Turbulent Molecular Mixing in Gaseous Free Shear Flows

Meyer, Terrence Raymond

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Description

Title

Turbulent Molecular Mixing in Gaseous Free Shear Flows

Author(s)

Meyer, Terrence Raymond

Issue Date

2001

Doctoral Committee Chair(s)

• Dutton, J. Craig
• Lucht, Robert P.

Department of Study

Mechanical Engineering

Discipline

Mechanical Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

Chemistry, Analytical

Language

eng

Abstract

The flow regimes studied in this investigation span three main stages of shear layer development. Vortex mixing in the near field of an axisymmetric jet (ReD = 2300) is studied by using an acoustic pulse to obtain repeatable vortex formation and merging events. Results indicate that the mixing process is initially slow within the laminar vortex rollers, but a dramatic increase in mixing is detected prior to and during vortex coalescence. In the next stage of research, non-pulsed axisymmetric jets from ReD = 16,200 to 29,200 were used to study the transition to small-scale turbulence. This transition was found to take place near the average location of vortex merging, and resulted in a 20 to 25% drop in the mixed jet fluid volume fraction, a 30 to 35% drop in the preferred mixed jet fluid fraction, and a shift from stationary to hybrid radial probability density functions. In the final stage of research, fully-developed turbulence was studied in the far-field region of a planar shear layer with low- to high-speed velocity ratios of 0.25 to 0.44. Statistical analysis in this regime indicated that the physics of molecular mixing differs between the lowand high-speed fluids, and that molecularly mixed fluid quantities are not uniform across the shear layer.

Graduation Semester

2001

Type of Resource

text

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