Wake control of a bluff-body via distributed jets over its surface

The flow passing a circular cylinder can trigger flow-induced vibrations such as the vortex-induced vibration. In this paper, the authors investigated an active method to control the cylinder wake flow. The control scheme was achieved by active blowing through a structured porous surface that was manufactured by 3D printing precisely. The blowing momentum was changed by various mass flow rates so that it defined different values of a non-dimensional momentum coefficient Cμ. The experimental investigation was conducted in a wind tunnel. A 2D particle image velocimetry system was used to measure global flow fields. The Reynolds number based on D was 10 000 in the subcritical region, where D is the cylinder diameter. The proper orthogonal decomposition (POD) was utilized as a reduced-order model. Experimental results showed that transformations could be found in POD modal characteristics and vortex shedding frequencies. Fluctuations in the global wake were suppressed. Moreover, intensities of turbulence kinetic energy and elements of the Reynolds stress tensor T were decreased in the near wake region. It can be concluded that active blowing jets through the structured porous surface of the circular cylinder can be used to control the surrounding flow with effective Cμ values.