多射流冲击形成的气水空腔
Air-water cavity in multi-plunging jet impacts
AI总结：
本研究发现紧密排列的多射流冲击会形成穹顶状气水空腔，阐明其气泡产生等机制，测量不同参数下的空腔尺寸，提出其由液体卷吸形成的机制。
AI中文摘要：
我们报道了紧密排列的 plunging 水射流冲击处形成的一种新型穹顶状气水空腔。喷射器组件由同心环形的圆形射流组成，类似淋浴头结构。通过高速成像、激光诱导荧光和光学相位探测探针推断，该空腔由多个气柱和气 sheet 构成，这些气体会拉伸、收缩并断裂产生气泡。我们还阐明了空腔内的多种气泡产生机制，以及后续气泡云中的气泡合并与破碎场景。由此描述了此类射流产生的广泛气泡尺寸范围，从几微米到约5毫米。针对不同冲击速度、射流数量和射流间距，我们对空腔尺寸进行了测量。我们提出，这种独特的气水空腔是由连续环形 plunging 射流与池内水逐渐混合时的液体卷吸作用产生的。
英文摘要：
We report the formation of an original dome-shaped air-water cavity at the impact site of closely-packed plunging water jets. The injector assembly consists of concentric rings of circular jets, similar to a shower-head configuration. We infer from high-speed imaging, LASER-induced fluorescence, and optical phase detection probes that the cavity consists of multiple stems and sheets of air that stretch, retract and pinch off to produce bubbles. We also illustrate various bubble production mechanisms in the cavity, along with coalescence and bubble breakup scenarios in the subsequent bubble cloud. Thereby, we describe the wide range of bubble sizes generated by such jets, from a few micrometers up to about $5$~mm. Measurements of the cavity size are carried out for varying impact velocity, number of jets, and jet spacing. We propose that this distinctive air-water cavity is generated by liquid entrainment when successive rings of plunging jets progressively mix with the pool water.
