1.

論文(リポジトリ)

論文(リポジトリ)
永井, 實 ; Nagai, Minoru
出版情報: 日本機械学会論文集. B編 — Transactions of the Japan Society of Mechanical Engineers. B.  46  pp.394-399,  1980-03-25.  日本機械学会
URL: http://hdl.handle.net/20.500.12000/362
概要: 擬似衝撃波の前後に存在する流れの非一様性を評価するために,質量流量,運動量流量およびエネルギの修正係数を導入すると,これらの係数をパラメータとして擬似衝撃波前後の圧力比,密度比などの関数が疑似衝撃波直前の主流のマッハ数の関数としてexpli citに求められることを示した.具体例として疑似襲撃波に前後の相似の速度分布が存在する場合について計算を行い,本理論が従来の実験値をかなりよく説明することを示した.
論文
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2.

論文(リポジトリ)

論文(リポジトリ)
永井, 實 ; 佐久川, 恵博 ; Nagai, Minoru ; Sakugawa, Keihaku
出版情報: 琉球大学工学部紀要.  pp.1-11,  1980-03.  琉球大学工学部
URL: http://hdl.handle.net/20.500.12000/12127
概要: Flat plate standing perpendicularly in the wind receives large drag because of the flow separation from the plate edge a nd the following large eddy region. This eddy region, called wake, is affected by the boundary condition around the plate, and then affects the drag force. In this study, the aerodynamic characteristics of the rectangular flat plate with a special opening were experimentally investigated at the various boundary conditions. The model plate was manufactured as a sliding shutter by the company O and the company K. The opening ratio of the plate is about 18 percent. According to the experiment, the drag coefficient of the specimen did not vary from the same plate but without the opening. Drag coefficient in the case of no boundary, specimen in the uniform flow, is 1.19, which is somewhat higher than the value 1.12 of the thin rectangular flat plate. The difference is seemed to be caused by the thickness and the edge shape of the plate. In the worst boundary condition, the flat plate placed on the center of the large wall, the drag coefficient reachs to 1.59, which is 34 percent larger than the value in the case of no boundary. However, if a kind of wind shutter is placed behind the model, the drag force acting to the model becomes almost negligible. Pressure oscillating phenomena are also researched, and it is tried to explain the frequency by the Kármán vortices and Helmholts resonance.
紀要論文
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