Ning Renjie, Acree Blake, Wu Mengren, Gao Yuan
Department of Mechanical Engineering, The University of Memphis, Memphis, TN 38152, USA.
Micromachines (Basel). 2024 Dec 23;15(12):1531. doi: 10.3390/mi15121531.
Microbubbles, acting as cavitation nuclei, undergo cycles of expansion, contraction, and collapse. This collapse generates shockwaves, alters local shear forces, and increases local temperature. Cavitation causes severe changes in pressure and temperature, resulting in surface erosion. Shockwaves strip material from surfaces, forming pits and cracks. Prolonged cavitation reduces the mechanical strength and fatigue life of materials, potentially leading to failure. Controlling bubble size and generating monodispersed bubbles is crucial for accurately modeling cavitation phenomena. In this work, we generate monodispersed microbubbles with controllable size using a novel and low-cost microfluidic method. We created an innovative T-junction structure that controls the two-phase flow for tiny, monodispersed bubble generation. Monodisperse microbubbles with diameters below one-fifth of the channel width (W = 100 µm) are produced due to the controlled pressure gradient. This microstructure, fabricated by a CNC milling technique, produces 20 μm bubbles without requiring high-resolution equipment and cleanroom environments. Bubble size is controlled with gas and liquid pressure ratio and microgeometry. This microbubble generation method provides a controllable and reproducible way for cavitation research.
微泡作为空化核，经历膨胀、收缩和坍塌的循环。这种坍塌会产生冲击波，改变局部剪切力，并升高局部温度。空化会导致压力和温度发生剧烈变化，从而造成表面侵蚀。冲击波会从表面剥离材料，形成凹坑和裂缝。长时间的空化会降低材料的机械强度和疲劳寿命，可能导致材料失效。控制气泡大小并产生单分散气泡对于准确模拟空化现象至关重要。在这项工作中，我们使用一种新颖且低成本的微流体方法生成了尺寸可控的单分散微泡。我们创建了一种创新的T型结结构，用于控制两相流以产生微小的单分散气泡。由于受控的压力梯度，产生了直径小于通道宽度五分之一（W = 100 µm）的单分散微泡。这种通过数控铣削技术制造的微结构，无需高分辨率设备和洁净室环境就能产生20 µm的气泡。气泡大小通过气体与液体的压力比和微几何形状来控制。这种微泡生成方法为空化研究提供了一种可控且可重复的方式。
