Self-Suction and Self-Jet Control on Wind Loads and Turbulent Flow Structures over a Circular Cylinder

Abstract

An experimental study on a passive, self-suction, and self-jet control method was conducted to manipulate the flow around a circular cylinder at the Reynolds number R≈5.0×104. The influence of the spacing of the passive bypass jet rings on the aerodynamic forces and flow structures was investigated in detail. The results indicate that the aerodynamic forces acting on the cylinder increase with distance from the jet rings until reaching a critical distance. The critical spacing ratio, S/D, is approximately 2.69 for the convex surface case (Case 1) and S/D=5.00 for the plane surface case (Case 2). Compared to a bare cylinder, the fluctuations of the lift coefficient and mean drag coefficient are reduced by approximately 94.61% and 33.18%, respectively, when S/D=0.38 (the most effective case) due to the stable wake and reduction of the dissipation of turbulent kinetic energy in the near wake, as well as the extra energy input by the flow from the outlet holes.