柱形料腔中超声空化效应的空间分布特性研究

研究了20 kHz的圆柱形料腔中超声空化效应的形成及其空间分布特性。应用柱贝塞尔函数,推导获取了柱形声场内超声传播的声能密度的分布,并采用有限元方法进行仿真分析。针对频率为20 kHz的功率超声实验,结合声学测量方法和鲁米诺声致化学发光方法,对理论分析结果进行了验证对照。结果表明:料腔半径R=50 mm,20 kHz谐振液位高度H=90 mm时,若功放电流<40 mA,超声空化效应出现在变幅杆端部区域;若40 mA≤功放电流≤80 mA,空化效应显著增强,空化效应的空间分布与场内声压分布一致,空化效应受声模态影响,形成远场空化效应的分布特性;若功放电流>80 mA,受非线性因素影响,谐振液位时,空化效应在声流作用下呈柱形拖尾状分布,并在底部壁面边界形成平铺状分布;非谐振液位高度等于75 mm时,超声空化效应随功率增加仅在变幅杆端部区域出现,且呈现局域空化分布特性。

Study on the spatial distribution of ultrasonic cavitation effect in cylindrical reactor

The formation and spatial distribution of ultrasonic cavitation in the cylindrical reactor of 20 kHz are studied.The distribution of the acoustic energy density in the cylindrical sound field is obtained by using Bessel function,and the finite element method is used for simulation analysis.By combining the acoustic measurement method and the sono-chemi luminescent(SCL)method,the theoretical analysis results are verified in the power ultrasonic experiment of 20 kHz.The results show that the ultrasonic cavitation effect appears in the end region of the horn when the cavity radius is R=50 mm,the resonant liquid level of 20 kHz is H=90mm and the current of Power Amplifier is<40 mA,in the case of 40 mA≤the current of Power Amplifier≤80 mA,the cavitation effect is significantly enhanced;that the spatial distribution of the cavitation effect is consistent with the distribution of sound pressure in the field,the acoustic modes affect the cavitation effect to form the distribution characteristics of the far-field cavitation effect,and when the current of Power Amplifier is>80 mA,due to nonlinear factors,the cavitation effect is distributed in a cylindrical tail shape under the action of the acoustic flow at the resonant liquid level,and a tile-like distribution is formed at the boundary of the bottom wall;and that for the non-resonant liquid level of 75 mm,with the increase of power,the ultrasonic cavitation effect appears only in the end region of the horn and presents the local cavitation distribution characteristics.