Instantaneous Surface Pressure Measurements of Quasi-Periodic Behavior of Laminar Separation Bubble in the Angles of Attack Near Airfoil Stall

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  • FUJIWARA Go
    東京大学大学院
  • SUNADA Yasuto
    東京大学大学院工学系研究科航空宇宙工学専攻
  • RINOIE Kenichi
    連絡先著者（Corresponding author）：trinoie@mail.ecc.utokyo.ac.jp 東京大学大学院工学系研究科航空宇宙工学専攻

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Other Title
  • 翼型失速付近の迎角における層流離泡の準周期的挙動に関する 表面圧力変動の測定
  • 翼型失速付近の迎角における層流剝離泡の準周期的挙動に関する表面圧力変動の測定
  • ヨクガタ シッソク フキン ノ ゲイカク ニ オケル ソウリュウ ハクリ アワ ノ ジュンシュウキテキ キョドウ ニ カンスル ヒョウメン アツリョク ヘンドウ ノ ソクテイ

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To investigate quasi-periodic behavior of laminar separation bubble near airfoil stall, instantaneous surface pressure distributions of NACA0012 airfoil were measured. Reynolds number based on the airfoil chord length was 1.3 × 105 and the measured angles of attack were 11.3º, 11.6º and 12.0º. At α = 11.6º, the flow around the airfoil indicated quasi-periodical switching behavior between an attached flow with laminar separation bubble (short bubble) and a large separated flow at a frequency of about 2Hz. At α = 11.3º, the flow attaches to the airfoil for a longer period and switches between these two flow patterns irregularly. At α = 12.0º, two different flow phases were observed. One is the phase when the flow switches between the large separated flow and the attached flow with short bubble. At the other phase which was observed longer than the first phase, the flow oscillates without forming the short bubble. Wavelet analysis was performed on the instantaneous surface pressure distributions. Results indicated that pressure fluctuations at frequency of 20--40Hz were observed when the flow was switching from an attached flow with short bubble to large separated one. These fluctuations were observed for all the three tested angles of attack.

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