Numerical Analysis of Internal and External Flow Fields of a Fluidic Actuator for Active Flow Control Applications

A numerical study is conducted to explore the unsteady nature of fluidic oscillators which is responsible for generating sweeping jets for effective flow control of large-scale applications. Two- and Three-dimensional (2D and 3D) Unsteady Reynolds-Averaged Navier-Stokes (URANS) and 3D Improved Delayed Detached Eddy Simulation (IDDES) are employed to simulate and resolve the flow structures in the internal flow passages of a fluidic oscillator and external flow field in a quiescent flow condition. The predicted flow generated by an enlarged actuator with an outlet diameter of 25 mm using air as a working fluid is validated against measurements at various supply rates. Comparison of current computational results using 2D and 3D URANS with experiments indicates a reasonable agreement in the jet oscillation frequency. However, a significant discrepancy in the streamwise velocity field is observed between the 2D URANS and experimental data. The 3D URANS also under-predicts the jet width and consequently over-predicts the extension of the jet in the axial direction downstream of the actuator exit. Excellent agreement in the jet oscillation frequency and internal and external flow field is obtained at two supply rates between 3D IDDES and measurements.