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A FLOW-THROUGH ACOUSTIC WAVEGUIDE FOR TWO-PHASE BUBBLY FLOW VOID FRACTION MEASUREMENT

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dc.contributor.author Ormonde, Christopher E.
dc.date.accessioned 2010-11-29T16:57:36Z
dc.date.available 2010-11-29T16:57:36Z
dc.date.issued 2009
dc.identifier.uri http://hdl.handle.net/2144/1382
dc.description.abstract In the Spallation Neutron Source (SNS) facility at Oak Ridge National Laboratory (ORNL), the deposition of a high-energy proton beam into the liquid mercury target forms bubbles whose asymmetric collapse cause Cavitation Damage Erosion (CDE) to the container walls, thereby reducing its usable lifetime. One proposed solution for mitigation of this damage is to inject a population of microbubbles into the mercury, yielding a compliant and attenuative medium that will reduce the resulting cavitation damage. This potential solution presents the task of creating a diagnostic tool to monitor bubble population in the mercury flow in order to correlate void fraction and damage. Details of an acoustic waveguide for the eventual measurement of two-phase mercury-helium flow void fraction are discussed. The assembly’s waveguide is a vertically oriented stainless steel cylinder with 5.08cm ID, 1.27cm wall thickness and 40cm length. For water experiments, a 2.54cm thick stainless steel plate at the bottom supports the fluid, provides an acoustically rigid boundary condition, and is the mounting point for a hydrophone. A port near the bottom is the inlet for the fluid of interest. A spillover reservoir welded to the upper portion of the main tube allows for a flow-through design, yielding a pressure release top boundary condition for the waveguide. A cover on the reservoir supports an electrodynamic shaker that is driven by linear frequency sweeps to excite the tube. The hydrophone captures the frequency response of the waveguide. The sound speed of the flowing medium is calculated, assuming a linear dependence of axial mode number on modal frequency (plane wave). Assuming that the medium has an effective-mixture sound speed, and that it contains bubbles which are much smaller than the resonance radii at the highest frequency of interest (Wood’s limit), the void fraction of the flow is calculated. Results for water and bubbly water of varying void fraction are presented, and serve to demonstrate the accuracy and precision of the apparatus. en_US
dc.description.sponsorship Supported by the ORNL Spallation Neutron Source, which is managed by UT- Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. en_US
dc.language.iso en_US en_US
dc.publisher Boston University en_US
dc.rights Attribution 3.0 Unported *
dc.rights.uri http://creativecommons.org/licenses/by/3.0/ *
dc.subject Acoustics en_US
dc.subject Bubbly liquids en_US
dc.subject Sound speed en_US
dc.subject Acoustic resonator en_US
dc.subject Void fraction en_US
dc.title A FLOW-THROUGH ACOUSTIC WAVEGUIDE FOR TWO-PHASE BUBBLY FLOW VOID FRACTION MEASUREMENT en_US
dc.type Thesis en_US


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