Stochastic regimes in very-low-frequency fluidic oscillator

Abstract

Abstract. Paper discusses interesting unexpected stochastic regimes discovered in a fluidic oscillator designed for operation at very low oscillation frequencies -without the inconvenience of the long feedback loops needed in standard low-frequency oscillator designs. The new oscillator contains a pair of bistable turn-down active valves operating in anti-parallel -essentially analogous to Abraham & Bloch electric "multibrateur" invented in 1919. Three different self-excited oscillation regimes were found. In the order of increasing supplied flow rate, these regimes are characterised by: (A) generation of stochastic-duration multi-pulse packs, (B) generation of individual pulses with a degree of periodicity, and (C) regime with randomly appearing flow pulses separated by intervals of the order of seconds.

Taxonomic trees of fluidic oscillators

“…Again, it was the turn-down capability in the amplifiers that was obtained by applying the idea of vortex amplifier. the amplifiers discussed in [15] are the CSVA version (Coanda-switched vortex amplifier) -in fact an integral combination of a bistable diverter and vortex amplifier. Upstream from the vortex chamber there are antechambers with a pair of mutually inclined attachment walls to which attaches the jet, formed by issuing from the supply nozzle.…”

“…Upstream from the vortex chamber there are antechambers with a pair of mutually inclined attachment walls to which attaches the jet, formed by issuing from the supply nozzle. Figure 18 One version of the oscillator described in [15], with Coanda-switched turn-down valves.…”