High power ultrasonic application using a multi-mode ultrasonic transducer

点击翻译按钮获取中文摘要

Near-field acoustic levitation (NFAL) is one of the high-power ultrasonic applications that are based on the nonlinear phenomena. The NFAL enables non-contact transportation by levitating kg-order objects. Until now, various NFAL researches had been reported; however they used only the simple sinusoidal vibration wave for a levitation force.In this study, we propose to utilize various wave forms to improve NFAL performances. For this purpose, new designed ultrasonic transducer was fabricated, whose resonant frequencies ratio can be controlled precisely, f3/f1 = 2. Using this transducer, fundamental and second vibration modes are easily combined. From the experimental results, we confirmed the nonlinear bulk modulus of air contributes to NFAL significantly and found the appropriate model using Poisson's law. According to this calculation, it was clarified that the form controlled wave is effective especially in the case of highly-loaded conditions.