@inproceedings{oai:jaxa.repo.nii.ac.jp:00036934,
 author = {内藤, 隆 and 今井, 伸治 and 山田, 日出夫 and Naito, Takashi and Imai, Shinji and Yamada, Hideo},
 book = {航空宇宙技術研究所特別資料, Special Publication of National Aerospace Laboratory},
 month = {Sep},
 note = {28-29 Sep. 1995 (17th). 28-29 Mar. 1996 (18th), 28-29 Sep. 1995 (17th). 28-29 Mar. 1996 (18th), フィンガ状の構造を有する渦(以後フィンガ渦)をRe=2,600の渦輪が平板に衝突する流れ場で初めて発見した。フィンガ渦は主渦と誘起渦の周方向の周期性を促進し、その後の流れ場の発展に決定的な役割を果たす。流れ場の周方向の周期はいつでも2π/14ラジアンであった。周期性の原因解明のため、煙可視化法を用いて、自由空間を移行する渦輪を空間的および時間的に詳細に調べた。Widnall不安定性と呼ぶ波の数が渦輪の下流への移動につれて減少することを偶然発見した。さらに渦輪が平板に衝突する場合、周方向の周期はノズルと平板の間隔が大きくなるにつれて増加することも分かった。この結果が自由空間での結果と良い一致を示したことにより、平板との干渉によって出現する周方向の周期性はWidnall不安定性によるものとの結論を得た。, A vortex with fingers structure (named as fingers vortex) was for the first time found in a flow in which a vortex ring at Re = 2,600 impinged on a flat plate. The fingers vortex accelerates to make the main and other induced vortices more wavy azimuthally and plays a crucial role in the subsequent development of the flow field. The azimuthal period of the flow field remained 2 x pi/14 radian all that while. To clarify the origin of the periodicity, vortex ring travelling in free space was examined in detail, spatially and temporally, using smoke visualization method. Then it happened to be found that the number of waves called Widnall instability decreases as the ring travells downstream. Moreover in the case of the vortex ring impinging on the flat plate, the azimuthal period also increases as the distance between the nozzle and the plate becomes longer. Since the result in impinging case has shown good agreement with that in free space, it is concluded that the azimuthal periodicity appeared on the interaction with a plate is caused by Widnall instability., 資料番号: AA0000867003, レポート番号: NAL SP-33},
 pages = {11--16},
 publisher = {航空宇宙技術研究所, National Aerospace Laboratory (NAL)},
 title = {渦輪の周方向の不安定波に関する研究},
 volume = {33},
 year = {1996}
}