The Study Of Unconventional Horn Design In Ultrasonic Levitation Application

The Near-field Ultrasonic Levitation attracted widespread attention in recent years, it used the high-intensity sound field to generated acoustic radiation pressure, and when the pressure force and the gravity of the object comes to the balance level, the levitated state will be achieved. The sound pressure distribution of the sound field influence the stability of the suspension quite a lot for the Near-field levitation, it might provide great help to improve the levitation stability for us to realize sound pressure distribution law for the complexity sound field, especially the complex sound field generated by the unconventional ultrasonic horn which more suitable for the Near-field Ultrasonic Levitation. However, for complex sound field, there is no available theory to describe the sound pressure distribution law, and the experimental studies are very rare too, in order to obtain the sound pressure distribution of complex sound field and improve the suspension stability, this paper conducted the following researches:We design the unconventional horn, which used in the Near-field Levitation by using the existing horn design theory and finite element software. Based on this unconventional horn, derive the theoretical levitated height and get the relationship between the areal density and the levitation height. Then, measure the experimental levitated heights for seven different thickness standard aluminum plate by using the optical triangulation method, and compare the difference between the experimental levitation heights and theoretical levitation heights, then, calculate the experimental levitation heights errors which caused by the air absorption and the energy loss when ultrasonic propagated in unconventional horn, and at last, we obtain the calculation formula with a correction coefficient for the theoretical levitation height.Respectively, we used the electret microphone and piezoelectric acceleration sensor to measure the sound pressure at different points in each plane, which parallel to the end face of the unconventional horn at different heights. The sound pressure distribution figures for each plane were got by the measured sound pressure data, through the sound pressure distribution figure of each planes, we could realize description of the sound field.Based on the measured sound pressure distribution characteristics, we study the levitation stability for different types of levitated plates. In the analysis of the horizontal force acted on the levitated plate, we assuming that the direction of the viscous force which formed by the air flow is from the high sound pressure side point to the low sound pressure side, and then, verify the correctness of the proposed assumption through the experiment by observing the horizontal moving direction of the special shape levitated plate.These researches make a useful exploration to improve the suspension stability and make a beneficial exploration for realizing the application of ultrasonic horn in non-contact operation.