Abstract The process of a circular free falling jet entering an idle pool was studied with the objective of determining a relation between the naturally occurring disturbances on the jet surface and air entrainment. To this end the instabilities of the free falling jet were characterized and compared with the bubble count distribution and an estimated amount of entrained air in the plume. Different jet lengths were considered. The aeration process was captured through image sequences. Individual analysis of each disturbance in the jet surface was made. Our results show that both the bubble count and entrained air have a linear relation with the steepness of the jet disturbances. Moreover, the wave-jet ratio is introduced, which defines an entrainment condition for all the studied cases.

中文翻译：

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圆形自由落体射流引气实验

摘要 为了确定射流表面自然发生的扰动与空气夹带之间的关系，研究了圆形自由落体射流进入闲置水池的过程。为此，对自由落体射流的不稳定性进行了表征，并将其与气泡计数分布和羽流中夹带空气的估计量进行了比较。考虑了不同的射流长度。曝气过程是通过图像序列捕获的。对射流表面的每个扰动进行了单独分析。我们的结果表明，气泡数和夹带的空气都与射流扰动的陡度呈线性关系。此外，还引入了波射流比，它定义了所有研究案例的夹带条件。