Levitação acústica: uma abordagem introdutória para protótipos de levitadores de eixo único com ajuste de fases

Abstract

In this dissertation, the phenomenon of acoustic levitation without physical contact was investigated through the acoustic levitation technique, using high frequency sound waves. Several levitation techniques have attracted the attention of researchers in recent years, mainly for applications in the transport, handling and storage of components that must not be contaminated by mechanical contact. Levitation is a process in which forces are generated in order to counterbalance the force of gravity on the particle, in order to balance it without contact. This phenomenon can be obtained through different techniques such as magnetic, optical, electrostatic fields or acoustics. The present work is dedicated to the computational and experimental analysis of the far-field acoustic levitation technique. In this approach, the particles are levitated through the pressure field, generated by ceramic emitters that vibrate harmonically at an ultrasonic frequency. This technique stands out in particular to the unconstraint as to the intrinsic properties of the particles to be levitated, expanding the pharmacological applications for products with high purity content, transport of electronic components that is increasingly directed to micro and nanotechnology. In this work, the relationship between the positioning of the transducers and the resulting acoustic pressure amplitude was addressed, where a non-monotonic behavior was observed for the 16mm diameter transducers, that is, there is a positioning between the central transducer and the others, so that the acoustic pressure field is amplified using a smaller number of transducers. Therefore, a computational analysis was carried out through the model proposed by Kinsler for the acoustic pressure amplitude of a levitator, making it possible to determine the best positions for the emitters and several peculiarities to improve the efficiency of the levitation equipment. Still, you can compare the efficiency of the two models of transducers and, with the intensification of the we could levitate particles different from the EPS. In addition to the analysis regarding the positioning of the transducers, the relationship between tension and density of the material was observed, seeking to predict the limitation of the proposed levitator models. As for the experimental analyses, they are intended to compare the computational results, through the confection of levitator models and collection of experimental data.