Fluidic low-frequency oscillator consisting of load-switched diverter and a pair of vortex chambers

Abstract

Abstract. Paper discusses a new configuration of fluidic oscillators, a subject of recent Patent application. There is some similarity with the standard Warren oscillator with its bistable jet-deflection diverter and two feedbacks -which is not suitable for situations demanding very low oscillation frequency. For these conditions the new design replaces jet-deflection switching in the diverter by load-switching effects, with the gradually increased loading by spin-up of fluid in the vortex chambers. The spin-up time also provides the needed time delays. Behaviour is characterised by the oscillation frequency increasing with increasing fluid flow rate -for which was derived a surprisingly simple theoretical solution.

Taxonomic trees of fluidic oscillators

“…The basic principle of the recent relaxation oscillator [13,14]. The monostable version is similar to Fig.…”

“…The main plate of fluidic oscillator according to [14,13]. In experimental evaluation it was capable of oscillating at extremely low frequencies.…”

Computational Modeling of a Low‐Cost Fluidic Oscillator for Use in an Educational Respiratory Simulator

“…[ 7 ] The switching time for an oscillator is related to the characteristic time of the vortex chamber; that is, the time taken to fill the vortex chamber with fluid for a given mass flow ratewhere is the characteristic time, D and h are the diameter and height of the vortex chamber, respectively, v is the specific volume of the fluid, and is the mass flow rate. [ 8 ] To improve upon the A.R.M.E.E. ventilator oscillation period of ≈1 s, we use a larger vortex chamber (88 vs 22 mm) and a central outlet to keep the vortex captive inside a chamber.…”

“…The nozzle-diverter region exploits the Coanda effect (the tendency of a fluid to remain attached to walls), so that nozzle flow is not divided between the lungs and exhaust outlets throughout the respiratory cycle, but instead oscillates from one to the other. [8,9] The high-velocity, low-pressure air in the feedback channel (FC) pulls nozzle flow toward the vortex chamber during the inspiration (Figure 1A). This feedback loop serves the purpose of transporting a small portion of the outflow back to the nozzle-diverting region to create the desired return flow behavior between the vortex chamber and exhaust channel (EC).…”

Bluff Body Drag Control using Synthetic Jet

“…Active flow control includes steady jets, suction or unsteady jets see (Sudin et al (2014); Littlewood & Passmore (2012); Rouméas et al (2009); Zhang et al (2008); Freud & Mungal (1994); Englar (2003); Geropp & Odenthal (2000); Tesař et al (2016); Tounsi et al (2016) and Kavousfar et al (2016)). Amitay et al (1997) investigated flow separation on 2-D cylinder using spanwise pair of synthetic jet actuators.…”