Synchronization and Flow Characteristics of the Opposed Facing Oscillator Pair in Back-to-Back Configuration

This study quantifies the flow characteristics of an opposed facing fluidic oscillator pair that was arranged in a back-to-back configuration. The objective was to obtain two synchronized oscillating sweeping jets using a shared feedback channel, incorporated in a no moving parts design. The oscillation frequency and the sweep angle of the fluidic oscillator exiting jets were obtained with hot-wire measurements and water visualizations, respectively. The dynamics of the fluidic flow characteristics were assessed using the compressible Unsteady Reynolds-Averaged Navier-Stokes and the Large Eddy Simulation methods, that were validated against the hot-wire measurements. Five different Reynolds number (Re) flow conditions were considered and the proposed setup was capable of producing a synchronized oscillation in the range 101 to 422 Hz, and with a sweep angle up to 80°. Water flow visualization and hot-wire measurement identified two synchronized sweeping exiting jets, which was observed from the opposed facing oscillator pair. The oscillation frequency of the exiting jets was found to be a linearly function w.r.t. Re, which resulted in a Strouhal number in the order of 0.01. It was quantified that the pressure variation and the accompanying flow momentum were balanced and in-phase between both halves of the fluidic oscillator, which was established by means of the shared feedback channel. The opposed facing oscillator pair design provides two synchronized exiting sweeping jets, which widens the application range of the single feedback type fluidic oscillator.