Research On Ultrasonic Standing Wave Levitation And Directional Transportation

Ultrasonic standing wave levitation is an important means to realize non-contact and container-free treatment.Compared with other non-contact processing methods,ultrasonic standing wave levitation technology can be applied in manufacturing,biochemical trace analysis,electrical equipment,droplet dynamics and other fields owing to its obvious advantages such as unlimited material and good levitation stability.The ultrasonic standing wave levitation technology is provided with broad prospects.Therefore,it is of great theoretical significance and practical value to study the methods of ultrasonic standing wave levitation and directional transportation.Aiming at the challenges of imperfect levitation transportation mechanism and complex space transportation,systematic and in-depth research on the main influencing factors of standing wave levitation and directional transportation process is studied.The main research work of the thesis is as follows:The experimental research and mechanism analysis of ultrasonic standing wave levitation.In order to realize the stable levitation of polystyrene spheres in air,the formation principle of ultrasonic standing wave sound field is described.The parametric levitation model is established based on COMSOL Multiphysics to optimize the structural parameters of sound field.Based on the optimized parameters,the experimental system is built to conduct research,and the simulation analysis of the levitation sound field is carried out.It is found that when the distance between the radiating end and the reflecting surface is adjusted to an integer multiple of half wavelength,the peak sound pressure appears.The amplitude of sound pressure increases first and then decreases with the increase of the reflector size.When the resonator length is 35 mm,a maximum of eight layers of polystyrene spheres can be levitated stably.Placing several spheres on the same node,the spheres are gathered and levitated under the action of elastic restoring force.The experimental research and mechanism analysis of transversal transportation in ultrasonic standing wave levitation.In order to realize the long distance transversal transportation of polystyrene spheres,the propellant force is derived based on the superimposed sound field,and the horizontal acceleration of the polystyrene spheres is used to characterize the transversal transportation stability.The control methods of amplitude modulation and phase modulation are used to realize the horizontal one-way,reciprocating and multi-layer transportation of the spheres.The results show that both of the two control methods have good repeatability and displacement symmetry,but the phase modulation method has better stability during the spheres transportation.Based on the 1×4 transducer array,the sphere is transported 51.8mm laterally,which verifies the feasibility of phase modulation to realize long distance transversal transportation.The experimental research and mechanism analysis of longitudinal transportation in ultrasonic standing wave levitation.In order to realize the long distance longitudinal transportation of polystyrene balls,the control methods of frequency modulation and phase modulation are used.Based on the opposing sound field,the conditions for the formation of standing wave sound field are deduced,and the experimental system is built to investigate the influence of different phase deviations on the distance and stability of longitudinal transportation.The dynamic sound field of longitudinal transportation realized by phase modulation is simulated by COMSOL.The results show that the smooth longitudinal transportation over the long distance of the spheres can be realized by adjusting the phase deviation to an integer multiple of half of pi.The phase devitation is set as pi,the longitudinal transportation distance is 16.652 mm.The experimental research and mechanism analysis of space transportation in ultrasonic standing wave levitation.The basic principle of space transportation of ultrasonic standing wave levitation is described in this paper.The linear transducer array based on parallel contra type for experiments is built.The dynamic sound field of space transport is simulated by COMSOL.The results show that the threedimensional space transportation of the spheres can be realized by properly arranging the transducer array and exciting each array element with proper phase modulation signal.