Laboratory of Environmental Engineering, Department of Process Engineering, Faculty of Engineering, Badji Mokhtar - Annaba University, P.O. Box 12, 23000 Annaba, Algeria.
Laboratory of Environmental Engineering, Department of Process Engineering, Faculty of Engineering, Badji Mokhtar - Annaba University, P.O. Box 12, 23000 Annaba, Algeria.
Ultrason Sonochem. 2018 Apr;42:508-516. doi: 10.1016/j.ultsonch.2017.12.015. Epub 2017 Dec 9.
The mechanical disturbance created by an ultrasonic wave travelling through a liquid medium induces the formation of cavitation that oscillates due to rarefaction and compression of the wave. The duration and the magnitude of the pressure applied by the ultrasonic wave at each instant would generate a specific impact on the variation of the bubble radius, the temperature, the pressure and the mass inside it. In this paper, a numerical study is conducted to simulate four waveforms (sinusoidal, square, triangular and sawtooth) travelling an aqueous media saturated with oxygen with an amplitude of 1.5 and 2 atm and a frequency of 200, 300 and 500 kHz. The purpose is to highlight the mass evolution within acoustic cavitation bubble during one cycle due to physical transformations and sonochemical effect. The obtained results demonstrated that square signal enhances temperature and pressure growth inside the bubble, as well as mass transfer by evaporation and condensation. This leads to an improvement of produced quantities of free radicals but also to a selectivity of O as a major product in the detriment of HO and OH. These trends are less and less observed when passing to sinusoidal, triangular and square signal.
超声波在液体介质中传播所产生的机械干扰会引起空化的形成，由于波的稀疏和压缩，空化会发生振荡。超声波在每一瞬时施加的压力的持续时间和幅度将对气泡半径、温度、压力和内部质量的变化产生特定的影响。在本文中，进行了数值研究来模拟四种波形（正弦波、方波、三角波和锯齿波）在氧气饱和的水溶液中传播，幅度为 1.5 和 2 个大气压，频率为 200、300 和 500 kHz。目的是突出由于物理转化和超声化学效应，在一个周期内声空化泡内的质量演变。得到的结果表明，方波信号增强了气泡内的温度和压力的增长，以及通过蒸发和凝结的质量传递。这导致自由基的产量增加，但也导致 O 作为主要产物的选择性，而不是 HO 和 OH。当信号从正弦波、三角波过渡到方波时，这些趋势越来越不明显。
