Characterisation and comparison of unsteady actuators: a fluidic oscillator and a sweeping jet

Abstract

Purpose The purpose of this study is to compare two unsteady actuators: an oscillator and a sweeping jet. Both actuators can produce an oscillating jet of different amplitudes and frequencies without any moving parts, making them an attractive actuator concept. The Coanda effect phenomenon can explain the operating principles of these two unsteady actuators. Design/methodology/approach A numerical study was conducted to compare the amplitudes and frequencies of fluidic and sweeping jet (SJ) oscillators to obtain an efficient actuator to control separated flows at high Reynolds numbers. For this goal, two-dimensional unsteady Reynolds-averaged Navier-Stokes simulations were carried out using computational fluid dynamics (CFD) fluent code to evaluate the actuator performances. The discrete fast Fourier transform method determined the oscillation frequencies. Findings The oscillation frequencies gradually increase as the inlet pressure increases. The characteristics and dimensions of the vortices produced in the mixing chamber and feedback loops vary overtime when the injected fluid is swept sideways. The frequencies supplied by the SJ are stronger than those obtained by the fluidic oscillator, which may contribute to improving the aerodynamic performance at a lower power supply cost. Originality/value The existence of the splitter in the fluidic oscillator led to the production of separate pulses, which would be useful in various industrial applications, including active control of combustion and mixing processes while other applications such as flow separation control require SJs. With the latter actuator higher and interesting frequencies can be obtained, leading to efficient flow control.

Active Flow Control of a Supercritical Airfoil and Flap with Sweeping Jets

“…As one kind of effective AFC technology, the sweeping jet has been considered a more practical flow controller than other existing technologies [11], and it is widely applied in other different sceneries. For example, the dynamics of oscillating jet emitted in confined and non-confined backward-facing step geometries were investigated with TR-PIV to resolve the mechanism of flow separation and reattachment that occurs at a sharp corner, which will help the application of fluidic oscillators in heat transfer enhancement or cooling process [12].…”

Raster Angle Impact on Fdm-Based Additive Manufactured Fluidic Oscillator

“…Synthetic and steady jets have been widely studied for flow control and heat transfer enhancement [19][20][21][22][23][24][25][26]. The unsteady characteristics of fluidic oscillators are desirable for the development of next-generation heat exchangers with extremely high heat flux removal capacity [27][28][29]. The heating uniformity index is a critical factor in heat transfer is controlled by various printing parameters, such as the printing raster angle, the thickness of the layer, air gap, the orientation of printing, and raster width [46].…”