Computational Characterization and Boundary Condition Models of a Jet Interaction Fluidic Oscillator

Koukpaizan, Nicholson; Glezer, Ari; Smith, Marilyn J.

doi:10.2514/1.j060182

Cited by 2 publications

(1 citation statement)

References 31 publications

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“…Unsteady jets have a time-varying velocity at the orifice and can be driven by an oscillating or pulsed (Bidan & Nikitopoulos 2013) pressure source (or sometimes driven by internal instability; Viets 1975; Koukpaizan, Glezer & Smith 2021). Note that the term unsteady jet covers a wide array of jet types, including periodic jets and ones with a more arbitrary velocity characteristic.…”

Section: Introductionmentioning

confidence: 99%

Comparing steady and unsteady rectangular jets issuing into a crossflow

2022

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The foundational differences of steady and unsteady jets issued into a laminar boundary layer crossflow are considered. Jets have been used widely for flow control applications, due to their ability to enhance mixing and mitigate separation, but it is unclear what role jet steadiness plays in flow control effectiveness. Here we compare experimentally unsteady (synthetic) and steady rectangular jets issued into a flat-plate laminar boundary layer with varying orifice pitch and skew. The coherent streamwise vortices produced by unsteady jets were shown to be much stronger than those produced by steady jets, despite producing similar flow patterns. These differences are rooted in how vorticity is generated in the orifice, through either a Stokes layer (unsteady) or a Blasius boundary layer (steady). Exploring the time- and phase-averaged vorticity transport equation reveals that the time-varying vorticity term is the reason for the enhanced vortical structure. When considering flow control metrics, we find that the unsteady jet produced greater added momentum in the boundary layer and added vorticity when compared to a momentum-matched steady jet. Both the steady and unsteady jets produced similar jet penetration characteristics.

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Section: Introductionmentioning

confidence: 99%