Title page for ETD etd-08222011-111356


Type of Document Master's Thesis
Author Drew, Brady Patterson
Author's Email Address drewbr@vt.edu
URN etd-08222011-111356
Title Entrainment Characteristics of Turbulent Round Gas Jets Submerged in Water
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Charonko, John J. Committee Co-Chair
Vlachos, Pavlos P. Committee Co-Chair
Jung, Sunghwan Committee Member
Keywords
  • Entrainment
  • Particle Image Velocimetry (PIV)
  • Submerged Gas Jets
  • Spectral Phase Correlation
  • Multi-phase flow
Date of Defense 2011-07-29
Availability unrestricted
Abstract
The entrainment process in two-phase buoyant jets differs significantly from their singlephase

counterparts, and is not well understood. Entrainment models developed for singlephase

flow are often used in two-phase jetting simulations, albeit with limited success. In

this work, Particle Image Velocimetry (PIV) and shadowgraph flow visualization experiments

have been conducted on submerged round gas jets of varying speeds and nozzle diameters

with the goal of improving our understanding of the entrainment process in a two-phase

(gas-liquid) jet. The total entrainment estimated using the PIV measurements is higher

than the respective values suggested by a common empirical model developed for singlephase

buoyant jets. A two-phase theoretical entrainment model used for comparison shows

an overestimation of entrainment, but predicts the increase in the rate of entrainment with

axial distance from the jet nozzle seen in the PIV results.

This thesis also presents advances in PIV processing methodology that were developed

concurrently with the entrainment research. The novel Spectral Phase Correlation (SPC)

allows for particle displacement to be determined directly from phase information in the

Fourier domain. Some of the potential benefits of the SPC explored here include (1) avoidance

of errors introduced by spatial peak-finding routines; (2) use of a modal analysis that

can be used to provide information such as correlation quality; and (3) introduction of a

means of incorporating information from multiple image windows. At low image noise levels,

the method performs as well as an advanced CC-based method. However, difficulties

unwrapping the aliased phase information cause the SPC’s performance to degrade at high

noise levels.

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