Flow Around a Circular Cylinder with Tangential Blowing near a Plane Boundary (1st Report, A Study on Fluid Force)

The flow around a circular cylinder, which is placed near a rigid plane boundary, with tangential blowing is investigated experimentally under the condition of Re=2.7×104. The time-mean surface pressure measurements on the circular cylinder and flow visualizations were carried out for various momentum coefficient Cμ and clearances between the circular cylinder and the rigid plane boundary. The fluid force on the circular cylinder was calculated from these surface pressure distributions. The results of experiment show that the lift reaches the maximum value at certain Cμ and then starts decreasing, and this tendency has never been observed for the cylinder placed in the open flow field. It is considered that the phenomenon is attributed to change in the flow pattern around the circular cylinder, more specifically, due to the occurrence of reverse flow in the gap. In addition, the characteristics of the lift forces can be represented by newly defined nominal jet coefficient C'μ and nominal lift coefficient C'L.