On Dynamics of Acoustically Driven Bistable Fluidic Valves

Abstract

The dynamics of an actively controlled fluidic diverter with novel actuation method are presented. This bistable fluidic valve is based on the Coanda effect and is able to switch the main flow solely by means of acoustic excitation. The switching is explained through a combination of experiments and large eddy simulations (LES). The switching time and minimum energy required are characterized for a range of pressure ratios, acoustic excitation frequencies, and input powers. It is shown that the switching mechanism depends on the excitation of natural instabilities inside the free shear layer. An enhanced roll-up of vortices at the excitation frequency increases the rate of entrainment and results in a transverse pressure gradient sufficient to counteract the Coanda effect leading to jet detachment and switching.

Temperature-driven Switching and Deflection of Bistable Flow Crossing Side- by-side Tubes

“…The bistability in flow is a phenomenon that the fluid can flow along one side and can be provoked to the other side and keep stable state, which occurs when the fluid flowing across tubes arranged in a characteristic pitch or through a slit. This flow behavior is highly lighted not only in academic researches but also in applications as the fluid amplifier, the fluid oscillator and the logic circuit [1] . This study adopts numerical simulation to study the bistable slit jet deflection under different temperature gradients in detail.…”

Comparative Analysis of Monitoring Methods for Vortex-induced Vibration of Multistage Pressure Reducing Valves

“…The regulating valve is an indispensable component in modern control systems, as it can control ow rate and stabilize pressure [1][2][3]. This valve is widely used in petrochemical, water conservancy, energy and other industrial sectors.…”

Closed-loop control of a piezo-fluidic amplifier

“…However, unlike conventional flow control valves, neither of these approaches allows for controlled modulation of the output flow according to a desired reference trajectory. Piezo-fluidic amplifiers [14][15][16] rely on the fundamental physics of jet dynamics when subjected to sound injection in a transverse direction. The purpose of this paper is to demonstrate the effective closed-loop control of such dynamics thereby enabling continuous output flow modulation according to a desired output trajectory.…”

“…In this paper, we employ the same piezo actuation method as in [14] where a highly reliable piezo buzzer is used to deflect the jet inside a Coandă diverter causing the device to switch its state. However, the response of the device is limited in Mair et al [14][15][16] in applications that require strong synchronisation. In this paper we propose the use of closed-loop control to tackle both of these deficiencies by utilising pressure measurements from the total pressure tappings in the output channels as feedback signals (see Fig.…”

“…These have been utilised for a range of flow control applications from improving the effectiveness of a vertical tail [10,11] to noise control [12]. Another means to achieve both high bandwidth and high authority is by amplifying the effect of plasma or piezo actuators by switching fluidic diverters [13][14][15][16]. However, unlike conventional flow control valves, neither of these approaches allows for controlled modulation of the output flow according to a desired reference trajectory.…”