Abstract
Instantaneous, quantitative, planar images of molecularly mixed-jet fluid fraction were obtained for the purpose of studying the mixing transition in a gaseous axisymmetric jet from ReD = 16200-29200. By using a simultaneous nitric oxide and acetone planar laser-induced fluorescence technique, the mixing transition was detected from sudden changes in the molecularly mixed-jet fluid volume fraction, the growth rate of the shear layer, the preferred mixed-jet fluid fraction, and the character of axial/radial probability density functions. The mixing transition for all Reynolds numbers in this regime was found to begin after the first vortex pairing near Rx/λ = 6 and was completed by the second vortex pairing near Rx/λ = 12, where R = (1 - r)/(1 + r), r is the low-to high-speed freestream velocity ratio, and λ is the natural instability wavelength. The statistical quantities at all Reynolds numbers were found to collapse when scaled with Rx/λ, with the exception of the mixing layer width. The latter collapsed for all Reynolds numbers when scaled by Rx/λ prior to the mixing transition, and by x/D beyond the mixing transition, as expected for turbulent jets for which r ≈ 0.
Original language | English (US) |
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Pages (from-to) | 3411-3424 |
Number of pages | 14 |
Journal | Physics of fluids |
Volume | 13 |
Issue number | 11 |
DOIs | |
State | Published - Nov 2001 |
ASJC Scopus subject areas
- Computational Mechanics
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering
- Fluid Flow and Transfer Processes