Ultrasonic pulse echography for bubbles traveling in the proximity of a wall
Ultrasonic pulse echography for bubbles traveling in the proximity of a wall
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DOI：
10.1088/0957-0233/26/12/125301
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发表时间：
2015-10
影响因子：
2.4
通讯作者：
H. Park;Y. Tasaka;Y. Murai
中科院分区：
文献类型：
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作者：
H. Park;Y. Tasaka;Y. Murai
在壁附近的气泡两相流的行为影响热量，质量和动量传递，因此，有很大的兴趣在开发一种定量的技术来监测这种行为。本文提出了一种基于超声回波信号处理的新方法，该方法适用于工业应用，其中边界层被移动气泡修改。通过引入时间分辨直接波形分析在100 MHz，我们已经成功地在时空探测气泡表面的回波轮廓频率在15-20 kHz的范围内。与使用短脉冲的常规方法不同，应用相对长的脉冲长度以允许液相中的超声多普勒测速。水平的气泡两相湍流通道流的检查证明了这种方法的可行性，时空回波成像的移动气泡表面成功地实现了气泡的旅行长度尺度小于空间超声波脉冲长度附近的壁。通过对波浪方程的三维数值分析及其在平底船模下气泡流动中的应用，确定了气泡尺寸、形状和流速等参数的适用范围。
The behavior of a bubbly two-phase flow in the vicinity of a wall affects heat, mass, and momentum transfer; therefore, there is great interest in developing a quantitative technique to monitor this behavior. Herein we propose a new method based on ultrasound echo signal processing that it feasible for industrial applications where the boundary layer is modified by traveling bubbles. By introducing time-resolved direct waveform analysis at 100 MHz, we have succeeded in the spatio-temporal detection of bubble surfaces at echographic profiling frequencies in the range of 15–20 kHz. Unlike conventional approaches, which use short pulses, a relatively long pulse length is applied to allow ultrasound Doppler velocimetry in the liquid phase. Examination of the horizontal bubbly two-phase turbulent channel flows demonstrated the feasibility of this method; spatio-temporal echography of moving bubble surfaces is successfully achieved as the bubbles travel on length scales smaller than the spatial ultrasonic pulse length near the wall. The applicable range of parameters (e.g. bubble size and shape, and flow speed) was determined by 3D numerical analysis of the wave equation and its application to bubbles flowing beneath a flat-bottom model ship.