Mesoscale Chemical Systems Group, MESA+ Research Institute, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands.
Ultrason Sonochem. 2013 Jan;20(1):510-24. doi: 10.1016/j.ultsonch.2012.07.024. Epub 2012 Aug 9.
We describe the ejection of bubbles from air-filled pits micromachined on a silicon surface when exposed to ultrasound at a frequency of approximately 200 kHz. As the pressure amplitude is increased the bubbles ejected from the micropits tend to be larger and they interact in complex ways. With more than one pit, there is a threshold pressure beyond which the bubbles follow a trajectory parallel to the substrate surface and converge at the center point of the pit array. We have determined the size distribution of bubbles ejected from one, two and three pits, for three different pressure amplitudes and correlated them with sonochemical OH· radical production. Experimental evidence of shock wave emission from the bubble clusters, deformed bubble shapes and jetting events that might lead to surface erosion are presented. We describe numerical simulations of sonochemical conversion using the empirical bubble size distributions, and compare the calculated values with experimental results.
我们描述了当暴露于约 200 kHz 频率的超声时，从硅表面微加工的充满空气的凹坑中喷射出气泡的情况。随着压力幅度的增加，从微坑中喷出的气泡趋于更大，并且它们以复杂的方式相互作用。对于多个凹坑，存在超过该压力的阈值，超过该阈值后，气泡会沿着与基底表面平行的轨迹运动，并在凹坑阵列的中心点会聚。我们已经确定了从一个、两个和三个凹坑中喷出的气泡的大小分布，对于三个不同的压力幅度，并将其与声化学 OH·自由基的产生相关联。从气泡簇发射冲击波、变形的气泡形状和可能导致表面侵蚀的射流事件的实验证据都被呈现出来。我们使用经验性的气泡大小分布描述了声化学转换的数值模拟，并将计算值与实验结果进行了比较。
