Award Date


Degree Type


Degree Name

Master of Science (MS)


Mechanical Engineering

First Committee Member

Samir F. Moujaes

Number of Pages



Local, time-averaged measurements of gas void fraction, gas velocity, gas bubble diameter, and bubble passage frequency were made in a concurrent-flow, vertical rectangular channel (15.0 x 1.25 cm) having an aspect ratio of 12:1. Twenty (20) flows were analyzed with superficial gas and liquid velocities ranging from 0.04 to 0.40 m/s and 0.41 to 0.65 m/s, respectively; A dual-tipped optical-fiber probe was constructed and mounted to a 3-degree-of-freedom traversing mechanism above the channel to obtain cross-sectional profiles at a distance of 23.0 cm down inside of the flow channel. A Visual Basic software program was created for the data acquisition and the probe traversing systems, and a Fortran program was written to process the data; Data was collected at 50 kHz per channel for a duration of 15 seconds for each cross-sectional location inside the channel. Measurements were made along the major and minor axes with 151 points each, and 54 locations were probed within one quadrant; The work conducted for this experimental thesis expands the existing data for vertical two-phase flows in rectangular channels. Profiles of the axial gas velocity, gas void fraction, bubble diameter, and gas passage frequency appear to distinguish the flows as one of bubbly, slug, or churn types; The flow regimes were also identified visually and, using the average experimental gas velocities and gas passage frequencies, the slug intervals were calculated for each flow. It was determined that the slug interval accurately identifies the transitions of bubbly, slug, and churn regimes. Lastly, the centerline gas void fractions for all of the bubbly flows were found to remain below 21%.


Experimental; Flow; Fluid; Hydrodynamics; Investigation; Local; Phase; Properties; Two

Controlled Subject

Mechanical engineering; Plasma astrophysics; Optics

File Format


File Size

3450.88 KB

Degree Grantor

University of Nevada, Las Vegas


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