In this study, we measured void fractions in vertical air–water bubbly flow using echo intensity and visualization techniques. To check the reliability of the echo intensity technique, void fractions obtained from the visualization technique was used. For echo intensity technique, ultrasonic wave amplitudes were acquired at different gas flow rates, and the amplitudes varied with gas flow rates. The averaged value of the amplitude kept decreasing with increasing gas flow rates. Images of bubbly flow were captured by a high-speed camera to evaluate void fractions. The images were processing to obtain area-averaged void fractions, then averaged over time to obtain time-averaged void fractions. The amplitudes obtained from the echo intensity and void fraction obtained from visualization can be correlated in the form of an exponential function: as the amplitude increases, the void fraction exponentially decreases.

在这项研究中，我们使用回波强度和可视化技术测量了垂直空气-水气泡流中的空隙率。为了检查回波强度技术的可靠性，使用了从可视化技术获得的空隙率。对于回波强度技术，在不同的气体流速下获取超声波振幅，并且振幅随气体流速而变化。振幅的平均值随着气体流速的增加而不断减小。用高速照相机捕获气泡流的图像，以评估空隙率。对图像进行处理以获得面积平均的空隙率，然后随时间取平均值以获得时间平均的空隙率。从回波强度获得的幅度和从可视化获得的空隙率可以以指数函数的形式关联：