Effect of geometrical parameters on flow-switching frequencies in 3D printed fluidic oscillators containing different liquids

- Liquid-based single feedback loop fluidic oscillators have been characterised.
- Switching frequencies of 2-22 Hz were produced in the range of Re = 600-12,000.
- The frequency was mainly dependent on flow rate for viscosities of 1.00-4.37 mm2/s.
- No oscillations occurred using liquid viscosities of 29.8 and 75.9 mm2/s.
- The splitter distance had the greatest effect on the frequencies.

There is limited information available regarding fluidic oscillator design for liquid phase applications. In this paper, the results of a simple parametric study investigating the effects of seven geometrical parameters on the flow-switching frequencies produced in 3D printed single feedback loop bistable oscillators are reported for a variety of glycerol-water mixtures. The most consequential parameter was the splitter distance (distance between the power nozzle and two outlet streams). Reducing the splitter distance from 10 mm to 5 mm produced higher frequencies at the same flow rate. The angle between the outlet channels was also important, with wider angles (18-24°) producing slightly higher frequencies. Feedback loop widths of 4 mm and greater did not produce flow switching. Other factors that inhibited oscillations were reducing the inlet zone length from 32 mm to 22 mm and changing the feedback channel orientation from horizontal to vertical. Increasing the convergence length of the power nozzle (from 5 to 25 mm) and changing the feedback loop length (from 101 to 113 mm) did not greatly affect the frequencies obtained. Overall, frequencies of 2-22 Hz were produced for kinematic viscosities of 1.00-4.37 mm2/s, in the range of Re = 600-12,000.