Growth Process of Vortex Structure Formed by a Sweeping jet in Cross Flow near a Wall

Abstract

The Fluidic Oscillator can permanently generate a high-velocity oscillating jet (Sweeping jet) and give a large fluctuation to the flow field without driving parts. Therefore, it is attracting attention as a new active flow control device. However, the flow characteristics that directly contribute to flow separation control have not been sufficiently clarified, and their optimization and practical application have not progressed. Therefore, in order to clarify the details of the flow characteristics that contribute to the flow separation control, it is necessary to clarify the flow structure generated by the sweeping jet that blows into the main flow from the wall surface．In this study, we clarify the growth process of the vortex structure generated by the interaction of the sweeping jet, which blows out from the wall at 30 degrees to the main flow, by numerical simulation. It is conducted to understand the complex and large-scale flow structure and its generation process generated by a sweeping jet in the main flow. The vortex structure forms one flow tube at z/d < 4.5 and splits into two at z/d > 4.5. Shear layer vortices with the same frequency as the oscillation frequency are generated in the stream tube, and after splitting into two, it is generated alternately to the left and right. After that, at z/d > 6.0, the shear layer vortex begins to collapse due to wall interference, and at z/d > 7.5 it transforms into discrete vortices.