Abstract
This experimental study investigates the effects of internal geometry modifications on the performance of a curved Sweeping Jet actuator. The modifications are applied to the geometry of the feedback channel and the mixing chamber Coanda surface, and the resulting actuator properties are evaluated using time-resolved static pressure measurements inside the actuator and hot-wire measurements of the external flow. The major result is that small, localized modifications of the curved sweeping jet actuator geometry can lead to a complete change in the external flow regime, making the jet velocity distribution homogeneous, similar to the angled variant of the actuator. The Coanda surface shape is identified as the primary cause of the external jet adopting the bifurcated or homogeneous flow regime. The relationships between the sweeping frequency, jet deflection angle, required supply pressure, and pressure fluctuations are analyzed and discussed in detail. External flow behavior and coherence are characterized by phase-averaged, phase-locked velocity profiles and auto-correlation of the velocity signals.Graphical abstract
Highlights
Numerous designs of fluidic oscillators have been present since the 1950s
Some jet velocity profiles in this group are broadly similar to a plain jet profile, but the associated Power Spectral Density (PSD) of pressure signals confirm that they still oscillate at a specific frequency related to the Strouhal number of the sweeping
The term “homogeneous” in the above discussion refers to the mean velocity profile that does not represent a typical twinpeak distribution expected from a bi-stable jet, but is still dominated by a well-defined oscillation period accompanied by a lower jet deflection angle
Summary
There is a renewed interest in their design, optimization, and application in recent years, due to their significant potential for flow control. They are simple to fabricate, since they do not involve any moving parts, and can be fairly implemented. The Sweeping Jet (SWJ) actuator with two feedback channels is one of the most common fluidic oscillator designs, with oscillation frequencies ranging from a few Hertz to several kilo-Hertz. It has been widely studied for many applications, such as: heat transfer
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