Characterization of Various Types of Two Feedback Channel Fluidic Oscillator Using Computational Methods

The modified fluidic oscillator (FO) mixing chamber produces significant changes in fluid flow characteristics, but the underlying physical mechanisms are not yet comprehensively understood. A two-dimensional computational fluid dynamics (CFD) analysis was conducted using the URANS SST k - ω turbulence model. The FO configurations studied in this study were the backward-facing step (BFS) FO, cusp, and ramp trailing-edge FO. All FO configurations are evaluated using the FO baseline as the benchmark model. The study results revealed a clear performance trade-off. The BFS FO configuration produced the highest frequency with a frequency increase of 22.69% compared with the baseline model. However, the sudden geometric changes in BFS in the mixing chamber and shear stress caused a pressure drop surge of 85.52%, accompanied by a decrease in the deflection angle of 18.39%. The cusp and ramp prevent sudden flow separation in the mixing chamber. Thus, the increase in pressure drop for the cusp and ramp trailing-edge FO configurations was 2.25% and 0.13%, respectively. Both models have a frequency increase of only 1.02%. According to an Frequency-Deflection-to-Pressure Ratio (FDPR) evaluation, the cusp and ramp models are more suitable for airfoil-based active flow control device applications such as airfoils. The BFS FO model is more suitable for internal flow applications, such as combustion chambers, which require frequencies that do not consider the pressure drop and deflection angle as much.