Strangely behaving fluidic oscillator

Abstract

Fluidic oscillators became recently of increasing importance for a number of applications. Two alternative variants have been known so far: (a) feedback-loop configurations, with Strouhal number invariance and (b) configurations with a resonator and frequency not dependent on flow rate. Authors tested an oscillator of seemingly quite conventional two-loop design. Surprisingly, its properties fit to neither of the two established categories. Its Strouhal number is not constant and the frequency of oscillation is flow-rate dependent. There is, so far, no reasonable physical explanation for this strange behaviour.