Application of ultrasonic multi-wave method for two-phase bubbly and slug flows
Application of ultrasonic multi-wave method for two-phase bubbly and slug flows
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DOI：
10.1016/j.flowmeasinst.2007.06.010
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发表时间：
2008-06-01
影响因子：
2.2
通讯作者：
Aritomi, Masanori
中科院分区：
文献类型：
--
作者：
Murakawa, Hideki;Kikura, Hiroshige;Aritomi, Masanori
本文提出了一种利用超声波测量两相泡状流和弹状流的方法。为了同时获得气液速度分布，提出了一种分离气液速度数据的新方法。该技术采用了一种独特的超声换能器称为多波换能器（TDX）。多波TDX由两种不同谐振频率的超声压电元件组成。直径为3mm的中心元件具有8MHz的基频，外部元件具有2MHz的基频。多波TDX可以独立地发射两个超声频率。在我们以前的调查中，这两个元件连接到两个超声波速度剖面（UVP）监测器来测量液体和气泡的速度分布。然而，该技术仅限于在低空隙率的泡状流的测量。此外，由于设备的限制，不可能同步液体和气泡的瞬时速度。为了克服这些缺点，互相关方法在这项研究中的测量。为了将该技术应用于流量测量，测量超声压力场。结果发现，TDX必须设置在距离测试部分20 mm处。该技术适用于测量泡状流和弹状流。通过2 MHz和8 MHz超声回波信号的组合，可以区分颗粒反射的回波信号和气泡反射的回波信号。通过与多波法和高速摄像机测量结果的比较，证实了该技术在1000 Hz采样率下可以分离出液相和气相的信息。(c)2007爱思唯尔有限公司保留所有权利。
This paper proposes a measurement technique for two-phase bubbly and slug flows using ultrasound. In order to obtain both liquid and gas velocity distributions simultaneously, a new technique for separating liquid and gas velocity data is developed. The technique employs a unique ultrasonic transducer referred to as multi-wave transducer (TDX). The multi-wave TDX consists of two kinds of ultrasonic piezoelectric elements which have different resonant frequencies. The central element of 3 mm diameter has a basic frequency of 8 MHz and the outer element has a basic frequency of 2 MHz. The multi-wave TDX can emit the two ultrasonic frequencies independently. In our previous investigations, both elements were connected with two ultrasonic velocity profile (UVP) monitors to measure liquid and bubble velocity distributions. However, the technique was limited to the measurement of bubbly flows at low void-fraction. Furthermore, it was impossible to synchronize the instantaneous velocities of liquid and bubbles because of the facility limitation. In order to overcome these disadvantages, cross-correlation method is employed for the measurements in this study. In order to apply the technique to flow measurements, ultrasound pressure fields are measured. As a result, it is found that the TDX must be set 20 mm away from the test section. The technique is applied to measuring bubbly and slug flows. By the combination of 2 and 8 MHz ultrasonic echo signals, the echo signals are distinguished between reflected from particles and bubbles. Compared with the results of obtaining with the multi-wave method and a high-speed camera, it is confirmed that the technique can separate the information of liquid and gas phases at a sampling rate of 1000 Hz. (c) 2007 Elsevier Ltd. All rights reserved.