School of Computing and Engineering, College of Science and Engineering, University of Derby, Derby DE22 3AW, United Kingdom; Faculty of Technology, Design and Environment, Oxford Brookes University, Oxford OX33 1HX, United Kingdom.
Faculty of Technology, Design and Environment, Oxford Brookes University, Oxford OX33 1HX, United Kingdom.
Ultrason Sonochem. 2023 Mar;94:106328. doi: 10.1016/j.ultsonch.2023.106328. Epub 2023 Feb 14.
This paper follows our earlier work where a strong high frequency pressure peak has been observed as a consequence of the formation of shock waves due to the collapse of cavitation bubbles in water, excited by an ultrasonic source at 24 kHz. We study here the effects of liquid physical properties on the shock wave characteristics by replacing water as the medium successively with ethanol, glycerol and finally a 1:1 ethanol-water solution. The pressure frequency spectra obtained in our experiments (from more than 1.5 million cavitation collapsing events) show that the expected prominent shockwave pressure peak was barely detected for ethanol and glycerol, particularly at low input powers, but was consistently observed for the 1:1 ethanol-water solution as well as in water, with a slight shift in peak frequency for the solution. We also report two distinct features of shock waves in raising the frequency peak at MHz (inherent) and contributing to the raising of sub-harmonics (periodic). Empirically constructed acoustic pressure maps revealed significantly higher overall pressure amplitudes for the ethanol-water solution than for other liquids. Furthermore, a qualitative analysis revealed that mist-like patterns are developed in ethanol-water solution leading to higher pressures.
本文是我们早期工作的延续，我们观察到，由于 24 kHz 超声源激发水中空化泡的坍塌而形成冲击波，会产生一个很强的高频压力峰值。我们通过依次用乙醇、甘油以及最终的 1:1 乙醇-水溶液替代水作为介质来研究液体物理性质对冲击波特性的影响。我们的实验获得的压力频谱（超过 150 万个空化坍塌事件）表明，对于乙醇和甘油，几乎检测不到预期的显著冲击波压力峰值，特别是在低输入功率下，但在 1:1 乙醇-水溶液以及水中都能持续观察到该峰值，溶液的峰值频率略有移动。我们还报告了在提高 MHz 频率峰值（固有）和提高亚谐波（周期性）方面的两个冲击波的独特特征。经验构建的声压图谱显示，乙醇-水溶液的总压力幅值明显高于其他液体。此外，定性分析表明，在乙醇-水溶液中会形成雾状图案，从而导致更高的压力。
