Simulation And Experiment For Levitation And Transmission Of Ultrasonic Standing Wave

The ultrasonic standing wave technology has been deeply applied in the area of astronomy、biology、medical science because of its advantages, such as simple structure、 excellent smoothness during transportation、contact-free、be similar to the microgravity environment. Especially in the development of vaccines、DNA infection aspects, the ultrasonic standing wave shows its incommutably status.The ultrasonic standing wave could be made by the interference of radiation waves and reflection waves. Radiation waves are shoot as the emitting surfaces vibrating in an extremely high frequency. On the other hand, the reflection wave is made by the reflect reaction of the radiation wave on reflector. Finally, when the length of cavity resonator equals to the multiple of λ/2, standing wave could be formed. In addition, the buoyance in some circumstances could be large enough to levitate particles.In the first place, the equation of standing wave was induced. On the bases of the equation of standing wave, the expression of acoustic coefficient(e.g. acoustic pressure、time average potential、relative time average potential、elastic comeback power and elastic comeback coefficient) could be deduced. Furthermore, the relationship among steady levitation positions、coefficients of transportation and coefficients of levitation could be described.Secondly, the influences on the ability of levitation from structural coefficients(including the length of cavity resonator、size of the reflector、shape of the reflector as well as the gap length between two transducers) were simulated. Moreover, the vibrations of the smoothness during transportation, which is made by using divergent structural coefficients like length of cavity resonator and size of reflector 、excitation functions as well as distinct phases, were also simulated in this paper. According to the results from simulations, some specific structure coefficients were used to ensure the levitation power could be maximized. Also concave spherical surface was simulated to have the focusing effect of acoustic standing wave. The effects on the smoothness during transportation by structural coefficients appeared to show the same trend of the effects on the ability of levitation. Based on these elements, the suitable coefficients(e.g. structural coefficients 、excitation functions as well as distinct phases) were defined to make the best smoothness during transportation.Eventually, the acoustic standing wave levitation and transportation devices were set up. Multiple layers of polystyrene particles were levitation in the acoustic standing wave, in addition, the levitation positions fits well with the simulation results. Besides, the focusing effect made by concave spherical surface was verified. Finally, trigonometric excitation functions with phase of p/ 2 was proved to get the smoothest transportation.The results from the experiments showed the same trend as it in the simulations.