This experimental study explored the effects of axisymmetric sinusoidal excitation on structural and mixing characteristics in the equidensity jet in crossflow (JICF). Planar laser-induced fluorescence imaging of acetone seeded in the jet fluid was used in this quantification, where the jet Reynolds number was fixed at and crossflow velocity was varied. Jet-to-crossflow momentum-flux ratios ranged from , with a convectively unstable upstream shear layer (USL) in the absence of forcing, to , with a globally unstable USL. Sinusoidal excitation had a relatively significant influence on the convectively unstable JICF at larger values, especially when the USL was locked-in to the forcing frequency, causing the jet cross section to become more symmetric and causing molecular mixing, quantified in both centerplane and cross-sectional planes, to improve. For a globally unstable JICF, only sinusoidal forcing corresponding to clear lock-in conditions, close to the fundamental shear-layer frequency and/or at very high amplitudes, affected jet structure, with somewhat moderate improvements in molecular mixing. Typically, excitation conditions creating enhanced jet penetration and spread did not correlate directly with improved molecular mixing; there was a stronger correlation of improved mixing with creation of a more symmetric jet cross section, in some cases with a counter-rotating vortex pair structure.
Effects of Sinusoidal Excitation on Transverse Jet Dynamics, Structure, and Mixing
AIAA Journal ; 58 , 9 ; 3889-3901
2020-06-26
13 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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