Flow and Frequency Characterization of the Synchronized Stacked Sweeping Jets

Abstract

This work characterizes a pair of feedback-type fluidic oscillators in a stacked arrangement. Quasi-rectangular synchronization channels were used to connect both feedback channels of each oscillator; thus communication between fluidic oscillators was established. Synchronization through these channels provided strong cross-correlation values () obtained with hot-wire probes for a total flow rate range of 10–30 standard liters per minute. The oscillation frequencies were varied from 263 to 672 Hz for a Reynolds number range from 5660 to 17,000, respectively. The resultant sweeping jets were also observed through water flow visualizations. Details of the internal flowfield leading to synchronized behavior were extracted employing numerical simulations that were validated with the frequency measurements. It was determined that the feedback flow in feedback channels occurs simultaneously in a periodic manner, and thus jet switching inside each oscillator is synchronized. It was also observed that a pair of strong recirculation zone forms for every period inside both synchronization channels, and this zone plays a major role in balancing the momentum in the feedback channels, thus creating simultaneous feedback flow. The overall switching mechanism of the fluidic oscillators seems to be intact, whereas the pair found to act as a single dynamic system.