Measurement of Bubbly Flow in a Vertical Pipe Using Ultrasonic Doppler Method
Measurement of Bubbly Flow in a Vertical Pipe Using Ultrasonic Doppler Method
复制标题
超声波多普勒法测量垂直管道中的气泡流
DOI：
10.1115/fedsm2003-45384
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发表时间：
2003
影响因子：
3.2
通讯作者：
M. Mori
中科院分区：
文献类型：
--
作者：
H. Murakawa;H. Kikura;M. Aritomi;M. Mori
为了研究垂直管内两相泡状流的微观流动结构，将超声多普勒法应用于垂直管内(即50 mm)两相泡状流的测量。液体流动结构受注入气泡的特性，即气泡的大小和含气率的影响很大。在本研究中，设计了一种新的气泡发生器，其目的是控制气泡的大小和含气率，而不受液体主流量的影响。实验是在气泡发生器的z/d=66下进行的。液体流速在Rem=3700-6200的雷诺数范围内。在测量位置，气体流量在Jg=0.00348(m/S)时保持恒定。通过对气泡图像的分析，证实了当液体流量改变时，气泡尺寸分布和平均气泡尺寸几乎不变。超声多普勒法具有同时测量两相瞬时速度分布的能力。通过基于模式识别来处理数据，可以将记录的数据分类为几个组。用该方法对矩形流道内的气泡流进行了测量。在本研究中，将该方法应用于圆管内的泡状流，得到了泡状流及其周围气泡内的液体速度分布，结果令人满意。结果表明，圆管内泡状流的速度分布在管壁附近有一个极大值。此外，气泡周围的速度分布还受先导气泡的影响。版权所有©2003，ASME
In order to clarify the microscopic flow structure, the ultrasonic Doppler method was applied to the measurement of two-phase bubbly flow in vertical pipe (i.d.50mm). Liquid flow structure might strongly be influenced by the characteristic of the injected bubbles, i.e. bubbles’ size and void fraction. In this study, a bubble generator was newly designed with the purpose to control the bubble size and void fraction, independent of liquid main-flow rate. The experiment was performed at z/d = 66 from the bubble generator. Liquid flow rates were of the Reynolds numbers ranging from Rem = 3700 to 6200. The gas flow rate was constant at JG = 0.00348(m/s) at the measurement position. By analyzing the bubbles’ picture, it was confirmed that bubble size distribution and average bubble size were almost constant if the liquid flow rate were changed. The ultrasonic Doppler method has the capability of measuring the instantaneous velocity profiles of both phases at the same time. By processing the data based on pattern recognition, the recorded data can be classified to several groups. Using this method, the authors have tried to measure the bubbly flow in rectangular channel. In the present study, the application of this method to bubbly flow in circular pipe was satisfactory to obtain the liquid velocity distribution in bubbly flow and surrounding bubbles. From these results, it was clarified that velocity profile in bubbly flow in circular pipe has a maximum value near the pipe wall. Furthermore, velocity profiles around the bubble are influenced by leading bubbles.Copyright © 2003 by ASME