Control of flow around a square prism by slot jet injection from the rear surface

The flow around a square prism with slot jet injection from its base into the vortex formation region has been investigated experimentally for Reynolds number of 8000. For various injection rates, the mean and fluctuating pressure distributions on the square prism were measured and the velocity measurements were carried out by using a hot-wire anemometer. Flow visualization was performed by using the smoke-wire method. It was found that the slot jet injection has a substantial influence on the flow characteristics of the square prism. Increase of the injection ratio up to a certain value causes an important pressure recovery in the wake. For this lower range of blowing rates, blowing fluid tends to fill the wake region around the prism and extend it but the jet does not have enough momentum to penetrate the main vortices. By the further increasing of the blowing rate, the slot jet injection from the base side of the prism splits the near wake like a splitter plate. This causes a thinner wake width and weak vortices resulting in a higher vortex shedding frequency.