Comparing steady and unsteady rectangular jets issuing into a crossflow

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Author(s)Tricouros, Frank A.
Author(s)Amitay, Michael
Author(s)Van Buren, Tyler
Date Accessioned2022-06-23T15:06:50Z
Date Available2022-06-23T15:06:50Z
Publication Date2022-05-31
DescriptionThis article was originally published in Journal of Fluid Mechanics. The version of record is available at: https://doi.org/10.1017/jfm.2022.413. © The Author(s), 2022. Published by Cambridge University Press.en_US
AbstractThe 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.en_US
CitationTricouros, F., Amitay, M., & Van Buren, T. (2022). Comparing steady and unsteady rectangular jets issuing into a crossflow. Journal of Fluid Mechanics, 942, A56. doi:10.1017/jfm.2022.413en_US
ISSN1469-7645
URLhttps://udspace.udel.edu/handle/19716/31016
Languageen_USen_US
PublisherJournal of Fluid Mechanicsen_US
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
Keywordsjetsen_US
TitleComparing steady and unsteady rectangular jets issuing into a crossflowen_US
TypeArticleen_US
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