This dissertation describes the propagation of near atmospheric nitrogen gas that rushes into a liquid helium cooled vacuum
tube after the tube suddenly loses vacuum. The loss-of-vacuum scenario resembles accidental venting of atmospheric air to the beam-line of
a superconducting radio frequency particle accelerator and is investigated to understand how in the presence of condensation, the
in-flowing air will propagate in such geometry. In a series of controlled experiments, room temperature nitrogen gas (a substitute for
air) at a variety of mass flow rates was vented to a high vacuum tube immersed in a bath of liquid helium. Pressure probes and
thermometers installed on the tube along its length measured respectively the tube pressure and tube wall temperature rise due to gas
flooding and condensation. At high mass in-flow rates a gas front propagated down the vacuum tube but with a continuously decreasing
speed. Regression analysis of the measured front arrival times indicates that the speed decreases nearly exponentially with the travel
length. At low enough mass in-flow rates, no front propagated in the vacuum tube. Instead, the in-flowing gas steadily condensed over a
short section of the tube near its entrance and the front appeared to `freeze-out'. An analytical expression is derived for gas front
propagation speed in a vacuum tube in the presence of condensation. The analytical model qualitatively explains the front deceleration and
flow freeze-out. The model is then simplified and supplemented with condensation heat/mass transfer data to again find the front to
decelerate exponentially while going away from the tube entrance. Within the experimental and procedural uncertainty, the exponential
decay length-scales obtained from the front arrival time regression and from the simplified model agree. / A Dissertation submitted to the Department of Mechanical Engineering in partial fulfillment of the
requirements for the degree of Doctor of Philosophy. / Spring Semester 2016. / February 23, 2016. / accelerator, accident, condensation, shock, superconducting, vacuum / Includes bibliographical references. / Steven W. Van Sciver, Professor Directing Dissertation; David A. Kopriva, University
Representative; Eric E. Hellstrom, Committee Member; Wei Guo, Committee Member; Kunihiko Taira, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_360341 |
| Contributors | Dhuley, Ram (authoraut), Van Sciver, Steven W. (professor directing dissertation), Kopriva, David A. (university representative), Hellstrom, Eric (committee member), Guo, Wei (committee member), Taira, Kunihiko (committee member), Florida State University (degree granting institution), College of Engineering (degree granting college), Department of Mechanical Engineering (degree granting department) |
| Publisher | Florida State University, Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text |
| Format | 1 online resource (116 pages), computer, application/pdf |
| Rights | This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them. |
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