristics and cancellation of vertical pressure gradient above the hydrofoil were confirmed, which entrain the atmospheric air into water flow. Secondly, we mounted the hydrofoil to a model ship that runs in a 100-m-towing facility and found three different two-phase flow patterns in realizing bubble generation. Volume flow rate of generated bubbles increased with the ship speed to the power of greater than two, thus wall-occupation fraction of bubbles also increases with the ship speed. Furthermore, hydrofoil drag during bubble generation was measured and used to estimate net power-saving, having proved advantage of the hydrofoil bubble generator for long ships at high speed conditions. |
| Rights: | © <2020>. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/ | | https://creativecommons.org/licenses/by-nc-nd/4.0/ |
| Type: | article (author version) |
| URI: | http://hdl.handle.net/2115/86805 |
| Appears in Collections: | 工学院・工学研究院 (Graduate School of Engineering / Faculty of Engineering) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: 村井 祐一
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