Hydrodynamics of vortical gas jets coupled to point-like suction

Vortical jet flows in the Reynolds number (Re) range from 1000 to 3425 and swirl number (S) below 0.5, alone and in combination with suction through a small aperture, are experimentally investigated using optical visualization. Schlieren photography is employed to assess the vortical flow structure...

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Bibliographic Details
Published in:Physics of fluids (1994) 2020-10, Vol.32 (10)
Main Authors: Lee, Jung Y., Kottke, Peter A., Fedorov, Andrei G.
Format: Article
Language:English
Subjects:
Apertures
Coupling
Flow velocity
Fluid dynamics
Fluid flow
Free jets
Gas jets
Hydrodynamics
Jet boundaries
Jet flow
Reynolds number
Schlieren photography
Stability
Suction
Swirling
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Summary:Vortical jet flows in the Reynolds number (Re) range from 1000 to 3425 and swirl number (S) below 0.5, alone and in combination with suction through a small aperture, are experimentally investigated using optical visualization. Schlieren photography is employed to assess the vortical flow structure and establish the fundamental understanding of the source-to-sink gas-dynamic coupling, including the role played by the flow rate, jet diameter, and separation distance between the gas jet source and the suction sink. Compared to vortex-free jets, vortical jets for Re > 2700 with swirl number S > 0.27 experience earlier laminar-to-turbulent transition, resulting in a rapid growth of the jet boundary. The ability to control the growth of the jet expansion and mass and momentum dissipation into the surrounding is demonstrated via the use of a coaxially aligned flow suction placed in the path of a jet. When a swirling jet is completely coupled with a flow suction, jet expansion is significantly suppressed. The suction/sink flow rate imposes a limit on the maximum input/source flow rate of the gas jet to achieve complete coupling. Furthermore, there is a maximum distance over which effective coupling can occur, and for all Reynolds numbers considered, this distance is shorter than the distance at which the jet structure breaks up into turbulent eddies in the absence of a sink.
ISSN:1070-6631
1089-7666
DOI:10.1063/5.0019840