431 ピッチング運動とヒービング運動が組合った非定常運動翼後流の渦流れ(S35-3 乱流渦構造(3),S35 乱流渦構造)  [in Japanese] 431 Vortex Flow behind an Unsteady Airfoil in Pitching and Heaving Motions  [in Japanese]

Many studies on unsteady flow around an unsteady airfoil, such as a pitching airfoil and a heaving airfoil, at low Reynolds number region have been carried out with experimental and numerical approaches and vortex flow patterns and dynamic thrust of them have been reported. However, the flow field around an unsteady airfoil in pitching and heaving motions has not been understood. We have carried out PIV measurement behind an unsteady airfoil in pitching and heaving motions at low Reynolds number region, Re=4000. The thrust producing vortex street was formed behind an unsteady airfoil at low non-dimensional trailing edge velocity and low non-dimensional heaving velocity. Moreover, it was found that the thrust producing vortex street was formed by vortices of strong vorticity at ψ=π/2 and 3π/2. However, large vortex rolled up from the leading edge at ψ=π/2 and 3π/2.