Optimum Design And Levitation Performance Study For Single-axis Acoustic Levitator

Acoustic levitation is an important technique for containerless processing, because it can gain continuous microgravity environment, it can be applied to containerless processing for materials, uncontact measurements of physical properties for liquids, biochemical analysis, et al.The advantage of acoustic levitation is that it does not require the electric or magnetic properties of materials to be processed. Aims at the lower acoustic force and poor stability, two types of single-axis acoustic levitators were developed. In order to enhance the levitation performance, the sound system and the chamber were optimized based on the fundamental principles of acoustic levitation. The steel ball, ceramic ball, liquid drops and some other normal solids or liquids can be levitated easily by the levitator after optimized. The experiment showed that the reflector with concave surface provides not only a larger levitation force but also better levitation stability than that of the reflector with plane surface,what's more, the levitation force can be remarkably enhanced by optimized curvature radius R or section radius Rb. Finite element models for open-style and tube-type acoustic levitation were developed, which were used to analyze the levitation performance of levitator with different geometry parameters. Distributions of acoustic radiation force along horizontal direction and vertical direction were discussed. The relationship between sample position and R was performed. The change of time-averaged potential of acoustic field under gravity was raveled. Gravity makes the levitation potential wells shallower, even disappearing near the plane reflector. The distributions of sound pressure of two types of resonant chamber were analyzed using numerical calculation and simulation, the results demonstrated that the excitation wave in the resonant chamber with plane reflector is standing wave, the sound pressure is constant along radial direction, so the stability is unsatisfied as lack of enough radial location force, whereas, the sound pressure gradient can be excited in the resonant chamber with concave reflector, so the stability and capability of levitation can be remarkably enhanced.