Geng Hao, Chen Tairan, Chen Jiacheng, Huang Biao, Wang Guoyu
School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China.
School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China; Beijing Institute of Technology Chongqing Innovation Center, Chongqing 401120, China.
Ultrason Sonochem. 2025 Sep;120:107520. doi: 10.1016/j.ultsonch.2025.107520. Epub 2025 Aug 17.
This paper examines how water temperature affects the dynamics of a single cavitation bubble in free field conditions. Both experimental and theoretical approaches are employed to explore the bubble dynamics in water under different temperatures. A series of single bubble experiments are conducted in water using the capacitive discharge method, with water temperature ranging from room temperature to near boiling point under atmospheric pressure. A high-speed photography system is utilized to capture the bubble evolution during the experiments. The experimental results suggest that (1) At all temperatures, the bubble evolutions progress through expansion, shrinkage, and oscillation stages, with significant changes observed in bubble dynamics when temperatures are above 60 °C. (2) The maximum bubble radius and the oscillation period of the cavitation bubble increase with increasing temperatures. The minimum bubble radius remains almost constant at 1.00 mm for water temperatures below 60 °C, but a rapid increase occurs above 60 °C. Thus, the bubble shrinkage ratio (R/R) in the first cycle at 95 °C is 6 times more than that at 30 °C, corresponding to the weaker collapse. (3) Near the boiling point, the cavitation bubble hardly rebounds after the first cycle and the bubble breaks into multiple micro-bubbles which continue to oscillate instead of collapsing. Meanwhile, a theoretical model accounting for heat transfer, phase change, and compressibility has been used to quantify the vapor mass transfer rate, the bubble internal pressure, and the bubble internal temperature. It is found that the mass transfer rate at 30 °C is significantly higher than at 95 °C. As a result, the bubble boundary collapse velocity is dozens of times lower at 95 °C compared to that at 30 °C. Moreover, the bubble internal pressure and internal temperature significantly decrease with increasing temperature due to the weaker collapse. In general, high temperatures (above 60 °C) significantly reduce the non-equilibrium interphase mass transfer effect of the bubble, and the bubble boundary retraction speed is slower and the collapse is weaker. This investigation is essential for better clarifying and explaining how water temperature affects the single cavitation bubble dynamics.
本文研究了水温如何在自由场条件下影响单个空化泡的动力学特性。采用实验和理论方法来探究不同温度下水中空化泡的动力学特性。在大气压力下，利用电容放电法在水中进行了一系列单泡实验，水温范围从室温到接近沸点。实验过程中使用高速摄影系统捕捉气泡的演化过程。实验结果表明：（1）在所有温度下，气泡演化均经历膨胀、收缩和振荡阶段，当温度高于60°C时，气泡动力学特性出现显著变化。（2）空化泡的最大气泡半径和振荡周期随温度升高而增大。水温低于60°C时，最小气泡半径几乎保持恒定在1.00毫米，但在60°C以上时迅速增大。因此，95°C时第一个周期的气泡收缩率（R/R）比30°C时大6倍，对应着较弱的溃灭。（3）在接近沸点时，空化泡在第一个周期后几乎不再反弹，气泡破裂成多个微气泡并继续振荡而非溃灭。同时，采用考虑传热、相变和可压缩性的理论模型来量化蒸汽质量传递速率、气泡内部压力和气泡内部温度。研究发现，30°C时的质量传递速率显著高于95°C时。结果，95°C时气泡边界溃灭速度比30°C时低几十倍。此外，由于溃灭较弱，气泡内部压力和内部温度随温度升高而显著降低。总体而言，高温（高于60°C）显著降低了气泡的非平衡相间传质效应，气泡边界回缩速度较慢且溃灭较弱。这项研究对于更好地阐明和解释水温如何影响单个空化泡动力学特性至关重要。
