Numerical investigation of sonochemical production in a single bubble under dual-frequency acoustic excitation

Abstract

Abstract A numerical computation study about sonochemical activity of an oxygen bubble oscillations in a dual-frequency acoustic field is presented in this paper. The variation of excitation frequency causes the change of magnitude and duration of pressure acting on the bubble, affecting the instantaneous bubble radius, internal bubble temperature as well as chemical reactions. The numerical results indicate the formation of O2, HO2 •, •OH, H•, O, H2 and H2O2 in an O2 bubble during oscillations. The main oxidant is •OH radical. The influence of several parameters (e.g. couples of frequencies, the total pressure amplitude and the ratio of pressure amplitudes of the two waves) on the molar yields of free radicals is analyzed. There is an optimum bubble collapse temperature (around 5648 K) for the •OH production. Moreover, the corresponding frequency intervals of enhanced effect and weakened effect under different coupled frequencies (i.e. 40, 140, 213, 355 and 515 kHz) are also investigated.