No-moving-part hybrid-synthetic jet actuator

Abstract

In contrast to usual synthetic jets, the "hybrid-synthetic jets" of non-zero timemean nozzle mass flow rate are increasingly often considered for control of flow separation and/or transition to turbulence as well as heat and mass transfer. The paper describes tests of a scaled-up laboratory model of a new actuator version, generating the hybrid-synthetic jets without any moving components. Self-excited flow oscillation is produced by aerodynamic instability in fixed-wall cavities. The return flow in the exit nozzles is generated by jet-pumping effect. Elimination of the delicate and easily damaged moving parts in the actuator simplifies its manufacture and assembly. Operating frequency is adjusted by the length of feedback loop path. Laboratory investigations concentrated on the propagation processes taking place in the loop.

Performance Study of a Fluidic Hammer Controlled by an Output-Fed Bistable Fluidic Oscillator

“…Presumably due to the traditional planar design of the fluidic devices, the challenges existing in the difficulty of convergence, and huge demand on computer resources, there have been fewer CFD studies based on the 3D computational models on fluidic oscillators than other numerical studies, namely, the use of 2D simulation models or the analytical modeling. Considering that the relaxation bistable oscillator is a 2D analogue of the Tesar-Zimmerman oscillator [29] (3D feedback loops), the output-fed bistable fluidic oscillator studied here can certainly loop around the vents in 2D topologically. However, for an output-fed bistable fluidic oscillator in the fluidic hammer, the movement of the impact body is influential to the oscillating behavior of the oscillator.…”

Flow pulsation in the near-wall layer of impinging jets

“…The amplifier is of the Coandaeffect bistable version so that the oscillation consists of alternating switching of the flow between the two attachment walls. Details of the amplifier are based on earlier experience with the author's successful geometry as it is described, e.g., in references [13] and [14].…”

Strangely behaving fluidic oscillator

“…The geometry of the amplifier cavities was designed to correspond to the also already well proven earlier version described in detail, e.g., in [6,7]. The feedback chosen was the well-known Warren's twoloops type [9].…”