壁面近傍に置かれた接線方向吹出し円柱周りの流れ : 第2報,非定常特性に関する考察(流体工学,流体機械)  [in Japanese] Flow Around a Circular Cylinder with Tangential Blowing near a Plane Boundary : 2nd Report, A Study on Unsteady Characteristics(Fluids Engineering)  [in Japanese]

The wake oscillation of a circular cylinder, which is placed near a rigid plane boundary, with tangential blowing from a surface slot is investigated experimentally under the condition of Re=2.7×10^4. The time-mean surface pressure measurements on the circular cylinder, flow visualizations and velocity fluctuation measurements were carried out for various momentum coefficient Cμ and clearances between the circular cylinder and the rigid plane boundary changed. Based on these experiments it is found that periodic velocity fluctuation, which is associated with vortex shedding (Karman vortices), is suppressed by the tangential blowing. However, in the case of the cylinder placed near the rigid plane boundary, the reverse flow occurs in the clearance between the cylinder and the boundary, in particular Cμ increases. The level of flow unsteadiness naturally increases. Moreover, velocity fluctuation measurements revealed that the velocity fluctuation classified into two cases, one being the velocity fluctuation occurring periodically (H/D>0.1) and the other occurring non-periodically (H/D=0.1).