Parametric Study on the Backward-facing Step Height in the Mixing Chamber of Fluidic Oscillator

The improvement of the fluidic oscillator as an active flow control device is studied in depth. The interior geometry of the fluidic oscillator is modified by adding backward-facing step (BFS). Variations of BFS height (H) are 2, 4, 6, 8, and 10 mm. The study is carried out computationally using OpenFoam. An unstructured mesh is used in this study, with the mesh quality maintained at y⁺<5. The highest frequency increase occurs at BFS height of 10 mm, which is 36.45%. On the other hand, BFS also increases the average pressure drop by less than 5%, as observed across all height variations. Overall, this study suggests using BFS height of 10 mm. The increase in the momentum of the return flow within the feedback channel leads to a higher oscillation frequency of the fluidic oscillator. The increase in average pressure drop is due to the presence of a recirculation bubble right in the step.