• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Gas propagation in a liquid helium cooled vacuum tube following a sudden vacuum loss.
【24h】

Gas propagation in a liquid helium cooled vacuum tube following a sudden vacuum loss.

机译：突然失去真空后，气体在液氦冷却的真空管中传播。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

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.
机译：本文描述了在突然失去真空之后，接近大气中的氮气的传播，该氮气冲入液氦冷却的真空管中。真空损失的情况类似于大气意外排放到超导射频粒子加速器的光束线，并进行了研究以了解在存在冷凝的情况下流入的空气将如何以这种几何形状传播。在一系列受控实验中，将各种质量流量的室温氮气（替代空气）排放到浸入液氦浴中的高真空管中。沿管子长度方向安装在管子上的压力探头和温度计分别测量了由于气体溢流和冷凝而引起的管子压力和管壁温度升高。在高质量流入速率下，气体前沿沿真空管向下传播，但速度不断降低。对所测得的到达时间的回归分析表明，速度随行进长度成指数增长。在足够低的质量流入速率下，真空管中没有前端扩散。取而代之的是，流入的气体在其入口附近的一小段管子中稳定凝结，并且前端看上去“冻结”了。导出存在冷凝的情况下真空管中气体前沿传播速度的解析表达式。分析模型定性地解释了前端的减速和流量冻结。然后简化模型，并补充冷凝热/质量传递数据，以便在远离管子入口的同时再次找到前端以指数方式减速。在实验和程序不确定性范围内，从前到达时间回归和简化模型获得的指数衰减长度尺度是一致的。

著录项

  • 作者

    Dhuley, Ram C.;

  • 作者单位

    The Florida State University.;

  • 授予单位 The Florida State University.;
  • 学科 Mechanical engineering.;Low temperature physics.
  • 学位 Ph.D.
  • 年度 2016
  • 页码 117 p.
  • 总页数 117
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号