Experimental investigation of threshold velocities for air-water two-phase flow in a vertical tube and annular channels

IF 2.6 3区 工程技术 Q1 NUCLEAR SCIENCE & TECHNOLOGY
Almog Biton, Evgeny Rabinovich, Erez Gilad
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Abstract

This work presents an experimental study of five threshold velocities for air-water flow in three different vertical channels. The measured threshold velocities included onset flooding (OF), end flooding (EF), onset deflooding (OD), end deflooding (ED), and minimum pressure (MP) velocities. The experimental system includes a transparent vertical tube of 52.5 mm inner diameter and 1500 mm length. The test channel can be easily changed from a tube to an annular shape by inserting a cylindrical test element. A counter-current or concurrent upward flow was achieved by blowing air upward from the channel's bottom and flowing water from its top. The threshold velocities were determined by analyzing the pressure drop versus air superficial velocity. Findings revealed evident hysteresis between the end flooding and onset deflooding velocities. In contrast, the end deflooding and onset flooding velocities were found to be identical. The end flooding velocity was indifferent to the water's superficial velocity for all three channel geometries. A generalized gas-liquid flow state diagram for vertical channels is developed based on the present empirical analysis for different threshold velocities.
垂直管道和环形通道中气水两相流阈值速度的实验研究
本研究对三个不同垂直通道中空气-水流的五个阈值速度进行了实验研究。测得的阈值速度包括起始淹没速度 (OF)、末端淹没速度 (EF)、起始脱水速度 (OD)、末端脱水速度 (ED) 和最小压力速度 (MP)。实验系统包括一个内径 52.5 毫米、长 1500 毫米的透明垂直管。通过插入一个圆柱形测试元件,可以轻松地将测试通道从管状变为环状。通过从通道底部向上吹气和从顶部流水来实现逆流或同时向上流动。通过分析压降与空气表面速度的关系,确定了阈值速度。研究结果表明,末端淹没速度和开始泄洪速度之间存在明显的滞后现象。与此相反,末端排洪速度和开始排洪速度被发现是相同的。在所有三种水道几何形状中,末端淹没速度与水的表层速度无关。根据对不同阈值速度的经验分析,绘制了垂直水道的通用气液流动状态图。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Nuclear Engineering and Technology
Nuclear Engineering and Technology 工程技术-核科学技术
CiteScore
4.80
自引率
7.40%
发文量
431
审稿时长
3.5 months
期刊介绍: Nuclear Engineering and Technology (NET), an international journal of the Korean Nuclear Society (KNS), publishes peer-reviewed papers on original research, ideas and developments in all areas of the field of nuclear science and technology. NET bimonthly publishes original articles, reviews, and technical notes. The journal is listed in the Science Citation Index Expanded (SCIE) of Thomson Reuters. NET covers all fields for peaceful utilization of nuclear energy and radiation as follows: 1) Reactor Physics 2) Thermal Hydraulics 3) Nuclear Safety 4) Nuclear I&C 5) Nuclear Physics, Fusion, and Laser Technology 6) Nuclear Fuel Cycle and Radioactive Waste Management 7) Nuclear Fuel and Reactor Materials 8) Radiation Application 9) Radiation Protection 10) Nuclear Structural Analysis and Plant Management & Maintenance 11) Nuclear Policy, Economics, and Human Resource Development
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