Guo Yong, Zhu Qingqing, Song Shiliang, Li Yan, Zhang Zongbo, Gong Liang
College of New Energy, China University of Petroleum (East China), Qingdao, Shandong 266580, PR China.
College of Mechanical and Electrical Engineering, China University of Petroleum (East China), Qingdao, Shandong 266580, PR China.
Ultrason Sonochem. 2024 Dec;111:107099. doi: 10.1016/j.ultsonch.2024.107099. Epub 2024 Oct 17.
Bubble dynamics is paramount in comprehending the heat transfer mechanisms of flow boiling in the microchannel within ultrasonic field, which is regarded as a promising method to confront challenges of thermal management posed by microelectronic devices. Nevertheless, the impact of ultrasound on bubble behaviors and its underlying mechanisms remain largely unexplored. This study first delves into the effect of ultrasonic parameters on bubble dynamic behaviors and associated mechanisms, subsequently further analyzing the forces acting on bubbles through the constructed force model. The findings suggest that although growth force serves as the significant resistance, the primary Bjerknes force dominates the rapid detachment of bubbles. The secondary Bjerknes force results in the bubble only sliding along the bottom wall rather than lifting off. Furthermore, the elevated ultrasonic pressure amplitude resulting from augmenting ultrasonic power induces a substantial increase in the critical detachment diameter and growth rate by 55.49 % and 59.42 %, respectively. The enhanced primary Bjerknes force, attributed to the rise in ultrasonic frequency, leads to a 71.42 % increase in sliding velocity and a 46.45 % reduction in growth time. The positive impacts arising from ultrasonic power and frequency are anticipated to notably enhance the thermal performance of microchannels. Besides, surface tension acts as the resistance and diminishes slightly with an augmentation of the boiling number, resulting in a moderate variation in sliding velocity and growth time.
气泡动力学对于理解超声场内微通道中流动沸腾的传热机制至关重要，这被视为应对微电子设备带来的热管理挑战的一种有前景的方法。然而，超声对气泡行为的影响及其潜在机制在很大程度上仍未得到探索。本研究首先深入探讨超声参数对气泡动力学行为及相关机制的影响，随后通过构建的力模型进一步分析作用于气泡的力。研究结果表明，尽管生长力是主要阻力，但主要的 Bjerknes 力主导了气泡的快速脱离。次要的 Bjerknes 力导致气泡仅沿底壁滑动而不是脱离。此外，超声功率增加导致超声压力振幅升高，使临界脱离直径和生长速率分别大幅增加了55.49%和59.42%。超声频率升高导致主要 Bjerknes力增强，使滑动速度增加了71.42%，生长时间减少了46.45%。预计超声功率和频率产生的积极影响将显著提高微通道的热性能。此外，表面张力起到阻力作用，并随着沸腾数的增加而略有减小，导致滑动速度和生长时间有适度变化。
