Characterization of the Microfluidic Oscillator
The microfluidic oscillator is a new microscale actuator developed for flow control applications. These patented devices can produce a 325-ytm-wide oscillating gas jet at high frequencies (over 22 kHz) and very low flow rates (∼1 1/ min or ∼1 g/ min). Furthermore, microfluidic oscillators have no moving parts; the jet oscillations depend solely on the internal fluid dynamics. In this work, the flowfield of a microfluidic oscillator is characterized using pressure transducers, water visualization, and pressure-sensitive paint. The acoustic field and frequency spectrum were characterized for the oscillator at several flow rates. The results indicate that the external flowfield of the microfluidic oscillator is marked by two distinct operating regimes, separated by a transitional increase in turbulent noise. This work also demonstrates a significant advance in pressure-sensitive paint technology. New instrumentation was developed to resolve small-scale, time-resolved measurements of a high-frequency micro flowfield. A macro imaging system was used to provide a spatial resolution of approximately 3 mm per pixel and time-resolved, full-unsteady pressure measurements at oscillation frequencies up to 21 kHz.